1 <!doctype linuxdoc system>
4 <title>cc65 Users Guide
5 <author><url url="mailto:uz@cc65.org" name="Ullrich von Bassewitz">,<newline>
6 <url url="mailto:gregdk@users.sf.net" name="Greg King">
10 cc65 is a C compiler for 6502 targets. It supports several 6502 based home
11 computers like the Commodore and Atari machines, but it is easily retargetable.
14 <!-- Table of contents -->
17 <!-- Begin the document -->
21 cc65 was originally a C compiler for the Atari 8-bit machines written by
22 John R. Dunning. In prior releases I've described the compiler by listing
23 up the changes made by me. I have made many more changes in the meantime
24 (and rewritten major parts of the compiler), so I will no longer do that,
25 since the list would be too large and of no use to anyone. Instead I will
26 describe the compiler in respect to the ANSI/ISO C standard.
28 There are separate documents named <url url="library.html"> and <url
29 url="funcref.html"> that cover the library that is available for the compiler.
30 If you know C, and are interested in doing actual programming, the library
31 documentation is probably of much more use than this document.
33 If you need some hints for getting the best code out of the compiler, you
34 may have a look at <url url="coding.html"> which covers some code generation
41 The compiler translates C files into files containing assembly code that
42 may be translated by the ca65 macroassembler (for more information about
43 the assembler, have a look at <url url="ca65.html">).
46 <sect1>Command line option overview<p>
48 The compiler may be called as follows:
51 ---------------------------------------------------------------------------
52 Usage: cc65 [options] file
54 -Cl Make local variables static
55 -Dsym[=defn] Define a symbol
56 -E Stop after the preprocessing stage
57 -I dir Set an include directory search path
59 -Oi Optimize code, inline more code
60 -Or Enable register variables
61 -Os Inline some standard functions
62 -T Include source as comment
63 -V Print the compiler version number
64 -W warning[,...] Suppress warnings
66 -g Add debug info to object file
68 -j Default characters are signed
69 -mm model Set the memory model
70 -o name Name the output file
71 -r Enable register variables
72 -t sys Set the target system
76 --add-source Include source as comment
77 --all-cdecl Make functions default to __cdecl__
78 --bss-name seg Set the name of the BSS segment
79 --check-stack Generate stack overflow checks
80 --code-name seg Set the name of the CODE segment
81 --codesize x Accept larger code by factor x
82 --cpu type Set cpu type (6502, 65c02)
83 --create-dep name Create a make dependency file
84 --create-full-dep name Create a full make dependency file
85 --data-name seg Set the name of the DATA segment
87 --debug-info Add debug info to object file
88 --debug-opt name Debug optimization steps
89 --dep-target target Use this dependency target
90 --disable-opt name Disable an optimization step
91 --eagerly-inline-funcs Eagerly inline some known functions
92 --enable-opt name Enable an optimization step
93 --help Help (this text)
94 --include-dir dir Set an include directory search path
95 --inline-stdfuncs Inline some standard functions
96 --list-opt-steps List all optimizer steps and exit
97 --list-warnings List available warning types for -W
98 --local-strings Emit string literals immediately
99 --memory-model model Set the memory model
100 --register-space b Set space available for register variables
101 --register-vars Enable register variables
102 --rodata-name seg Set the name of the RODATA segment
103 --signed-chars Default characters are signed
104 --standard std Language standard (c89, c99, cc65)
105 --static-locals Make local variables static
106 --target sys Set the target system
107 --verbose Increase verbosity
108 --version Print the compiler version number
109 --writable-strings Make string literals writable
110 ---------------------------------------------------------------------------
114 <sect1>Command line options in detail<p>
116 Here is a description of all the command line options:
120 <tag><tt>--all-cdecl</tt></tag>
122 Tells the compiler that functions which aren't declared explicitly with
123 either the <tt/__cdecl__/ or <tt/__fastcall__/ calling conventions should
124 have the cdecl convention. (Normally, functions that aren't variadic are
128 <label id="option-bss-name">
129 <tag><tt>--bss-name seg</tt></tag>
131 Set the name of the bss segment. See also <tt/<ref id="pragma-bss-name"
132 name="#pragma bss-name">/.
135 <label id="option-check-stack">
136 <tag><tt>--check-stack</tt></tag>
138 Tells the compiler to generate code that checks for stack overflows. See
139 <tt/<ref id="pragma-check-stack" name="#pragma check-stack">/ for an
140 explanation of this feature.
143 <label id="option-code-name">
144 <tag><tt>--code-name seg</tt></tag>
146 Set the name of the code segment. See also <tt/<ref id="pragma-code-name"
147 name="#pragma code-name">/
150 <label id="option-codesize">
151 <tag><tt>--codesize x</tt></tag>
153 This options allows finer control about speed vs. size decisions in the code
154 generation and optimization phases. It gives the allowed size increase
155 factor (in percent). The default is 100 when not using <tt/-Oi/ and 200 when
156 using <tt/-Oi/ (<tt/-Oi/ is the same as <tt/-O --codesize 200/).
159 <label id="option--cpu">
160 <tag><tt>--cpu CPU</tt></tag>
162 Set the CPU, the compiler generates code for. You may specify "6502" or
163 "65C02" as the CPU. The default depends on the selected target (see option
164 <tt/<ref id="option-t" name="-t">/). It is the 6502 CPU for most targets or
165 if no target has been set. Specifying 65C02 will use a few 65C02
166 instructions when generating code. Don't expect too much from this option:
167 In most cases the difference in size and speed is just 1-2%.
170 <label id="option-create-dep">
171 <tag><tt>--create-dep name</tt></tag>
173 Tells the compiler to generate a file containing the dependency list for the
174 compiled module in makefile syntax. The output is written to a file with the
175 given name. The output does not include system include files (in angle
179 <label id="option-create-full-dep">
180 <tag><tt>--create-full-dep name</tt></tag>
182 Tells the compiler to generate a file containing the dependency list for the
183 compiled module in makefile syntax. The output is written to a file with the
184 given name. The output does include system include files (in angle
188 <label id="option-data-name">
189 <tag><tt>--data-name seg</tt></tag>
191 Set the name of the data segment. See also <tt/<ref id="pragma-data-name"
192 name="#pragma data-name">/
195 <tag><tt>-d, --debug</tt></tag>
197 Enables debug mode, something that should not be needed for mere
201 <label id="option-dep-target">
202 <tag><tt>--dep-target target</tt></tag>
204 When generating a dependency file, don't use the actual output file as the
205 target of the dependency, but the file specified with this option. The
206 option has no effect if neither <tt/<ref id="option-create-dep"
207 name="--create-dep">/ nor <tt/<ref id="option-create-full-dep"
208 name="--create-full-dep">/ is specified.
211 <tag><tt>-D sym[=definition]</tt></tag>
213 Define a macro on the command line. If no definition is given, the macro
214 is defined to the value "1".
217 <tag><tt>-g, --debug-info</tt></tag>
219 This will cause the compiler to insert a <tt/.DEBUGINFO/ command into the
220 generated assembler code. This will cause the assembler to include all
221 symbols in a special section in the object file.
224 <label id="option-eagerly-inline-funcs">
225 <tag><tt>--eagerly-inline-funcs</tt></tag>
227 Have the compiler eagerly inline these functions from the C library:
234 <item>most of the functions declared in <tt/<ctype.h>/
237 Note: This has two consequences:
239 <item>You may not use names of standard C functions for your own functions.
240 If you do that, your program is not standard-compliant anyway; but,
241 using <tt/--eagerly-inline-funcs/ actually will break things.
243 <item>The inlined string and memory functions will not handle strings or
244 memory areas larger than 255 bytes. Similarly, the inlined <tt/is..()/
245 functions will not work with values outside the char. range (such as
250 <tt/--eagerly-inline-funcs/ implies the <tt><ref id="option-inline-stdfuncs"
251 name="--inline-stdfuncs"></tt> command line option.
253 See also <tt><ref id="pragma-allow-eager-inline" name="#pragma allow-eager-inline"></tt>.
256 <tag><tt>-h, --help</tt></tag>
258 Print the short option summary shown above.
261 <label id="option-inline-stdfuncs">
262 <tag><tt>--inline-stdfuncs</tt></tag>
264 Allow the compiler to inline some standard functions from the C library like
265 strlen. This will not only remove the overhead for a function call, but will
266 make the code visible for the optimizer. See also the <tt><ref id="option-O"
267 name="-Os"></tt> command line option and <tt><ref id="pragma-inline-stdfuncs"
268 name="#pragma inline-stdfuncs"></tt>.
271 <label id="option-list-warnings">
272 <tag><tt>--list-warnings</tt></tag>
274 List the names of warning types available for use with <tt><ref
275 id="option-W" name="-W"></tt>.
278 <label id="option-local-strings">
279 <tag><tt>--local-strings</tt></tag>
281 Emit string literals into the rodata segment as soon as they're encountered
282 in the source (even if you do nothing but get the sizeof those strings). The
283 default is to keep string literals until end of assembly, merge read only
284 literals if possible, and then output the literals into the data or rodata
285 segment that is active at that point. Use of this option prevents merging of
286 duplicate strings, but the options that change the name of one of the data
289 You can also use <tt><ref id="pragma-local-strings"
290 name="#pragma local-strings"></tt> for fine grained control.
293 <tag><tt>-o name</tt></tag>
295 Specify the name of the output file. If you don't specify a name, the
296 name of the C input file is used, with the extension replaced by ".s".
299 <label id="option-register-vars">
300 <tag><tt>-r, --register-vars</tt></tag>
302 <tt/-r/ will make the compiler honor the <tt/register/ keyword. Local
303 variables may be placed in registers (which are actually zero page
304 locations). There is some overhead involved with register variables, since
305 the old contents of the registers must be saved and restored. Since register
306 variables are of limited use without the optimizer, there is also a combined
307 switch: <tt/-Or/ will enable both, the optimizer and register variables.
309 For more information about register variables see <ref id="register-vars"
310 name="register variables">.
312 The compiler setting can also be changed within the source file by using
313 <tt/<ref id="pragma-register-vars" name="#pragma register-vars">/.
316 <label id="option-register-space">
317 <tag><tt>--register-space</tt></tag>
319 This option takes a numeric parameter and is used to specify, how much
320 zero page register space is available. Please note that just giving this
321 option will not increase or decrease by itself, it will just tell the
322 compiler about the available space. You will have to allocate that space
323 yourself using an assembler module with the necessary allocations, and a
324 linker configuration that matches the assembler module. The default value
325 for this option is 6 (bytes).
327 If you don't know what all this means, please don't use this option.
330 <label id="option-rodata-name">
331 <tag><tt>--rodata-name seg</tt></tag>
333 Set the name of the rodata segment (the segment used for readonly data).
334 See also <tt/<ref id="pragma-rodata-name" name="#pragma rodata-name">/
336 <label id="option-signed-chars">
337 <tag><tt>-j, --signed-chars</tt></tag>
339 Using this option, you can make the default characters signed. Since the
340 6502 has no provisions for sign extending characters (which is needed on
341 almost any load operation), this will make the code larger and slower. A
342 better way is to declare characters explicitly as "signed" if needed. You
343 can also use <tt><ref id="pragma-signed-chars"
344 name="#pragma signed-chars"></tt> for better control of this option.
347 <label id="option--standard">
348 <tag><tt>--standard std</tt></tag>
350 This option allows to set the language standard supported. The argument is
354 This disables anything that is illegal in C89/C90. Among those things
355 are <tt>//</tt> comments and the non-standard keywords without
356 underscores. Please note that cc65 is not a fully C89 compliant compiler
357 despite this option. A few more things (like floats) are missing.
360 This enables a few features from the C99 standard. With this option,
361 <tt>//</tt> comments are allowed. It will also cause warnings and even
362 errors in a few situations that are allowed with <tt/--standard c89/.
363 For example, a call to a function without a prototype is an error in
367 This is the default mode. It is like c99 mode, but additional features
368 are enabled. Among these are "void data", non-standard keywords without
369 the underlines, unnamed function parameters and the requirement for
370 main() to return an int.
373 Please note that the compiler does not support the C99 standard and never
374 will. c99 mode is actually c89 mode with a few selected C99 extensions.
377 <label id="option-t">
378 <tag><tt>-t target, --target target</tt></tag>
380 This option is used to set the target system. The target system determines
381 the character set that is used for strings and character constants and the
382 default CPU. The CPU setting can be overriden by use of the <tt/<ref
383 id="option--cpu" name="--cpu">/ option.
385 The following target systems are supported:
394 <item>c16 (works also for the c116 with memory up to 32K)
397 <item>cbm510 (CBM-II series with 40 column video)
398 <item>cbm610 (all CBM-II II computers with 80 column video)
405 <item>pet (all CBM PET systems except the 2001)
413 <tag><tt>-v, --verbose</tt></tag>
415 Using this option, the compiler will be somewhat more verbose if errors
416 or warnings are encountered.
419 <label id="option-writable-strings">
420 <tag><tt>--writable-strings</tt></tag>
422 Make string literals writable by placing them into the data segment instead
423 of the rodata segment. You can also use <tt><ref id="pragma-writable-strings"
424 name="#pragma writable-strings"></tt> to control this option from within
428 <label id="option-static-locals">
429 <tag><tt>-Cl, --static-locals</tt></tag>
431 Use static storage for local variables instead of storage on the stack.
432 Since the stack is emulated in software, this gives shorter and usually
433 faster code, but the code is no longer reentrant. The difference between
434 <tt/-Cl/ and declaring local variables as static yourself is, that
435 initializer code is executed each time, the function is entered. So when
446 the variable <tt/a/ will always have the value <tt/1/ when entering the
447 function and using <tt/-Cl/, while in
452 static unsigned a = 1;
457 the variable <tt/a/ will have the value <tt/1/ only the first time that the
458 function is entered, and will keep the old value from one call of the
459 function to the next.
461 You may also use <tt><ref id="pragma-static-locals"
462 name="#pragma static-locals"></tt> to change this setting in your
466 <label id="option-include-dir">
467 <tag><tt>-I dir, --include-dir dir</tt></tag>
469 Set a directory where the compiler searches for include files. You may
470 use this option multiple times to add more than one directory to the
474 <label id="option-O">
475 <tag><tt>-O, -Oi, -Or, -Os</tt></tag>
477 Enable an optimizer run over the produced code.
479 Using <tt/-Oi/, the code generator will inline some code where otherwise a
480 runtime functions would have been called, even if the generated code is
481 larger. This will not only remove the overhead for a function call, but will
482 make the code visible for the optimizer. <tt/-Oi/ is an alias for
483 <tt/-O --codesize 200/.
485 <tt/-Or/ will make the compiler honor the <tt/register/ keyword. Local
486 variables may be placed in registers (which are actually zero page
487 locations). See also the <tt/<ref id="option-register-vars"
488 name="--register-vars">/ command line option, and the <ref
489 id="register-vars" name="discussion of register variables"> below.
491 Using <tt/-Os/ will allow the compiler to inline some standard functions
492 from the C library like strlen. This will not only remove the overhead
493 for a function call, but will make the code visible for the optimizer.
494 See also <tt/<ref id="option-inline-stdfuncs" name="--inline-stdfuncs">/.
496 It is possible to concatenate the modifiers for <tt/-O/. For example, to
497 enable register variables and inlining of standard functions, you may use
501 <tag><tt>-T, --add-source</tt></tag>
503 This include the source code as comments in the generated code. This is
507 <tag><tt>-V, --version</tt></tag>
509 Print the version number of the compiler. When submitting a bug report,
510 please include the operating system you're using, and the compiler
514 <label id="option-W">
515 <tag><tt>-W name[,name,...]</tt></tag>
517 This option allows to control warnings generated by the compiler. It is
518 followed by a comma-separated list of warnings that should be enabled or
519 disabled. To disable a warning, its name is prefixed by a minus sign. If
520 no such prefix exists, or the name is prefixed by a plus sign, the warning
523 The following warning names currently are recognized:
525 <tag><tt/const-comparison/</tag>
526 Warn if the result of a comparison is constant.
527 <tag><tt/error/</tag>
528 Treat all warnings as errors.
529 <tag><tt/no-effect/</tag>
530 Warn about statements that don't have an effect.
531 <tag><tt/remap-zero/</tag>
532 Warn about a <tt/<ref id="pragma-charmap" name="#pragma charmap()">/
533 that changes a character's code number from/to 0x00.
534 <tag><tt/struct-param/</tag>
535 Warn when passing structs by value.
536 <tag><tt/unknown-pragma/</tag>
537 Warn about #pragmas that aren't recognized by cc65.
538 <tag><tt/unused-label/</tag>
539 Warn about unused labels.
540 <tag><tt/unused-param/</tag>
541 Warn about unused function parameters.
542 <tag><tt/unused-var/</tag>
543 Warn about unused variables.
546 The full list of available warning names can be retrieved by using the
547 option <tt><ref id="option-list-warnings" name="--list-warnings"></tt>.
549 You may use also <tt><ref id="pragma-warn" name="#pragma warn"></tt> to
550 control this setting, for smaller pieces of code, from within your sources.
556 <sect>Input and output<p>
558 The compiler will accept one C file per invocation and create a file with
559 the same base name, but with the extension replaced by ".s". The output
560 file contains assembler code suitable for use with the ca65 macro
563 Include files in quotes are searched in the following places:
565 <item>The current file's directory.
566 <item>Any directory added with the <tt/-I/ option on the command line.
567 <item>The value of the environment variable <tt/CC65_INC/ if it is defined.
570 Include files in angle brackets are searched in the following places:
572 <item>Any directory added with the <tt/-I/ option on the command line.
573 <item>The value of the environment variable <tt/CC65_INC/ if it is defined.
574 <item>A subdirectory named <tt/include/ of the directory defined in the
575 environment variable <tt/CC65_HOME/, if it is defined.
576 <item>An optionally compiled-in directory.
581 <sect>Differences to the ISO standard<p>
583 Apart from the things listed below, the compiler does support additional
584 keywords, has several functions in the standard headers with names outside the
585 reserved namespace and a few syntax extensions. All these can be disabled with
586 the <tt><ref id="option--standard" name="--standard"></tt> command line
587 option. Its use for maximum standards compatibility is advised.
589 Here is a list of differences between the language, the compiler accepts,
590 and the one defined by the ISO standard:
594 <item> The datatypes "float" and "double" are not available.
596 <item> C Functions may not return structs (or unions), and structs may not
597 be passed as parameters by value. However, struct assignment *is*
600 <item> Most of the C library is available with only the fastcall calling
601 convention (<ref id="extension-fastcall" name="see below">). It means
602 that you must not mix pointers to those functions with pointers to
603 user-written, cdecl functions (the calling conventions are incompatible).
605 <item> The <tt/volatile/ keyword has almost no effect. That is not as bad
606 as it sounds, since the 6502 has so few registers that it isn't
607 possible to keep values in registers anyway.
611 There may be some more minor differences I'm currently not aware of. The
612 biggest problem is the missing float data type. With this limitation in
613 mind, you should be able to write fairly portable code.
619 This cc65 version has some extensions to the ISO C standard.
623 <item> The compiler allows to insert assembler statements into the output
627 asm [optional volatile] (<string literal>[, optional parameters]) ;
631 __asm__ [optional volatile] (<string literal>[, optional parameters]) ;
634 The first form is in the user namespace; and, is disabled if the <tt/-A/
637 There is a whole section covering inline assembler statements,
638 <ref id="inline-asm" name="see there">.
641 <label id="extension-fastcall">
642 <item> The normal calling convention -- for non-variadic functions -- is
643 named "fastcall". The syntax for a function declaration that
644 <em/explicitly/ uses fastcall is
647 <return type> fastcall <function name> (<parameter list>)
651 <return type> __fastcall__ <function name> (<parameter list>)
655 void __fastcall__ f (unsigned char c)
657 The first form of the fastcall keyword is in the user namespace and can
658 therefore be disabled with the <tt><ref id="option--standard"
659 name="--standard"></tt> command line option.
661 For functions that are <tt/fastcall/, the rightmost parameter is not
662 pushed on the stack but left in the primary register when the function
663 is called. That significantly reduces the cost of calling those functions.
666 <item> There is another calling convention named "cdecl". Variadic functions
667 (their prototypes have an ellipsis [<tt/.../]) always use that
668 convention. The syntax for a function declaration using cdecl is
671 <return type> cdecl <function name> (<parameter list>)
675 <return type> __cdecl__ <function name> (<parameter list>)
679 int* __cdecl__ f (unsigned char c)
682 The first form of the cdecl keyword is in the user namespace;
683 and therefore, can be disabled with the <tt/<ref id="option--standard"
684 name="--standard">/ command-line option.
686 For functions that are <tt/cdecl/, the rightmost parameter is pushed
687 onto the stack before the function is called. That increases the cost
688 of calling those functions, especially when they are called from many
692 <item> There are two pseudo variables named <tt/__AX__/ and <tt/__EAX__/.
693 Both refer to the primary register that is used by the compiler to
694 evaluate expressions or return function results. <tt/__AX__/ is of
695 type <tt/unsigned int/ and <tt/__EAX__/ of type <tt/long unsigned int/
696 respectively. The pseudo variables may be used as lvalue and rvalue as
697 every other variable. They are most useful together with short
698 sequences of assembler code. For example, the macro
708 will give the high byte of any unsigned value.
711 <item> Inside a function, the identifier <tt/__func__/ gives the name of the
712 current function as a string. Outside of functions, <tt/__func__/ is
717 #define PRINT_DEBUG(s) printf ("%s: %s\n", __func__, s);
720 The macro will print the name of the current function plus a given
724 <item> cc65 allows the initialization of <tt/void/ variables. This may be
725 used to create arbitrary structures that are more compatible with
726 interfaces written for assembler languages. Here is an example:
729 void GCmd = { (char)3, (unsigned)0x2000, (unsigned)0x3000 };
732 That will be translated as follows:
741 Since the variable is of type <tt/void/, you may not use it as-is.
742 However, taking the address of the variable results in a <tt/void*/
743 which may be passed to any function expecting a pointer. Also, the
744 <tt/sizeof/ operator will give the length of the initializer:
750 will assign the value 5 to <tt/GLen/.
752 See the <url url="geos.html" name="GEOS library document"> for examples
753 on how to use that feature.
756 <item> cc65 implements flexible array struct members as defined in the C99 ISO
757 standard. As an extension, these fields may be initialized. There are
758 several exceptions, however (which is probably the reason why the
759 standard does not define this feature, because it is highly
760 unorthogonal). Flexible array members cannot be initialized ...
763 <item>... when defining an array of structs with flexible
765 <item>... if such a struct is a member field of another struct
766 which is not the last field.
767 <item>... if the struct which contains a flexible array member is
768 declared as <tt/register/, and the size and compiler settings
769 do allow the compiler actually to place the struct into the
770 register bank in the zero page.
773 Please note that -- as defined in the ISO C standard -- the <tt/sizeof/
774 operator returns the struct size with the flexible array member having
775 size zero, even if it is initialized.
783 <sect>Predefined macros<p>
785 The compiler defines several macros at startup:
788 <tag><tt>__APPLE2__</tt></tag>
790 This macro is defined if the target is the Apple ][ (-t apple2) or the enhanced Apple //e (-t apple2enh).
792 <tag><tt>__APPLE2ENH__</tt></tag>
794 This macro is defined if the target is the enhanced Apple //e (-t apple2enh).
796 <tag><tt>__ATARI2600__</tt></tag>
798 This macro is defined if the target is the Atari 2600 game console.
800 <tag><tt>__ATARI5200__</tt></tag>
802 This macro is defined if the target is the Atari 5200 game console.
804 <tag><tt>__ATARI__</tt></tag>
806 This macro is defined if the target is the Atari 400/800 (-t atari) or the Atari 800XL/130XE (-t atarixl).
808 <tag><tt>__ATARIXL__</tt></tag>
810 This macro is defined if the target is the Atari 800XL/130XE (-t atarixl).
812 <tag><tt>__ATMOS__</tt></tag>
814 This macro is defined if the target is the Oric Atmos (-t atmos).
816 <tag><tt>__C128__</tt></tag>
818 This macro is defined if the target is the Commodore 128 (-t c128).
820 <tag><tt>__C16__</tt></tag>
822 This macro is defined if the target is the Commodore 16/116 (-t c16) or the Commodore Plus/4 (-t plus4).
824 <tag><tt>__C64__</tt></tag>
826 This macro is defined if the target is the Commodore 64 (-t c64).
828 <tag><tt>__CBM__</tt></tag>
830 This macro is defined if the target system is one of the CBM targets.
832 <tag><tt>__CBM510__</tt></tag>
834 This macro is defined if the target is the CBM 500 series of computers.
836 <tag><tt>__CBM610__</tt></tag>
838 This macro is defined if the target is one of the CBM 600/700 family of
839 computers (called B series in the US).
841 <tag><tt>__CC65__</tt></tag>
843 This macro is always defined. Its value is the version number of the
844 compiler in hex. For example, version 2.14 of the compiler has this macro
845 defined as <tt/0x02E0/.
847 <tag><tt>__CC65_STD__</tt></tag>
849 This macro is defined to one of the following depending on the <tt><ref
850 id="option--standard" name="--standard"></tt> command line option:
852 <item><tt/__CC65_STD_C89__/
853 <item><tt/__CC65_STD_C99__/
854 <item><tt/__CC65_STD_CC65__/
857 <tag><tt>__DATE__</tt></tag>
859 This macro expands to the date of translation of the preprocessing
860 translation unit in the form "Mmm dd yyyy".
862 <tag><tt>__EAGERLY_INLINE_FUNCS__</tt></tag>
864 Is defined if the compiler was called with the <tt><ref id="option-eagerly-inline-funcs"
865 name="--eagerly-inline-funcs"></tt> command line option.
867 <tag><tt>__FILE__</tt></tag>
869 This macro expands to a string containing the name of the C source file.
871 <tag><tt>__GEOS__</tt></tag>
873 This macro is defined if you are compiling for one of the GEOS systems.
875 <tag><tt>__GEOS_APPLE__</tt></tag>
877 This macro is defined if you are compiling for the Apple GEOS system (-t geos-apple).
879 <tag><tt>__GEOS_CBM__</tt></tag>
881 This macro is defined if you are compiling for the GEOS 64/128 system (-t geos-cbm).
883 <tag><tt>__LINE__</tt></tag>
885 This macro expands to the current line number.
887 <tag><tt>__LUNIX__</tt></tag>
889 This macro is defined if you are compiling for the LUnix system (-t lunix).
891 <tag><tt>__LYNX__</tt></tag>
893 This macro is defined if the target is the Atari Lynx (-t lynx).
895 <tag><tt>__NES__</tt></tag>
897 This macro is defined if the target is the Nintendo Entertainment System (-t nes).
899 <tag><tt>__OPT__</tt></tag>
901 Is defined if the compiler was called with the <tt/-O/ command line option.
903 <tag><tt>__OPT_i__</tt></tag>
905 Is defined if the compiler was called with the <tt/-Oi/ command line option.
907 <tag><tt>__OPT_r__</tt></tag>
909 Is defined if the compiler was called with the <tt/-Or/ command line option.
911 <tag><tt>__OPT_s__</tt></tag>
913 Is defined if the compiler was called with the <tt/-Os/ command line option.
915 <tag><tt>__OSIC1P__</tt></tag>
917 This macro is defined if the target is the Ohio Scientific Challenger 1P
920 <tag><tt>__PET__</tt></tag>
922 This macro is defined if the target is the PET family of computers (-t pet).
924 <tag><tt>__PLUS4__</tt></tag>
926 This macro is defined if the target is the Commodore Plus/4 (-t plus4).
928 <tag><tt>__STDC_HOSTED__</tt></tag>
930 This macro is expands to the integer constant 1.
932 <tag><tt>__SIM6502__</tt></tag>
934 This macro is defined if the target is sim65 in 6502 mode (-t sim6502).
936 <tag><tt>__SIM65C02__</tt></tag>
937 This macro is defined if the target is sim65 in 65C02 mode (-t sim65c02).
939 <tag><tt>__SUPERVISION__</tt></tag>
941 This macro is defined if the target is the Supervision (-t supervision).
943 <tag><tt>__TIME__</tt></tag>
945 This macro expands to the time of translation of the preprocessing
946 translation unit in the form "hh:mm:ss".
948 <tag><tt>__VIC20__</tt></tag>
950 This macro is defined if the target is the Commodore VIC20 (-t vic20).
955 <sect>#pragmas<label id="pragmas"><p>
957 The compiler understands some pragmas that may be used to change code
958 generation and other stuff. Some of these pragmas understand a special form:
959 If the first parameter is <tt/push/, the old value is saved onto a stack
960 before changing it. The value may later be restored by using the <tt/pop/
961 parameter with the <tt/#pragma/.
964 <sect1><tt>#pragma allow-eager-inline ([push,] on|off)</tt><label id="pragma-allow-eager-inline"><p>
966 Allow eager inlining of known functions. If the argument is "off", eager
967 inlining is disabled, otherwise it is enabled. Please note that (in contrast
968 to the <tt><ref id="option-eagerly-inline-funcs" name="--eagerly-inline-funcs"></tt>
969 command line option) this pragma does not imply the <tt><ref id="option-inline-stdfuncs"
970 name="--inline-stdfuncs"></tt> command line option. Rather it marks code to be safe for
971 eager inlining of known functions if inlining of standard functions is enabled.
973 The <tt/#pragma/ understands the push and pop parameters as explained above.
976 <sect1><tt>#pragma bss-name ([push,] <name>)</tt><label id="pragma-bss-name"><p>
978 This pragma changes the name used for the BSS segment (the BSS segment
979 is used to store uninitialized data). The argument is a string enclosed
982 Note: The default linker configuration file does only map the standard
983 segments. If you use other segments, you have to create a new linker
986 Beware: The startup code will zero only the default BSS segment. If you
987 use another BSS segment, you have to do that yourself, otherwise
988 uninitialized variables do not have the value zero.
990 The <tt/#pragma/ understands the push and pop parameters as explained above.
994 #pragma bss-name ("MyBSS")
998 <sect1><tt>#pragma charmap (<index>, <code>)</tt><label id="pragma-charmap"><p>
1000 Each literal string and each literal character in the source is translated
1001 by use of a translation table. That translation table is preset when the
1002 compiler is started, depending on the target system; for example, to map
1003 ISO-8859-1 characters into PETSCII if the target is a Commodore machine.
1005 This pragma allows to change entries in the translation table, so the
1006 translation for individual characters, or even the complete table may be
1007 adjusted. Both arguments are assumed to be unsigned characters with a valid
1010 Beware of some pitfalls:
1012 <item>The character index is actually the code of the character in the
1013 C source; so, character mappings do always depend on the source
1014 character set. That means that <tt/#pragma charmap()/ is not
1015 portable -- it depends on the build environment.
1016 <item>While it is possible to use character literals as indices, the
1017 result may be somewhat unexpected, since character literals are
1018 themselves translated. For that reason, I would suggest to avoid
1019 character literals, and use numeric character codes instead.
1020 <item>It is risky to change index <tt/0x00/, because string functions depend
1021 on it. If it is changed, then the <tt/'\0'/ at the end of string
1022 literals will become non-zero. Functions that are used on those
1023 literals won't stop at the end of them. cc65 will warn you if you do
1024 change that code number. You can turn off that <tt/remap-zero/ warning
1025 if you are certain that you know what you are doing (see <tt/<ref
1026 id="pragma-warn" name="#pragma warn()">/).
1031 /* Use a space wherever an 'a' occurs in ISO-8859-1 source */
1032 #pragma charmap (0x61, 0x20);
1036 <sect1><tt>#pragma check-stack ([push,] on|off)</tt><label id="pragma-check-stack"><p>
1038 Tells the compiler to insert calls to a stack checking subroutine to detect
1039 stack overflows. The stack checking code will lead to somewhat larger and
1040 slower programs, so you may want to use this pragma when debugging your
1041 program and switch it off for the release version. If a stack overflow is
1042 detected, the program is aborted.
1044 If the argument is "off", stack checks are disabled (the default), otherwise
1047 The <tt/#pragma/ understands the push and pop parameters as explained above.
1050 <sect1><tt>#pragma code-name ([push,] <name>)</tt><label id="pragma-code-name"><p>
1052 This pragma changes the name used for the CODE segment (the CODE segment
1053 is used to store executable code). The argument is a string enclosed in
1056 Note: The default linker configuration file does only map the standard
1057 segments. If you use other segments, you have to create a new linker
1060 The <tt/#pragma/ understands the push and pop parameters as explained above.
1064 #pragma code-name ("MyCODE")
1068 <sect1><tt>#pragma codesize ([push,] <int>)</tt><label id="pragma-codesize"><p>
1070 This pragma allows finer control about speed vs. size decisions in the code
1071 generation and optimization phase. It gives the allowed size increase factor
1072 (in percent). The default is can be changed by use of the <tt/<ref
1073 id="option-codesize" name="--codesize">/ compiler option.
1075 The <tt/#pragma/ understands the push and pop parameters as explained above.
1078 <sect1><tt>#pragma data-name ([push,] <name>)</tt><label id="pragma-data-name"><p>
1080 This pragma changes the name used for the DATA segment (the DATA segment
1081 is used to store initialized data). The argument is a string enclosed in
1084 Note: The default linker configuration file does only map the standard
1085 segments. If you use other segments, you have to create a new linker
1088 The <tt/#pragma/ understands the push and pop parameters as explained above.
1092 #pragma data-name ("MyDATA")
1096 <sect1><tt>#pragma inline-stdfuncs ([push,] on|off)</tt><label id="pragma-inline-stdfuncs"><p>
1098 Allow the compiler to inline some standard functions from the C library like
1099 strlen. If the argument is "off", inlining is disabled, otherwise it is enabled.
1101 See also the the <tt/<ref id="option-inline-stdfuncs" name="--inline-stdfuncs">/
1102 command line option.
1104 The <tt/#pragma/ understands the push and pop parameters as explained above.
1107 <sect1><tt>#pragma local-strings ([push,] on|off)</tt><label id="pragma-local-strings"><p>
1109 When "on", emit string literals to the data segment when they're encountered
1110 in the source. The default ("off") is to keep string literals until end of
1111 assembly, merge read only literals if possible, and then output the literals
1112 into the data or rodata segment that is active at that point.
1114 Using this <tt/#pragma/ it is possible to control the behaviour from within
1115 the source. When <tt/#pragma local-strings/ is active, string literals are
1116 output immediately, which means that they go into the currently active data
1117 or rodata segment, but cannot be merged. When inactive, string literals are
1118 remembered and output as a whole when translation is finished.
1121 <sect1><tt>#pragma optimize ([push,] on|off)</tt><label id="pragma-optimize"><p>
1123 Switch optimization on or off. If the argument is "off", optimization is
1124 disabled, otherwise it is enabled. Please note that this pragma only effects
1125 whole functions. The setting in effect when the function is encountered will
1126 determine if the generated code is optimized or not.
1128 Optimization and code generation is also controlled by the <ref
1129 id="pragma-codesize" name="codesize pragma">.
1131 The default is "off", but may be changed with the <tt/<ref name="-O"
1132 id="option-O">/ compiler option.
1134 The <tt/#pragma/ understands the push and pop parameters as explained above.
1137 <sect1><tt>#pragma rodata-name ([push,] <name>)</tt><label id="pragma-rodata-name"><p>
1139 This pragma changes the name used for the RODATA segment (the RODATA
1140 segment is used to store readonly data). The argument is a string
1141 enclosed in double quotes.
1143 Note: The default linker configuration file does only map the standard
1144 segments. If you use other segments, you have to create a new linker
1147 The <tt/#pragma/ understands the push and pop parameters as explained above.
1151 #pragma rodata-name ("MyRODATA")
1155 <sect1><tt>#pragma regvaraddr ([push,] on|off)</tt><label id="pragma-regvaraddr"><p>
1157 The compiler does not allow to take the address of register variables.
1158 The regvaraddr pragma changes this. Taking the address of a register
1159 variable is allowed after using this pragma with "on" as argument.
1160 Using "off" as an argument switches back to the default behaviour.
1162 Beware: The C standard does not allow taking the address of a variable
1163 declared as register. So your programs become non-portable if you use
1164 this pragma. In addition, your program may not work. This is usually the
1165 case if a subroutine is called with the address of a register variable,
1166 and this subroutine (or a subroutine called from there) uses
1167 register variables. So be careful with this #pragma.
1169 The <tt/#pragma/ understands the push and pop parameters as explained above.
1173 #pragma regvaraddr(on) /* Allow taking the address
1174 * of register variables
1179 <sect1><tt>#pragma register-vars ([push,] on|off)</tt><label id="pragma-register-vars"><p>
1181 Enables or disables use of register variables. If register variables are
1182 disabled (the default), the <tt/register/ keyword is ignored. Register
1183 variables are explained in more detail in <ref id="register-vars" name="a separate
1186 The <tt/#pragma/ understands the push and pop parameters as explained above.
1189 <sect1><tt>#pragma signed-chars ([push,] on|off)</tt><label id="pragma-signed-chars"><p>
1191 Changes the signedness of the default character type. If the argument is
1192 "on", default characters are signed, otherwise characters are unsigned. The
1193 compiler default is to make characters unsigned since this creates a lot
1194 better code. This default may be overridden by the <tt/<ref
1195 name="--signed-chars" id="option-signed-chars">/ command line option.
1197 The <tt/#pragma/ understands the push and pop parameters as explained above.
1200 <sect1><tt>#pragma static-locals ([push,] on|off)</tt><label id="pragma-static-locals"<p>
1202 Use variables in the bss segment instead of variables on the stack. This
1203 pragma changes the default set by the compiler option <tt/<ref
1204 name="--static-locals" id="option-static-locals">/. If the argument is "on",
1205 local variables are allocated in the BSS segment, leading to shorter and in
1206 most cases faster, but non-reentrant code.
1208 The <tt/#pragma/ understands the push and pop parameters as explained above.
1211 <sect1><tt>#pragma warn (name, [push,] on|off)</tt><label id="pragma-warn"><p>
1213 Switch compiler warnings on or off. "name" is the name of a warning (see the
1214 <tt/<ref name="-W" id="option-W">/ compiler option for a list). The name is
1215 followed either by "pop", which restores the last pushed state, or by "on" or
1216 "off", optionally preceeded by "push" to push the current state before
1221 /* Don't warn about the unused parameter in function func */
1222 #pragma warn (unused-param, push, off)
1223 static int func (int unused)
1227 #pragma warn (unused-param, pop)
1231 <sect1><tt>#pragma writable-strings ([push,] on|off)</tt><label id="pragma-writable-strings"><p>
1233 Changes the storage location of string literals. For historical reasons,
1234 the C standard defines that string literals are of type "char[]", but
1235 writing to such a literal causes undefined behaviour. Most compilers
1236 (including cc65) place string literals in the read-only data segment, which
1237 may cause problems with old C code that writes to string literals.
1239 Using this pragma (or the corresponding command line option <tt/<ref
1240 name="--writable-strings" id="option-writable-strings">/) causes the
1241 literals to be placed in the data segment so they can be written to without
1244 The <tt/#pragma/ understands the push and pop parameters as explained above.
1247 <sect1><tt>#pragma zpsym (<name>)</tt><p>
1249 Tell the compiler that the -- previously as external declared -- symbol with
1250 the given name is a zero page symbol (usually from an assembler file).
1251 The compiler will create a matching import declaration for the assembler.
1256 #pragma zpsym ("foo"); /* foo is in the zeropage */
1261 <sect>Register variables<label id="register-vars"><p>
1263 The runtime for all supported platforms has 6 bytes of zero page space
1264 available for register variables (this could be increased, but I think it's a
1265 good value). So you can declare register variables up to a total size of 6 per
1266 function. The compiler will allocate register space on a "first come, first
1267 served" base and convert any <tt/register/ declarations that exceed the
1268 available register space silently to <tt/auto/. Parameters can also be
1269 declared as <tt/register/, this will in fact give slightly shorter code than
1270 using a register variable.
1272 Since a function must save the current values of the registers on entry and
1273 restore them on exit, there is an overhead associated with register variables,
1274 and this overhead is quite high (about 20 bytes per variable). This means that
1275 just declaring anything as <tt/register/ is not a good idea.
1277 The best use for register variables are pointers, especially those that point
1278 to structures. The magic number here is about 3 uses of a struct field: If the
1279 function contains this number or even more, the generated code will be usually
1280 shorter and faster when using a register variable for the struct pointer. The
1281 reason for this is that the register variable can in many cases be used as a
1282 pointer directly. Having a pointer in an auto variable means that this pointer
1283 must first be copied into a zero page location, before it can be dereferenced.
1285 Second best use for register variables are counters. However, there is not
1286 much difference in the code generated for counters, so you will need at least
1287 100 operations on this variable (for example in a loop) to make it worth the
1288 trouble. The only savings you get here are by the use of a zero page variable
1289 instead of one on the stack or in the data segment.
1291 Register variables must be explicitly enabled, either by using <tt/<ref
1292 name="-Or" id="option-O">/ or <tt/<ref name="--register-vars"
1293 id="option-register-vars">/ on the command line or by use of <tt/<ref
1294 name="#pragma register-vars" id="pragma-register-vars">/. Register variables
1295 are only accepted on function top level, register variables declared in
1296 interior blocks are silently converted to <tt/auto/. With register variables
1297 disabled, all variables declared as <tt/register/ are actually auto variables.
1299 Please take care when using register variables: While they are helpful and can
1300 lead to a tremendous speedup when used correctly, improper usage will cause
1301 bloated code and a slowdown.
1305 <sect>Inline assembler<label id="inline-asm"><p>
1307 The compiler allows to insert assembler statements into the output file. The
1311 asm [optional volatile] (<string literal>[, optional parameters]) ;
1315 __asm__ [optional volatile] (<string literal>[, optional parameters]) ;
1319 The first form is in the user namespace; and, is disabled by <tt><ref
1320 id="option--standard" name="--standard"></tt> if the argument is not <tt/cc65/.
1322 The <tt/asm/ statement can be used only inside a function. Please note that
1323 the result of an inline assembler expression is always of type <tt/void/.
1325 The contents of the string literal are preparsed by the compiler; and, inserted
1326 into the generated assembly output, so that it can be processed further by
1327 the backend -- and, especially the optimizer. For that reason, the compiler does
1328 allow only regular 6502 opcodes to be used with the inline assembler. Pseudo
1329 instructions (like <tt/.import/, <tt/.byte/, and so on) are <em/not/ allowed,
1330 even if the ca65 assembler (which is used to translate the generated assembler
1331 code) would accept them. The built-in inline assembler is not a replacement for
1332 the full-blown macro assembler which comes with the compiler.
1334 Note: Inline assembler statements are subject to all optimizations done by the
1335 compiler. There currently is no way to protect an inline assembler statement
1336 -- alone -- from being moved or removed completely by the optimizer. If in
1337 doubt, check the generated assembler output; or, disable optimizations (for
1340 As a shortcut, you can put the <tt/volatile/ qualifier in your <tt/asm/
1341 statements. It will disable optimization for the functions in which those
1342 <tt/asm volatile/ statements sit. The effect is the same as though you put
1343 <tt/#pragma optimize(push, off)/ above those functions, and <tt/#pragma
1344 optimize(pop)/ below those functions.
1346 The string literal may contain format specifiers from the following list. For
1347 each format specifier, an argument is expected which is inserted instead of
1348 the format specifier, before passing the assembly code line to the backend.
1351 <item><tt/%b/ - Numerical 8-bit value
1352 <item><tt/%w/ - Numerical 16-bit value
1353 <item><tt/%l/ - Numerical 32-bit value
1354 <item><tt/%v/ - Assembler name of a global variable or function
1355 <item><tt/%o/ - Stack offset of a local variable
1356 <item><tt/%g/ - Assembler name of a C label
1357 <item><tt/%s/ - The argument is converted to a string
1358 <item><tt/%%/ - The % sign itself
1361 Using those format specifiers, you can access C <tt/#defines/, variables, or
1362 similar stuff from the inline assembler. For example, to load the value of
1363 a C <tt/#define/ into the Y index register, one would use
1367 __asm__ ("ldy #%b", OFFS);
1370 Or, to access a struct member of a static variable:
1376 unsigned char color;
1378 static pixel_t pixel;
1379 __asm__ ("ldy #%b", offsetof(pixel_t, color));
1380 __asm__ ("lda %v,y", pixel);
1383 The next example shows how to use global variables to exchange data between C
1384 and assembler; and, how to handle assembler jumps:
1387 static unsigned char globalSubA, globalSubB, globalSubResult;
1389 /* return a-b, return 255 if b>a */
1390 unsigned char sub (unsigned char a, unsigned char b)
1395 __asm__ ("lda %v", globalSubA);
1396 __asm__ ("sbc %v", globalSubB);
1397 __asm__ ("bcs %g", jumpSubNoError);
1398 __asm__ ("lda #$FF");
1400 __asm__ ("sta %v", globalSubResult);
1401 return globalSubResult;
1406 Arrays also can be accessed:
1409 static const unsigned char globalSquareTable[] = {
1410 0, 1, 4, 9, 16, 25, 36, 49, 64, 81,
1411 100, 121, 144, 169, 196, 225
1413 static unsigned char globalSquareA, globalSquareResult;
1415 /* return a*a for a<16, else 255 */
1416 unsigned char square (unsigned char a)
1422 __asm__ ("ldx %v", globalSquareA);
1423 __asm__ ("lda %v,x", globalSquareTable);
1424 __asm__ ("sta %v", globalSquareResult);
1425 return globalSquareResult;
1430 Note: Do not embed the assembler labels that are used as names of global
1431 variables or functions into your <tt/asm/ statements. Code such as this:
1435 int bar (void) { return 1; }
1437 __asm__ ("lda _foo"); /* DON'T DO THAT! */
1439 __asm__ ("jsr _bar"); /* DON'T DO THAT EITHER! */
1443 might stop working if the way that the compiler generates those names is changed in
1444 a future version. Instead, use the format specifiers from the table above:
1447 __asm__ ("lda %v", foo); /* OK */
1449 __asm__ ("jsr %v", bar); /* OK */
1455 <sect>Implementation-defined behavior<p>
1457 This section describes the behavior of cc65 when the standard describes the
1458 behavior as implementation-defined.
1464 This is the original compiler copyright:
1467 --------------------------------------------------------------------------
1470 This is the copyright notice for RA65, LINK65, LIBR65, and other
1471 Atari 8-bit programs. Said programs are Copyright 1989, by John R.
1472 Dunning. All rights reserved, with the following exceptions:
1474 Anyone may copy or redistribute these programs, provided that:
1476 1: You don't charge anything for the copy. It is permissable to
1477 charge a nominal fee for media, etc.
1479 2: All source code and documentation for the programs is made
1480 available as part of the distribution.
1482 3: This copyright notice is preserved verbatim, and included in
1485 You are allowed to modify these programs, and redistribute the
1486 modified versions, provided that the modifications are clearly noted.
1488 There is NO WARRANTY with this software, it comes as is, and is
1489 distributed in the hope that it may be useful.
1491 This copyright notice applies to any program which contains
1492 this text, or the refers to this file.
1494 This copyright notice is based on the one published by the Free
1495 Software Foundation, sometimes known as the GNU project. The idea
1496 is the same as theirs, ie the software is free, and is intended to
1497 stay that way. Everybody has the right to copy, modify, and re-
1498 distribute this software. Nobody has the right to prevent anyone
1499 else from copying, modifying or redistributing it.
1501 --------------------------------------------------------------------------
1504 Small parts of the compiler (parts of the preprocessor and main parser) are
1505 still covered by this copyright. The main portion is covered by the usual
1506 cc65 license, which reads:
1508 This software is provided 'as-is', without any expressed or implied
1509 warranty. In no event will the authors be held liable for any damages
1510 arising from the use of this software.
1512 Permission is granted to anyone to use this software for any purpose,
1513 including commercial applications, and to alter it and redistribute it
1514 freely, subject to the following restrictions:
1517 <item> The origin of this software must not be misrepresented; you must not
1518 claim that you wrote the original software. If you use this software
1519 in a product, an acknowledgment in the product documentation would be
1520 appreciated but is not required.
1521 <item> Altered source versions must be plainly marked as such, and must not
1522 be misrepresented as being the original software.
1523 <item> This notice may not be removed or altered from any source