1 <!doctype linuxdoc system>
4 <title>cc65 Users Guide
5 <author>Ullrich von Bassewitz, <htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">
6 <date>03.09.2000, 02.10.2001
9 cc65 is a C compiler for 6502 targets. It supports several 6502 based home
10 computers like the Commodore and Atari machines, but it is easily retargetable.
13 <!-- Table of contents -->
16 <!-- 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. In fact, I'm
27 planning a complete rewrite (that is, a complete new compiler) for the
28 next release, since there are too many limitations in the current code,
29 and removing these limitations would mean a rewrite of many more parts of
32 There is a separate document named "library.txt" that covers the library
33 available for the compiler. If you know C and are interested in doing
34 actual programming, the library documentation is probably of much more use
37 If you need some hints for getting the best code out of the compiler, you
38 may have a look at "coding.txt" which covers some code generation issues.
44 The compiler translates C files into files containing assembler code that
45 may be translated by the ca65 macroassembler (for more information about
46 the assembler, have a look at ca65.txt).
49 <sect1>Command line option overview<p>
51 The compiler may be called as follows:
54 ---------------------------------------------------------------------------
55 Usage: cc65 [options] file
58 -Cl Make local variables static
59 -Dsym[=defn] Define a symbol
60 -I dir Set an include directory search path
62 -Oi Optimize code, inline more code
63 -Or Enable register variables
64 -Os Inline some known functions
65 -T Include source as comment
66 -V Print the compiler version number
69 -g Add debug info to object file
71 -j Default characters are signed
72 -o name Name the output file
73 -r Enable register variables
74 -t sys Set the target system
78 --add-source Include source as comment
79 --ansi Strict ANSI mode
80 --bss-name seg Set the name of the BSS segment
81 --check-stack Generate stack overflow checks
82 --code-name seg Set the name of the CODE segment
83 --codesize x Accept larger code by factor x
84 --cpu type Set cpu type
85 --create-dep Create a make dependency file
86 --data-name seg Set the name of the DATA segment
88 --debug-info Add debug info to object file
89 --help Help (this text)
90 --include-dir dir Set an include directory search path
91 --register-space b Set space available for register variables
92 --register-vars Enable register variables
93 --rodata-name seg Set the name of the RODATA segment
94 --signed-chars Default characters are signed
95 --static-locals Make local variables static
96 --target sys Set the target system
97 --verbose Increase verbosity
98 --version Print the compiler version number
99 ---------------------------------------------------------------------------
103 <sect1>Command line options in detail<p>
105 Here is a description of all the command line options:
109 <label id="option-A">
110 <tag><tt>-A, --ansi</tt></tag>
112 This option disables any compiler exensions. Have a look at section 5
113 for a discussion of compiler extensions. In addition, the macro
114 <tt/__STRICT_ANSI__/ is defined, when using one of these options.
117 <tag><tt>--bss-name seg</tt></tag>
119 Set the name of the bss segment.
122 <tag><tt>--check-stack</tt></tag>
124 Tells the compiler to generate code that checks for stack overflows. See
125 <tt><ref id="pragma-checkstack" name="#pragma checkstack"></tt> for an
126 explanation of this feature.
129 <tag><tt>--code-name seg</tt></tag>
131 Set the name of the code segment.
134 <tag><tt>--codesize x</tt></tag>
136 This options allows finer control about speed vs. size decisions in the
137 code generation phase. It gives the allowed size increase factor (in
138 percent). The default is 100 when not using <tt/-Oi/ and 200 when using
139 <tt/-Oi/ (<tt/-Oi/ is the same as <tt/--codesize 200/).
142 <tag><tt>--cpu CPU</tt></tag>
144 A new, still experimental option. You may specify "6502" or "65C02" as
145 the CPU. 6502 is the default, so this will not change anything.
146 Specifying 65C02 will use a few 65C02 instructions when generating code.
147 Don't expect too much from this option: It is still new (and may have
148 bugs), and the additional instructions for the 65C02 are not that
152 <tag><tt>--create-dep</tt></tag>
154 Tells the compiler to generate a file containing the dependency list for
155 the compiled module in makefile syntax. The file is named as the C input
156 file with the extension replaced by <tt/.u/.
159 <tag><tt>-d, --debug</tt></tag>
161 Enables debug mode, something that should not be needed for mere
165 <tag><tt>-D sym[=definition]</tt></tag>
167 Define a macro on the command line. If no definition is given, the macro
168 is defined to the value "1".
171 <tag><tt>-g, --debug-info</tt></tag>
173 This will cause the compiler to insert a <tt/.DEBUGINFO/ command into the
174 generated assembler code. This will cause the assembler to include all
175 symbols in a special section in the object file.
178 <tag><tt>-h, --help</tt></tag>
180 Print the short option summary shown above.
183 <tag><tt>-o name</tt></tag>
185 Specify the name of the output file. If you don't specify a name, the
186 name of the C input file is used, with the extension replaced by ".s".
189 <tag><tt>-r, --register-vars</tt></tag>
191 <tt/-r/ will make the compiler honor the <tt/register/ keyword. Local
192 variables may be placed in registers (which are actually zero page
193 locations). There is some overhead involved with register variables, since
194 the old contents of the registers must be saved and restored. Since register
195 variables are of limited use without the optimizer, there is also a combined
196 switch: <tt/-Or/ will enable both, the optmizer and register variables.
198 For more information about register variables see <ref id="regvars"
199 name="register variables">.
202 <tag><tt>--register-space</tt></tag>
204 This option takes a numeric parameter and is used to specify, how much
205 zero page register space is available. Please note that just giving this
206 option will not increase or decrease by itself, it will just tell the
207 compiler about the available space. You will have to allocate that space
208 yourself using an assembler module with the necessary allocations, and a
209 linker configuration that matches the assembler module. The default value
210 for this option is 6 (bytes).
212 If you don't know what all this means, please don't use this option.
215 <tag><tt>--rodata-name seg</tt></tag>
217 Set the name of the rodata segment (the segment used for readonly data).
220 <tag><tt>-j, --signed-chars</tt></tag>
222 Using this option, you can make the default characters signed. Since the
223 6502 has no provisions for sign extending characters (which is needed on
224 almost any load operation), this will make the code larger and slower. A
225 better way is to declare characters explicitly as "signed" if needed. You
226 can also use <tt><ref id="pragma-signedchars" name="#pragma
227 signedchars"></tt> for better control of this option.
230 <tag><tt>-t target, --target target</tt></tag>
232 This option is used to set the target system. The target system
233 determines things like the character set that is used for strings and
234 character constants. The following target systems are supported:
241 <item>c16 (works also for the c116 with memory up to 32K)
245 <item>cbm510 (CBM-II series with 40 column video)
246 <item>cbm610 (all CBM-II II computers with 80 column video)
247 <item>pet (all CBM PET systems except the 2001)
251 <tag><tt>-v, --verbose</tt></tag>
253 Using this option, the compiler will be somewhat more verbose if errors
254 or warnings are encountered.
257 <tag><tt>-Cl, --static-locals</tt></tag>
259 Use static storage for local variables instead of storage on the stack.
260 Since the stack is emulated in software, this gives shorter and usually
261 faster code, but the code is no longer reentrant. The difference between
262 <tt/-Cl/ and declaring local variables as static yourself is, that
263 initializer code is executed each time, the function is entered. So when
274 the variable a will always have the value 1 when entering the function
275 and using <tt/-Cl/, while in
280 static unsigned a = 1;
285 the variable a will have the value 1 only the first time, the function
286 is entered, and will keep the old value from one call of the function to
289 You may also use <tt><ref id="pragma-staticlocals" name="#pragma
290 staticlocals"></tt> to change this setting in your sources.
293 <tag><tt>-I dir, --include-dir dir</tt></tag>
295 Set a directory where the compiler searches for include files. You may
296 use this option multiple times to add more than one directory to the
300 <tag><tt>-O, -Oi, -Or, -Os</tt></tag>
302 Enable an optimizer run over the produced code.
304 Using <tt/-Oi/, the code generator will inline some code where otherwise a
305 runtime functions would have been called, even if the generated code is
306 larger. This will not only remove the overhead for a function call, but will
307 make the code visible for the optimizer. <tt/-Oi/ is an alias for
310 <tt/-Or/ will make the compiler honor the <tt/register/ keyword. Local
311 variables may be placed in registers (which are actually zero page
312 locations). There is some overhead involved with register variables, since
313 the old contents of the registers must be saved and restored. In addition,
314 the current implementation does not make good use of register variables, so
315 using <tt/-Or/ may make your program even slower and larger. Use with care!
317 Using <tt/-Os/ will force the compiler to inline some known functions from
318 the C library like strlen. Note: This has two consequences:
321 <item>You may not use names of standard C functions in your own code. If you
322 do that, your program is not standard compliant anyway, but using
323 <tt/-Os/ will actually break things.
325 <item>The inlined string and memory functions will not handle strings or
326 memory areas larger than 255 bytes. Similar, the inlined <tt/is..()/
327 functions will not work with values outside char range.
331 It is possible to concatenate the modifiers for <tt/-O/. For example, to
332 enable register variables and inlining of known functions, you may use
336 <tag><tt>-T, --add-source</tt></tag>
338 This include the source code as comments in the generated code. This is
342 <tag><tt>-V, --version</tt></tag>
344 Print the version number of the compiler. When submitting a bug report,
345 please include the operating system you're using, and the compiler
349 <tag><tt>-W</tt></tag>
351 This option will suppress any warnings generated by the compiler. Since
352 any source file may be written in a manner that it will not produce
353 compiler warnings, using this option is usually not a good idea.
358 <sect>Input and output<p>
360 The compiler will accept one C file per invocation and create a file with
361 the same base name, but with the extension replaced by ".s". The output
362 file contains assembler code suitable for the use with the ca65 macro
365 In addition to the paths named in the <tt/-I/ option on the command line, the
366 directory named in the environment variable <tt/CC65_INC/ is added to the
367 search path for include files on startup.
371 <sect>Differences to the ISO standard<p>
373 Here is a list of differences between the language, the compiler accepts,
374 and the one defined by the ISO standard:
378 <item> The compiler allows single line comments that start with //. This
379 feature is disabled in strict ANSI mode.
381 <item> The compiler allows unnamed parameters in parameter lists. The
382 compiler will not issue warnings about unused parameters that don't
383 have a name. This feature is disabled in strict ANSI mode.
385 <item> The compiler has some additional keywords:
391 <item><tt/__fastcall__/
395 <item><tt/__attribute__/
398 The keywords without the underlines are disabled in strict ANSI mode.
400 <item> The datatypes "float" and "double" are not available.
402 <item> The compiler does not support bit fields.
404 <item> C Functions may not return structs (or unions), and structs may not
405 be passed as parameters by value. However, struct assignment *is*
408 <item> Part of the C library is available only with fastcall calling
409 conventions (see below). This means, that you may not mix pointers to
410 those functions with pointers to user written functions.
414 There may be some more minor differences, I'm currently not aware off. The
415 biggest problem is the missing float data type. With this limitation in
416 mind, you should be able to write fairly portable code.
422 This cc65 version has some extensions to the ISO C standard.
426 <item> The compiler allows // comments (like in C++ and in the proposed C9x
427 standard). This feature is disabled by <tt><ref id="option-A"
431 <item> The compiler allows to insert assembler statements into the output
435 asm (<string literal>[, optional parameters]) ;
439 __asm__ (<string literal>[, optional parameters]) ;
442 The first form is in the user namespace and is disabled if the <tt/-A/
445 There is a whole section covering inline assembler statements,
446 <ref id="inline-asm" name="see there">.
449 <item> There is a special calling convention named "fastcall". This calling
450 convention is currently only usable for functions written in
451 assembler. The syntax for a function declaration using fastcall is
454 <return type> fastcall <function name> (<parameter list>)
458 <return type> __fastcall__ <function name> (<parameter list>)
462 void __fastcall__ f (unsigned char c)
464 The first form of the fastcall keyword is in the user namespace and is
465 therefore disabled in strict ANSI mode.
467 For functions declared as <tt/fastcall/, the rightmost parameter is not
468 pushed on the stack but left in the primary register when the function
469 is called. This will reduce the cost when calling assembler functions
470 significantly, especially when the function itself is rather small.
473 <item> There are two pseudo variables named <tt/__AX__/ and <tt/__EAX__/.
474 Both refer to the primary register that is used by the compiler to
475 evaluate expressions or return function results. <tt/__AX__/ is of
476 type <tt/unsigned int/ and <tt/__EAX__/ of type <tt/long unsigned int/
477 respectively. The pseudo variables may be used as lvalue and rvalue as
478 every other variable. They are most useful together with short
479 sequences of assembler code. For example, the macro
482 #define hi(x) (__AX__=(x),asm("\ttxa\n\tldx\t#$00",__AX__)
485 will give the high byte of any unsigned value.
488 <item> Inside a function, the identifier <tt/__func__/ gives the name of the
489 current function as a string. Outside of functions, <tt/__func__/ is
494 #define PRINT_DEBUG(s) printf ("%s: %s\n", __func__, s);
497 The macro will print the name of the current function plus a given
501 <item> cc65 allows the initialization of <tt/void/ variables. This may be
502 used to create variable structures that are more compatible with
503 interfaces written for assembler languages. Here is an example:
506 void GCmd = { (char)3, (unsigned)0x2000, (unsigned)0x3000 };
509 This will be translated as follows:
518 Since the variable is of type <tt/void/ you may not use it as is.
519 However, taking the address of the variable results in a <tt/void*/
520 which may be passed to any function expecting a pointer.
522 See the <htmlurl url="geos.html" name="GEOS library"> for examples on
523 how to use this feature.
526 <item> cc65 implements flexible array struct members as defined in the C99 ISO
527 standard. As an extension, in non ANSI mode, these fields may be
528 initialized. There are several exceptions, however (which is probably
529 the reason why the standard does not define this feature, because it is
530 highly unorthogonal). Flexible array members cannot be initialized...
533 <item> ...when defining an array of structs with flexible members.
534 <item> ...if such a struct is a member field of another struct which
535 is not the last field.
536 <item> If the struct which contains a flexible array member is
537 declared as <tt/register/ and the size and compiler settings
538 do allow the compiler to actually place the struct into the
539 register bank in the zero page.
542 Please note that - as defined in the ISO C standard - the <tt/sizeof/
543 operator returns the struct size with the flexible array member having
544 size zero, even if it is initialized.
551 <sect>Predefined macros<p>
553 The compiler defines several macros at startup:
557 <tag><tt>__CC65__</tt></tag>
559 This macro is always defined. Its value is the version number of the
560 compiler in hex. Version 2.0.1 of the compiler will have this macro defined
563 <tag><tt>__APPLE2__</tt></tag>
565 This macro is defined if the target is the Apple ][ (-t apple2).
567 <tag><tt>__ATARI__</tt></tag>
569 This macro is defined if the target is one of the Atari computers
570 (400/800/130XL/800XL).
572 <tag><tt>__ATMOS__</tt></tag>
574 This macro is defined if the target is the Oric Atmos (-t atmos).
576 <tag><tt>__CBM__</tt></tag>
578 This macro is defined if the target system is one of the CBM targets.
580 <tag><tt>__C16__</tt></tag>
582 This macro is defined if the target is the c16 (-t c16).
584 <tag><tt>__C64__</tt></tag>
586 This macro is defined if the target is the c64 (-t c64).
588 <tag><tt>__C128__</tt></tag>
590 This macro is defined if the target is the c128 (-t c128).
592 <tag><tt>__CBM510__</tt></tag>
594 This macro is defined if the target is the CBM 500 series of computers.
596 <tag><tt>__CBM610__</tt></tag>
598 This macro is defined if the target is one of the CBM 600/700 family of
599 computers (called B series in the US).
601 <tag><tt>__GEOS__</tt></tag>
603 This macro is defined if you are compiling for the GEOS system (-t geos).
605 <tag><tt>__PET__</tt></tag>
607 This macro is defined if the target is the PET family of computers (-t pet).
609 <tag><tt>__PLUS4__</tt></tag>
611 This macro is defined if the target is the plus/4 (-t plus4).
613 <tag><tt>__VIC20__</tt></tag>
615 This macro is defined if the target is the vic20 (-t vic20).
617 <tag><tt>__FILE__</tt></tag>
619 This macro expands to a string containing the name of the C source file.
621 <tag><tt>__LINE__</tt></tag>
623 This macro expands to the current line number.
625 <tag><tt>__STRICT_ANSI__</tt></tag>
627 This macro is defined to 1 if the <tt/-A/ compiler option was given, and
630 <tag><tt>__OPT__</tt></tag>
632 Is defined if the compiler was called with the <tt/-O/ command line option.
634 <tag><tt>__OPT_i__</tt></tag>
636 Is defined if the compiler was called with the <tt/-Oi/ command line option.
638 <tag><tt>__OPT_r__</tt></tag>
640 Is defined if the compiler was called with the <tt/-Or/ command line option.
642 <tag><tt>__OPT_s__</tt></tag>
644 Is defined if the compiler was called with the <tt/-Os/ command line option.
649 <sect>#pragmas<label id="pragmas"><p>
651 The compiler understands some pragmas that may be used to change code
652 generation and other stuff.
655 <sect1><tt>#pragma bssseg (<name>)</tt><p>
657 This pragma changes the name used for the BSS segment (the BSS segment
658 is used to store uninitialized data). The argument is a string enclosed
661 Note: The default linker configuration file does only map the standard
662 segments. If you use other segments, you have to create a new linker
665 Beware: The startup code will zero only the default BSS segment. If you
666 use another BSS segment, you have to do that yourself, otherwise
667 uninitialized variables do not have the value zero.
671 #pragma bssseg ("MyBSS")
675 <sect1><tt>#pragma charmap (<index>, <code>)</tt><p>
677 Each literal string and each literal character in the source is translated
678 by use of a translation table. This translation table is preset when the
679 compiler is started depending on the target system, for example to map
680 ISO-8859-1 characters into PETSCII if the target is a commodore machine.
682 This pragma allows to change entries in the translation table, so the
683 translation for individual characters, or even the complete table may be
686 Both arguments are assumed to be unsigned characters with a valid range of
689 Beware of two pitfalls:
692 <item>The character index is actually the code of the character in the
693 C source, so character mappings do always depend on the source
694 character set. This means that <tt/#pragma charmap/ is not portable
695 - it depends on the build environment.
696 <item>While it is possible to use character literals as indices, the
697 result may be somewhat unexpected, since character literals are
698 itself translated. For this reason I would suggest to avoid
699 character literals and use numeric character codes instead.
704 /* Use a space wherever an 'a' occurs in ISO-8859-1 source */
705 #pragma charmap (0x61, 0x20);
709 <sect1><tt>#pragma checkstack (on|off)</tt><label
710 id="pragma-checkstack"><p>
712 Tells the compiler to insert calls to a stack checking subroutine to detect
713 stack overflows. The stack checking code will lead to somewhat larger and
714 slower programs, so you may want to use this pragma when debugging your
715 program and switch it off for the release version. If a stack overflow is
716 detected, the program is aborted.
718 If the argument is "off", stack checks are disabled (the default), otherwise
722 <sect1><tt>#pragma codeseg (<name>)</tt><p>
724 This pragma changes the name used for the CODE segment (the CODE segment
725 is used to store executable code). The argument is a string enclosed in
728 Note: The default linker configuration file does only map the standard
729 segments. If you use other segments, you have to create a new linker
734 #pragma codeseg ("MyCODE")
738 <sect1><tt>#pragma dataseg (<name>)</tt><p>
740 This pragma changes the name used for the DATA segment (the DATA segment
741 is used to store initialized data). The argument is a string enclosed in
744 Note: The default linker configuration file does only map the standard
745 segments. If you use other segments, you have to create a new linker
750 #pragma dataseg ("MyDATA")
754 <sect1><tt>#pragma rodataseg (<name>)</tt><p>
756 This pragma changes the name used for the RODATA segment (the RODATA
757 segment is used to store readonly data). The argument is a string
758 enclosed in double quotes.
760 Note: The default linker configuration file does only map the standard
761 segments. If you use other segments, you have to create a new linker
766 #pragma rodataseg ("MyRODATA")
770 <sect1><tt>#pragma regvaraddr (on|off)</tt><p>
772 The compiler does not allow to take the address of register variables.
773 The regvaraddr pragma changes this. Taking the address of a register
774 variable is allowed after using this pragma with "on" as argument.
775 Using "off" as an argument switches back to the default behaviour.
777 Beware: The C standard does not allow taking the address of a variable
778 declared as register. So your programs become non-portable if you use
779 this pragma. In addition, your program may not work. This is usually the
780 case if a subroutine is called with the address of a register variable,
781 and this subroutine (or a subroutine called from there) uses itself
782 register variables. So be careful with this #pragma.
786 #pragma regvaraddr(1) /* Allow taking the address
787 * of register variables
792 <sect1><tt>#pragma signedchars (on|off)</tt><label id="pragma-signedchars"><p>
794 Changes the signedness of the default character type. If the argument is
795 "on", default characters are signed, otherwise characters are unsigned.
796 The compiler default is to make characters unsigned since this creates a
797 lot better code. This default may be overridden by the <tt/--signed-chars/
801 <sect1><tt>#pragma staticlocals (on|off)</tt><label
802 id="pragma-staticlocals"<p>
804 Use variables in the bss segment instead of variables on the stack. This
805 pragma changes the default set by the compiler option <tt/-Cl/. If the
806 argument is "on", local variables are allocated in the BSS segment,
807 leading to shorter and in most cases faster, but non-reentrant code.
810 <sect1><tt>#pragma zpsym (<name>)</tt><p>
812 Tell the compiler that the - previously as external declared - symbol with
813 the given name is a zero page symbol (usually from an assembler file).
814 The compiler will create a matching import declaration for the assembler.
819 #pragma zpsym ("foo"); /* foo is in the zeropage */
825 <sect>Register variables<label id="regvars"><p>
827 The runtime for all supported platforms has 6 bytes of zero page space
828 available for register variables (this could be increased, but I think it's a
829 good value). So you can declare register variables up to a total size of 6 per
830 function. The compiler will allocate register space on a "first come, first
831 served" base and convert any <tt/register/ declarations that exceed the
832 available register space silently to <tt/auto/. Parameters can also be
833 declared as <tt/register/, this will in fact give slightly shorter code than
834 using a register variable.
836 Since a function must save the current values of the registers on entry and
837 restore them on exit, there is an overhead associated with register variables,
838 and this overhead is quite high (about 20 bytes per variable). This means that
839 just declaring anything as <tt/register/ is not a good idea.
841 The best use for register variables are pointers, especially those that point
842 to structures. The magic number here is about 3 uses of a struct field: If the
843 function contains this number or even more, the generated code will be usually
844 shorter and faster when using a register variable for the struct pointer. The
845 reason for this is that the register variable can in many cases be used as a
846 pointer directly. Having a pointer in an auto variable means that this pointer
847 must first be copied into a zero page location, before it can be dereferenced.
849 Second best use for register variables are counters. However, there is not
850 much difference in the code generated for counters, so you will need at least
851 100 operations on this variable (for example in a loop) to make it worth the
852 trouble. The only savings you get here are by the use of a zero page variable
853 instead of one on the stack or in the data segment.
855 Register variables must be explicitly enabled by using <tt/-Or/ or <tt/-r/ on
856 the command line. Register variables are only accepted on function top level,
857 register variables declared in interior blocks are silently converted to
858 <tt/auto/. With register variables disabled, all variables declared as
859 <tt/register/ are actually auto variables.
861 Please take care when using register variables: While they are helpful and can
862 lead to a tremendous speedup when used correctly, improper usage will cause
863 bloated code and a slowdown.
867 <sect>Inline assembler<label id="inline-asm"><p>
869 The compiler allows to insert assembler statements into the output file. The
873 asm (<string literal>[, optional parameters]) ;
877 __asm__ (<string literal>[, optional parameters]) ;
881 The first form is in the user namespace and is disabled by <tt><ref
882 id="option-A" name="-A"></tt>.
884 The asm statement may be used inside a function and on global file level. An
885 inline assembler statement is a primary expression, so it may also be used as
886 part of an expression. Please note however that the result of an expression
887 containing just an inline assembler statement is always of type <tt/void/.
889 The contents of the string literal are preparsed by the compiler and inserted
890 into the generated assembly output, so that the can be further processed by
891 the backend and especially the optimizer. For this reason, the compiler does
892 only allow regular 6502 opcodes to be used with the inline assembler. Pseudo
893 instructions (like <tt/.import/, <tt/.byte/ and so on) are <em/not/ allowed,
894 even if the ca65 assembler (which is used to translate the generated assembler
895 code) would accept them. The builtin inline assembler is not a replacement for
896 the full blown macro assembler which comes with the compiler.
898 Note: Inline assembler statements are subject to all optimizations done by the
899 compiler. There is currently no way to protect an inline assembler statement
900 from being moved or removed completely by the optimizer. If in doubt, check
901 the generated assembler output, or disable optimizations.
903 The string literal may contain format specifiers from the following list. For
904 each format specifier, an argument is expected which is inserted instead of
905 the format specifier before passing the assembly code line to the backend.
908 <item><tt/%b/ - Numerical 8 bit value
909 <item><tt/%w/ - Numerical 16 bit value
910 <item><tt/%l/ - Numerical 32 bit value
911 <item><tt/%v/ - Assembler name of a (global) variable or function
912 <item><tt/%o/ - Stack offset of a (local) variable
913 <item><tt/%s/ - The argument is converted to a string
914 <item><tt/%%/ - The % sign itself
917 Using these format specifiers, you can access C <tt/#defines/, variables or
918 similar stuff from the inline assembler. For example, to load the value of
919 a C <tt/#define/ into the Y register, one would use
923 __asm__ ("ldy #%b", OFFS);
926 Or, to access a struct member of a static variable:
934 static pixel_t pixel;
935 __asm__ ("ldy #%b", offsetof(pixel_t, color));
936 __asm__ ("lda %v,y", pixel);
940 Note: Do not embedd the assembler labels that are used as names of global
941 variables or functions into your asm statements. Code like this
945 int bar () { return 1; }
946 __asm__ ("lda _foo"); /* DON'T DO THAT! */
948 __asm__ ("jsr _bar"); /* DON'T DO THAT EITHER! */
952 may stop working if the way, the compiler generates these names is changed in
953 a future version. Instead use the format specifiers from the table above.
957 <sect>Bugs/Feedback<p>
959 If you have problems using the compiler, if you find any bugs, or if you're
960 doing something interesting with it, I would be glad to hear from you. Feel
961 free to contact me by email (<htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">).
967 This is the original compiler copyright:
970 --------------------------------------------------------------------------
973 This is the copyright notice for RA65, LINK65, LIBR65, and other
974 Atari 8-bit programs. Said programs are Copyright 1989, by John R.
975 Dunning. All rights reserved, with the following exceptions:
977 Anyone may copy or redistribute these programs, provided that:
979 1: You don't charge anything for the copy. It is permissable to
980 charge a nominal fee for media, etc.
982 2: All source code and documentation for the programs is made
983 available as part of the distribution.
985 3: This copyright notice is preserved verbatim, and included in
988 You are allowed to modify these programs, and redistribute the
989 modified versions, provided that the modifications are clearly noted.
991 There is NO WARRANTY with this software, it comes as is, and is
992 distributed in the hope that it may be useful.
994 This copyright notice applies to any program which contains
995 this text, or the refers to this file.
997 This copyright notice is based on the one published by the Free
998 Software Foundation, sometimes known as the GNU project. The idea
999 is the same as theirs, ie the software is free, and is intended to
1000 stay that way. Everybody has the right to copy, modify, and re-
1001 distribute this software. Nobody has the right to prevent anyone
1002 else from copying, modifying or redistributing it.
1004 --------------------------------------------------------------------------
1007 In acknowledgment of this copyright, I will place my own changes to the
1008 compiler under the same copyright. Please note however, that the library
1009 and all binutils are covered by another copyright, and that I'm planning
1010 to do a complete rewrite of the compiler, after which the compiler
1011 copyright will also change.
1013 For the list of changes requested by this copyright see newvers.txt.