xasm.atari.org
-xasm is a 6502 cross-assembler. -It is mainly targeted at Atari 8-bit computers, -but it can be also used for programming -Atari 2600/5200/Lynx, Commodore C64, Apple ][ and others. -xasm is freeware.
-Version 3.0.0 is a complete rewrite from the x86 assembly language -to the D programming language. -xasm is now available for Linux.
-Features
-Although xasm does not support user-defined macros, it has a rich -set of built-in facilities.
-Here is some typical 6502 code (also valid in xasm):
-- lda #<dest - sta ptr - lda #>dest - sta ptr+1 - ldx #192 -do_line - ldy #39 -do_byte - lda pattern,y - sta (ptr),y - dey - bpl do_byte - lda #40 - clc - adc ptr - sta ptr - bcc skip - inc ptr+1 -skip - dex - bne do_line --
And here is the same code rewritten in a xasm-specific way:
-- mwa #dest ptr - ldx #192 -do_line - ldy #39 - mva:rpl pattern,y (ptr),y- - lda #40 - add:sta ptr - scc:inc ptr+1 - dex:bne do_line --
Usage
-Although xasm comes with no editor, the documentation -describes integration (syntax highlighting and single-keystroke compilation) -with a few general-purpose text editors. Here is a screenshot -of the Code-Genie editor:
-
Download
-| File | Size | Description |
|---|---|---|
| xasm-3.0.0-win32.zip | -98 KB | xasm 3.0.0 for Windows |
| xasm-3.0.0-linux.tar.gz | -128 KB | xasm 3.0.0 for Linux |
| xasm-3.0.0-src.zip | -16 KB | xasm 3.0.0 source code |
| xasm261.zip | -25 KB | xasm 2.6.1 for DOS/Windows |
| xasm252.zip | -38 KB | xasm 2.5.2 for DOS/Windows (includes -X-BOOT, X-LOAD and X-HEAD) |
Links
- --
Hosted by Atari Area
- - + + + + +xasm - 6502 cross-assembler
+xasm is a free tool for programming old 8-bit computers based on the 6502 processor.
+History
+First version of xasm was written in 1998. I needed a cross-assembler +that could understand the syntax of Quick Assembler +which I used for 8-bit Atari programming before I got a PC. +Initially xasm supported the syntax of QA and nothing more. +I quickly realized that I could extend the syntax to make it more expressive. +This led to xasm 2.0, still in 1998. I added some more features +next year. In 2002 I released many versions which contained +mostly bugfixes. In 2005 there were some minor enhancements and bug fixes, +as well as the whole assembler was rewritten from the x86 assembly language +it was initially written in to the +D programming language. +The rewrite introduced a bug, hopefully fixed in version 3.0.1 +released 22nd April 2007.
+Syntax
+6502 assembler code is usually full of LDA, STA, LDA, STA sequences. +With xasm you can use MVA as a shortcut for LDA/STA pair +or even MWA for 16-bit transfers. You can avoid defining labels +when you need short jumps, thanks to conditional skip +and repeat pseudo-instructions. You can put two instructions +that share their argument in one line. +These are just some of the features that help you program +in a more concise way. Let's look at typical 6502 code +(which is valid in xasm):
++ lda #<dest + sta ptr + lda #>dest + sta ptr+1 + ldx #192 +do_line + ldy #39 +do_byte + lda pattern,y + sta (ptr),y + dey + bpl do_byte + lda #40 + clc + adc ptr + sta ptr + bcc skip + inc ptr+1 +skip + dex + bne do_line ++
Using xasm features this code can be rewritten to:
++ mwa #dest ptr + ldx #192 +do_line + ldy #39 + mva:rpl pattern,y (ptr),y- + lda #40 + add:sta ptr + scc:inc ptr+1 + dex:bne do_line ++
Usage
+xasm is a command-line tool so you additionally need a general-purpose text editor. +I use SciTE. +Syntax highlighting definition for it is included with xasm. +To install it, copy xasm.properties to the SciTE directory, +select Options / Open Global Options File, type import xasm +at the end and save the global configuration file.
+
Download
+ +For other systems, such as GNU/Linux and MacOS X, install the latest D compiler +and compile xasm from source code.
+Inflate
+Need a good decompression routine for 6502? +See my inflate routine.
+Links
+-
+
- Atari800 emulator +
- Atari XL/XE Source Archive +
- cc65 cross-compiler +
- HardCore Assembler +
- Mad-Assembler +
OPTIONS
- /c -
- Enable listing false conditionals. -Lines skipped due to a false condition are not listed by default. -
- /d:label=value +
- List lines skipped due to a false condition. +
- /d:label=value
- Define a label. label should be a valid label name. value may be any expression (it may use forward references @@ -30,49 +29,42 @@ to labels defined in the source file). You may use several /d options to define many labels from the command line.
- /i -
- Disable listing included sources. Only main source file will be -listed. +
- Do not list included files. Only main source file will be listed.
- /l[:filename] -
- Enable listing. If no filename is given, the listing is written
+
- Generate a listing. If no filename is given, the listing is written to source.lst, where source is the name of the source file -(without the extension).
+without the extension. - /o:filename -
- Specify object file name. The default is source.obx.
+
- Set object file name. The default is source.obx. You may use the null device (/o:nul) to generate no object file.
- - /p +
- /p
- Print fully qualified file names in listing and error messages. -This option is useful for the Code-Genie editor, which can jump to the error -location only if the full path is given. -This option works only on Windows and is silently ignored on Linux. -
- /q +This option works only on Windows and is silently ignored on other platforms. +
- /q
- Suppress info messages. -Prevents xasm from printing its name and the summary (how many lines -assembled and bytes written). Good if you are building a project from many -source files and don't want tons of messages. +Quiet mode. Prevents xasm from printing the logo and the summary.
- /t[:filename] -
- List label table. If no filename given, the table is appended
+
- List label table. If filename is omitted then the table is appended to the listing.
- - /u -
- Warn of unused labels. A warning message will be issued for each label, -whose value is never used. +
- /u +
- Issue a warning message for each label whose value is unused.
Alternatively, you may use Unix-style options, for example:
xasm -i -d DEBUG=1 -l listing.lst source.asx
SYNTAX
-Source files should be plain ASCII files. Supported are LF, CR, CR/LF -and Atari line terminators. xasm is not case-sensitive, so you can mix -upper- and lower-case for labels and instructions.
+Source files should be plain ASCII files. LF, CR, CR/LF and Atari line terminators +are supported. Labels and instructions are case-insensitive.
xasm is backward compatible with Quick Assembler. -If you want to assembly QA sources with xasm, simply replace ATASCII -specific characters with their integer representation. You also have to change -all OPT directives, but usually you only need to remove them.
+To compile QA sources with xasm, simply replace ATASCII-specific characters +with their integer codes. You also have to change all OPT directives, +but usually you can simply remove them.A label is a symbol that represents a 32-bit signed integer. You can define a label by putting its name at the beginning of a line -(with no spaces before). If you do not use the EQU directive, +(with no spaces before). Unless you use the EQU directive, the label is assigned the current value of the origin counter.
-Instructions and directives must be preceded with -whitespace. Note that in xasm you can use instruction and directive +
Instructions and directives must be preceded with some whitespace. +Note that in xasm you can use instruction and directive names as label names. For example
nop
defines a label called nop, whereas
@@ -85,23 +77,21 @@ of full comment lines: * so it is label | and this too -Lines with instructions (and some directives) +
Lines with instructions (and some directives) may be repeated. A single line may be assembled several times, for example:
:4 asl @ table :32*5 dta 5-
In lines with instructions or directives, a comment starts after -the instruction/directive has been successfully parsed. That is, xasm -does not require a special character to start a comment. However, -you still can use one, because it is usually required for correct syntax -highlighting in text editors.
+In lines with instructions or directives, a comment starts immediately +after the instruction/directive has been successfully parsed. +That is, xasm does not require a special character to start a comment.
lda foo ; this is a comment sta bar so it is - tax #0 tax requires no operand, so #0 starts a comment + tax #0 tax has no operand, therefore #0 starts this comment-
You may put two instructions on the same line. -In this case they have the same operand. For example:
+You may put two instructions in one line +so they share the operand. For example:
eor:sta foo
is equivalent to
@@ -110,29 +100,28 @@ In this case they have the same operand. For example:Note that
lda:tax #0 -
is allowed (#0 is a comment for tax).
+is allowed because #0 is treated as a comment for tax.
EXPRESSIONS
Expressions are numbers combined with operators and brackets. You should use square brackets, because parentheses are reserved -for the indirect addressing.
-Numbers are 32-bit signed integers, in the range of -$7fffffff..$7fffffff. -A number may be:
+for 6502 indirect addressing. +Numbers can be expressed as:
-
-
- a decimal number, e.g. -12345 -
- a hexadecimal number, e.g. $abcd -
- a binary number, e.g. %10100101 +
- a 32-bit decimal integer, e.g. -12345 +
- a 32-bit hexadecimal integer, e.g. $abcd +
- a 32-bit binary integer, e.g. %10100101
- an ASCII character, e.g. 'a' or "a" -
- the origin counter value: * +
- origin counter: *
- a hardware register, e.g. ^4e -
- an op-code, e.g. {lda #0} equals +
- an op-code, e.g. {lda #0} equals $a9 -
- the line repeat counter: # +
- the line repeat counter: #
Abbreviations of Atari hardware registers are provided to save you the trouble of typing two extra characters (^4e vs $d40e) and to ease porting software between Atari 8-bit computers and the Atari 5200 console. These are very similar machines, one of the biggest differences is -different location of hardware registers.
+the location of hardware registers.| Syntax | Chip | Value in the Atari 8-bit computer mode (opt g-) |
@@ -150,17 +139,17 @@ different location of hardware registers.
$D40x | $D40x |
|---|
An op-code is the single-byte op-code of the instruction inside braces. -The operand of the instruction is discarded and is necessary only for -identifying the addressing mode. The instruction should begin just after +The operand of the instruction is discarded and is necessary only +to recognize the addressing mode. The instruction should begin right after the left brace and the right brace should immediately follow the operand or the instruction. -You can skip the operand if the addressing mode +You can skip the operand if the addressing mode is fixed. Examples: {lda #}, {jsr}, {bne}, {jmp ()}, {sta a:,x}.
You can use the line repeat counter (#) in the repeated lines. It counts the iterations starting from zero. Examples:
-:3 dta # ; generates three bytes: 00, 01, 02. +:3 dta # ; generates three bytes: 0, 1, 2. line_lo :192 dta l(screen+40*#) line_hi :192 dta h(screen+40*#) dl :59 dta $4f,a(screen+40*#),0,$4f,a(screen+40*#),0 @@ -188,7 +177,7 @@ dl :59 dta $4f,a(screen+40*#),0,$4f,a(screen+40*#),0
The following unary operators are supported:
+The following unary operators are supported:
- + Plus (does nothing)
- - Minus (changes the sign) @@ -221,25 +210,24 @@ and Java, their priorities are different than in these languages.
- EQU - assign a value of an expression to the label -
- Note that a label represents a number, not a text macro.
-Examples: +- Examples:
-five equ 5 here equ *
- Examples:
- OPT - set assembly options +
- OPT - set assembly options
- Five options are available:
- F - fill the space between ORGs -with $FF bytes +with $FF
- G - Atari 5200 mode for hardware register abbreviations
- H - generate Atari executable headers -
- L - generate listing -
- O - generate object file +
- L - write to the listing +
- O - write to the object file
The default (if no OPT specified) is opt f-g-h+l+o+.
@@ -249,15 +237,13 @@ Examples: opt f+g+h- useful for Atari 5200 cartridges - raw output format, 5200 hw regs - ORG - change value of the origin counter -
- You can set some options applied to the new header (if headers are
-enabled):
+
- If Atari executable headers are enabled, you can use a prefix:
--
-
- a: tells xasm to always make a header, even it is -unnecessary, like in ORG *. -
- f: works same as a:, but additionally tells to generate -a $FF,$FF prefix before the header. xasm adds it -at the beginning of the file by default, so use this option only if you want -the $FF's somewhere inside. +
- a: starts a new block even if it is not necessary because +the new address equals the current address. +
- f: is same as a:, but additionally generates +a $FF,$FF prefix before the new header. The prefix is automatically +generated at the beginning of the file.
org $600 @@ -267,13 +253,12 @@ table org *+100 In the latter example table points to 100 bytes of uninitialized data (label is assigned to * before the ORG directive is executed). -
Starting with version 2.6.0, xasm supports code +
Starting with version 2.6.0, xasm supports code that is relocated in the memory at runtime. Let's say you want your code -to be run at the zero page. Typically you can't load it directly into this -place, so you load it at a different address and then move at the runtime. -xasm differentiates between the address that it used -for code generation from the address that is used for generating -Atari executable headers. org r: affects only the former one. +to be located on the zero page. You can't normally load it directly into this +place, so you load it at a different address and then move in your program. +org r: changes the address that it used for code generation +but not the address used for generating Atari executable headers. Example:
org $8000 ldx #code_length-1 @@ -292,8 +277,8 @@ because I think this is not useful. If you really need it, you can always type something like:
where_am_i equ *-code_zpage+code_loaded
- If Atari executable headers are enabled, you can use a prefix:
- DTA - define data -
- There are various data types: +
- DTA - define data +
-
- integers
-
@@ -311,21 +296,20 @@ where:
- center is a number which is added to every sine value
- amp is the sine amplitude
- size is the sine period -
- first,last define range of values in the table. +
- first,last define the range of sine arguments. They are optional. The default are 0,size-1.
- real numbers: r(-1.23456e12)
-Real numbers are written in the 6-byte Atari Floating-Point format.
+Real numbers are stored in the 6-byte Atari Floating-Point format.
- text strings
- ASCII strings: c'Text' or c"Text"
- ANTIC strings: d'Text' or d"Text"
+marks. You can include the quotation marks in the string by doubling them.
Placing a * character after a string inverts the highest bit in every byte of the string.
- integers
- END - end assembling file
- Remaining part of the file is not assembled. If this statement does @@ -358,23 +342,20 @@ Example:
- INS - insert contents of file
- Copies every byte of the specified file into the object file and updates
the origin counter, as if these bytes were defined with DTA.
-You may specify a range of the inserted file. The syntax is following: +You may specify a range of the file to insert. The syntax is:ins 'file'[,offset[,length]]
The first byte in a file has the offset of zero.
-If the offset is negative, it is counted from the end of the file.
+If the offset is negative, it counts from the end of the file.
Examples:ins 'picture.raw' ins 'file',-256 insert last 256 bytes of file ins 'file',10,10 insert bytes 10..19 of file
- - RUN - generate run address -
- An Atari executable program should specify a run address.
-A program may be loaded in many areas of the memory and started from any
-address.
-
run addr +
- RUN - set run address in the Atari executable format +
run addr
is equivalent to:org $2e0 @@ -383,18 +364,16 @@ is equivalent to: Example:
run main
-- INI - generate init address -
- An Atari executable program may have some routines which are executed
-during the loading process. There may be many init blocks in one file.
-Example: + - INI - set init address in the Atari executable format +
- Example:
ini showpic
- - ERT - generate an error if an expression is true +
- ERT - generate error if expression evaluates to true
- Examples:
ert *>$c000 ert len1>$ff||len2>$ff
- - IFT - assemble if expression is
+
- IFT - assemble if expression is true
ELI - else if
ELS - else
@@ -433,11 +412,11 @@ to use a CLC before ADC for every simple addition.
CLC and ADC.- SUB - subtraction
- IFT - assemble if expression is true
- It is SEC and SBC. -
- RCC, RCS, REQ, RMI, RNE, RPL, RVC,
+
- RCC, RCS, REQ, RMI, RNE, RPL, RVC, RVS - conditional repeat
- These are branches to the previous instruction. They take no operand, because the branch target -is the address of previously assembled instruction.
jumps
+is the address of the previously assembled instruction.
Example:ldx #0 mva:rne $500,x $600,x+ @@ -465,7 +444,7 @@ In the above example the word-sized variable $80 is incremented by 40.
- These are a kind of 'long' branches. While standard branches
(such as BNE) have range of -128..+127, these jumps have range
-of all 64 kB.
+of 64 kB.
Example:jne dest
is equivalent to: @@ -486,28 +465,28 @@ and substitutes two commands: mvx source dest = ldx source : stx dest mvy source dest = ldy source : sty dest
- - MWA, MWX, MWY - move word using
+
- MWA, MWX, MWY - move word using accumulator, X or Y
- These pseudo-commands require two operands
and are combinations of two MV*'s:
one to move the low byte, and the other to move the high byte.
You can't use indirect nor pseudo addressing mode with MW*. -Destination must be an absolute address (optionally indexed).
-When source is also absolute, an mw* source dest will be: +Destination must be an absolute address, optionally indexed.
+When source is also an absolute address, an mw* source dest expands to:mv* source dest mv* source+1 dest+1
-When source is an immediate, an mw* #immed dest will be: +When source is an immediate value, an mw* #immed dest expands to:mv* <immed dest mv* >immed dest+1
When <immed equals >immed and immed -is not forward-referenced, xasm uses an optimization: +is not forward-referenced, xasm skips the second LD*:mv* <immed dest st* dest+1
If possible, MWX and MWY use increment/decrement -commands. E.g. mwx #1 dest is assembled as: +commands. For example, mwx #1 dest expands to:ldx #1 stx dest dex @@ -523,24 +502,24 @@ the @ character (as in Quick Assembler). which use the low/high byte of a 16-bit word constant. They are for Quick Assembler compatibility. You can use traditional #< and #>. -Note lda >$ff+5 loads 1 (>$104), +Note that lda >$ff+5 loads 1 (>$104), while lda #>$ff+5 loads 5 (0+5) to the accumulator, because the unary operator > has a higher priority than the binary plus. -
-In absolute addressing modes, xasm examines the expression -and uses zero-page addressing mode if it supposes it's possible. -You may override it with a: and z: prefixes.
+You can explicitly choose absolute (a:) +and zero-page (z:) addressing modes.
Examples:
nop asl @ - lda >$1234 assembles to lda #$12 + lda >$1234 assembles to lda #$12 lda $100,x - lda a:0 generates 16-bit address + lda 0 zero-page (8-bit address) + lda a:0 absolute (16-bit address) jmp ($0a) lda ($80),y
-There are also pseudo addressing modes, which are similar to +
There are pseudo addressing modes, which are similar to pseudo-commands. You may use them just like standard addressing modes in all 6502 commands and pseudo-commands, except for MWA, MWX and MWY:
@@ -552,10 +531,16 @@ in all 6502 commands and pseudo-commands, except for cmd (z),y- = cmd (z),y : dey cmd (z,0) = ldx #0 : cmd (z,x) cmd (z),0 = ldy #0 : cmd (z),y - cmd (z),0+ = ldy #0 : cmd (z),y : iny + cmd (z),0+ = ldy #0 : cmd (z),y : iny cmd (z),0- = ldy #0 : cmd (z),y : deyCHANGES
+HISTORY
+Version 3.0.1 (2007-04-22)
+-
+
- fixed a bug in OPT H- mode +
- made xasm compilable with the latest D compiler v1.010 +(there were incompatible changes in the D language and library) +
Version 3.0.0 (2005-05-22)
- rewritten from the x86 assembly language to the @@ -714,8 +699,6 @@ addressing modes
AUTHOR
Piotr Fusik (fox@scene.pl)
SEE ALSO
-How to configure a text editor for a convenient use -of xasm
xasm home page (http://xasm.atari.org)
diff --git a/syntax/xasm.properties b/xasm.properties similarity index 89% rename from syntax/xasm.properties rename to xasm.properties index 8bb3a7a..909f64d 100644 --- a/syntax/xasm.properties +++ b/xasm.properties @@ -1,5 +1,4 @@ -# xasm settings for SciTE (www.scintilla.org) -# written by Piotr Fusik
Compare and logical operators assume that zero is false and a non-zero is true. They return 1 for true.
While calculating an expression, signed 32-bit arithmetic is used. -When range of 32 bits is exceeded, the 'Arithmetic overflow' error -is generated.
+When range of 32 bits is exceeded, an 'Arithmetic overflow' error +occurs.