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354 lines
12 KiB
Plaintext
<!doctype linuxdoc system>
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<article>
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<title>co65 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>12.02.2003
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<abstract>
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co65 is an object file conversion utility. It converts o65 object files into
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the native object file format used by the cc65 tool chain. Since o65 is the
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file format used by cc65 for loadable drivers, the co65 utility allows (among
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other things) to link drivers statically to the generated executables instead
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of loading them from disk.
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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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co65 is an object file conversion utility. It converts o65 object files into
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assembler files, which may be translated by ca65 to generate object files in
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the native object file format used by the cc65 tool chain.
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Since loadable drivers used by the library that comes with cc65 use the o65
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relocatable object code format, using the co65 utility allows to link these
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drivers statically. This enables the use of these drivers without loading
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additional files from a disk or other secondary storage.
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Another use would be to link object files generated by other development tools
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to projects using the cc65 tool chain, but this has not been tested until now,
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since such tools are currently rare.
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<sect>Usage<p>
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The co65 utility converts one o65 file per run into one assembler files in
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ca65 format. The utility tries to autodetect the type of the o65 input file
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using the operating system identifier contained in the o65 option list.
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<sect1>Command line option overview<p>
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The converter may be called as follows:
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<tscreen><verb>
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---------------------------------------------------------------------------
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Usage: co65 [options] file
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Short options:
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-V Print the version number
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-g Add debug info to object file
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-h Help (this text)
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-m model Override the o65 model
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-n Don't generate an output file
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-o name Name the output file
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-v Increase verbosity
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Long options:
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--bss-label name Define and export a BSS segment label
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--bss-name seg Set the name of the BSS segment
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--code-label name Define and export a CODE segment label
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--code-name seg Set the name of the CODE segment
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--data-label name Define and export a DATA segment label
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--data-name seg Set the name of the DATA segment
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--debug-info Add debug info to object file
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--help Help (this text)
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--no-output Don't generate an output file
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--o65-model model Override the o65 model
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--verbose Increase verbosity
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--version Print the version number
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--zeropage-label name Define and export a ZEROPAGE segment label
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--zeropage-name seg Set the name of the ZEROPAGE segment
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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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<tag><tt>--bss-label name</tt></tag>
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Set the label used to mark the start of the bss segment. When this option is
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given, the label is also exported and may be accessed from other code. When
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accessing such a label from C code, be sure to include the leading
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underscore. If you don't need to access the bss segment, there's no need to
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use this option.
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<tag><tt>--bss-name seg</tt></tag>
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Set the name of the bss segment. The default name is "BSS" which is
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compatible with the standard ld65 linker configurations.
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<tag><tt>--code-label name</tt></tag>
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Set the label used to mark the start of the code segment. When this option
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is given, the label is also exported and may be accessed from other code.
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When accessing such a label from C code, be sure to include the leading
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underscore. If you don't need to access the code segment, there's no need to
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use this option.
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<tag><tt>--code-name seg</tt></tag>
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Set the name of the code segment. The default name is "CODE" which is
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compatible with the standard ld65 linker configurations.
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<tag><tt>--data-label name</tt></tag>
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Set the label used to mark the start of the data segment. When this option
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is given, the label is also exported and may be accessed from other code.
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When accessing such a label from C code, be sure to include the leading
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underscore. If you don't need to access the data segment, there's no need to
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use this option.
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<tag><tt>--data-name seg</tt></tag>
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Set the name of the data segment. The default name is "DATA" which is
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compatible with the standard ld65 linker configurations.
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<tag><tt>-d, --debug</tt></tag>
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Enables debug mode, something that should not be needed for mere mortals.
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Currently the converter does only accept cc65 loadable modules generated by
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ld65 when not in debug mode. Please note that correct conversion has never
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been tested for o65 files from other sources, so be careful when using
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<tt/-d/.
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<tag><tt>-g, --debug-info</tt></tag>
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This will cause the converter to insert a <tt/.DEBUGINFO/ command into the
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generated assembler code. This will cause the assembler to include all
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symbols in a special section in the object file.
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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>-m model, --o65-model model</tt></tag>
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Set an o65 model. This option changes the way, output is generated for the
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given o65 file. For example, cc65 loadable drivers have a zero page segment,
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but this segment must not be defined in the file itself, because the
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standard module loader will overlay it with the zeropage space used by the
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application that loads this module. So instead of allocating space in the
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zero page segment, the converter will reference the start of the zero page
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area used by the application.
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Currently, the following models are defined:
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<itemize>
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<item>lunix
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<item>os/a65
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<item>cc65-module
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</itemize>
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The default is to autodetect the model to use from the input file, so
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there's rarely a need to use this option.
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<tag><tt>-n, --no-output</tt></tag>
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Don't do the actual conversion, just read in the o65 file checking for
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problems. This option may be used in conjunction with <tt/--verbose/ to
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view some information about the input file.
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<tag><tt>-o name</tt></tag>
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Specify the name of the output file. If you don't specify a name, the
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name of the o65 input file is used, with the extension replaced by ".s".
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<tag><tt>-v, --verbose</tt></tag>
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Using this option, the converter will be somewhat more verbose and print
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some information about the o65 input file (among other things). You may use
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this option together with <tt/--no-output/ to just get the o65 info.
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<tag><tt>-V, --version</tt></tag>
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Print the version number of the compiler. When submitting a bug report,
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please include the operating system you're using, and the compiler
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version.
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<tag><tt>--zeropage-label name</tt></tag>
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Set the label used to mark the start of the zeropage segment. When this
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option is given, the label is also exported and may be accessed from other
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code. When accessing such a label from C code, be sure to include the
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leading underscore. If you don't need to access the zeropage segment,
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there's no need to use this option.
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<tag><tt>--zeropage-name seg</tt></tag>
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Set the name of the data segment. The default name is "ZEROPAGE" which is
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compatible with the standard ld65 linker configurations.
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</descrip>
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<sect>Input and output<p>
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The converter will accept one o65 file per invocation and create a file with
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the same base name, but with the extension replaced by ".s". The output
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file contains assembler code suitable for the use with the ca65 macro
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assembler.
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<sect>Converting loadable drivers<p>
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<sect1>Differences between static linking and runtime loading<p>
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One main use of the utility is conversion of loadable drivers, so they may be
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linked statically to an application. Statically linking will cause a few
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things to be different from runtime loading:
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<itemize>
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<item> Without changing the segment names, all segments take the default
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names used by the standard linker configurations. This means that the
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driver code is no longer contingous in memory, instead the code
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segment is placed somewhere in between all other code segments, the
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data segment is placed with all other data segments and so on. If the
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driver doesn't do strange things this shouldn't be a problem.
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<item> With statically linked code, data and bss segments will get intialized
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once (when the application is loaded), while a loadable driver will
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get its initialization each time the driver is loaded into memory
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(which may be more than once in the lifetime of a program). It depends
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on the driver if this is a problem. Currently, most drivers supplied
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with cc65 behave correctly when linked statically.
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</itemize>
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<sect1>Additional requirements<p>
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All loadable drivers used by cc65 have a header and a jump table at the start
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of the code segment. The header is needed to detect the driver (it may also
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contain some data that is necessary to access the driver). The jump table is
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used to access the functions in the driver code.
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When loading a driver at runtime, the load address of the driver is also the
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address of the code segment, so the locations of the header and jump table are
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known. However, when linking the driver statically, it is up to the programmer
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to provide this information to the driver API.
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For this purpose, it is necessary to define a code segment label that can be
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accessed from the outside later. Please note that the converter does currently
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<em/not/ create such a label without being ordered to do so, even if the input
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file is a cc65 module.
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To create such a label, use the <tt/--code-label/ option when calling the
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converter. Be sure to begin the label with a leading underscore when accessing
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it from C code. In your code, define an arbitrary variable with this name. Use
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the address of this variable as the address of the code segment of the driver.
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Be sure to never modify the variable which is in reality the start of your
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driver!
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<sect1>Example: Convert and link a graphics driver<p>
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As an example, here are some instructions to convert and use the c64-hi.tgi
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graphics driver:
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First, convert the driver, generating a label named "_c64_hi" for the code
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segment. Use the assembler to generate an object file from the assembler
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output.
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<tscreen><verb>
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co65 --code-label _c64_hi c64-hi.tgi
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ca65 c64-hi.s
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</verb></tscreen>
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Next, change your C code to declare a variable that is actually the first byte
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of the driver:
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<tscreen><verb>
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extern char c64_hi;
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</verb></tscreen>
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Instead of loading and unloading the driver, change the code to install and
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uninstall the driver, which will be already in memory after linking:
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<tscreen><verb>
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/* Install the driver */
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tgi_install (&c64_hi);
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...
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/* Uninstall the driver */
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tgi_uninstall ();
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</verb></tscreen>
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Don't forget to link the driver object file to your application, otherwise you
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will get an "undefined external" error for the _c64_hi symbol.
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<sect>Bugs/Feedback<p>
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If you have problems using the converter, if you find any bugs, or if you're
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doing something interesting with the code, I would be glad to hear from you.
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Feel free to contact me by email (<htmlurl url="mailto:uz@cc65.org"
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name="uz@cc65.org">).
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<sect>Copyright<p>
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co65 is (C) Copyright 2003 Ullrich von Bassewitz. For usage of the binaries
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and/or sources the following conditions apply:
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This software is provided 'as-is', without any expressed or implied
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warranty. In no event will the authors be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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<enum>
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<item> The origin of this software must not be misrepresented; you must not
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claim that you wrote the original software. If you use this software
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in a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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<item> Altered source versions must be plainly marked as such, and must not
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be misrepresented as being the original software.
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<item> This notice may not be removed or altered from any source
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distribution.
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</enum>
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</article>
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