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4136 lines
134 KiB
Plaintext
<!doctype linuxdoc system>
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<article>
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<title>ca65 Users Guide
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<author>Ullrich von Bassewitz, <htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">
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<date>2000-07-19, 2000-11-29, 2001-10-02, 2005-09-08
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<abstract>
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ca65 is a powerful macro assembler for the 6502, 65C02 and 65816 CPUs. It is
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used as a companion assembler for the cc65 crosscompiler, but it may also be
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used as a standalone product.
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</abstract>
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<!-- Table of contents -->
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<toc>
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<!-- Begin the document -->
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<sect>Overview<p>
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ca65 is a replacement for the ra65 assembler that was part of the cc65 C
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compiler, originally developed by John R. Dunning. I had some problems with
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ra65 and the copyright does not permit some things which I wanted to be
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possible, so I decided to write a completely new assembler/linker/archiver
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suite for the cc65 compiler. ca65 is part of this suite.
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Some parts of the assembler (code generation and some routines for symbol
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table handling) are taken from an older crossassembler named a816 written
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by me a long time ago.
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<sect1>Design criteria<p>
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Here's a list of the design criteria, that I considered important for the
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development:
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<itemize>
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<item> The assembler must support macros. Macros are not essential, but they
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make some things easier, especially when you use the assembler in the
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backend of a compiler.
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<item> The assembler must support the newer 65C02 and 65816 CPUs. I have been
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thinking about a 65816 backend for the C compiler, and even my old
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a816 assembler had support for these CPUs, so this wasn't really a
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problem.
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<item> The assembler must produce relocatable code. This is necessary for the
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compiler support, and it is more convenient.
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<item> Conditional assembly must be supported. This is a must for bigger
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projects written in assembler (like Elite128).
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<item> The assembler must support segments, and it must support more than
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three segments (this is the count, most other assemblers support).
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Having more than one code segments helps developing code for systems
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with a divided ROM area (like the C64).
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<item> The linker must be able to resolve arbitrary expressions. It should
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be able to get things like
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<tscreen><verb>
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.import S1, S2
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.export Special
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Special = 2*S1 + S2/7
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</verb></tscreen>
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right.
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<item> True lexical nesting for symbols. This is very convenient for larger
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assembly projects.
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<item> "Cheap" local symbols without lexical nesting for those quick, late
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night hacks.
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<item> I liked the idea of "options" as Anre Fachats .o65 format has it, so I
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introduced the concept into the object file format use by the new cc65
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binutils.
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<item> The assembler will be a one pass assembler. There was no real need for
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this decision, but I've written several multipass assemblers, and it
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started to get boring. A one pass assembler needs much more elaborated
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data structures, and because of that it's much more fun:-)
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<item> Non-GPLed code that may be used in any project without restrictions or
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fear of "GPL infecting" other code.
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</itemize>
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<p>
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<sect>Usage<p>
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<sect1>Command line option overview<p>
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The assembler accepts the following options:
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<tscreen><verb>
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---------------------------------------------------------------------------
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Usage: ca65 [options] file
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Short options:
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-D name[=value] Define a symbol
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-I dir Set an include directory search path
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-U Mark unresolved symbols as import
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-V Print the assembler version
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-W n Set warning level n
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-g Add debug info to object file
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-h Help (this text)
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-i Ignore case of symbols
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-l Create a listing if assembly was ok
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-mm model Set the memory model
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-o name Name the output file
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-s Enable smart mode
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-t sys Set the target system
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-v Increase verbosity
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Long options:
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--auto-import Mark unresolved symbols as import
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--cpu type Set cpu type
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--debug-info Add debug info to object file
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--feature name Set an emulation feature
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--help Help (this text)
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--ignore-case Ignore case of symbols
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--include-dir dir Set an include directory search path
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--listing Create a listing if assembly was ok
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--list-bytes n Maximum number of bytes per listing line
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--macpack-dir dir Set a macro package directory
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--memory-model model Set the memory model
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--pagelength n Set the page length for the listing
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--smart Enable smart mode
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--target sys Set the target system
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--verbose Increase verbosity
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--version Print the assembler version
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---------------------------------------------------------------------------
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</verb></tscreen>
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<sect1>Command line options in detail<p>
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Here is a description of all the command line options:
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<descrip>
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<label id="option--cpu">
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<tag><tt>--cpu type</tt></tag>
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Set the default for the CPU type. The option takes a parameter, which
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may be one of
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6502, 65SC02, 65C02, 65816, sunplus, sweet16, HuC6280
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The sunplus cpu is not available in the freeware version, because the
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instruction set is "proprietary and confidential".
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<label id="option--feature">
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<tag><tt>--feature name</tt></tag>
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Enable an emulation feature. This is identical as using <tt/.FEATURE/
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in the source with two exceptions: Feature names must be lower case, and
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each feature must be specified by using an extra <tt/--feature/ option,
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comma separated lists are not allowed.
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See the discussion of the <tt><ref id=".FEATURE" name=".FEATURE"></tt>
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command for a list of emulation features.
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<label id="option-g">
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<tag><tt>-g, --debug-info</tt></tag>
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When this option (or the equivalent control command <tt/.DEBUGINFO/) is
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used, the assembler will add a section to the object file that contains
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all symbols (including local ones) together with the symbol values and
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source file positions. The linker will put these additional symbols into
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the VICE label file, so even local symbols can be seen in the VICE
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monitor.
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<tag><tt>-h, --help</tt></tag>
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Print the short option summary shown above.
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<tag><tt>-i, --ignore-case</tt></tag>
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This option makes the assembler case insensitive on identifiers and labels.
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This option will override the default, but may itself be overridden by the
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<tt><ref id=".CASE" name=".CASE"></tt> control command.
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<tag><tt>-l, --listing</tt></tag>
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Generate an assembler listing. The listing file will always have the
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name of the main input file with the extension replaced by ".lst". This
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may change in future versions.
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<tag><tt>--list-bytes n</tt></tag>
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Set the maximum number of bytes printed in the listing for one line of
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input. See the <tt><ref id=".LISTBYTES" name=".LISTBYTES"></tt> directive
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for more information. The value zero can be used to encode an unlimited
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number of printed bytes.
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<tag><tt>--macpack-dir dir</tt></tag>
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This options allows to specify a directory containing macro files that are
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used instead of the builtin images when a <tt><ref id=".MACPACK"
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name=".MACPACK"></tt> directive is encountered. If <tt>--macpack-dir</tt>
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was specified, a <tt>.mac</tt> extension is added to the package name and
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the resulting file is loaded from the given directory. This is most useful
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when debugging the builtin macro packages.
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<tag><tt>-mm model, --memory-model model</tt></tag>
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Define the default memory model. Possible model specifiers are near, far and
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huge.
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<tag><tt>-o name</tt></tag>
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The default output name is the name of the input file with the extension
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replaced by ".o". If you don't like that, you may give another name with
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the -o option. The output file will be placed in the same directory as
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the source file, or, if -o is given, the full path in this name is used.
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<tag><tt>--pagelength n</tt></tag>
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sets the length of a listing page in lines. See the <tt><ref
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id=".PAGELENGTH" name=".PAGELENGTH"></tt> directive for more information.
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<tag><tt>-s, --smart-mode</tt></tag>
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In smart mode (enabled by -s or the <tt><ref id=".SMART" name=".SMART"></tt>
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pseudo instruction) the assembler will track usage of the <tt/REP/ and
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<tt/SEP/ instructions in 65816 mode and update the operand sizes
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accordingly. If the operand of such an instruction cannot be evaluated by
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the assembler (for example, because the operand is an imported symbol), a
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warning is issued.
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Beware: Since the assembler cannot trace the execution flow this may
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lead to false results in some cases. If in doubt, use the .ixx and .axx
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instructions to tell the assembler about the current settings. Smart
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mode is off by default.
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<label id="option-t">
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<tag><tt>-t sys, --target sys</tt></tag>
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Set the target system. This will enable translation of character strings
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and character constants into the character set of the target platform.
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The default for the target system is "none", which means that no translation
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will take place. The assembler supports the same target systems as the
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compiler, see there for a list.
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<tag><tt>-v, --verbose</tt></tag>
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Increase the assembler verbosity. Usually only needed for debugging
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purposes. You may use this option more than one time for even more
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verbose output.
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<tag><tt>-D</tt></tag>
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This option allows you to define symbols on the command line. Without a
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value, the symbol is defined with the value zero. When giving a value,
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you may use the '$' prefix for hexadecimal symbols. Please note
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that for some operating systems, '$' has a special meaning, so
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you may have to quote the expression.
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<tag><tt>-I dir, --include-dir dir</tt></tag>
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Name a directory which is searched for include files. The option may be
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used more than once to specify more than one directory to search. The
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current directory is always searched first before considering any
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additional directories.
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<tag><tt>-U, --auto-import</tt></tag>
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Mark symbols that are not defined in the sources as imported symbols. This
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should be used with care since it delays error messages about typos and such
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until the linker is run. The compiler uses the equivalent of this switch
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(<tt><ref id=".AUTOIMPORT" name=".AUTOIMPORT"></tt>) to enable auto imported
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symbols for the runtime library. However, the compiler is supposed to
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generate code that runs through the assembler without problems, something
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which is not always true for assembler programmers.
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<tag><tt>-V, --version</tt></tag>
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Print the version number of the assembler. If you send any suggestions
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or bugfixes, please include the version number.
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<label id="option-W">
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<tag><tt>-Wn</tt></tag>
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Set the warning level for the assembler. Using -W2 the assembler will
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even warn about such things like unused imported symbols. The default
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warning level is 1, and it would probably be silly to set it to
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something lower.
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</descrip>
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<p>
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<sect>Input format<p>
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<sect1>Assembler syntax<p>
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The assembler accepts the standard 6502/65816 assembler syntax. One line may
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contain a label (which is identified by a colon), and, in addition to the
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label, an assembler mnemonic, a macro, or a control command (see section <ref
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id="control-commands" name="Control Commands"> for supported control
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commands). Alternatively, the line may contain a symbol definition using
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the '=' token. Everything after a semicolon is handled as a comment (that is,
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it is ignored).
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Here are some examples for valid input lines:
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<tscreen><verb>
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Label: ; A label and a comment
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lda #$20 ; A 6502 instruction plus comment
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L1: ldx #$20 ; Same with label
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L2: .byte "Hello world" ; Label plus control command
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mymac $20 ; Macro expansion
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MySym = 3*L1 ; Symbol definition
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MaSym = Label ; Another symbol
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</verb></tscreen>
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The assembler accepts
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<itemize>
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<item>all valid 6502 mnemonics when in 6502 mode (the default or after the
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<tt><ref id=".P02" name=".P02"></tt> command was given).
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<item>all valid 6502 mnemonics plus a set of illegal instructions when in
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<ref id="6502X-mode" name="6502X mode">.
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<item>all valid 65SC02 mnemonics when in 65SC02 mode (after the
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<tt><ref id=".PSC02" name=".PSC02"></tt> command was given).
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<item>all valid 65C02 mnemonics when in 65C02 mode (after the
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<tt><ref id=".PC02" name=".PC02"></tt> command was given).
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<item>all valid 65618 mnemonics when in 65816 mode (after the
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<tt><ref id=".P816" name=".P816"></tt> command was given).
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<item>all valid SunPlus mnemonics when in SunPlus mode (after the
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<tt><ref id=".SUNPLUS" name=".SUNPLUS"></tt> command was given).
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</itemize>
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<sect1>65816 mode<p>
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In 65816 mode several aliases are accepted in addition to the official
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mnemonics:
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<tscreen><verb>
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BGE is an alias for BCS
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BLT is an alias for BCC
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CPA is an alias for CMP
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DEA is an alias for DEC A
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INA is an alias for INC A
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SWA is an alias for XBA
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TAD is an alias for TCD
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TAS is an alias for TCS
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TDA is an alias for TDC
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TSA is an alias for TSC
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</verb></tscreen>
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<sect1>6502X mode<label id="6502X-mode"><p>
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6502X mode is an extension to the normal 6502 mode. In this mode, several
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mnemonics for illegal instructions of the NMOS 6502 CPUs are accepted. Since
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these instructions are illegal, there are no official mnemonics for them. The
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unofficial ones are taken from <htmlurl
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url="http://oxyron.net/graham/opcodes02.html"
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name="http://oxyron.net/graham/opcodes02.html">. Please note that only the
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ones marked as "stable" are supported. The following table uses information
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from the mentioned web page, for more information, see there.
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<itemize>
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<item><tt>ALR: A:=(A and #{imm})*2;</tt>
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<item><tt>ANC: A:=A and #{imm};</tt> Generates opcode $0B.
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<item><tt>ARR: A:=(A and #{imm})/2;</tt>
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<item><tt>AXS: X:=A and X-#{imm};</tt>
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<item><tt>DCP: {adr}:={adr}-1; A-{adr};</tt>
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<item><tt>ISC: {adr}:={adr}+1; A:=A-{adr};</tt>
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<item><tt>LAS: A,X,S:={adr} and S;</tt>
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<item><tt>LAX: A,X:={adr};</tt>
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<item><tt>RLA: {adr}:={adr}rol; A:=A and {adr};</tt>
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<item><tt>RRA: {adr}:={adr}ror; A:=A adc {adr};</tt>
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<item><tt>SAX: {adr}:=A and X;</tt>
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<item><tt>SLO: {adr}:={adr}*2; A:=A or {adr};</tt>
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<item><tt>SRE: {adr}:={adr}/2; A:=A xor {adr};</tt>
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</itemize>
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<sect1>sweet16 mode<label id="sweet16-mode"><p>
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SWEET 16 is an interpreter for a pseudo 16 bit CPU written by Steve Wozniak
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for the Apple ][ machines. It is available in the Apple ][ ROM. ca65 can
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generate code for this pseudo CPU when switched into sweet16 mode. The
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following is special in sweet16 mode:
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<itemize>
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<item>The '@' character denotes indirect addressing and is no longer available
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for cheap local labels. If you need cheap local labels, you will have to
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switch to another lead character using the <tt/<ref id=".LOCALCHAR"
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name=".LOCALCHAR">/ command.
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<item>Registers are specified using <tt/R0/ .. <tt/R15/. In sweet16 mode,
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these identifiers are reserved words.
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</itemize>
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Please note that the assembler does neither supply the interpreter needed for
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SWEET 16 code, nor the zero page locations needed for the SWEET 16 registers,
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nor does it call the interpreter. All this must be done by your program. Apple
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][ programmers do probably know how to use sweet16 mode.
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For more information about SWEET 16, see
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<htmlurl url="http://www.6502.org/source/interpreters/sweet16.htm"
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name="http://www.6502.org/source/interpreters/sweet16.htm">.
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<sect1>Number format<p>
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For literal values, the assembler accepts the widely used number formats: A
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preceding '$' or a trailing 'h' denotes a hex value, a preceding '%'
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denotes a binary value, and a bare number is interpreted as a decimal. There
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are currently no octal values and no floats.
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<sect1>Conditional assembly<p>
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Please note that when using the conditional directives (<tt/.IF/ and friends),
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the input must consist of valid assembler tokens, even in <tt/.IF/ branches
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that are not assembled. The reason for this behaviour is that the assembler
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must still be able to detect the ending tokens (like <tt/.ENDIF/), so
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conversion of the input stream into tokens still takes place. As a consequence
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conditional assembly directives may <bf/not/ be used to prevent normal text
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(used as a comment or similar) from being assembled. <p>
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<sect>Expressions<p>
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<sect1>Expression evaluation<p>
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All expressions are evaluated with (at least) 32 bit precision. An
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expression may contain constant values and any combination of internal and
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external symbols. Expressions that cannot be evaluated at assembly time
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are stored inside the object file for evaluation by the linker.
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Expressions referencing imported symbols must always be evaluated by the
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linker.
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<sect1>Size of an expression result<p>
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Sometimes, the assembler must know about the size of the value that is the
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result of an expression. This is usually the case, if a decision has to be
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made, to generate a zero page or an absolute memory references. In this
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case, the assembler has to make some assumptions about the result of an
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expression:
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<itemize>
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<item> If the result of an expression is constant, the actual value is
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checked to see if it's a byte sized expression or not.
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<item> If the expression is explicitly casted to a byte sized expression by
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one of the '>', '<' or '^' operators, it is a byte expression.
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<item> If this is not the case, and the expression contains a symbol,
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explicitly declared as zero page symbol (by one of the .importzp or
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.exportzp instructions), then the whole expression is assumed to be
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byte sized.
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<item> If the expression contains symbols that are not defined, and these
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symbols are local symbols, the enclosing scopes are searched for a
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symbol with the same name. If one exists and this symbol is defined,
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it's attributes are used to determine the result size.
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<item> In all other cases the expression is assumed to be word sized.
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</itemize>
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Note: If the assembler is not able to evaluate the expression at assembly
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time, the linker will evaluate it and check for range errors as soon as
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the result is known.
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<sect1>Boolean expressions<p>
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In the context of a boolean expression, any non zero value is evaluated as
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true, any other value to false. The result of a boolean expression is 1 if
|
|
it's true, and zero if it's false. There are boolean operators with extreme
|
|
low precedence with version 2.x (where x > 0). The <tt/.AND/ and <tt/.OR/
|
|
operators are shortcut operators. That is, if the result of the expression is
|
|
already known, after evaluating the left hand side, the right hand side is
|
|
not evaluated.
|
|
|
|
|
|
<sect1>Constant expressions<p>
|
|
|
|
Sometimes an expression must evaluate to a constant without looking at any
|
|
further input. One such example is the <tt/<ref id=".IF" name=".IF">/ command
|
|
that decides if parts of the code are assembled or not. An expression used in
|
|
the <tt/.IF/ command cannot reference a symbol defined later, because the
|
|
decision about the <tt/.IF/ must be made at the point when it is read. If the
|
|
expression used in such a context contains only constant numerical values,
|
|
there is no problem. When unresolvable symbols are involved it may get harder
|
|
for the assembler to determine if the expression is actually constant, and it
|
|
is even possible to create expressions that aren't recognized as constant.
|
|
Simplifying the expressions will often help.
|
|
|
|
In cases where the result of the expression is not needed immediately, the
|
|
assembler will delay evaluation until all input is read, at which point all
|
|
symbols are known. So using arbitrary complex constant expressions is no
|
|
problem in most cases.
|
|
|
|
|
|
|
|
<sect1>Available operators<label id="operators"><p>
|
|
|
|
<table>
|
|
<tabular ca="clc">
|
|
<bf/Operator/| <bf/Description/| <bf/Precedence/@<hline>
|
|
| Built-in string functions| 0@
|
|
||~@
|
|
| Built-in pseudo-variables| 1@
|
|
| Built-in pseudo-functions| 1@
|
|
+| Unary positive| 1@
|
|
-| Unary negative| 1@
|
|
˜<newline>
|
|
.BITNOT| Unary bitwise not| 1@
|
|
<<newline>
|
|
.LOBYTE| Unary low-byte operator| 1@
|
|
><newline>
|
|
.HIBYTE| Unary high-byte operator| 1@
|
|
^<newline>
|
|
.BANKBYTE| Unary bank-byte operator| 1@
|
|
||~@
|
|
*| Multiplication| 2@
|
|
/| Division| 2@
|
|
.MOD| Modulo operator| 2@
|
|
&<newline>
|
|
.BITAND| Bitwise and| 2@
|
|
^<newline>
|
|
.BITXOR| Binary bitwise xor| 2@
|
|
<<<newline>
|
|
.SHL| Shift-left operator| 2@
|
|
>><newline>
|
|
.SHR| Shift-right operator| 2@
|
|
||~@
|
|
+| Binary addition| 3@
|
|
-| Binary subtraction| 3@
|
|
|<newline>
|
|
.BITOR| Bitwise or| 3@
|
|
||~@
|
|
= | Compare operator (equal)| 4@
|
|
<>| Compare operator (not equal)| 4@
|
|
<| Compare operator (less)| 4@
|
|
>| Compare operator (greater)| 4@
|
|
<=| Compare operator (less or equal)| 4@
|
|
>=| Compare operator (greater or equal)| 4@
|
|
||~@
|
|
&&<newline>
|
|
.AND| Boolean and| 5@
|
|
.XOR| Boolean xor| 5@
|
|
||~@
|
|
||<newline>
|
|
.OR| Boolean or| 6@
|
|
||~@
|
|
!<newline>
|
|
.NOT| Boolean not| 7@<hline>
|
|
</tabular>
|
|
<caption>Available operators, sorted by precedence
|
|
</table>
|
|
|
|
To force a specific order of evaluation, parentheses may be used, as usual.
|
|
|
|
|
|
|
|
<sect>Symbols and labels<p>
|
|
|
|
The assembler allows you to use symbols instead of naked values to make
|
|
the source more readable. There are a lot of different ways to define and
|
|
use symbols and labels, giving a lot of flexibility.
|
|
|
|
|
|
<sect1>Numeric constants<p>
|
|
|
|
Numeric constants are defined using the equal sign or the label assignment
|
|
operator. After doing
|
|
|
|
<tscreen><verb>
|
|
two = 2
|
|
</verb></tscreen>
|
|
|
|
may use the symbol "two" in every place where a number is expected, and it is
|
|
evaluated to the value 2 in this context. The label assignment operator causes
|
|
the same, but causes the symbol to be marked as a label, which may cause a
|
|
different handling in the debugger:
|
|
|
|
<tscreen><verb>
|
|
io := $d000
|
|
</verb></tscreen>
|
|
|
|
The right side can of course be an expression:
|
|
|
|
<tscreen><verb>
|
|
four = two * two
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1>Standard labels<p>
|
|
|
|
A label is defined by writing the name of the label at the start of the line
|
|
(before any instruction mnemonic, macro or pseudo directive), followed by a
|
|
colon. This will declare a symbol with the given name and the value of the
|
|
current program counter.
|
|
|
|
|
|
<sect1>Local labels and symbols<p>
|
|
|
|
Using the <tt><ref id=".PROC" name=".PROC"></tt> directive, it is possible to
|
|
create regions of code where the names of labels and symbols are local to this
|
|
region. They are not known outside of this region and cannot be accessed from
|
|
there. Such regions may be nested like PROCEDUREs in Pascal.
|
|
|
|
See the description of the <tt><ref id=".PROC" name=".PROC"></tt>
|
|
directive for more information.
|
|
|
|
|
|
<sect1>Cheap local labels<p>
|
|
|
|
Cheap local labels are defined like standard labels, but the name of the
|
|
label must begin with a special symbol (usually '@', but this can be
|
|
changed by the <tt><ref id=".LOCALCHAR" name=".LOCALCHAR"></tt>
|
|
directive).
|
|
|
|
Cheap local labels are visible only between two non cheap labels. As soon as a
|
|
standard symbol is encountered (this may also be a local symbol if inside a
|
|
region defined with the <tt><ref id=".PROC" name=".PROC"></tt> directive), the
|
|
cheap local symbol goes out of scope.
|
|
|
|
You may use cheap local labels as an easy way to reuse common label
|
|
names like "Loop". Here is an example:
|
|
|
|
<tscreen><verb>
|
|
Clear: lda #$00 ; Global label
|
|
ldy #$20
|
|
@Loop: sta Mem,y ; Local label
|
|
dey
|
|
bne @Loop ; Ok
|
|
rts
|
|
Sub: ... ; New global label
|
|
bne @Loop ; ERROR: Unknown identifier!
|
|
</verb></tscreen>
|
|
|
|
<sect1>Unnamed labels<p>
|
|
|
|
If you really want to write messy code, there are also unnamed labels. These
|
|
labels do not have a name (you guessed that already, didn't you?). A colon is
|
|
used to mark the absence of the name.
|
|
|
|
Unnamed labels may be accessed by using the colon plus several minus or plus
|
|
characters as a label designator. Using the '-' characters will create a back
|
|
reference (use the n'th label backwards), using '+' will create a forward
|
|
reference (use the n'th label in forward direction). An example will help to
|
|
understand this:
|
|
|
|
<tscreen><verb>
|
|
: lda (ptr1),y ; #1
|
|
cmp (ptr2),y
|
|
bne :+ ; -> #2
|
|
tax
|
|
beq :+++ ; -> #4
|
|
iny
|
|
bne :- ; -> #1
|
|
inc ptr1+1
|
|
inc ptr2+1
|
|
bne :- ; -> #1
|
|
|
|
: bcs :+ ; #2 -> #3
|
|
ldx #$FF
|
|
rts
|
|
|
|
: ldx #$01 ; #3
|
|
: rts ; #4
|
|
</verb></tscreen>
|
|
|
|
As you can see from the example, unnamed labels will make even short
|
|
sections of code hard to understand, because you have to count labels
|
|
to find branch targets (this is the reason why I for my part do
|
|
prefer the "cheap" local labels). Nevertheless, unnamed labels are
|
|
convenient in some situations, so it's your decision.
|
|
|
|
|
|
<sect1>Using macros to define labels and constants<p>
|
|
|
|
While there are drawbacks with this approach, it may be handy in some
|
|
situations. Using <tt><ref id=".DEFINE" name=".DEFINE"></tt>, it is
|
|
possible to define symbols or constants that may be used elsewhere. Since
|
|
the macro facility works on a very low level, there is no scoping. On the
|
|
other side, you may also define string constants this way (this is not
|
|
possible with the other symbol types).
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.DEFINE two 2
|
|
.DEFINE version "SOS V2.3"
|
|
|
|
four = two * two ; Ok
|
|
.byte version ; Ok
|
|
|
|
.PROC ; Start local scope
|
|
two = 3 ; Will give "2 = 3" - invalid!
|
|
.ENDPROC
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1>Symbols and <tt>.DEBUGINFO</tt><p>
|
|
|
|
If <tt><ref id=".DEBUGINFO" name=".DEBUGINFO"></tt> is enabled (or <ref
|
|
id="option-g" name="-g"> is given on the command line), global, local and
|
|
cheap local labels are written to the object file and will be available in the
|
|
symbol file via the linker. Unnamed labels are not written to the object file,
|
|
because they don't have a name which would allow to access them.
|
|
|
|
|
|
|
|
<sect>Scopes<label id="scopes"><p>
|
|
|
|
ca65 implements several sorts of scopes for symbols.
|
|
|
|
<sect1>Global scope<p>
|
|
|
|
All (non cheap local) symbols that are declared outside of any nested scopes
|
|
are in global scope.
|
|
|
|
|
|
<sect1>Cheap locals<p>
|
|
|
|
A special scope is the scope for cheap local symbols. It lasts from one non
|
|
local symbol to the next one, without any provisions made by the programmer.
|
|
All other scopes differ in usage but use the same concept internally.
|
|
|
|
|
|
<sect1>Generic nested scopes<p>
|
|
|
|
A nested scoped for generic use is started with <tt/<ref id=".SCOPE"
|
|
name=".SCOPE">/ and closed with <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/.
|
|
The scope can have a name, in which case it is accessible from the outside by
|
|
using <ref id="scopesyntax" name="explicit scopes">. If the scope does not
|
|
have a name, all symbols created within the scope are local to the scope, and
|
|
aren't accessible from the outside.
|
|
|
|
A nested scope can access symbols from the local or from enclosing scopes by
|
|
name without using explicit scope names. In some cases there may be
|
|
ambiguities, for example if there is a reference to a local symbol that is not
|
|
yet defined, but a symbol with the same name exists in outer scopes:
|
|
|
|
<tscreen><verb>
|
|
.scope outer
|
|
foo = 2
|
|
.scope inner
|
|
lda #foo
|
|
foo = 3
|
|
.endscope
|
|
.endscope
|
|
</verb></tscreen>
|
|
|
|
In the example above, the <tt/lda/ instruction will load the value 3 into the
|
|
accumulator, because <tt/foo/ is redefined in the scope. However:
|
|
|
|
<tscreen><verb>
|
|
.scope outer
|
|
foo = $1234
|
|
.scope inner
|
|
lda foo,x
|
|
foo = $12
|
|
.endscope
|
|
.endscope
|
|
</verb></tscreen>
|
|
|
|
Here, <tt/lda/ will still load from <tt/$12,x/, but since it is unknown to the
|
|
assembler that <tt/foo/ is a zeropage symbol when translating the instruction,
|
|
absolute mode is used instead. In fact, the assembler will not use absolute
|
|
mode by default, but it will search through the enclosing scopes for a symbol
|
|
with the given name. If one is found, the address size of this symbol is used.
|
|
This may lead to errors:
|
|
|
|
<tscreen><verb>
|
|
.scope outer
|
|
foo = $12
|
|
.scope inner
|
|
lda foo,x
|
|
foo = $1234
|
|
.endscope
|
|
.endscope
|
|
</verb></tscreen>
|
|
|
|
In this case, when the assembler sees the symbol <tt/foo/ in the <tt/lda/
|
|
instruction, it will search for an already defined symbol <tt/foo/. It will
|
|
find <tt/foo/ in scope <tt/outer/, and a close look reveals that it is a
|
|
zeropage symbol. So the assembler will use zeropage addressing mode. If
|
|
<tt/foo/ is redefined later in scope <tt/inner/, the assembler tries to change
|
|
the address in the <tt/lda/ instruction already translated, but since the new
|
|
value needs absolute addressing mode, this fails, and an error message "Range
|
|
error" is output.
|
|
|
|
Of course the most simple solution for the problem is to move the definition
|
|
of <tt/foo/ in scope <tt/inner/ upwards, so it precedes its use. There may be
|
|
rare cases when this cannot be done. In these cases, you can use one of the
|
|
address size override operators:
|
|
|
|
<tscreen><verb>
|
|
.scope outer
|
|
foo = $12
|
|
.scope inner
|
|
lda a:foo,x
|
|
foo = $1234
|
|
.endscope
|
|
.endscope
|
|
</verb></tscreen>
|
|
|
|
This will cause the <tt/lda/ instruction to be translated using absolute
|
|
addressing mode, which means changing the symbol reference later does not
|
|
cause any errors.
|
|
|
|
|
|
<sect1>Nested procedures<p>
|
|
|
|
A nested procedure is created by use of <tt/<ref id=".PROC" name=".PROC">/. It
|
|
differs from a <tt/<ref id=".SCOPE" name=".SCOPE">/ in that it must have a
|
|
name, and a it will introduce a symbol with this name in the enclosing scope.
|
|
So
|
|
|
|
<tscreen><verb>
|
|
.proc foo
|
|
...
|
|
.endscope
|
|
</verb></tscreen>
|
|
|
|
is actually the same as
|
|
|
|
<tscreen><verb>
|
|
foo:
|
|
.scope foo
|
|
...
|
|
.endscope
|
|
</verb></tscreen>
|
|
|
|
This is the reason why a procedure must have a name. If you want a scope
|
|
without a name, use <tt/<ref id=".SCOPE" name=".SCOPE">/.
|
|
|
|
<bf/Note:/ As you can see from the example above, scopes and symbols live in
|
|
different namespaces. There can be a symbol named <tt/foo/ and a scope named
|
|
<tt/foo/ without any conflicts (but see the section titled <ref
|
|
id="scopesearch" name=""Scope search order"">).
|
|
|
|
|
|
<sect1>Structs, unions and enums<p>
|
|
|
|
Structs, unions and enums are explained in a <ref id="structs" name="separate
|
|
section">, I do only cover them here, because if they are declared with a
|
|
name, they open a nested scope, similar to <tt/<ref id=".SCOPE"
|
|
name=".SCOPE">/. However, when no name is specified, the behaviour is
|
|
different: In this case, no new scope will be opened, symbols declared within
|
|
a struct, union, or enum declaration will then be added to the enclosing scope
|
|
instead.
|
|
|
|
|
|
<sect1>Explicit scope specification<label id="scopesyntax"><p>
|
|
|
|
Accessing symbols from other scopes is possible by using an explicit scope
|
|
specification, provided that the scope where the symbol lives in has a name.
|
|
The namespace token (<tt/::/) is used to access other scopes:
|
|
|
|
<tscreen><verb>
|
|
.scope foo
|
|
bar: .word 0
|
|
.endscope
|
|
|
|
...
|
|
lda foo::bar ; Access foo in scope bar
|
|
</verb></tscreen>
|
|
|
|
The only way to deny access to a scope from the outside is to declare a scope
|
|
without a name (using the <tt/<ref id=".SCOPE" name=".SCOPE">/ command).
|
|
|
|
A special syntax is used to specify the global scope: If a symbol or scope is
|
|
preceded by the namespace token, the global scope is searched:
|
|
|
|
<tscreen><verb>
|
|
bar = 3
|
|
|
|
.scope foo
|
|
bar = 2
|
|
lda #::bar ; Access the global bar (which is 3)
|
|
.endscope
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1>Scope search order<label id="scopesearch"><p>
|
|
|
|
The assembler searches for a scope in a similar way as for a symbol. First, it
|
|
looks in the current scope, and then it walks up the enclosing scopes until
|
|
the scope is found.
|
|
|
|
However, one important thing to note when using explicit scope syntax is, that
|
|
a symbol may be accessed before it is defined, but a scope may <bf/not/ be
|
|
used without a preceding definition. This means that in the following
|
|
example:
|
|
|
|
<tscreen><verb>
|
|
.scope foo
|
|
bar = 3
|
|
.endscope
|
|
|
|
.scope outer
|
|
lda #foo::bar ; Will load 3, not 2!
|
|
.scope foo
|
|
bar = 2
|
|
.endscope
|
|
.endscope
|
|
</verb></tscreen>
|
|
|
|
the reference to the scope <tt/foo/ will use the global scope, and not the
|
|
local one, because the local one is not visible at the point where it is
|
|
referenced.
|
|
|
|
Things get more complex if a complete chain of scopes is specified:
|
|
|
|
<tscreen><verb>
|
|
.scope foo
|
|
.scope outer
|
|
.scope inner
|
|
bar = 1
|
|
.endscope
|
|
.endscope
|
|
.scope another
|
|
.scope nested
|
|
lda #outer::inner::bar ; 1
|
|
.endscope
|
|
.endscope
|
|
.endscope
|
|
|
|
.scope outer
|
|
.scope inner
|
|
bar = 2
|
|
.endscope
|
|
.endscope
|
|
</verb></tscreen>
|
|
|
|
When <tt/outer::inner::bar/ is referenced in the <tt/lda/ instruction, the
|
|
assembler will first search in the local scope for a scope named <tt/outer/.
|
|
Since none is found, the enclosing scope (<tt/another/) is checked. There is
|
|
still no scope named <tt/outer/, so scope <tt/foo/ is checked, and finally
|
|
scope <tt/outer/ is found. Within this scope, <tt/inner/ is searched, and in
|
|
this scope, the assembler looks for a symbol named <tt/bar/.
|
|
|
|
Please note that once the anchor scope is found, all following scopes
|
|
(<tt/inner/ in this case) are expected to be found exactly in this scope. The
|
|
assembler will search the scope tree only for the first scope (if it is not
|
|
anchored in the root scope). Starting from there on, there is no flexibility,
|
|
so if the scope named <tt/outer/ found by the assembler does not contain a
|
|
scope named <tt/inner/, this would be an error, even if such a pair does exist
|
|
(one level up in global scope).
|
|
|
|
Ambiguities that may be introduced by this search algorithm may be removed by
|
|
anchoring the scope specification in the global scope. In the example above,
|
|
if you want to access the "other" symbol <tt/bar/, you would have to write:
|
|
|
|
<tscreen><verb>
|
|
.scope foo
|
|
.scope outer
|
|
.scope inner
|
|
bar = 1
|
|
.endscope
|
|
.endscope
|
|
.scope another
|
|
.scope nested
|
|
lda #::outer::inner::bar ; 2
|
|
.endscope
|
|
.endscope
|
|
.endscope
|
|
|
|
.scope outer
|
|
.scope inner
|
|
bar = 2
|
|
.endscope
|
|
.endscope
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect>Address sizes and memory models<label id="address-sizes"><p>
|
|
|
|
<sect1>Address sizes<p>
|
|
|
|
ca65 assigns each segment and each symbol an address size. This is true, even
|
|
if the symbol is not used as an address. You may also think of a value range
|
|
of the symbol instead of an address size.
|
|
|
|
Possible address sizes are:
|
|
|
|
<itemize>
|
|
<item>Zeropage or direct (8 bits)
|
|
<item>Absolute (16 bits)
|
|
<item>Far (24 bits)
|
|
<item>Long (32 bits)
|
|
</itemize>
|
|
|
|
Since the assembler uses default address sizes for the segments and symbols,
|
|
it is usually not necessary to override the default behaviour. In cases, where
|
|
it is necessary, the following keywords may be used to specify address sizes:
|
|
|
|
<itemize>
|
|
<item>DIRECT, ZEROPAGE or ZP for zeropage addressing (8 bits).
|
|
<item>ABSOLUTE, ABS or NEAR for absolute addressing (16 bits).
|
|
<item>FAR for far addressing (24 bits).
|
|
<item>LONG or DWORD for long addressing (32 bits).
|
|
</itemize>
|
|
|
|
|
|
<sect1>Address sizes of segments<p>
|
|
|
|
The assembler assigns an address size to each segment. Since the
|
|
representation of a label within this segment is "segment start + offset",
|
|
labels will inherit the address size of the segment they are declared in.
|
|
|
|
The address size of a segment may be changed, by using an optional address
|
|
size modifier. See the <tt/<ref id=".SEGMENT" name="segment directive">/ for
|
|
an explanation on how this is done.
|
|
|
|
|
|
<sect1>Address sizes of symbols<p>
|
|
|
|
|
|
|
|
|
|
<sect1>Memory models<p>
|
|
|
|
The default address size of a segment depends on the memory model used. Since
|
|
labels inherit the address size from the segment they are declared in,
|
|
changing the memory model is an easy way to change the address size of many
|
|
symbols at once.
|
|
|
|
|
|
|
|
|
|
<sect>Pseudo variables<label id="pseudo-variables"><p>
|
|
|
|
Pseudo variables are readable in all cases, and in some special cases also
|
|
writable.
|
|
|
|
<sect1><tt>*</tt><p>
|
|
|
|
Reading this pseudo variable will return the program counter at the start
|
|
of the current input line.
|
|
|
|
Assignment to this variable is possible when <tt/<ref id=".FEATURE"
|
|
name=".FEATURE pc_assignment">/ is used. Note: You should not use
|
|
assignments to <tt/*/, use <tt/<ref id=".ORG" name=".ORG">/ instead.
|
|
|
|
|
|
<sect1><tt>.CPU</tt><label id=".CPU"><p>
|
|
|
|
Reading this pseudo variable will give a constant integer value that
|
|
tells which CPU is currently enabled. It can also tell which instruction
|
|
set the CPU is able to translate. The value read from the pseudo variable
|
|
should be further examined by using one of the constants defined by the
|
|
"cpu" macro package (see <tt/<ref id=".MACPACK" name=".MACPACK">/).
|
|
|
|
It may be used to replace the .IFPxx pseudo instructions or to construct
|
|
even more complex expressions.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.macpack cpu
|
|
.if (.cpu .bitand CPU_ISET_65816)
|
|
phx
|
|
phy
|
|
.else
|
|
txa
|
|
pha
|
|
tya
|
|
pha
|
|
.endif
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.PARAMCOUNT</tt><label id=".PARAMCOUNT"><p>
|
|
|
|
This builtin pseudo variable is only available in macros. It is replaced by
|
|
the actual number of parameters that were given in the macro invocation.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.macro foo arg1, arg2, arg3
|
|
.if .paramcount <> 3
|
|
.error "Too few parameters for macro foo"
|
|
.endif
|
|
...
|
|
.endmacro
|
|
</verb></tscreen>
|
|
|
|
See section <ref id="macros" name="Macros">.
|
|
|
|
|
|
<sect1><tt>.TIME</tt><label id=".TIME"><p>
|
|
|
|
Reading this pseudo variable will give a constant integer value that
|
|
represents the current time in POSIX standard (as seconds since the
|
|
Epoch).
|
|
|
|
It may be used to encode the time of translation somewhere in the created
|
|
code.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.dword .time ; Place time here
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.VERSION</tt><label id=".VERSION"><p>
|
|
|
|
Reading this pseudo variable will give the assembler version according to
|
|
the following formula:
|
|
|
|
VER_MAJOR*$100 + VER_MINOR*$10 + VER_PATCH
|
|
|
|
It may be used to encode the assembler version or check the assembler for
|
|
special features not available with older versions.
|
|
|
|
Example:
|
|
|
|
Version 2.11.1 of the assembler will return $2B1 as numerical constant when
|
|
reading the pseudo variable <tt/.VERSION/.
|
|
|
|
|
|
|
|
<sect>Pseudo functions<label id="pseudo-functions"><p>
|
|
|
|
Pseudo functions expect their arguments in parenthesis, and they have a result,
|
|
either a string or an expression.
|
|
|
|
|
|
<sect1><tt>.BANKBYTE</tt><label id=".BANKBYTE"><p>
|
|
|
|
The function returns the bank byte (that is, bits 16-23) of its argument.
|
|
It works identical to the '^' operator.
|
|
|
|
See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
|
|
<tt><ref id=".LOBYTE" name=".LOBYTE"></tt>
|
|
|
|
|
|
<sect1><tt>.BLANK</tt><label id=".BLANK"><p>
|
|
|
|
Builtin function. The function evaluates its argument in braces and yields
|
|
"false" if the argument is non blank (there is an argument), and "true" if
|
|
there is no argument. The token list that makes up the function argument
|
|
may optionally be enclosed in curly braces. This allows the inclusion of
|
|
tokens that would otherwise terminate the list (the closing right
|
|
parenthesis). The curly braces are not considered part of the list, a list
|
|
just consisting of curly braces is considered to be empty.
|
|
|
|
As an example, the <tt/.IFBLANK/ statement may be replaced by
|
|
|
|
<tscreen><verb>
|
|
.if .blank({arg})
|
|
</verb></tscreen>
|
|
|
|
|
|
|
|
<sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
|
|
|
|
Builtin string function. The function allows to concatenate a list of string
|
|
constants separated by commas. The result is a string constant that is the
|
|
concatenation of all arguments. This function is most useful in macros and
|
|
when used together with the <tt/.STRING/ builtin function. The function may
|
|
be used in any case where a string constant is expected.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.include .concat ("myheader", ".", "inc")
|
|
</verb></tscreen>
|
|
|
|
This is the same as the command
|
|
|
|
<tscreen><verb>
|
|
.include "myheader.inc"
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.CONST</tt><label id=".CONST"><p>
|
|
|
|
Builtin function. The function evaluates its argument in braces and
|
|
yields "true" if the argument is a constant expression (that is, an
|
|
expression that yields a constant value at assembly time) and "false"
|
|
otherwise. As an example, the .IFCONST statement may be replaced by
|
|
|
|
<tscreen><verb>
|
|
.if .const(a + 3)
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.HIBYTE</tt><label id=".HIBYTE"><p>
|
|
|
|
The function returns the high byte (that is, bits 8-15) of its argument.
|
|
It works identical to the '>' operator.
|
|
|
|
See: <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>,
|
|
<tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
|
|
|
|
|
|
<sect1><tt>.HIWORD</tt><label id=".HIWORD"><p>
|
|
|
|
The function returns the high word (that is, bits 16-31) of its argument.
|
|
|
|
See: <tt><ref id=".LOWORD" name=".LOWORD"></tt>
|
|
|
|
|
|
<sect1><tt>.IDENT</tt><label id=".IDENT"><p>
|
|
|
|
The function expects a string as its argument, and converts this argument
|
|
into an identifier. If the string starts with the current <tt/<ref
|
|
id=".LOCALCHAR" name=".LOCALCHAR">/, it will be converted into a cheap local
|
|
identifier, otherwise it will be converted into a normal identifier.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.macro makelabel arg1, arg2
|
|
.ident (.concat (arg1, arg2)):
|
|
.endmacro
|
|
|
|
makelabel "foo", "bar"
|
|
|
|
.word foobar ; Valid label
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.LEFT</tt><label id=".LEFT"><p>
|
|
|
|
Builtin function. Extracts the left part of a given token list.
|
|
|
|
Syntax:
|
|
|
|
<tscreen><verb>
|
|
.LEFT (<int expr>, <token list>)
|
|
</verb></tscreen>
|
|
|
|
The first integer expression gives the number of tokens to extract from
|
|
the token list. The second argument is the token list itself. The token
|
|
list may optionally be enclosed into curly braces. This allows the
|
|
inclusion of tokens that would otherwise terminate the list (the closing
|
|
right paren in the given case).
|
|
|
|
Example:
|
|
|
|
To check in a macro if the given argument has a '#' as first token
|
|
(immediate addressing mode), use something like this:
|
|
|
|
<tscreen><verb>
|
|
.macro ldax arg
|
|
...
|
|
.if (.match (.left (1, {arg}), #))
|
|
|
|
; ldax called with immediate operand
|
|
...
|
|
|
|
.endif
|
|
...
|
|
.endmacro
|
|
</verb></tscreen>
|
|
|
|
See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
|
|
name=".RIGHT"></tt> builtin functions.
|
|
|
|
|
|
<sect1><tt>.LOBYTE</tt><label id=".LOBYTE"><p>
|
|
|
|
The function returns the low byte (that is, bits 0-7) of its argument.
|
|
It works identical to the '<' operator.
|
|
|
|
See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
|
|
<tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
|
|
|
|
|
|
<sect1><tt>.LOWORD</tt><label id=".LOWORD"><p>
|
|
|
|
The function returns the low word (that is, bits 0-15) of its argument.
|
|
|
|
See: <tt><ref id=".HIWORD" name=".HIWORD"></tt>
|
|
|
|
|
|
<sect1><tt>.MATCH</tt><label id=".MATCH"><p>
|
|
|
|
Builtin function. Matches two token lists against each other. This is
|
|
most useful within macros, since macros are not stored as strings, but
|
|
as lists of tokens.
|
|
|
|
The syntax is
|
|
|
|
<tscreen><verb>
|
|
.MATCH(<token list #1>, <token list #2>)
|
|
</verb></tscreen>
|
|
|
|
Both token list may contain arbitrary tokens with the exception of the
|
|
terminator token (comma resp. right parenthesis) and
|
|
|
|
<itemize>
|
|
<item>end-of-line
|
|
<item>end-of-file
|
|
</itemize>
|
|
|
|
The token lists may optionally be enclosed into curly braces. This allows
|
|
the inclusion of tokens that would otherwise terminate the list (the closing
|
|
right paren in the given case). Often a macro parameter is used for any of
|
|
the token lists.
|
|
|
|
Please note that the function does only compare tokens, not token
|
|
attributes. So any number is equal to any other number, regardless of the
|
|
actual value. The same is true for strings. If you need to compare tokens
|
|
<em/and/ token attributes, use the <tt><ref id=".XMATCH"
|
|
name=".XMATCH"></tt> function.
|
|
|
|
Example:
|
|
|
|
Assume the macro <tt/ASR/, that will shift right the accumulator by one,
|
|
while honoring the sign bit. The builtin processor instructions will allow
|
|
an optional "A" for accu addressing for instructions like <tt/ROL/ and
|
|
<tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
|
|
to check for this and print and error for invalid calls.
|
|
|
|
<tscreen><verb>
|
|
.macro asr arg
|
|
|
|
.if (.not .blank(arg)) .and (.not .match ({arg}, a))
|
|
.error "Syntax error"
|
|
.endif
|
|
|
|
cmp #$80 ; Bit 7 into carry
|
|
lsr a ; Shift carry into bit 7
|
|
|
|
.endmacro
|
|
</verb></tscreen>
|
|
|
|
The macro will only accept no arguments, or one argument that must be the
|
|
reserved keyword "A".
|
|
|
|
See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
|
|
|
|
|
|
<sect1><tt>.MID</tt><label id=".MID"><p>
|
|
|
|
Builtin function. Takes a starting index, a count and a token list as
|
|
arguments. Will return part of the token list.
|
|
|
|
Syntax:
|
|
|
|
<tscreen><verb>
|
|
.MID (<int expr>, <int expr>, <token list>)
|
|
</verb></tscreen>
|
|
|
|
The first integer expression gives the starting token in the list (the first
|
|
token has index 0). The second integer expression gives the number of tokens
|
|
to extract from the token list. The third argument is the token list itself.
|
|
The token list may optionally be enclosed into curly braces. This allows the
|
|
inclusion of tokens that would otherwise terminate the list (the closing
|
|
right paren in the given case).
|
|
|
|
Example:
|
|
|
|
To check in a macro if the given argument has a '<tt/#/' as first token
|
|
(immediate addressing mode), use something like this:
|
|
|
|
<tscreen><verb>
|
|
.macro ldax arg
|
|
...
|
|
.if (.match (.mid (0, 1, {arg}), #))
|
|
|
|
; ldax called with immediate operand
|
|
...
|
|
|
|
.endif
|
|
...
|
|
.endmacro
|
|
</verb></tscreen>
|
|
|
|
See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
|
|
name=".RIGHT"></tt> builtin functions.
|
|
|
|
|
|
<sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
|
|
|
|
Builtin function. The function expects an identifier as argument in braces.
|
|
The argument is evaluated, and the function yields "true" if the identifier
|
|
is a symbol that has already been referenced somewhere in the source file up
|
|
to the current position. Otherwise the function yields false. As an example,
|
|
the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
|
|
|
|
<tscreen><verb>
|
|
.if .referenced(a)
|
|
</verb></tscreen>
|
|
|
|
See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
|
|
|
|
|
|
<sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
|
|
|
|
Builtin function. Extracts the right part of a given token list.
|
|
|
|
Syntax:
|
|
|
|
<tscreen><verb>
|
|
.RIGHT (<int expr>, <token list>)
|
|
</verb></tscreen>
|
|
|
|
The first integer expression gives the number of tokens to extract from the
|
|
token list. The second argument is the token list itself. The token list
|
|
may optionally be enclosed into curly braces. This allows the inclusion of
|
|
tokens that would otherwise terminate the list (the closing right paren in
|
|
the given case).
|
|
|
|
See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
|
|
name=".MID"></tt> builtin functions.
|
|
|
|
|
|
<sect1><tt>.SIZEOF</tt><label id=".SIZEOF"><p>
|
|
|
|
<tt/.SIZEOF/ is a pseudo function that returns the size of its argument. The
|
|
argument can be a struct/union, a struct member, a procedure, or a label. In
|
|
case of a procedure or label, its size is defined by the amount of data
|
|
placed in the segment where the label is relative to. If a line of code
|
|
switches segments (for example in a macro) data placed in other segments
|
|
does not count for the size.
|
|
|
|
Please note that a symbol or scope must exist, before it is used together with
|
|
<tt/.SIZEOF/ (this may get relaxed later, but will always be true for scopes).
|
|
A scope has preference over a symbol with the same name, so if the last part
|
|
of a name represents both, a scope and a symbol, the scope is chosen over the
|
|
symbol.
|
|
|
|
After the following code:
|
|
|
|
<tscreen><verb>
|
|
.struct Point ; Struct size = 4
|
|
xcoord .word
|
|
xcoord .word
|
|
.endstruct
|
|
|
|
P: .tag Point ; Declare a point
|
|
@P: .tag Point ; Declare another point
|
|
|
|
.code
|
|
.proc Code
|
|
nop
|
|
.proc Inner
|
|
nop
|
|
.endproc
|
|
nop
|
|
.endproc
|
|
|
|
.proc Data
|
|
.data ; Segment switch!!!
|
|
.res 4
|
|
.endproc
|
|
</verb></tscreen>
|
|
|
|
<descrip>
|
|
<tag><tt/.sizeof(Point)/</tag>
|
|
will have the value 4, because this is the size of struct <tt/Point/.
|
|
|
|
<tag><tt/.sizeof(Point::xcoord)/</tag>
|
|
will have the value 2, because this is the size of the member <tt/xcoord/
|
|
in struct <tt/Point/.
|
|
|
|
<tag><tt/.sizeof(P)/</tag>
|
|
will have the value 4, this is the size of the data declared on the same
|
|
source line as the label <tt/P/, which is in the same segment that <tt/P/
|
|
is relative to.
|
|
|
|
<tag><tt/.sizeof(@P)/</tag>
|
|
will have the value 4, see above. The example demonstrates that <tt/.SIZEOF/
|
|
does also work for cheap local symbols.
|
|
|
|
<tag><tt/.sizeof(Code)/</tag>
|
|
will have the value 3, since this is amount of data emitted into the code
|
|
segment, the segment that was active when <tt/Code/ was entered. Note that
|
|
this value includes the amount of data emitted in child scopes (in this
|
|
case <tt/Code::Inner/).
|
|
|
|
<tag><tt/.sizeof(Code::Inner)/</tag>
|
|
will have the value 1 as expected.
|
|
|
|
<tag><tt/.sizeof(Data)/</tag>
|
|
will have the value 0. Data is emitted within the scope <tt/Data/, but since
|
|
the segment is switched after entry, this data is emitted into another
|
|
segment.
|
|
</descrip>
|
|
|
|
|
|
<sect1><tt>.STRAT</tt><label id=".STRAT"><p>
|
|
|
|
Builtin function. The function accepts a string and an index as
|
|
arguments and returns the value of the character at the given position
|
|
as an integer value. The index is zero based.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.macro M Arg
|
|
; Check if the argument string starts with '#'
|
|
.if (.strat (Arg, 0) = '#')
|
|
...
|
|
.endif
|
|
.endmacro
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.SPRINTF</tt><label id=".SPRINTF"><p>
|
|
|
|
Builtin function. It expects a format string as first argument. The number
|
|
and type of the following arguments depend on the format string. The format
|
|
string is similar to the one of the C <tt/printf/ function. Missing things
|
|
are: Length modifiers, variable width.
|
|
|
|
The result of the function is a string.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
num = 3
|
|
|
|
; Generate an identifier:
|
|
.ident (.sprintf ("%s%03d", "label", num)):
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.STRING</tt><label id=".STRING"><p>
|
|
|
|
Builtin function. The function accepts an argument in braces and converts
|
|
this argument into a string constant. The argument may be an identifier, or
|
|
a constant numeric value.
|
|
|
|
Since you can use a string in the first place, the use of the function may
|
|
not be obvious. However, it is useful in macros, or more complex setups.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
; Emulate other assemblers:
|
|
.macro section name
|
|
.segment .string(name)
|
|
.endmacro
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
|
|
|
|
Builtin function. The function accepts a string argument in braces and
|
|
evaluates to the length of the string.
|
|
|
|
Example:
|
|
|
|
The following macro encodes a string as a pascal style string with
|
|
a leading length byte.
|
|
|
|
<tscreen><verb>
|
|
.macro PString Arg
|
|
.byte .strlen(Arg), Arg
|
|
.endmacro
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
|
|
|
|
Builtin function. The function accepts a token list in braces. The function
|
|
result is the number of tokens given as argument. The token list may
|
|
optionally be enclosed into curly braces which are not considered part of
|
|
the list and not counted. Enclosement in curly braces allows the inclusion
|
|
of tokens that would otherwise terminate the list (the closing right paren
|
|
in the given case).
|
|
|
|
Example:
|
|
|
|
The <tt/ldax/ macro accepts the '#' token to denote immediate addressing (as
|
|
with the normal 6502 instructions). To translate it into two separate 8 bit
|
|
load instructions, the '#' token has to get stripped from the argument:
|
|
|
|
<tscreen><verb>
|
|
.macro ldax arg
|
|
.if (.match (.mid (0, 1, {arg}), #))
|
|
; ldax called with immediate operand
|
|
lda #<(.right (.tcount ({arg})-1, {arg}))
|
|
ldx #>(.right (.tcount ({arg})-1, {arg}))
|
|
.else
|
|
...
|
|
.endif
|
|
.endmacro
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
|
|
|
|
Builtin function. Matches two token lists against each other. This is
|
|
most useful within macros, since macros are not stored as strings, but
|
|
as lists of tokens.
|
|
|
|
The syntax is
|
|
|
|
<tscreen><verb>
|
|
.XMATCH(<token list #1>, <token list #2>)
|
|
</verb></tscreen>
|
|
|
|
Both token list may contain arbitrary tokens with the exception of the
|
|
terminator token (comma resp. right parenthesis) and
|
|
|
|
<itemize>
|
|
<item>end-of-line
|
|
<item>end-of-file
|
|
</itemize>
|
|
|
|
The token lists may optionally be enclosed into curly braces. This allows
|
|
the inclusion of tokens that would otherwise terminate the list (the closing
|
|
right paren in the given case). Often a macro parameter is used for any of
|
|
the token lists.
|
|
|
|
The function compares tokens <em/and/ token values. If you need a function
|
|
that just compares the type of tokens, have a look at the <tt><ref
|
|
id=".MATCH" name=".MATCH"></tt> function.
|
|
|
|
See: <tt><ref id=".MATCH" name=".MATCH"></tt>
|
|
|
|
|
|
|
|
<sect>Control commands<label id="control-commands"><p>
|
|
|
|
Here's a list of all control commands and a description, what they do:
|
|
|
|
|
|
<sect1><tt>.A16</tt><label id=".A16"><p>
|
|
|
|
Valid only in 65816 mode. Switch the accumulator to 16 bit.
|
|
|
|
Note: This command will not emit any code, it will tell the assembler to
|
|
create 16 bit operands for immediate accumulator addressing mode.
|
|
|
|
See also: <tt><ref id=".SMART" name=".SMART"></tt>
|
|
|
|
|
|
<sect1><tt>.A8</tt><label id=".A8"><p>
|
|
|
|
Valid only in 65816 mode. Switch the accumulator to 8 bit.
|
|
|
|
Note: This command will not emit any code, it will tell the assembler to
|
|
create 8 bit operands for immediate accu addressing mode.
|
|
|
|
See also: <tt><ref id=".SMART" name=".SMART"></tt>
|
|
|
|
|
|
<sect1><tt>.ADDR</tt><label id=".ADDR"><p>
|
|
|
|
Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
|
|
may be used for better readability if the data words are address values. In
|
|
65816 mode, the address is forced to be 16 bit wide to fit into the current
|
|
segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
|
|
must be followed by a sequence of (not necessarily constant) expressions.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.addr $0D00, $AF13, _Clear
|
|
</verb></tscreen>
|
|
|
|
See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
|
|
name=".WORD"></tt>
|
|
|
|
|
|
<sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
|
|
|
|
Align data to a given boundary. The command expects a constant integer
|
|
argument that must be a power of two, plus an optional second argument
|
|
in byte range. If there is a second argument, it is used as fill value,
|
|
otherwise the value defined in the linker configuration file is used
|
|
(the default for this value is zero).
|
|
|
|
Since alignment depends on the base address of the module, you must
|
|
give the same (or a greater) alignment for the segment when linking.
|
|
The linker will give you a warning, if you don't do that.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.align 256
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
|
|
|
|
Define a string with a trailing zero.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
Msg: .asciiz "Hello world"
|
|
</verb></tscreen>
|
|
|
|
This will put the string "Hello world" followed by a binary zero into
|
|
the current segment. There may be more strings separated by commas, but
|
|
the binary zero is only appended once (after the last one).
|
|
|
|
|
|
<sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
|
|
|
|
Add an assertion. The command is followed by an expression, an action
|
|
specifier, and an optional message that is output in case the assertion
|
|
fails. If no message was given, the string "Assertion failed" is used. The
|
|
action specifier may be one of <tt/warning/ or <tt/error/. The assertion is
|
|
evaluated by the assembler if possible, and also passed to the linker in the
|
|
object file (if one is generated). The linker will then evaluate the
|
|
expression when segment placement has been done.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.assert * = $8000, error, "Code not at $8000"
|
|
</verb></tscreen>
|
|
|
|
The example assertion will check that the current location is at $8000,
|
|
when the output file is written, and abort with an error if this is not
|
|
the case. More complex expressions are possible. The action specifier
|
|
<tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
|
|
an error message. In the latter case, generation if the output file is
|
|
suppressed in both the assembler and linker.
|
|
|
|
|
|
<sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
|
|
|
|
Is followed by a plus or a minus character. When switched on (using a
|
|
+), undefined symbols are automatically marked as import instead of
|
|
giving errors. When switched off (which is the default so this does not
|
|
make much sense), this does not happen and an error message is
|
|
displayed. The state of the autoimport flag is evaluated when the
|
|
complete source was translated, before outputting actual code, so it is
|
|
<em/not/ possible to switch this feature on or off for separate sections
|
|
of code. The last setting is used for all symbols.
|
|
|
|
You should probably not use this switch because it delays error
|
|
messages about undefined symbols until the link stage. The cc65
|
|
compiler (which is supposed to produce correct assembler code in all
|
|
circumstances, something which is not true for most assembler
|
|
programmers) will insert this command to avoid importing each and every
|
|
routine from the runtime library.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.autoimport + ; Switch on auto import
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.BSS</tt><label id=".BSS"><p>
|
|
|
|
Switch to the BSS segment. The name of the BSS segment is always "BSS",
|
|
so this is a shortcut for
|
|
|
|
<tscreen><verb>
|
|
.segment "BSS"
|
|
</verb></tscreen>
|
|
|
|
See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
|
|
|
|
|
|
<sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
|
|
|
|
Define byte sized data. Must be followed by a sequence of (byte ranged)
|
|
expressions or strings.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.byte "Hello "
|
|
.byt "world", $0D, $00
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.CASE</tt><label id=".CASE"><p>
|
|
|
|
Switch on or off case sensitivity on identifiers. The default is off
|
|
(that is, identifiers are case sensitive), but may be changed by the
|
|
-i switch on the command line.
|
|
The command must be followed by a '+' or '-' character to switch the
|
|
option on or off respectively.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.case - ; Identifiers are not case sensitive
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
|
|
|
|
Apply a custom mapping for characters. The command is followed by two
|
|
numbers in the range 1..255. The first one is the index of the source
|
|
character, the second one is the mapping. The mapping applies to all
|
|
character and string constants when they generate output, and overrides
|
|
a mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
|
|
command line switch.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.charmap $41, $61 ; Map 'A' to 'a'
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.CODE</tt><label id=".CODE"><p>
|
|
|
|
Switch to the CODE segment. The name of the CODE segment is always
|
|
"CODE", so this is a shortcut for
|
|
|
|
<tscreen><verb>
|
|
.segment "CODE"
|
|
</verb></tscreen>
|
|
|
|
See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
|
|
|
|
|
|
<sect1><tt>.CONDES</tt><label id=".CONDES"><p>
|
|
|
|
Export a symbol and mark it in a special way. The linker is able to build
|
|
tables of all such symbols. This may be used to automatically create a list
|
|
of functions needed to initialize linked library modules.
|
|
|
|
Note: The linker has a feature to build a table of marked routines, but it
|
|
is your code that must call these routines, so just declaring a symbol with
|
|
<tt/.CONDES/ does nothing by itself.
|
|
|
|
All symbols are exported as an absolute (16 bit) symbol. You don't need to
|
|
use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
|
|
is implied by <tt/.CONDES/.
|
|
|
|
<tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
|
|
<tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
|
|
specifying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
|
|
The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
|
|
id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
|
|
name=".INTERRUPTOR"></tt> commands are actually shortcuts for <tt/.CONDES/
|
|
with a type of <tt/constructor/ resp. <tt/destructor/ or <tt/interruptor/.
|
|
|
|
After the type, an optional priority may be specified. Higher numeric values
|
|
mean higher priority. If no priority is given, the default priority of 7 is
|
|
used. Be careful when assigning priorities to your own module constructors
|
|
so they won't interfere with the ones in the cc65 library.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.condes ModuleInit, constructor
|
|
.condes ModInit, 0, 16
|
|
</verb></tscreen>
|
|
|
|
See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
|
|
id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
|
|
name=".INTERRUPTOR"></tt> commands and the separate section <ref id="condes"
|
|
name="Module constructors/destructors"> explaining the feature in more
|
|
detail.
|
|
|
|
|
|
<sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
|
|
|
|
Export a symbol and mark it as a module constructor. This may be used
|
|
together with the linker to build a table of constructor subroutines that
|
|
are called by the startup code.
|
|
|
|
Note: The linker has a feature to build a table of marked routines, but it
|
|
is your code that must call these routines, so just declaring a symbol as
|
|
constructor does nothing by itself.
|
|
|
|
A constructor is always exported as an absolute (16 bit) symbol. You don't
|
|
need to use an additional <tt/.export/ statement, this is implied by
|
|
<tt/.constructor/. It may have an optional priority that is separated by a
|
|
comma. Higher numeric values mean a higher priority. If no priority is
|
|
given, the default priority of 7 is used. Be careful when assigning
|
|
priorities to your own module constructors so they won't interfere with the
|
|
ones in the cc65 library.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.constructor ModuleInit
|
|
.constructor ModInit, 16
|
|
</verb></tscreen>
|
|
|
|
See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
|
|
id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
|
|
<ref id="condes" name="Module constructors/destructors"> explaining the
|
|
feature in more detail.
|
|
|
|
|
|
<sect1><tt>.DATA</tt><label id=".DATA"><p>
|
|
|
|
Switch to the DATA segment. The name of the DATA segment is always
|
|
"DATA", so this is a shortcut for
|
|
|
|
<tscreen><verb>
|
|
.segment "DATA"
|
|
</verb></tscreen>
|
|
|
|
See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
|
|
|
|
|
|
<sect1><tt>.DBYT</tt><label id=".DBYT"><p>
|
|
|
|
Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
|
|
create word sized data in native 65XX format). Must be followed by a
|
|
sequence of (word ranged) expressions.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.dbyt $1234, $4512
|
|
</verb></tscreen>
|
|
|
|
This will emit the bytes
|
|
|
|
<tscreen><verb>
|
|
$12 $34 $45 $12
|
|
</verb></tscreen>
|
|
|
|
into the current segment in that order.
|
|
|
|
|
|
<sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
|
|
|
|
Switch on or off debug info generation. The default is off (that is,
|
|
the object file will not contain debug infos), but may be changed by the
|
|
-g switch on the command line.
|
|
The command must be followed by a '+' or '-' character to switch the
|
|
option on or off respectively.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.debuginfo + ; Generate debug info
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
|
|
|
|
Start a define style macro definition. The command is followed by an
|
|
identifier (the macro name) and optionally by a list of formal arguments
|
|
in braces.
|
|
See section <ref id="macros" name="Macros">.
|
|
|
|
|
|
<sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
|
|
|
|
Builtin function. The function expects an identifier as argument in braces.
|
|
The argument is evaluated, and the function yields "true" if the identifier
|
|
is a symbol that is already defined somewhere in the source file up to the
|
|
current position. Otherwise the function yields false. As an example, the
|
|
<tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
|
|
|
|
<tscreen><verb>
|
|
.if .defined(a)
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
|
|
|
|
Export a symbol and mark it as a module destructor. This may be used
|
|
together with the linker to build a table of destructor subroutines that
|
|
are called by the startup code.
|
|
|
|
Note: The linker has a feature to build a table of marked routines, but it
|
|
is your code that must call these routines, so just declaring a symbol as
|
|
constructor does nothing by itself.
|
|
|
|
A destructor is always exported as an absolute (16 bit) symbol. You don't
|
|
need to use an additional <tt/.export/ statement, this is implied by
|
|
<tt/.destructor/. It may have an optional priority that is separated by a
|
|
comma. Higher numerical values mean a higher priority. If no priority is
|
|
given, the default priority of 7 is used. Be careful when assigning
|
|
priorities to your own module destructors so they won't interfere with the
|
|
ones in the cc65 library.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.destructor ModuleDone
|
|
.destructor ModDone, 16
|
|
</verb></tscreen>
|
|
|
|
See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
|
|
id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
|
|
section <ref id="condes" name="Module constructors/destructors"> explaining
|
|
the feature in more detail.
|
|
|
|
|
|
<sect1><tt>.DWORD</tt><label id=".DWORD"><p>
|
|
|
|
Define dword sized data (4 bytes) Must be followed by a sequence of
|
|
expressions.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.dword $12344512, $12FA489
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.ELSE</tt><label id=".ELSE"><p>
|
|
|
|
Conditional assembly: Reverse the current condition.
|
|
|
|
|
|
<sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
|
|
|
|
Conditional assembly: Reverse current condition and test a new one.
|
|
|
|
|
|
<sect1><tt>.END</tt><label id=".END"><p>
|
|
|
|
Forced end of assembly. Assembly stops at this point, even if the command
|
|
is read from an include file.
|
|
|
|
|
|
<sect1><tt>.ENDENUM</tt><label id=".ENDENUM"><p>
|
|
|
|
End a <tt><ref id=".ENUM" name=".ENUM"></tt> declaration.
|
|
|
|
|
|
<sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
|
|
|
|
Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
|
|
<tt><ref id=".ELSE" name=".ELSE"></tt> branch.
|
|
|
|
|
|
<sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
|
|
|
|
End of macro definition (see section <ref id="macros" name="Macros">).
|
|
|
|
|
|
<sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
|
|
|
|
End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
|
|
|
|
|
|
<sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
|
|
|
|
End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
|
|
|
|
|
|
<sect1><tt>.ENDSCOPE</tt><label id=".ENDSCOPE"><p>
|
|
|
|
End of local lexical level (see <tt/<ref id=".SCOPE" name=".SCOPE">/).
|
|
|
|
|
|
<sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
|
|
|
|
Ends a struct definition. See the <tt/<ref id=".STRUCT" name=".STRUCT">/
|
|
command and the separate section named <ref id="structs" name=""Structs
|
|
and unions"">.
|
|
|
|
|
|
<sect1><tt>.ENUM</tt><label id=".ENUM"><p>
|
|
|
|
Start an enumeration. This directive is very similar to the C <tt/enum/
|
|
keyword. If a name is given, a new scope is created for the enumeration,
|
|
otherwise the enumeration members are placed in the enclosing scope.
|
|
|
|
In the enumeration body, symbols are declared. The first symbol has a value
|
|
of zero, and each following symbol will get the value of the preceding plus
|
|
one. This behaviour may be overridden by an explicit assignment. Two symbols
|
|
may have the same value.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.enum errorcodes
|
|
no_error
|
|
file_error
|
|
parse_error
|
|
.endenum
|
|
</verb></tscreen>
|
|
|
|
Above example will create a new scope named <tt/errorcodes/ with three
|
|
symbols in it that get the values 0, 1 and 2 respectively. Another way
|
|
to write this would have been:
|
|
|
|
<tscreen><verb>
|
|
.scope errorcodes
|
|
no_error = 0
|
|
file_error = 1
|
|
parse_error = 2
|
|
.endscope
|
|
</verb></tscreen>
|
|
|
|
Please note that explicit scoping must be used to access the identifiers:
|
|
|
|
<tscreen><verb>
|
|
.word errorcodes::no_error
|
|
</verb></tscreen>
|
|
|
|
A more complex example:
|
|
|
|
<tscreen><verb>
|
|
.enum
|
|
EUNKNOWN = -1
|
|
EOK
|
|
EFILE
|
|
EBUSY
|
|
EAGAIN
|
|
EWOULDBLOCK = EAGAIN
|
|
.endenum
|
|
</verb></tscreen>
|
|
|
|
In this example, the enumeration does not have a name, which means that the
|
|
members will be visible in the enclosing scope and can be used in this scope
|
|
without explicit scoping. The first member (<tt/EUNKNOWN/) has the value -1.
|
|
The value for the following members is incremented by one, so <tt/EOK/ would
|
|
be zero and so on. <tt/EWOULDBLOCK/ is an alias for <tt/EGAIN/, so it has an
|
|
override for the value using an already defined symbol.
|
|
|
|
|
|
<sect1><tt>.ERROR</tt><label id=".ERROR"><p>
|
|
|
|
Force an assembly error. The assembler will output an error message
|
|
preceded by "User error" and will <em/not/ produce an object file.
|
|
|
|
This command may be used to check for initial conditions that must be
|
|
set before assembling a source file.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.if foo = 1
|
|
...
|
|
.elseif bar = 1
|
|
...
|
|
.else
|
|
.error "Must define foo or bar!"
|
|
.endif
|
|
</verb></tscreen>
|
|
|
|
See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
|
|
id=".OUT" name=".OUT"></tt> directives.
|
|
|
|
|
|
<sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
|
|
|
|
Abort a macro expansion immediately. This command is often useful in
|
|
recursive macros. See separate section <ref id="macros" name="Macros">.
|
|
|
|
|
|
<sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
|
|
|
|
Make symbols accessible from other modules. Must be followed by a comma
|
|
separated list of symbols to export, with each one optionally followed by an
|
|
address specification and (also optional) an assignment. Using an additional
|
|
assignment in the export statement allows to define and export a symbol in
|
|
one statement. The default is to export the symbol with the address size it
|
|
actually has. The assembler will issue a warning, if the symbol is exported
|
|
with an address size smaller than the actual address size.
|
|
|
|
Examples:
|
|
|
|
<tscreen><verb>
|
|
.export foo
|
|
.export bar: far
|
|
.export foobar: far = foo * bar
|
|
.export baz := foobar, zap: far = baz - bar
|
|
</verb></tscreen>
|
|
|
|
As with constant definitions, using <tt/:=/ instead of <tt/=/ marks the
|
|
symbols as a label.
|
|
|
|
See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
|
|
|
|
|
|
<sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
|
|
|
|
Make symbols accessible from other modules. Must be followed by a comma
|
|
separated list of symbols to export. The exported symbols are explicitly
|
|
marked as zero page symbols. An assignment may be included in the
|
|
<tt/.EXPORTZP/ statement. This allows to define and export a symbol in one
|
|
statement.
|
|
|
|
Examples:
|
|
|
|
<tscreen><verb>
|
|
.exportzp foo, bar
|
|
.exportzp baz := $02
|
|
</verb></tscreen>
|
|
|
|
See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
|
|
|
|
|
|
<sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
|
|
|
|
Define far (24 bit) address data. The command must be followed by a
|
|
sequence of (not necessarily constant) expressions.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.faraddr DrawCircle, DrawRectangle, DrawHexagon
|
|
</verb></tscreen>
|
|
|
|
See: <tt><ref id=".ADDR" name=".ADDR"></tt>
|
|
|
|
|
|
<sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
|
|
|
|
This directive may be used to enable one or more compatibility features
|
|
of the assembler. While the use of <tt/.FEATURE/ should be avoided when
|
|
possible, it may be useful when porting sources written for other
|
|
assemblers. There is no way to switch a feature off, once you have
|
|
enabled it, so using
|
|
|
|
<tscreen><verb>
|
|
.FEATURE xxx
|
|
</verb></tscreen>
|
|
|
|
will enable the feature until end of assembly is reached.
|
|
|
|
The following features are available:
|
|
|
|
<descrip>
|
|
|
|
<tag><tt>at_in_identifiers</tt></tag>
|
|
|
|
Accept the at character (`@') as a valid character in identifiers. The
|
|
at character is not allowed to start an identifier, even with this
|
|
feature enabled.
|
|
|
|
<tag><tt>dollar_in_identifiers</tt></tag>
|
|
|
|
Accept the dollar sign (`$') as a valid character in identifiers. The
|
|
at character is not allowed to start an identifier, even with this
|
|
feature enabled.
|
|
|
|
<tag><tt>dollar_is_pc</tt></tag>
|
|
|
|
The dollar sign may be used as an alias for the star (`*'), which
|
|
gives the value of the current PC in expressions.
|
|
Note: Assignment to the pseudo variable is not allowed.
|
|
|
|
<tag><tt>labels_without_colons</tt></tag>
|
|
|
|
Allow labels without a trailing colon. These labels are only accepted,
|
|
if they start at the beginning of a line (no leading white space).
|
|
|
|
<tag><tt>leading_dot_in_identifiers</tt></tag>
|
|
|
|
Accept the dot (`.') as the first character of an identifier. This may be
|
|
used for example to create macro names that start with a dot emulating
|
|
control directives of other assemblers. Note however, that none of the
|
|
reserved keywords built into the assembler, that starts with a dot, may be
|
|
overridden. When using this feature, you may also get into trouble if
|
|
later versions of the assembler define new keywords starting with a dot.
|
|
|
|
<tag><tt>loose_char_term</tt></tag>
|
|
|
|
Accept single quotes as well as double quotes as terminators for char
|
|
constants.
|
|
|
|
<tag><tt>loose_string_term</tt></tag>
|
|
|
|
Accept single quotes as well as double quotes as terminators for string
|
|
constants.
|
|
|
|
<tag><tt>missing_char_term</tt></tag>
|
|
|
|
Accept single quoted character constants where the terminating quote is
|
|
missing.
|
|
<tscreen><verb>
|
|
lda #'a
|
|
</verb></tscreen>
|
|
<bf/Note:/ This does not work in conjunction with <tt/.FEATURE
|
|
loose_string_term/, since in this case the input would be ambiguous.
|
|
|
|
<tag><tt>org_per_seg</tt><label id="org_per_seg"></tag>
|
|
|
|
This feature makes relocatable/absolute mode local to the current segment.
|
|
Using <tt><ref id=".ORG" name=".ORG"></tt> when <tt/org_per_seg/ is in
|
|
effect will only enable absolute mode for the current segment. Dito for
|
|
<tt><ref id=".RELOC" name=".RELOC"></tt>.
|
|
|
|
<tag><tt>pc_assignment</tt></tag>
|
|
|
|
Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
|
|
is enabled). Such an assignment is handled identical to the <tt><ref
|
|
id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
|
|
removing the lines with the assignments may also be an option when porting
|
|
code written for older assemblers).
|
|
|
|
<tag><tt>ubiquitous_idents</tt></tag>
|
|
|
|
Allow the use of instructions names as names for macros and symbols. This
|
|
makes it possible to "overload" instructions by defining a macro with the
|
|
same name. This does also make it possible to introduce hard to find errors
|
|
in your code, so be careful!
|
|
|
|
</descrip>
|
|
|
|
It is also possible to specify features on the command line using the
|
|
<tt><ref id="option--feature" name="--feature"></tt> command line option.
|
|
This is useful when translating sources written for older assemblers, when
|
|
you don't want to change the source code.
|
|
|
|
As an example, to translate sources written for Andre Fachats xa65
|
|
assembler, the features
|
|
|
|
<verb>
|
|
labels_without_colons, pc_assignment, loose_char_term
|
|
</verb>
|
|
|
|
may be helpful. They do not make ca65 completely compatible, so you may not
|
|
be able to translate the sources without changes, even when enabling these
|
|
features. However, I have found several sources that translate without
|
|
problems when enabling these features on the command line.
|
|
|
|
|
|
<sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
|
|
|
|
Insert an option string into the object file. There are two forms of
|
|
this command, one specifies the option by a keyword, the second
|
|
specifies it as a number. Since usage of the second one needs knowledge
|
|
of the internal encoding, its use is not recommended and I will only
|
|
describe the first form here.
|
|
|
|
The command is followed by one of the keywords
|
|
|
|
<tscreen><verb>
|
|
author
|
|
comment
|
|
compiler
|
|
</verb></tscreen>
|
|
|
|
a comma and a string. The option is written into the object file
|
|
together with the string value. This is currently unidirectional and
|
|
there is no way to actually use these options once they are in the
|
|
object file.
|
|
|
|
Examples:
|
|
|
|
<tscreen><verb>
|
|
.fileopt comment, "Code stolen from my brother"
|
|
.fileopt compiler, "BASIC 2.0"
|
|
.fopt author, "J. R. User"
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
|
|
|
|
Import an absolute symbol from another module. The command is followed by a
|
|
comma separated list of symbols to import. The command is similar to <tt>
|
|
<ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
|
|
written to the generated object file, even if the symbol is never referenced
|
|
(<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
|
|
references for unused symbols).
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.forceimport needthisone, needthistoo
|
|
</verb></tscreen>
|
|
|
|
See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
|
|
|
|
|
|
<sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
|
|
|
|
Declare symbols as global. Must be followed by a comma separated list of
|
|
symbols to declare. Symbols from the list, that are defined somewhere in the
|
|
source, are exported, all others are imported. Additional <tt><ref
|
|
id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
|
|
name=".EXPORT"></tt> commands for the same symbol are allowed.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.global foo, bar
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
|
|
|
|
Declare symbols as global. Must be followed by a comma separated list of
|
|
symbols to declare. Symbols from the list, that are defined somewhere in the
|
|
source, are exported, all others are imported. Additional <tt><ref
|
|
id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
|
|
name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
|
|
in the list are explicitly marked as zero page symbols.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.globalzp foo, bar
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.I16</tt><label id=".I16"><p>
|
|
|
|
Valid only in 65816 mode. Switch the index registers to 16 bit.
|
|
|
|
Note: This command will not emit any code, it will tell the assembler to
|
|
create 16 bit operands for immediate operands.
|
|
|
|
See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
|
|
name=".SMART"></tt> commands.
|
|
|
|
|
|
<sect1><tt>.I8</tt><label id=".I8"><p>
|
|
|
|
Valid only in 65816 mode. Switch the index registers to 8 bit.
|
|
|
|
Note: This command will not emit any code, it will tell the assembler to
|
|
create 8 bit operands for immediate operands.
|
|
|
|
See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
|
|
name=".SMART"></tt> commands.
|
|
|
|
|
|
<sect1><tt>.IF</tt><label id=".IF"><p>
|
|
|
|
Conditional assembly: Evaluate an expression and switch assembler output
|
|
on or off depending on the expression. The expression must be a constant
|
|
expression, that is, all operands must be defined.
|
|
|
|
A expression value of zero evaluates to FALSE, any other value evaluates
|
|
to TRUE.
|
|
|
|
|
|
<sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
|
|
|
|
Conditional assembly: Check if there are any remaining tokens in this line,
|
|
and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
|
|
condition is not true, further lines are not assembled until an <tt><ref
|
|
id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
|
|
<tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
|
|
|
|
This command is often used to check if a macro parameter was given. Since an
|
|
empty macro parameter will evaluate to nothing, the condition will evaluate
|
|
to FALSE if an empty parameter was given.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.macro arg1, arg2
|
|
.ifblank arg2
|
|
lda #arg1
|
|
.else
|
|
lda #arg2
|
|
.endif
|
|
.endmacro
|
|
</verb></tscreen>
|
|
|
|
See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
|
|
|
|
|
|
<sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
|
|
|
|
Conditional assembly: Evaluate an expression and switch assembler output
|
|
on or off depending on the constness of the expression.
|
|
|
|
A const expression evaluates to to TRUE, a non const expression (one
|
|
containing an imported or currently undefined symbol) evaluates to
|
|
FALSE.
|
|
|
|
See also: <tt><ref id=".CONST" name=".CONST"></tt>
|
|
|
|
|
|
<sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
|
|
|
|
Conditional assembly: Check if a symbol is defined. Must be followed by
|
|
a symbol name. The condition is true if the the given symbol is already
|
|
defined, and false otherwise.
|
|
|
|
See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
|
|
|
|
|
|
<sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
|
|
|
|
Conditional assembly: Check if there are any remaining tokens in this line,
|
|
and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
|
|
condition is not true, further lines are not assembled until an <tt><ref
|
|
id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
|
|
<tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
|
|
|
|
This command is often used to check if a macro parameter was given.
|
|
Since an empty macro parameter will evaluate to nothing, the condition
|
|
will evaluate to FALSE if an empty parameter was given.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.macro arg1, arg2
|
|
lda #arg1
|
|
.ifnblank arg2
|
|
lda #arg2
|
|
.endif
|
|
.endmacro
|
|
</verb></tscreen>
|
|
|
|
See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
|
|
|
|
|
|
<sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
|
|
|
|
Conditional assembly: Check if a symbol is defined. Must be followed by
|
|
a symbol name. The condition is true if the the given symbol is not
|
|
defined, and false otherwise.
|
|
|
|
See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
|
|
|
|
|
|
<sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
|
|
|
|
Conditional assembly: Check if a symbol is referenced. Must be followed
|
|
by a symbol name. The condition is true if if the the given symbol was
|
|
not referenced before, and false otherwise.
|
|
|
|
See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
|
|
|
|
|
|
<sect1><tt>.IFP02</tt><label id=".IFP02"><p>
|
|
|
|
Conditional assembly: Check if the assembler is currently in 6502 mode
|
|
(see <tt><ref id=".P02" name=".P02"></tt> command).
|
|
|
|
|
|
<sect1><tt>.IFP816</tt><label id=".IFP816"><p>
|
|
|
|
Conditional assembly: Check if the assembler is currently in 65816 mode
|
|
(see <tt><ref id=".P816" name=".P816"></tt> command).
|
|
|
|
|
|
<sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
|
|
|
|
Conditional assembly: Check if the assembler is currently in 65C02 mode
|
|
(see <tt><ref id=".PC02" name=".PC02"></tt> command).
|
|
|
|
|
|
<sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
|
|
|
|
Conditional assembly: Check if the assembler is currently in 65SC02 mode
|
|
(see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
|
|
|
|
|
|
<sect1><tt>.IFREF</tt><label id=".IFREF"><p>
|
|
|
|
Conditional assembly: Check if a symbol is referenced. Must be followed
|
|
by a symbol name. The condition is true if if the the given symbol was
|
|
referenced before, and false otherwise.
|
|
|
|
This command may be used to build subroutine libraries in include files
|
|
(you may use separate object modules for this purpose too).
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.ifref ToHex ; If someone used this subroutine
|
|
ToHex: tay ; Define subroutine
|
|
lda HexTab,y
|
|
rts
|
|
.endif
|
|
</verb></tscreen>
|
|
|
|
See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
|
|
|
|
|
|
<sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
|
|
|
|
Import a symbol from another module. The command is followed by a comma
|
|
separated list of symbols to import, with each one optionally followed by
|
|
an address specification.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.import foo
|
|
.import bar: zeropage
|
|
</verb></tscreen>
|
|
|
|
See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
|
|
|
|
|
|
<sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
|
|
|
|
Import a symbol from another module. The command is followed by a comma
|
|
separated list of symbols to import. The symbols are explicitly imported
|
|
as zero page symbols (that is, symbols with values in byte range).
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.importzp foo, bar
|
|
</verb></tscreen>
|
|
|
|
See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
|
|
|
|
|
|
<sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
|
|
|
|
Include a file as binary data. The command expects a string argument
|
|
that is the name of a file to include literally in the current segment.
|
|
In addition to that, a start offset and a size value may be specified,
|
|
separated by commas. If no size is specified, all of the file from the
|
|
start offset to end-of-file is used. If no start position is specified
|
|
either, zero is assumed (which means that the whole file is inserted).
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
; Include whole file
|
|
.incbin "sprites.dat"
|
|
|
|
; Include file starting at offset 256
|
|
.incbin "music.dat", $100
|
|
|
|
; Read 100 bytes starting at offset 200
|
|
.incbin "graphics.dat", 200, 100
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
|
|
|
|
Include another file. Include files may be nested up to a depth of 16.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.include "subs.inc"
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.INTERRUPTOR</tt><label id=".INTERRUPTOR"><p>
|
|
|
|
Export a symbol and mark it as an interruptor. This may be used together
|
|
with the linker to build a table of interruptor subroutines that are called
|
|
in an interrupt.
|
|
|
|
Note: The linker has a feature to build a table of marked routines, but it
|
|
is your code that must call these routines, so just declaring a symbol as
|
|
interruptor does nothing by itself.
|
|
|
|
An interruptor is always exported as an absolute (16 bit) symbol. You don't
|
|
need to use an additional <tt/.export/ statement, this is implied by
|
|
<tt/.interruptor/. It may have an optional priority that is separated by a
|
|
comma. Higher numeric values mean a higher priority. If no priority is
|
|
given, the default priority of 7 is used. Be careful when assigning
|
|
priorities to your own module constructors so they won't interfere with the
|
|
ones in the cc65 library.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.interruptor IrqHandler
|
|
.interruptor Handler, 16
|
|
</verb></tscreen>
|
|
|
|
See the <tt><ref id=".CONDES" name=".CONDES"></tt> command and the separate
|
|
section <ref id="condes" name="Module constructors/destructors"> explaining
|
|
the feature in more detail.
|
|
|
|
|
|
<sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
|
|
|
|
Switch on or off line continuations using the backslash character
|
|
before a newline. The option is off by default.
|
|
Note: Line continuations do not work in a comment. A backslash at the
|
|
end of a comment is treated as part of the comment and does not trigger
|
|
line continuation.
|
|
The command must be followed by a '+' or '-' character to switch the
|
|
option on or off respectively.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.linecont + ; Allow line continuations
|
|
|
|
lda \
|
|
#$20 ; This is legal now
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.LIST</tt><label id=".LIST"><p>
|
|
|
|
Enable output to the listing. The command must be followed by a boolean
|
|
switch ("on", "off", "+" or "-") and will enable or disable listing
|
|
output.
|
|
The option has no effect if the listing is not enabled by the command line
|
|
switch -l. If -l is used, an internal counter is set to 1. Lines are output
|
|
to the listing file, if the counter is greater than zero, and suppressed if
|
|
the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
|
|
counter.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.list on ; Enable listing output
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
|
|
|
|
Set, how many bytes are shown in the listing for one source line. The
|
|
default is 12, so the listing will show only the first 12 bytes for any
|
|
source line that generates more than 12 bytes of code or data.
|
|
The directive needs an argument, which is either "unlimited", or an
|
|
integer constant in the range 4..255.
|
|
|
|
Examples:
|
|
|
|
<tscreen><verb>
|
|
.listbytes unlimited ; List all bytes
|
|
.listbytes 12 ; List the first 12 bytes
|
|
.incbin "data.bin" ; Include large binary file
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
|
|
|
|
This command may only be used inside a macro definition. It declares a
|
|
list of identifiers as local to the macro expansion.
|
|
|
|
A problem when using macros are labels: Since they don't change their name,
|
|
you get a "duplicate symbol" error if the macro is expanded the second time.
|
|
Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
|
|
name mapped to an internal unique name (<tt/___ABCD__/) with each macro
|
|
invocation.
|
|
|
|
Some other assemblers start a new lexical block inside a macro expansion.
|
|
This has some drawbacks however, since that will not allow <em/any/ symbol
|
|
to be visible outside a macro, a feature that is sometimes useful. The
|
|
<tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
|
|
to address the problem.
|
|
|
|
You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
|
|
a macro.
|
|
|
|
|
|
<sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
|
|
|
|
Defines the character that start "cheap" local labels. You may use one
|
|
of '@' and '?' as start character. The default is '@'.
|
|
|
|
Cheap local labels are labels that are visible only between two non
|
|
cheap labels. This way you can reuse identifiers like "<tt/loop/" without
|
|
using explicit lexical nesting.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.localchar '?'
|
|
|
|
Clear: lda #$00 ; Global label
|
|
?Loop: sta Mem,y ; Local label
|
|
dey
|
|
bne ?Loop ; Ok
|
|
rts
|
|
Sub: ... ; New global label
|
|
bne ?Loop ; ERROR: Unknown identifier!
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
|
|
|
|
Insert a predefined macro package. The command is followed by an
|
|
identifier specifying the macro package to insert. Available macro
|
|
packages are:
|
|
|
|
<tscreen><verb>
|
|
atari Defines the scrcode macro.
|
|
cbm Defines the scrcode macro.
|
|
cpu Defines constants for the .CPU variable.
|
|
generic Defines generic macros like add and sub.
|
|
longbranch Defines conditional long jump macros.
|
|
</verb></tscreen>
|
|
|
|
Including a macro package twice, or including a macro package that
|
|
redefines already existing macros will lead to an error.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.macpack longbranch ; Include macro package
|
|
|
|
cmp #$20 ; Set condition codes
|
|
jne Label ; Jump long on condition
|
|
</verb></tscreen>
|
|
|
|
Macro packages are explained in more detail in section <ref
|
|
id="macropackages" name="Macro packages">.
|
|
|
|
|
|
<sect1><tt>.MAC, .MACRO</tt><label id=".MAC"><p>
|
|
|
|
Start a classic macro definition. The command is followed by an identifier
|
|
(the macro name) and optionally by a comma separated list of identifiers
|
|
that are macro parameters.
|
|
|
|
See section <ref id="macros" name="Macros">.
|
|
|
|
|
|
<sect1><tt>.ORG</tt><label id=".ORG"><p>
|
|
|
|
Start a section of absolute code. The command is followed by a constant
|
|
expression that gives the new PC counter location for which the code is
|
|
assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
|
|
relocatable code.
|
|
|
|
By default, absolute/relocatable mode is global (valid even when switching
|
|
segments). Using <tt>.FEATURE <ref id="org_per_seg" name="org_per_seg"></tt>
|
|
it can be made segment local.
|
|
|
|
Please note that you <em/do not need/ <tt/.ORG/ in most cases. Placing
|
|
code at a specific address is the job of the linker, not the assembler, so
|
|
there is usually no reason to assemble code to a specific address.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.org $7FF ; Emit code starting at $7FF
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.OUT</tt><label id=".OUT"><p>
|
|
|
|
Output a string to the console without producing an error. This command
|
|
is similar to <tt/.ERROR/, however, it does not force an assembler error
|
|
that prevents the creation of an object file.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.out "This code was written by the codebuster(tm)"
|
|
</verb></tscreen>
|
|
|
|
See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
|
|
id=".ERROR" name=".ERROR"></tt> directives.
|
|
|
|
|
|
<sect1><tt>.P02</tt><label id=".P02"><p>
|
|
|
|
Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
|
|
instructions. This is the default if not overridden by the
|
|
<tt><ref id="option--cpu" name="--cpu"></tt> command line option.
|
|
|
|
See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
|
|
name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
|
|
|
|
|
|
<sect1><tt>.P816</tt><label id=".P816"><p>
|
|
|
|
Enable the 65816 instruction set. This is a superset of the 65SC02 and
|
|
6502 instruction sets.
|
|
|
|
See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
|
|
name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
|
|
|
|
|
|
<sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
|
|
|
|
Set the page length for the listing. Must be followed by an integer
|
|
constant. The value may be "unlimited", or in the range 32 to 127. The
|
|
statement has no effect if no listing is generated. The default value is -1
|
|
(unlimited) but may be overridden by the <tt/--pagelength/ command line
|
|
option. Beware: Since ca65 is a one pass assembler, the listing is generated
|
|
after assembly is complete, you cannot use multiple line lengths with one
|
|
source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
|
|
|
|
Examples:
|
|
|
|
<tscreen><verb>
|
|
.pagelength 66 ; Use 66 lines per listing page
|
|
|
|
.pagelength unlimited ; Unlimited page length
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.PC02</tt><label id=".PC02"><p>
|
|
|
|
Enable the 65C02 instructions set. This instruction set includes all
|
|
6502 and 65SC02 instructions.
|
|
|
|
See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
|
|
name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
|
|
|
|
|
|
<sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
|
|
|
|
Pop the last pushed segment from the stack, and set it.
|
|
|
|
This command will switch back to the segment that was last pushed onto the
|
|
segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
|
|
command, and remove this entry from the stack.
|
|
|
|
The assembler will print an error message if the segment stack is empty
|
|
when this command is issued.
|
|
|
|
See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
|
|
|
|
|
|
<sect1><tt>.PROC</tt><label id=".PROC"><p>
|
|
|
|
Start a nested lexical level with the given name and adds a symbol with this
|
|
name to the enclosing scope. All new symbols from now on are in the local
|
|
lexical level and are accessible from outside only via <ref id="scopesyntax"
|
|
name="explicit scope specification">. Symbols defined outside this local
|
|
level may be accessed as long as their names are not used for new symbols
|
|
inside the level. Symbols names in other lexical levels do not clash, so you
|
|
may use the same names for identifiers. The lexical level ends when the
|
|
<tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
|
|
may be nested up to a depth of 16 (this is an artificial limit to protect
|
|
against errors in the source).
|
|
|
|
Note: Macro names are always in the global level and in a separate name
|
|
space. There is no special reason for this, it's just that I've never
|
|
had any need for local macro definitions.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.proc Clear ; Define Clear subroutine, start new level
|
|
lda #$00
|
|
L1: sta Mem,y ; L1 is local and does not cause a
|
|
; duplicate symbol error if used in other
|
|
; places
|
|
dey
|
|
bne L1 ; Reference local symbol
|
|
rts
|
|
.endproc ; Leave lexical level
|
|
</verb></tscreen>
|
|
|
|
See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
|
|
name=".SCOPE">/
|
|
|
|
|
|
<sect1><tt>.PSC02</tt><label id=".PSC02"><p>
|
|
|
|
Enable the 65SC02 instructions set. This instruction set includes all
|
|
6502 instructions.
|
|
|
|
See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
|
|
name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
|
|
|
|
|
|
<sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
|
|
|
|
Push the currently active segment onto a stack. The entries on the stack
|
|
include the name of the segment and the segment type. The stack has a size
|
|
of 16 entries.
|
|
|
|
<tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
|
|
to switch to another segment and to restore the old segment later, without
|
|
even knowing the name and type of the current segment.
|
|
|
|
The assembler will print an error message if the segment stack is already
|
|
full, when this command is issued.
|
|
|
|
See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
|
|
|
|
|
|
<sect1><tt>.RELOC</tt><label id=".RELOC"><p>
|
|
|
|
Switch back to relocatable mode. See the <tt><ref id=".ORG"
|
|
name=".ORG"></tt> command.
|
|
|
|
|
|
<sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
|
|
|
|
Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
|
|
name=".ENDREPEAT"></tt> constant number of times. The command is followed by
|
|
a constant expression that tells how many times the commands in the body
|
|
should get repeated. Optionally, a comma and an identifier may be specified.
|
|
If this identifier is found in the body of the repeat statement, it is
|
|
replaced by the current repeat count (starting with zero for the first time
|
|
the body is repeated).
|
|
|
|
<tt/.REPEAT/ statements may be nested. If you use the same repeat count
|
|
identifier for a nested <tt/.REPEAT/ statement, the one from the inner
|
|
level will be used, not the one from the outer level.
|
|
|
|
Example:
|
|
|
|
The following macro will emit a string that is "encrypted" in that all
|
|
characters of the string are XORed by the value $55.
|
|
|
|
<tscreen><verb>
|
|
.macro Crypt Arg
|
|
.repeat .strlen(Arg), I
|
|
.byte .strat(Arg, I) ^ $55
|
|
.endrep
|
|
.endmacro
|
|
</verb></tscreen>
|
|
|
|
See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
|
|
|
|
|
|
<sect1><tt>.RES</tt><label id=".RES"><p>
|
|
|
|
Reserve storage. The command is followed by one or two constant
|
|
expressions. The first one is mandatory and defines, how many bytes of
|
|
storage should be defined. The second, optional expression must by a
|
|
constant byte value that will be used as value of the data. If there
|
|
is no fill value given, the linker will use the value defined in the
|
|
linker configuration file (default: zero).
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
; Reserve 12 bytes of memory with value $AA
|
|
.res 12, $AA
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.RODATA</tt><label id=".RODATA"><p>
|
|
|
|
Switch to the RODATA segment. The name of the RODATA segment is always
|
|
"RODATA", so this is a shortcut for
|
|
|
|
<tscreen><verb>
|
|
.segment "RODATA"
|
|
</verb></tscreen>
|
|
|
|
The RODATA segment is a segment that is used by the compiler for
|
|
readonly data like string constants.
|
|
|
|
See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
|
|
|
|
|
|
<sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
|
|
|
|
Start a nested lexical level with the given name. All new symbols from now
|
|
on are in the local lexical level and are accessible from outside only via
|
|
<ref id="scopesyntax" name="explicit scope specification">. Symbols defined
|
|
outside this local level may be accessed as long as their names are not used
|
|
for new symbols inside the level. Symbols names in other lexical levels do
|
|
not clash, so you may use the same names for identifiers. The lexical level
|
|
ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
|
|
read. Lexical levels may be nested up to a depth of 16 (this is an
|
|
artificial limit to protect against errors in the source).
|
|
|
|
Note: Macro names are always in the global level and in a separate name
|
|
space. There is no special reason for this, it's just that I've never
|
|
had any need for local macro definitions.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.scope Error ; Start new scope named Error
|
|
None = 0 ; No error
|
|
File = 1 ; File error
|
|
Parse = 2 ; Parse error
|
|
.endscope ; Close lexical level
|
|
|
|
...
|
|
lda #Error::File ; Use symbol from scope Error
|
|
</verb></tscreen>
|
|
|
|
See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
|
|
name=".PROC">/
|
|
|
|
|
|
<sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
|
|
|
|
Switch to another segment. Code and data is always emitted into a
|
|
segment, that is, a named section of data. The default segment is
|
|
"CODE". There may be up to 254 different segments per object file
|
|
(and up to 65534 per executable). There are shortcut commands for
|
|
the most common segments ("CODE", "DATA" and "BSS").
|
|
|
|
The command is followed by a string containing the segment name (there are
|
|
some constraints for the name - as a rule of thumb use only those segment
|
|
names that would also be valid identifiers). There may also be an optional
|
|
address size separated by a colon. See the section covering <tt/<ref
|
|
id="address-sizes" name="address sizes">/ for more information.
|
|
|
|
The default address size for a segment depends on the memory model specified
|
|
on the command line. The default is "absolute", which means that you don't
|
|
have to use an address size modifier in most cases.
|
|
|
|
"absolute" means that the is a segment with 16 bit (absolute) addressing.
|
|
That is, the segment will reside somewhere in core memory outside the zero
|
|
page. "zeropage" (8 bit) means that the segment will be placed in the zero
|
|
page and direct (short) addressing is possible for data in this segment.
|
|
|
|
Beware: Only labels in a segment with the zeropage attribute are marked
|
|
as reachable by short addressing. The `*' (PC counter) operator will
|
|
work as in other segments and will create absolute variable values.
|
|
|
|
Please note that a segment cannot have two different address sizes. A
|
|
segment specified as zeropage cannot be declared as being absolute later.
|
|
|
|
Examples:
|
|
|
|
<tscreen><verb>
|
|
.segment "ROM2" ; Switch to ROM2 segment
|
|
.segment "ZP2": zeropage ; New direct segment
|
|
.segment "ZP2" ; Ok, will use last attribute
|
|
.segment "ZP2": absolute ; Error, redecl mismatch
|
|
</verb></tscreen>
|
|
|
|
See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
|
|
name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt> and <tt><ref
|
|
id=".RODATA" name=".RODATA"></tt>
|
|
|
|
|
|
<sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
|
|
|
|
Switch the CPU instruction set. The command is followed by a string that
|
|
specifies the CPU. Possible values are those that can also be supplied to
|
|
the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
|
|
namely: 6502, 6502X, 65SC02, 65C02, 65816, sunplus and HuC6280. Please
|
|
note that support for the sunplus CPU is not available in the freeware
|
|
version, because the instruction set of the sunplus CPU is "proprietary
|
|
and confidential".
|
|
|
|
See: <tt><ref id=".CPU" name=".CPU"></tt>,
|
|
<tt><ref id=".IFP02" name=".IFP02"></tt>,
|
|
<tt><ref id=".IFP816" name=".IFP816"></tt>,
|
|
<tt><ref id=".IFPC02" name=".IFPC02"></tt>,
|
|
<tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
|
|
<tt><ref id=".P02" name=".P02"></tt>,
|
|
<tt><ref id=".P816" name=".P816"></tt>,
|
|
<tt><ref id=".PC02" name=".PC02"></tt>,
|
|
<tt><ref id=".PSC02" name=".PSC02"></tt>
|
|
|
|
|
|
<sect1><tt>.SMART</tt><label id=".SMART"><p>
|
|
|
|
Switch on or off smart mode. The command must be followed by a '+' or '-'
|
|
character to switch the option on or off respectively. The default is off
|
|
(that is, the assembler doesn't try to be smart), but this default may be
|
|
changed by the -s switch on the command line.
|
|
|
|
In smart mode the assembler will do the following:
|
|
|
|
<itemize>
|
|
<item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
|
|
and update the operand sizes accordingly. If the operand of such an
|
|
instruction cannot be evaluated by the assembler (for example, because
|
|
the operand is an imported symbol), a warning is issued. Beware: Since
|
|
the assembler cannot trace the execution flow this may lead to false
|
|
results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
|
|
instructions to tell the assembler about the current settings.
|
|
<item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
|
|
used within a procedure declared as <tt/far/, or if the procedure has
|
|
no explicit address specification, but it is <tt/far/ because of the
|
|
memory model used.
|
|
</itemize>
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.smart ; Be smart
|
|
.smart - ; Stop being smart
|
|
</verb></tscreen>
|
|
|
|
See: <tt><ref id=".A16" name=".A16"></tt>,
|
|
<tt><ref id=".A8" name=".A8"></tt>,
|
|
<tt><ref id=".I16" name=".I16"></tt>,
|
|
<tt><ref id=".I8" name=".I8"></tt>
|
|
|
|
|
|
<sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
|
|
|
|
Starts a struct definition. Structs are covered in a separate section named
|
|
<ref id="structs" name=""Structs and unions"">.
|
|
|
|
See: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>
|
|
|
|
|
|
<sect1><tt>.SUNPLUS</tt><label id=".SUNPLUS"><p>
|
|
|
|
Enable the SunPlus instructions set. This command will not work in the
|
|
freeware version of the assembler, because the instruction set is
|
|
"proprietary and confidential".
|
|
|
|
See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
|
|
name=".PSC02"></tt>, <tt><ref id=".PC02" name=".PC02"></tt>, and
|
|
<tt><ref id=".P816" name=".P816"></tt>
|
|
|
|
|
|
<sect1><tt>.TAG</tt><label id=".TAG"><p>
|
|
|
|
Allocate space for a struct or union.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.struct Point
|
|
xcoord .word
|
|
ycoord .word
|
|
.endstruct
|
|
|
|
.bss
|
|
.tag Point ; Allocate 4 bytes
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.WARNING</tt><label id=".WARNING"><p>
|
|
|
|
Force an assembly warning. The assembler will output a warning message
|
|
preceded by "User warning". This warning will always be output, even if
|
|
other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
|
|
command line option.
|
|
|
|
This command may be used to output possible problems when assembling
|
|
the source file.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.macro jne target
|
|
.local L1
|
|
.ifndef target
|
|
.warning "Forward jump in jne, cannot optimize!"
|
|
beq L1
|
|
jmp target
|
|
L1:
|
|
.else
|
|
...
|
|
.endif
|
|
.endmacro
|
|
</verb></tscreen>
|
|
|
|
See also the <tt><ref id=".ERROR" name=".ERROR"></tt> and <tt><ref id=".OUT"
|
|
name=".OUT"></tt> directives.
|
|
|
|
|
|
<sect1><tt>.WORD</tt><label id=".WORD"><p>
|
|
|
|
Define word sized data. Must be followed by a sequence of (word ranged,
|
|
but not necessarily constant) expressions.
|
|
|
|
Example:
|
|
|
|
<tscreen><verb>
|
|
.word $0D00, $AF13, _Clear
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
|
|
|
|
Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
|
|
The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
|
|
shortcut for
|
|
|
|
<tscreen><verb>
|
|
.segment "ZEROPAGE", zeropage
|
|
</verb></tscreen>
|
|
|
|
Because of the "zeropage" attribute, labels declared in this segment are
|
|
addressed using direct addressing mode if possible. You <em/must/ instruct
|
|
the linker to place this segment somewhere in the address range 0..$FF
|
|
otherwise you will get errors.
|
|
|
|
See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
|
|
|
|
|
|
|
|
<sect>Macros<label id="macros"><p>
|
|
|
|
|
|
<sect1>Introduction<p>
|
|
|
|
Macros may be thought of as "parametrized super instructions". Macros are
|
|
sequences of tokens that have a name. If that name is used in the source
|
|
file, the macro is "expanded", that is, it is replaced by the tokens that
|
|
were specified when the macro was defined.
|
|
|
|
|
|
<sect1>Macros without parameters<p>
|
|
|
|
In it's simplest form, a macro does not have parameters. Here's an
|
|
example:
|
|
|
|
<tscreen><verb>
|
|
.macro asr ; Arithmetic shift right
|
|
cmp #$80 ; Put bit 7 into carry
|
|
ror ; Rotate right with carry
|
|
.endmacro
|
|
</verb></tscreen>
|
|
|
|
The macro above consists of two real instructions, that are inserted into
|
|
the code, whenever the macro is expanded. Macro expansion is simply done
|
|
by using the name, like this:
|
|
|
|
<tscreen><verb>
|
|
lda $2010
|
|
asr
|
|
sta $2010
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1>Parametrized macros<p>
|
|
|
|
When using macro parameters, macros can be even more useful:
|
|
|
|
<tscreen><verb>
|
|
.macro inc16 addr
|
|
clc
|
|
lda addr
|
|
adc #$01
|
|
sta addr
|
|
lda addr+1
|
|
adc #$00
|
|
sta addr+1
|
|
.endmacro
|
|
</verb></tscreen>
|
|
|
|
When calling the macro, you may give a parameter, and each occurrence of
|
|
the name "addr" in the macro definition will be replaced by the given
|
|
parameter. So
|
|
|
|
<tscreen><verb>
|
|
inc16 $1000
|
|
</verb></tscreen>
|
|
|
|
will be expanded to
|
|
|
|
<tscreen><verb>
|
|
clc
|
|
lda $1000
|
|
adc #$01
|
|
sta $1000
|
|
lda $1000+1
|
|
adc #$00
|
|
sta $1000+1
|
|
</verb></tscreen>
|
|
|
|
A macro may have more than one parameter, in this case, the parameters
|
|
are separated by commas. You are free to give less parameters than the
|
|
macro actually takes in the definition. You may also leave intermediate
|
|
parameters empty. Empty parameters are replaced by empty space (that is,
|
|
they are removed when the macro is expanded). If you have a look at our
|
|
macro definition above, you will see, that replacing the "addr" parameter
|
|
by nothing will lead to wrong code in most lines. To help you, writing
|
|
macros with a variable parameter list, there are some control commands:
|
|
|
|
<tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
|
|
returns true, if there are any tokens on the remainder of the line. Since
|
|
empty parameters are replaced by nothing, this may be used to test if a given
|
|
parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
|
|
opposite.
|
|
|
|
Look at this example:
|
|
|
|
<tscreen><verb>
|
|
.macro ldaxy a, x, y
|
|
.ifnblank a
|
|
lda #a
|
|
.endif
|
|
.ifnblank x
|
|
ldx #x
|
|
.endif
|
|
.ifnblank y
|
|
ldy #y
|
|
.endif
|
|
.endmacro
|
|
</verb></tscreen>
|
|
|
|
This macro may be called as follows:
|
|
|
|
<tscreen><verb>
|
|
ldaxy 1, 2, 3 ; Load all three registers
|
|
|
|
ldaxy 1, , 3 ; Load only a and y
|
|
|
|
ldaxy , , 3 ; Load y only
|
|
</verb></tscreen>
|
|
|
|
There's another helper command for determining, which macro parameters are
|
|
valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt> This command is
|
|
replaced by the parameter count given, <em/including/ intermediate empty macro
|
|
parameters:
|
|
|
|
<tscreen><verb>
|
|
ldaxy 1 ; .PARAMCOUNT = 1
|
|
ldaxy 1,,3 ; .PARAMCOUNT = 3
|
|
ldaxy 1,2 ; .PARAMCOUNT = 2
|
|
ldaxy 1, ; .PARAMCOUNT = 2
|
|
ldaxy 1,2,3 ; .PARAMCOUNT = 3
|
|
</verb></tscreen>
|
|
|
|
Macro parameters may optionally be enclosed into curly braces. This allows the
|
|
inclusion of tokens that would otherwise terminate the parameter (the comma in
|
|
case of a macro parameter).
|
|
|
|
<tscreen><verb>
|
|
.macro foo arg1, arg2
|
|
...
|
|
.endmacro
|
|
|
|
foo ($00,x) ; Two parameters passed
|
|
foo {($00,x)} ; One parameter passed
|
|
</verb></tscreen>
|
|
|
|
In the first case, the macro is called with two parameters: '<tt/($00/'
|
|
and 'x)'. The comma is not passed to the macro, since it is part of the
|
|
calling sequence, not the parameters.
|
|
|
|
In the second case, '($00,x)' is passed to the macro, this time
|
|
including the comma.
|
|
|
|
|
|
<sect1>Detecting parameter types<p>
|
|
|
|
Sometimes it is nice to write a macro that acts differently depending on the
|
|
type of the argument supplied. An example would be a macro that loads a 16 bit
|
|
value from either an immediate operand, or from memory. The <tt/<ref
|
|
id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
|
|
functions will allow you to do exactly this:
|
|
|
|
<tscreen><verb>
|
|
.macro ldax arg
|
|
.if (.match (.left (1, {arg}), #))
|
|
; immediate mode
|
|
lda #<(.right (.tcount ({arg})-1, {arg}))
|
|
ldx #>(.right (.tcount ({arg})-1, {arg}))
|
|
.else
|
|
; assume absolute or zero page
|
|
lda arg
|
|
ldx 1+(arg)
|
|
.endif
|
|
.endmacro
|
|
</verb></tscreen>
|
|
|
|
Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
|
|
check if its argument begins with a hash mark. If so, two immediate loads are
|
|
emitted, Otherwise a load from an absolute zero page memory location is
|
|
assumed. Please note how the curly braces are used to enclose parameters to
|
|
pseudo functions handling token lists. This is necessary, because the token
|
|
lists may include commas or parens, which would be treated by the assembler
|
|
as end-of-list.
|
|
|
|
The macro can be used as
|
|
|
|
<tscreen><verb>
|
|
foo: .word $5678
|
|
...
|
|
ldax #$1234 ; X=$12, A=$34
|
|
...
|
|
ldax foo ; X=$56, A=$78
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1>Recursive macros<p>
|
|
|
|
Macros may be used recursively:
|
|
|
|
<tscreen><verb>
|
|
.macro push r1, r2, r3
|
|
lda r1
|
|
pha
|
|
.if .paramcount > 1
|
|
push r2, r3
|
|
.endif
|
|
.endmacro
|
|
</verb></tscreen>
|
|
|
|
There's also a special macro to help writing recursive macros: <tt><ref
|
|
id=".EXITMACRO" name=".EXITMACRO"></tt> This command will stop macro expansion
|
|
immediately:
|
|
|
|
<tscreen><verb>
|
|
.macro push r1, r2, r3, r4, r5, r6, r7
|
|
.ifblank r1
|
|
; First parameter is empty
|
|
.exitmacro
|
|
.else
|
|
lda r1
|
|
pha
|
|
.endif
|
|
push r2, r3, r4, r5, r6, r7
|
|
.endmacro
|
|
</verb></tscreen>
|
|
|
|
When expanding this macro, the expansion will push all given parameters
|
|
until an empty one is encountered. The macro may be called like this:
|
|
|
|
<tscreen><verb>
|
|
push $20, $21, $32 ; Push 3 ZP locations
|
|
push $21 ; Push one ZP location
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1>Local symbols inside macros<p>
|
|
|
|
Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
|
|
<tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
|
|
Have a look at the inc16 macro above. Here is it again:
|
|
|
|
<tscreen><verb>
|
|
.macro inc16 addr
|
|
clc
|
|
lda addr
|
|
adc #$01
|
|
sta addr
|
|
lda addr+1
|
|
adc #$00
|
|
sta addr+1
|
|
.endmacro
|
|
</verb></tscreen>
|
|
|
|
If you have a closer look at the code, you will notice, that it could be
|
|
written more efficiently, like this:
|
|
|
|
<tscreen><verb>
|
|
.macro inc16 addr
|
|
inc addr
|
|
bne Skip
|
|
inc addr+1
|
|
Skip:
|
|
.endmacro
|
|
</verb></tscreen>
|
|
|
|
But imagine what happens, if you use this macro twice? Since the label
|
|
"Skip" has the same name both times, you get a "duplicate symbol" error.
|
|
Without a way to circumvent this problem, macros are not as useful, as
|
|
they could be. One solution is, to start a new lexical block inside the
|
|
macro:
|
|
|
|
<tscreen><verb>
|
|
.macro inc16 addr
|
|
.proc
|
|
inc addr
|
|
bne Skip
|
|
inc addr+1
|
|
Skip:
|
|
.endproc
|
|
.endmacro
|
|
</verb></tscreen>
|
|
|
|
Now the label is local to the block and not visible outside. However,
|
|
sometimes you want a label inside the macro to be visible outside. To make
|
|
that possible, there's a new command that's only usable inside a macro
|
|
definition: <tt><ref id=".LOCAL" name=".LOCAL"></tt>. <tt/.LOCAL/ declares one
|
|
or more symbols as local to the macro expansion. The names of local variables
|
|
are replaced by a unique name in each separate macro expansion. So we could
|
|
also solve the problem above by using <tt/.LOCAL/:
|
|
|
|
<tscreen><verb>
|
|
.macro inc16 addr
|
|
.local Skip ; Make Skip a local symbol
|
|
clc
|
|
lda addr
|
|
adc #$01
|
|
sta addr
|
|
bcc Skip
|
|
inc addr+1
|
|
Skip: ; Not visible outside
|
|
.endmacro
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1>C style macros<p>
|
|
|
|
Starting with version 2.5 of the assembler, there is a second macro type
|
|
available: C style macros using the <tt/.DEFINE/ directive. These macros are
|
|
similar to the classic macro type described above, but behaviour is sometimes
|
|
different:
|
|
|
|
<itemize>
|
|
|
|
<item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
|
|
span more than a line. You may use line continuation (see <tt><ref
|
|
id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
|
|
more than one line for increased readability, but the macro itself
|
|
may not contain an end-of-line token.
|
|
|
|
<item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
|
|
the name space with classic macros, but they are detected and replaced
|
|
at the scanner level. While classic macros may be used in every place,
|
|
where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
|
|
name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
|
|
they are more versatile in some situations.
|
|
|
|
<item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
|
|
parameters. While classic macros may have empty parameters, this is
|
|
not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
|
|
For this macro type, the number of actual parameters must match
|
|
exactly the number of formal parameters.
|
|
|
|
To make this possible, formal parameters are enclosed in braces when
|
|
defining the macro. If there are no parameters, the empty braces may
|
|
be omitted.
|
|
|
|
<item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
|
|
contain end-of-line tokens, there are things that cannot be done. They
|
|
may not contain several processor instructions for example. So, while
|
|
some things may be done with both macro types, each type has special
|
|
usages. The types complement each other.
|
|
|
|
</itemize>
|
|
|
|
Let's look at a few examples to make the advantages and disadvantages
|
|
clear.
|
|
|
|
To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
|
|
following <tt/.DEFINE/:
|
|
|
|
<tscreen><verb>
|
|
.define EQU =
|
|
|
|
foo EQU $1234 ; This is accepted now
|
|
</verb></tscreen>
|
|
|
|
You may use the directive to define string constants used elsewhere:
|
|
|
|
<tscreen><verb>
|
|
; Define the version number
|
|
.define VERSION "12.3a"
|
|
|
|
; ... and use it
|
|
.asciiz VERSION
|
|
</verb></tscreen>
|
|
|
|
Macros with parameters may also be useful:
|
|
|
|
<tscreen><verb>
|
|
.define DEBUG(message) .out message
|
|
|
|
DEBUG "Assembling include file #3"
|
|
</verb></tscreen>
|
|
|
|
Note that, while formal parameters have to be placed in braces, this is
|
|
not true for the actual parameters. Beware: Since the assembler cannot
|
|
detect the end of one parameter, only the first token is used. If you
|
|
don't like that, use classic macros instead:
|
|
|
|
<tscreen><verb>
|
|
.macro message
|
|
.out message
|
|
.endmacro
|
|
</verb></tscreen>
|
|
|
|
(This is an example where a problem can be solved with both macro types).
|
|
|
|
|
|
<sect1>Characters in macros<p>
|
|
|
|
When using the <ref id="option-t" name="-t"> option, characters are translated
|
|
into the target character set of the specific machine. However, this happens
|
|
as late as possible. This means that strings are translated if they are part
|
|
of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
|
|
name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
|
|
used as part of an expression.
|
|
|
|
This behaviour is very intuitive outside of macros but may be confusing when
|
|
doing more complex macros. If you compare characters against numeric values,
|
|
be sure to take the translation into account.
|
|
|
|
|
|
|
|
|
|
<sect>Macro packages<label id="macropackages"><p>
|
|
|
|
Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
|
|
macro packages may be included with just one command. Available macro packages
|
|
are:
|
|
|
|
|
|
<sect1><tt>.MACPACK generic</tt><p>
|
|
|
|
This macro package defines macros that are useful in almost any program.
|
|
Currently, two macros are defined:
|
|
|
|
<tscreen><verb>
|
|
.macro add Arg
|
|
clc
|
|
adc Arg
|
|
.endmacro
|
|
|
|
.macro sub Arg
|
|
sec
|
|
sbc Arg
|
|
.endmacro
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1><tt>.MACPACK longbranch</tt><p>
|
|
|
|
This macro package defines long conditional jumps. They are named like the
|
|
short counterpart but with the 'b' replaced by a 'j'. Here is a sample
|
|
definition for the "<tt/jeq/" macro, the other macros are built using the same
|
|
scheme:
|
|
|
|
<tscreen><verb>
|
|
.macro jeq Target
|
|
.if .def(Target) .and ((*+2)-(Target) <= 127)
|
|
beq Target
|
|
.else
|
|
bne *+5
|
|
jmp Target
|
|
.endif
|
|
.endmacro
|
|
</verb></tscreen>
|
|
|
|
All macros expand to a short branch, if the label is already defined (back
|
|
jump) and is reachable with a short jump. Otherwise the macro expands to a
|
|
conditional branch with the branch condition inverted, followed by an absolute
|
|
jump to the actual branch target.
|
|
|
|
The package defines the following macros:
|
|
|
|
<tscreen><verb>
|
|
jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
|
|
</verb></tscreen>
|
|
|
|
|
|
|
|
<sect1><tt>.MACPACK cbm</tt><p>
|
|
|
|
The cbm macro package will define a macro named <tt/scrcode/. It takes a
|
|
string as argument and places this string into memory translated into screen
|
|
codes.
|
|
|
|
|
|
<sect1><tt>.MACPACK cpu</tt><p>
|
|
|
|
This macro package does not define any macros but constants used to examine
|
|
the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
|
|
each supported CPU a constant similar to
|
|
|
|
<tscreen><verb>
|
|
CPU_6502
|
|
CPU_65SC02
|
|
CPU_65C02
|
|
CPU_65816
|
|
CPU_SUNPLUS
|
|
CPU_SWEET16
|
|
CPU_HUC6280
|
|
</verb></tscreen>
|
|
|
|
is defined. These constants may be used to determine the exact type of the
|
|
currently enabled CPU. In addition to that, for each CPU instruction set,
|
|
another constant is defined:
|
|
|
|
<tscreen><verb>
|
|
CPU_ISET_6502
|
|
CPU_ISET_65SC02
|
|
CPU_ISET_65C02
|
|
CPU_ISET_65816
|
|
CPU_ISET_SUNPLUS
|
|
CPU_ISET_SWEET16
|
|
CPU_ISET_HUC6280
|
|
</verb></tscreen>
|
|
|
|
The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
|
|
be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
|
|
currently enabled CPU supports a specific instruction set. For example the
|
|
65C02 supports all instructions of the 65SC02 CPU, so it has the
|
|
<tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
|
|
bit. Using
|
|
|
|
<tscreen><verb>
|
|
.if (.cpu .bitand CPU_ISET_65SC02)
|
|
lda (sp)
|
|
.else
|
|
ldy #$00
|
|
lda (sp),y
|
|
.endif
|
|
</verb></tscreen>
|
|
|
|
it is possible to determine if the
|
|
|
|
<tscreen><verb>
|
|
lda (sp)
|
|
</verb></tscreen>
|
|
|
|
instruction is supported, which is the case for the 65SC02, 65C02 and 65816
|
|
CPUs (the latter two are upwards compatible to the 65SC02).
|
|
|
|
|
|
|
|
<sect>Predefined constants<label id="predefined-constants"><p>
|
|
|
|
For better orthogonality, the assembler defines similar symbols as the
|
|
compiler, depending on the target system selected:
|
|
|
|
<itemize>
|
|
<item><tt/__ACE__/ - Target system is <tt/ace/
|
|
<item><tt/__APPLE2__/ - Target system is <tt/apple2/
|
|
<item><tt/__APPLE2ENH__/ - Target system is <tt/apple2enh/
|
|
<item><tt/__ATARI__/ - Target system is <tt/atari/
|
|
<item><tt/__ATMOS__/ - Target system is <tt/atmos/
|
|
<item><tt/__BBC__/ - Target system is <tt/bbc/
|
|
<item><tt/__C128__/ - Target system is <tt/c128/
|
|
<item><tt/__C16__/ - Target system is <tt/c16/
|
|
<item><tt/__C64__/ - Target system is <tt/c64/
|
|
<item><tt/__CBM__/ - Target is a Commodore system
|
|
<item><tt/__CBM510__/ - Target system is <tt/cbm510/
|
|
<item><tt/__CBM610__/ - Target system is <tt/cbm610/
|
|
<item><tt/__GEOS__/ - Target system is <tt/geos/
|
|
<item><tt/__LUNIX__/ - Target system is <tt/lunix/
|
|
<item><tt/__NES__/ - Target system is <tt/nes/
|
|
<item><tt/__PET__/ - Target system is <tt/pet/
|
|
<item><tt/__PLUS4__/ - Target system is <tt/plus4/
|
|
<item><tt/__SUPERVISION__/ - Target system is <tt/supervision/
|
|
<item><tt/__VIC20__/ - Target system is <tt/vic20/
|
|
</itemize>
|
|
|
|
|
|
<sect>Structs and unions<label id="structs"><p>
|
|
|
|
<sect1>Overview<p>
|
|
|
|
Structs and unions are special forms of <ref id="scopes" name="scopes">. They
|
|
are to some degree comparable to their C counterparts. Both have a list of
|
|
members. Each member allocates storage and may optionally have a name, which,
|
|
in case of a struct, is the offset from the beginning and, in case of a union,
|
|
is always zero.
|
|
|
|
|
|
<sect1>Declaration<p>
|
|
|
|
Here is an example for a very simple struct with two members and a total size
|
|
of 4 bytes:
|
|
|
|
<tscreen><verb>
|
|
.struct Point
|
|
xcoord .word
|
|
ycoord .word
|
|
.endstruct
|
|
</verb></tscreen>
|
|
|
|
A union shares the total space between all its members, its size is the same
|
|
as that of the largest member.
|
|
|
|
A struct or union must not necessarily have a name. If it is anonymous, no
|
|
local scope is opened, the identifiers used to name the members are placed
|
|
into the current scope instead.
|
|
|
|
A struct may contain unnamed members and definitions of local structs. The
|
|
storage allocators may contain a multiplier, as in the example below:
|
|
|
|
<tscreen><verb>
|
|
.struct Circle
|
|
.struct Point
|
|
.word 2 ; Allocate two words
|
|
.endstruct
|
|
Radius .word
|
|
.endstruct
|
|
</verb></tscreen>
|
|
|
|
|
|
<sect1>The <tt/.TAG/ keyword<p>
|
|
|
|
Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to reserve space
|
|
for an already defined struct or unions within another struct:
|
|
|
|
<tscreen><verb>
|
|
.struct Point
|
|
xcoord .word
|
|
ycoord .word
|
|
.endstruct
|
|
|
|
.struct Circle
|
|
Origin .tag Point
|
|
Radius .byte
|
|
.endstruct
|
|
</verb></tscreen>
|
|
|
|
Space for a struct or union may be allocated using the <ref id=".TAG"
|
|
name=".TAG"> directive.
|
|
|
|
<tscreen><verb>
|
|
C: .tag Circle
|
|
</verb></tscreen>
|
|
|
|
Currently, members are just offsets from the start of the struct or union. To
|
|
access a field of a struct, the member offset has to be added to the address
|
|
of the struct itself:
|
|
|
|
<tscreen><verb>
|
|
lda C+Circle::Radius ; Load circle radius into A
|
|
</verb></tscreen>
|
|
|
|
This may change in a future version of the assembler.
|
|
|
|
|
|
<sect1>Limitations<p>
|
|
|
|
Structs and unions are currently implemented as nested symbol tables (in fact,
|
|
they were a by-product of the improved scoping rules). Currently, the
|
|
assembler has no idea of types. This means that the <ref id=".TAG"
|
|
name=".TAG"> keyword will only allocate space. You won't be able to initialize
|
|
variables declared with <ref id=".TAG" name=".TAG">, and adding an embedded
|
|
structure to another structure with <ref id=".TAG" name=".TAG"> will not make
|
|
this structure accessible by using the '::' operator.
|
|
|
|
|
|
|
|
<sect>Module constructors/destructors<label id="condes"><p>
|
|
|
|
<em>Note:</em> This section applies mostly to C programs, so the explanation
|
|
below uses examples from the C libraries. However, the feature may also be
|
|
useful for assembler programs.
|
|
|
|
|
|
<sect1>Overview<p>
|
|
|
|
Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
|
|
id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
|
|
name=".INTERRUPTOR"></tt> keywords it it possible to export functions in a
|
|
special way. The linker is able to generate tables with all functions of a
|
|
specific type. Such a table will <em>only</em> include symbols from object
|
|
files that are linked into a specific executable. This may be used to add
|
|
initialization and cleanup code for library modules, or a table of interrupt
|
|
handler functions.
|
|
|
|
The C heap functions are an example where module initialization code is used.
|
|
All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
|
|
variables that contain the start and the end of the heap, pointers to the free
|
|
list and so on. Since the end of the heap depends on the size and start of the
|
|
stack, it must be initialized at runtime. However, initializing these
|
|
variables for programs that do not use the heap are a waste of time and
|
|
memory.
|
|
|
|
So the central module defines a function that contains initialization code and
|
|
exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
|
|
this module is added to an executable by the linker, the initialization
|
|
function will be placed into the table of constructors by the linker. The C
|
|
startup code will call all constructors before <tt/main/ and all destructors
|
|
after <tt/main/, so without any further work, the heap initialization code is
|
|
called once the module is linked in.
|
|
|
|
While it would be possible to add explicit calls to initialization functions
|
|
in the startup code, the new approach has several advantages:
|
|
|
|
<enum>
|
|
<item>
|
|
If a module is not included, the initialization code is not linked in and not
|
|
called. So you don't pay for things you don't need.
|
|
|
|
<item>
|
|
Adding another library that needs initialization does not mean that the
|
|
startup code has to be changed. Before we had module constructors and
|
|
destructors, the startup code for all systems had to be adjusted to call the
|
|
new initialization code.
|
|
|
|
<item>
|
|
The feature saves memory: Each additional initialization function needs just
|
|
two bytes in the table (a pointer to the function).
|
|
|
|
</enum>
|
|
|
|
|
|
<sect1>Calling order<p>
|
|
|
|
The symbols are sorted in increasing priority order by the linker when using
|
|
one of the builtin linker configurations, so the functions with lower
|
|
priorities come first and are followed by those with higher priorities. The C
|
|
library runtime subroutine that walks over the function tables calls the
|
|
functions starting from the top of the table - which means that functions with
|
|
a high priority are called first.
|
|
|
|
So when using the C runtime, functions are called with high priority functions
|
|
first, followed by low priority functions.
|
|
|
|
|
|
<sect1>Pitfalls<p>
|
|
|
|
When using these special symbols, please take care of the following:
|
|
|
|
<itemize>
|
|
|
|
<item>
|
|
The linker will only generate function tables, it will not generate code to
|
|
call these functions. If you're using the feature in some other than the
|
|
existing C environments, you have to write code to call all functions in a
|
|
linker generated table yourself. See the <tt/condes/ and <tt/callirq/ modules
|
|
in the C runtime for an example on how to do this.
|
|
|
|
<item>
|
|
The linker will only add addresses of functions that are in modules linked to
|
|
the executable. This means that you have to be careful where to place the
|
|
condes functions. If initialization or an irq handler is needed for a group of
|
|
functions, be sure to place the function into a module that is linked in
|
|
regardless of which function is called by the user.
|
|
|
|
<item>
|
|
The linker will generate the tables only when requested to do so by the
|
|
<tt/FEATURE CONDES/ statement in the linker config file. Each table has to
|
|
be requested separately.
|
|
|
|
<item>
|
|
Constructors and destructors may have priorities. These priorities determine
|
|
the order of the functions in the table. If your initialization or cleanup code
|
|
does depend on other initialization or cleanup code, you have to choose the
|
|
priority for the functions accordingly.
|
|
|
|
<item>
|
|
Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
|
|
id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
|
|
name=".INTERRUPTOR"></tt> statements, there is also a more generic command:
|
|
<tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to specify an
|
|
additional type. Predefined types are 0 (constructor), 1 (destructor) and 2
|
|
(interruptor). The linker generates a separate table for each type on request.
|
|
|
|
</itemize>
|
|
|
|
|
|
<sect>Porting sources from other assemblers<p>
|
|
|
|
Sometimes it is necessary to port code written for older assemblers to ca65.
|
|
In some cases, this can be done without any changes to the source code by
|
|
using the emulation features of ca65 (see <tt><ref id=".FEATURE"
|
|
name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
|
|
source code.
|
|
|
|
Probably the biggest difference is the handling of the <tt><ref id=".ORG"
|
|
name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
|
|
done by the linker. Most other assemblers generate absolute code, placement is
|
|
done within the assembler and there is no external linker.
|
|
|
|
In general it is not a good idea to write new code using the emulation
|
|
features of the assembler, but there may be situations where even this rule is
|
|
not valid.
|
|
|
|
<sect1>TASS<p>
|
|
|
|
You need to use some of the ca65 emulation features to simulate the behaviour
|
|
of such simple assemblers.
|
|
|
|
<enum>
|
|
<item>Prepare your sourcecode like this:
|
|
|
|
<tscreen><verb>
|
|
; if you want TASS style labels without colons
|
|
.feature labels_without_colons
|
|
|
|
; if you want TASS style character constants
|
|
; ("a" instead of the default 'a')
|
|
.feature loose_char_term
|
|
|
|
.word *+2 ; the cbm load address
|
|
|
|
[yourcode here]
|
|
</verb></tscreen>
|
|
|
|
notice that the two emulation features are mostly useful for porting
|
|
sources originally written in/for TASS, they are not needed for the
|
|
actual "simple assembler operation" and are not recommended if you are
|
|
writing new code from scratch.
|
|
|
|
<item>Replace all program counter assignments (which are not possible in ca65
|
|
by default, and the respective emulation feature works different from what
|
|
you'd expect) by another way to skip to memory locations, for example the
|
|
<tt><ref id=".RES" name=".RES"></tt> directive.
|
|
|
|
<tscreen><verb>
|
|
; *=$2000
|
|
.res $2000-* ; reserve memory up to $2000
|
|
</verb></tscreen>
|
|
|
|
Please note that other than the original TASS, ca65 can never move the program
|
|
counter backwards - think of it as if you are assembling to disk with TASS.
|
|
|
|
<item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
|
|
rewritten to match ca65 syntax. Most importantly notice that due to the lack
|
|
of <tt/.goto/, everything involving loops must be replaced by
|
|
<tt><ref id=".REPEAT" name=".REPEAT"></tt>.
|
|
|
|
<item>To assemble code to a different address than it is executed at, use the
|
|
<tt><ref id=".ORG" name=".ORG"></tt> directive instead of
|
|
<tt/.offs/-constructs.
|
|
|
|
<tscreen><verb>
|
|
.org $1800
|
|
|
|
[floppy code here]
|
|
|
|
.reloc ; back to normal
|
|
</verb></tscreen>
|
|
|
|
<item>Then assemble like this:
|
|
|
|
<tscreen><verb>
|
|
cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
|
|
</verb></tscreen>
|
|
|
|
Note that you need to use the actual start address minus two, since two bytes
|
|
are used for the cbm load address.
|
|
|
|
</enum>
|
|
|
|
|
|
<sect>Bugs/Feedback<p>
|
|
|
|
If you have problems using the assembler, if you find any bugs, or if
|
|
you're doing something interesting with the assembler, I would be glad to
|
|
hear from you. Feel free to contact me by email
|
|
(<htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">).
|
|
|
|
|
|
|
|
<sect>Copyright<p>
|
|
|
|
ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
|
|
Bassewitz. For usage of the binaries and/or sources the following
|
|
conditions do apply:
|
|
|
|
This software is provided 'as-is', without any expressed or implied
|
|
warranty. In no event will the authors be held liable for any damages
|
|
arising from the use of this software.
|
|
|
|
Permission is granted to anyone to use this software for any purpose,
|
|
including commercial applications, and to alter it and redistribute it
|
|
freely, subject to the following restrictions:
|
|
|
|
<enum>
|
|
<item> The origin of this software must not be misrepresented; you must not
|
|
claim that you wrote the original software. If you use this software
|
|
in a product, an acknowledgment in the product documentation would be
|
|
appreciated but is not required.
|
|
<item> Altered source versions must be plainly marked as such, and must not
|
|
be misrepresented as being the original software.
|
|
<item> This notice may not be removed or altered from any source
|
|
distribution.
|
|
</enum>
|
|
|
|
|
|
|
|
</article>
|
|
|
|
|
|
|