1 <!doctype linuxdoc system> <!-- -*- text-mode -*- -->
4 <title>ca65 Users Guide
5 <author>Ullrich von Bassewitz, <htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">
6 <date>2000-07-19, 2000-11-29, 2001-10-02, 2005-09-08
9 ca65 is a powerful macro assembler for the 6502, 65C02 and 65816 CPUs. It is
10 used as a companion assembler for the cc65 crosscompiler, but it may also be
11 used as a standalone product.
14 <!-- Table of contents -->
17 <!-- Begin the document -->
21 ca65 is a replacement for the ra65 assembler that was part of the cc65 C
22 compiler, originally developed by John R. Dunning. I had some problems with
23 ra65 and the copyright does not permit some things which I wanted to be
24 possible, so I decided to write a completely new assembler/linker/archiver
25 suite for the cc65 compiler. ca65 is part of this suite.
27 Some parts of the assembler (code generation and some routines for symbol
28 table handling) are taken from an older crossassembler named a816 written
29 by me a long time ago.
32 <sect1>Design criteria<p>
34 Here's a list of the design criteria, that I considered important for the
39 <item> The assembler must support macros. Macros are not essential, but they
40 make some things easier, especially when you use the assembler in the
41 backend of a compiler.
42 <item> The assembler must support the newer 65C02 and 65816 CPUs. I have been
43 thinking about a 65816 backend for the C compiler, and even my old
44 a816 assembler had support for these CPUs, so this wasn't really a
46 <item> The assembler must produce relocatable code. This is necessary for the
47 compiler support, and it is more convenient.
48 <item> Conditional assembly must be supported. This is a must for bigger
49 projects written in assembler (like Elite128).
50 <item> The assembler must support segments, and it must support more than
51 three segments (this is the count, most other assemblers support).
52 Having more than one code segments helps developing code for systems
53 with a divided ROM area (like the C64).
54 <item> The linker must be able to resolve arbitrary expressions. It should
55 be able to get things like
62 <item> True lexical nesting for symbols. This is very convenient for larger
64 <item> "Cheap" local symbols without lexical nesting for those quick, late
66 <item> I liked the idea of "options" as Anre Fachats .o65 format has it, so I
67 introduced the concept into the object file format use by the new cc65
69 <item> The assembler will be a one pass assembler. There was no real need for
70 this decision, but I've written several multipass assemblers, and it
71 started to get boring. A one pass assembler needs much more elaborated
72 data structures, and because of that it's much more fun:-)
73 <item> Non-GPLed code that may be used in any project without restrictions or
74 fear of "GPL infecting" other code.
82 <sect1>Command line option overview<p>
84 The assembler accepts the following options:
87 ---------------------------------------------------------------------------
88 Usage: ca65 [options] file
90 -D name[=value] Define a symbol
91 -I dir Set an include directory search path
92 -U Mark unresolved symbols as import
93 -V Print the assembler version
94 -W n Set warning level n
96 -g Add debug info to object file
98 -i Ignore case of symbols
99 -l name Create a listing file if assembly was ok
100 -mm model Set the memory model
101 -o name Name the output file
103 -t sys Set the target system
104 -v Increase verbosity
107 --auto-import Mark unresolved symbols as import
108 --bin-include-dir dir Set a search path for binary includes
109 --cpu type Set cpu type
110 --create-dep name Create a make dependency file
111 --create-full-dep name Create a full make dependency file
113 --debug-info Add debug info to object file
114 --feature name Set an emulation feature
115 --help Help (this text)
116 --ignore-case Ignore case of symbols
117 --include-dir dir Set an include directory search path
118 --large-alignment Don't warn about large alignments
119 --listing name Create a listing file if assembly was ok
120 --list-bytes n Maximum number of bytes per listing line
121 --memory-model model Set the memory model
122 --pagelength n Set the page length for the listing
123 --relax-checks Relax some checks (see docs)
124 --smart Enable smart mode
125 --target sys Set the target system
126 --verbose Increase verbosity
127 --version Print the assembler version
128 ---------------------------------------------------------------------------
132 <sect1>Command line options in detail<p>
134 Here is a description of all the command line options:
138 <label id="option--bin-include-dir">
139 <tag><tt>--bin-include-dir dir</tt></tag>
141 Name a directory which is searched for binary include files. The option
142 may be used more than once to specify more than one directory to search. The
143 current directory is always searched first before considering any
144 additional directories. See also the section about <ref id="search-paths"
145 name="search paths">.
148 <label id="option--cpu">
149 <tag><tt>--cpu type</tt></tag>
151 Set the default for the CPU type. The option takes a parameter, which
154 6502, 65SC02, 65C02, 65816, sweet16, HuC6280
157 <label id="option-create-dep">
158 <tag><tt>--create-dep name</tt></tag>
160 Tells the assembler to generate a file containing the dependency list for
161 the assembled module in makefile syntax. The output is written to a file
162 with the given name. The output does not include files passed via debug
163 information to the assembler.
166 <label id="option-create-full-dep">
167 <tag><tt>--create-full-dep name</tt></tag>
169 Tells the assembler to generate a file containing the dependency list for
170 the assembled module in makefile syntax. The output is written to a file
171 with the given name. The output does include files passed via debug
172 information to the assembler.
175 <tag><tt>-d, --debug</tt></tag>
177 Enables debug mode, something that should not be needed for mere
181 <label id="option--feature">
182 <tag><tt>--feature name</tt></tag>
184 Enable an emulation feature. This is identical as using <tt/.FEATURE/
185 in the source with two exceptions: Feature names must be lower case, and
186 each feature must be specified by using an extra <tt/--feature/ option,
187 comma separated lists are not allowed.
189 See the discussion of the <tt><ref id=".FEATURE" name=".FEATURE"></tt>
190 command for a list of emulation features.
193 <label id="option-g">
194 <tag><tt>-g, --debug-info</tt></tag>
196 When this option (or the equivalent control command <tt/.DEBUGINFO/) is
197 used, the assembler will add a section to the object file that contains
198 all symbols (including local ones) together with the symbol values and
199 source file positions. The linker will put these additional symbols into
200 the VICE label file, so even local symbols can be seen in the VICE
204 <label id="option-h">
205 <tag><tt>-h, --help</tt></tag>
207 Print the short option summary shown above.
210 <label id="option-i">
211 <tag><tt>-i, --ignore-case</tt></tag>
213 This option makes the assembler case insensitive on identifiers and labels.
214 This option will override the default, but may itself be overridden by the
215 <tt><ref id=".CASE" name=".CASE"></tt> control command.
218 <label id="option-l">
219 <tag><tt>-l name, --listing name</tt></tag>
221 Generate an assembler listing with the given name. A listing file will
222 never be generated in case of assembly errors.
225 <label id="option--large-alignment">
226 <tag><tt>--large-alignment</tt></tag>
228 Disable warnings about a large combined alignment. See the discussion of the
229 <tt><ref id=".ALIGN" name=".ALIGN"></tt> directive for futher information.
232 <label id="option--list-bytes">
233 <tag><tt>--list-bytes n</tt></tag>
235 Set the maximum number of bytes printed in the listing for one line of
236 input. See the <tt><ref id=".LISTBYTES" name=".LISTBYTES"></tt> directive
237 for more information. The value zero can be used to encode an unlimited
238 number of printed bytes.
241 <label id="option-mm">
242 <tag><tt>-mm model, --memory-model model</tt></tag>
244 Define the default memory model. Possible model specifiers are near, far and
248 <label id="option-o">
249 <tag><tt>-o name</tt></tag>
251 The default output name is the name of the input file with the extension
252 replaced by ".o". If you don't like that, you may give another name with
253 the -o option. The output file will be placed in the same directory as
254 the source file, or, if -o is given, the full path in this name is used.
257 <label id="option--pagelength">
258 <tag><tt>--pagelength n</tt></tag>
260 sets the length of a listing page in lines. See the <tt><ref
261 id=".PAGELENGTH" name=".PAGELENGTH"></tt> directive for more information.
264 <label id="option--relax-checks">
265 <tag><tt>--relax-checks</tt></tag>
267 Relax some checks done by the assembler. This will allow code that is an
268 error in most cases and flagged as such by the assembler, but can be valid
269 in special situations.
273 <item>Short branches between two different segments.
274 <item>Byte sized address loads where the address is not a zeropage address.
278 <label id="option-s">
279 <tag><tt>-s, --smart-mode</tt></tag>
281 In smart mode (enabled by -s or the <tt><ref id=".SMART" name=".SMART"></tt>
282 pseudo instruction) the assembler will track usage of the <tt/REP/ and
283 <tt/SEP/ instructions in 65816 mode and update the operand sizes
284 accordingly. If the operand of such an instruction cannot be evaluated by
285 the assembler (for example, because the operand is an imported symbol), a
288 Beware: Since the assembler cannot trace the execution flow this may
289 lead to false results in some cases. If in doubt, use the .ixx and .axx
290 instructions to tell the assembler about the current settings. Smart
291 mode is off by default.
294 <label id="option-t">
295 <tag><tt>-t sys, --target sys</tt></tag>
297 Set the target system. This will enable translation of character strings and
298 character constants into the character set of the target platform. The
299 default for the target system is "none", which means that no translation
300 will take place. The assembler supports the same target systems as the
301 compiler, see there for a list.
303 Depending on the target, the default CPU type is also set. This can be
304 overriden by using the <tt/<ref id="option--cpu" name="--cpu">/ option.
307 <label id="option-v">
308 <tag><tt>-v, --verbose</tt></tag>
310 Increase the assembler verbosity. Usually only needed for debugging
311 purposes. You may use this option more than one time for even more
315 <label id="option-D">
316 <tag><tt>-D</tt></tag>
318 This option allows you to define symbols on the command line. Without a
319 value, the symbol is defined with the value zero. When giving a value,
320 you may use the '$' prefix for hexadecimal symbols. Please note
321 that for some operating systems, '$' has a special meaning, so
322 you may have to quote the expression.
325 <label id="option-I">
326 <tag><tt>-I dir, --include-dir dir</tt></tag>
328 Name a directory which is searched for include files. The option may be
329 used more than once to specify more than one directory to search. The
330 current directory is always searched first before considering any
331 additional directories. See also the section about <ref id="search-paths"
332 name="search paths">.
335 <label id="option-U">
336 <tag><tt>-U, --auto-import</tt></tag>
338 Mark symbols that are not defined in the sources as imported symbols. This
339 should be used with care since it delays error messages about typos and such
340 until the linker is run. The compiler uses the equivalent of this switch
341 (<tt><ref id=".AUTOIMPORT" name=".AUTOIMPORT"></tt>) to enable auto imported
342 symbols for the runtime library. However, the compiler is supposed to
343 generate code that runs through the assembler without problems, something
344 which is not always true for assembler programmers.
347 <label id="option-V">
348 <tag><tt>-V, --version</tt></tag>
350 Print the version number of the assembler. If you send any suggestions
351 or bugfixes, please include the version number.
354 <label id="option-W">
355 <tag><tt>-Wn</tt></tag>
357 Set the warning level for the assembler. Using -W2 the assembler will
358 even warn about such things like unused imported symbols. The default
359 warning level is 1, and it would probably be silly to set it to
367 <sect>Search paths<label id="search-paths"><p>
369 Normal include files are searched in the following places:
372 <item>The current file's directory.
373 <item>Any directory added with the <tt/<ref id="option-I" name="-I">/ option
375 <item>The value of the environment variable <tt/CA65_INC/ if it is defined.
376 <item>A subdirectory named <tt/asminc/ of the directory defined in the
377 environment variable <tt/CC65_HOME/, if it is defined.
378 <item>An optionally compiled-in directory.
381 Binary include files are searched in the following places:
384 <item>The current file's directory.
385 <item>Any directory added with the <tt/<ref id="option--bin-include-dir"
386 name="--bin-include-dir">/ option on the command line.
391 <sect>Input format<p>
393 <sect1>Assembler syntax<p>
395 The assembler accepts the standard 6502/65816 assembler syntax. One line may
396 contain a label (which is identified by a colon), and, in addition to the
397 label, an assembler mnemonic, a macro, or a control command (see section <ref
398 id="control-commands" name="Control Commands"> for supported control
399 commands). Alternatively, the line may contain a symbol definition using
400 the '=' token. Everything after a semicolon is handled as a comment (that is,
403 Here are some examples for valid input lines:
406 Label: ; A label and a comment
407 lda #$20 ; A 6502 instruction plus comment
408 L1: ldx #$20 ; Same with label
409 L2: .byte "Hello world" ; Label plus control command
410 mymac $20 ; Macro expansion
411 MySym = 3*L1 ; Symbol definition
412 MaSym = Label ; Another symbol
415 The assembler accepts
418 <item>all valid 6502 mnemonics when in 6502 mode (the default or after the
419 <tt><ref id=".P02" name=".P02"></tt> command was given).
420 <item>all valid 6502 mnemonics plus a set of illegal instructions when in
421 <ref id="6502X-mode" name="6502X mode">.
422 <item>all valid 65SC02 mnemonics when in 65SC02 mode (after the
423 <tt><ref id=".PSC02" name=".PSC02"></tt> command was given).
424 <item>all valid 65C02 mnemonics when in 65C02 mode (after the
425 <tt><ref id=".PC02" name=".PC02"></tt> command was given).
426 <item>all valid 65618 mnemonics when in 65816 mode (after the
427 <tt><ref id=".P816" name=".P816"></tt> command was given).
433 In 65816 mode several aliases are accepted in addition to the official
437 BGE is an alias for BCS
438 BLT is an alias for BCC
439 CPA is an alias for CMP
440 DEA is an alias for DEC A
441 INA is an alias for INC A
442 SWA is an alias for XBA
443 TAD is an alias for TCD
444 TAS is an alias for TCS
445 TDA is an alias for TDC
446 TSA is an alias for TSC
451 <sect1>6502X mode<label id="6502X-mode"><p>
453 6502X mode is an extension to the normal 6502 mode. In this mode, several
454 mnemonics for illegal instructions of the NMOS 6502 CPUs are accepted. Since
455 these instructions are illegal, there are no official mnemonics for them. The
456 unofficial ones are taken from <htmlurl
457 url="http://www.oxyron.de/html/opcodes02.html"
458 name="http://www.oxyron.de/html/opcodes02.html">. Please note that only the
459 ones marked as "stable" are supported. The following table uses information
460 from the mentioned web page, for more information, see there.
463 <item><tt>ALR: A:=(A and #{imm})/2;</tt>
464 <item><tt>ANC: A:=A and #{imm};</tt> Generates opcode $0B.
465 <item><tt>ARR: A:=(A and #{imm})/2;</tt>
466 <item><tt>AXS: X:=A and X-#{imm};</tt>
467 <item><tt>DCP: {adr}:={adr}-1; A-{adr};</tt>
468 <item><tt>ISC: {adr}:={adr}+1; A:=A-{adr};</tt>
469 <item><tt>LAS: A,X,S:={adr} and S;</tt>
470 <item><tt>LAX: A,X:={adr};</tt>
471 <item><tt>RLA: {adr}:={adr}rol; A:=A and {adr};</tt>
472 <item><tt>RRA: {adr}:={adr}ror; A:=A adc {adr};</tt>
473 <item><tt>SAX: {adr}:=A and X;</tt>
474 <item><tt>SLO: {adr}:={adr}*2; A:=A or {adr};</tt>
475 <item><tt>SRE: {adr}:={adr}/2; A:=A xor {adr};</tt>
480 <sect1>sweet16 mode<label id="sweet16-mode"><p>
482 SWEET 16 is an interpreter for a pseudo 16 bit CPU written by Steve Wozniak
483 for the Apple ][ machines. It is available in the Apple ][ ROM. ca65 can
484 generate code for this pseudo CPU when switched into sweet16 mode. The
485 following is special in sweet16 mode:
489 <item>The '@' character denotes indirect addressing and is no longer available
490 for cheap local labels. If you need cheap local labels, you will have to
491 switch to another lead character using the <tt/<ref id=".LOCALCHAR"
492 name=".LOCALCHAR">/ command.
494 <item>Registers are specified using <tt/R0/ .. <tt/R15/. In sweet16 mode,
495 these identifiers are reserved words.
499 Please note that the assembler does neither supply the interpreter needed for
500 SWEET 16 code, nor the zero page locations needed for the SWEET 16 registers,
501 nor does it call the interpreter. All this must be done by your program. Apple
502 ][ programmers do probably know how to use sweet16 mode.
504 For more information about SWEET 16, see
505 <htmlurl url="http://www.6502.org/source/interpreters/sweet16.htm"
506 name="http://www.6502.org/source/interpreters/sweet16.htm">.
509 <sect1>Number format<p>
511 For literal values, the assembler accepts the widely used number formats: A
512 preceding '$' or a trailing 'h' denotes a hex value, a preceding '%'
513 denotes a binary value, and a bare number is interpreted as a decimal. There
514 are currently no octal values and no floats.
517 <sect1>Conditional assembly<p>
519 Please note that when using the conditional directives (<tt/.IF/ and friends),
520 the input must consist of valid assembler tokens, even in <tt/.IF/ branches
521 that are not assembled. The reason for this behaviour is that the assembler
522 must still be able to detect the ending tokens (like <tt/.ENDIF/), so
523 conversion of the input stream into tokens still takes place. As a consequence
524 conditional assembly directives may <bf/not/ be used to prevent normal text
525 (used as a comment or similar) from being assembled. <p>
531 <sect1>Expression evaluation<p>
533 All expressions are evaluated with (at least) 32 bit precision. An
534 expression may contain constant values and any combination of internal and
535 external symbols. Expressions that cannot be evaluated at assembly time
536 are stored inside the object file for evaluation by the linker.
537 Expressions referencing imported symbols must always be evaluated by the
541 <sect1>Size of an expression result<p>
543 Sometimes, the assembler must know about the size of the value that is the
544 result of an expression. This is usually the case, if a decision has to be
545 made, to generate a zero page or an absolute memory references. In this
546 case, the assembler has to make some assumptions about the result of an
550 <item> If the result of an expression is constant, the actual value is
551 checked to see if it's a byte sized expression or not.
552 <item> If the expression is explicitly casted to a byte sized expression by
553 one of the '>', '<' or '^' operators, it is a byte expression.
554 <item> If this is not the case, and the expression contains a symbol,
555 explicitly declared as zero page symbol (by one of the .importzp or
556 .exportzp instructions), then the whole expression is assumed to be
558 <item> If the expression contains symbols that are not defined, and these
559 symbols are local symbols, the enclosing scopes are searched for a
560 symbol with the same name. If one exists and this symbol is defined,
561 its attributes are used to determine the result size.
562 <item> In all other cases the expression is assumed to be word sized.
565 Note: If the assembler is not able to evaluate the expression at assembly
566 time, the linker will evaluate it and check for range errors as soon as
570 <sect1>Boolean expressions<p>
572 In the context of a boolean expression, any non zero value is evaluated as
573 true, any other value to false. The result of a boolean expression is 1 if
574 it's true, and zero if it's false. There are boolean operators with extreme
575 low precedence with version 2.x (where x > 0). The <tt/.AND/ and <tt/.OR/
576 operators are shortcut operators. That is, if the result of the expression is
577 already known, after evaluating the left hand side, the right hand side is
581 <sect1>Constant expressions<p>
583 Sometimes an expression must evaluate to a constant without looking at any
584 further input. One such example is the <tt/<ref id=".IF" name=".IF">/ command
585 that decides if parts of the code are assembled or not. An expression used in
586 the <tt/.IF/ command cannot reference a symbol defined later, because the
587 decision about the <tt/.IF/ must be made at the point when it is read. If the
588 expression used in such a context contains only constant numerical values,
589 there is no problem. When unresolvable symbols are involved it may get harder
590 for the assembler to determine if the expression is actually constant, and it
591 is even possible to create expressions that aren't recognized as constant.
592 Simplifying the expressions will often help.
594 In cases where the result of the expression is not needed immediately, the
595 assembler will delay evaluation until all input is read, at which point all
596 symbols are known. So using arbitrary complex constant expressions is no
597 problem in most cases.
601 <sect1>Available operators<label id="operators"><p>
605 <bf/Operator/| <bf/Description/| <bf/Precedence/@<hline>
606 | Built-in string functions| 0@
608 | Built-in pseudo-variables| 1@
609 | Built-in pseudo-functions| 1@
610 +| Unary positive| 1@
611 -| Unary negative| 1@
613 .BITNOT| Unary bitwise not| 1@
615 .LOBYTE| Unary low-byte operator| 1@
617 .HIBYTE| Unary high-byte operator| 1@
619 .BANKBYTE| Unary bank-byte operator| 1@
621 *| Multiplication| 2@
623 .MOD| Modulo operator| 2@
625 .BITAND| Bitwise and| 2@
627 .BITXOR| Binary bitwise xor| 2@
629 .SHL| Shift-left operator| 2@
631 .SHR| Shift-right operator| 2@
633 +| Binary addition| 3@
634 -| Binary subtraction| 3@
636 .BITOR| Bitwise or| 3@
638 = | Compare operator (equal)| 4@
639 <>| Compare operator (not equal)| 4@
640 <| Compare operator (less)| 4@
641 >| Compare operator (greater)| 4@
642 <=| Compare operator (less or equal)| 4@
643 >=| Compare operator (greater or equal)| 4@
646 .AND| Boolean and| 5@
647 .XOR| Boolean xor| 5@
649 ||<newline>
653 .NOT| Boolean not| 7@<hline>
655 <caption>Available operators, sorted by precedence
658 To force a specific order of evaluation, parentheses may be used, as usual.
662 <sect>Symbols and labels<p>
664 A symbol or label is an identifier that starts with a letter and is followed
665 by letters and digits. Depending on some features enabled (see
666 <tt><ref id="at_in_identifiers" name="at_in_identifiers"></tt>,
667 <tt><ref id="dollar_in_identifiers" name="dollar_in_identifiers"></tt> and
668 <tt><ref id="leading_dot_in_identifiers" name="leading_dot_in_identifiers"></tt>)
669 other characters may be present. Use of identifiers consisting of a single
670 character will not work in all cases, because some of these identifiers are
671 reserved keywords (for example "A" is not a valid identifier for a label,
672 because it is the keyword for the accumulator).
674 The assembler allows you to use symbols instead of naked values to make
675 the source more readable. There are a lot of different ways to define and
676 use symbols and labels, giving a lot of flexibility.
678 <sect1>Numeric constants<p>
680 Numeric constants are defined using the equal sign or the label assignment
681 operator. After doing
687 may use the symbol "two" in every place where a number is expected, and it is
688 evaluated to the value 2 in this context. The label assignment operator is
689 almost identical, but causes the symbol to be marked as a label, so it may be
690 handled differently in a debugger:
696 The right side can of course be an expression:
703 <label id="variables">
704 <sect1>Numeric variables<p>
706 Within macros and other control structures (<tt><ref id=".REPEAT"
707 name=".REPEAT"></tt>, ...) it is sometimes useful to have some sort of
708 variable. This can be achieved by the <tt>.SET</tt> operator. It creates a
709 symbol that may get assigned a different value later:
713 lda #four ; Loads 4 into A
715 lda #four ; Loads 3 into A
718 Since the value of the symbol can change later, it must be possible to
719 evaluate it when used (no delayed evaluation as with normal symbols). So the
720 expression used as the value must be constant.
722 Following is an example for a macro that generates a different label each time
723 it is used. It uses the <tt><ref id=".SPRINTF" name=".SPRINTF"></tt> function
724 and a numeric variable named <tt>lcount</tt>.
727 .lcount .set 0 ; Initialize the counter
730 .ident (.sprintf ("L%04X", lcount)):
731 lcount .set lcount + 1
736 <sect1>Standard labels<p>
738 A label is defined by writing the name of the label at the start of the line
739 (before any instruction mnemonic, macro or pseudo directive), followed by a
740 colon. This will declare a symbol with the given name and the value of the
741 current program counter.
744 <sect1>Local labels and symbols<p>
746 Using the <tt><ref id=".PROC" name=".PROC"></tt> directive, it is possible to
747 create regions of code where the names of labels and symbols are local to this
748 region. They are not known outside of this region and cannot be accessed from
749 there. Such regions may be nested like PROCEDUREs in Pascal.
751 See the description of the <tt><ref id=".PROC" name=".PROC"></tt>
752 directive for more information.
755 <sect1>Cheap local labels<p>
757 Cheap local labels are defined like standard labels, but the name of the
758 label must begin with a special symbol (usually '@', but this can be
759 changed by the <tt><ref id=".LOCALCHAR" name=".LOCALCHAR"></tt>
762 Cheap local labels are visible only between two non cheap labels. As soon as a
763 standard symbol is encountered (this may also be a local symbol if inside a
764 region defined with the <tt><ref id=".PROC" name=".PROC"></tt> directive), the
765 cheap local symbol goes out of scope.
767 You may use cheap local labels as an easy way to reuse common label
768 names like "Loop". Here is an example:
771 Clear: lda #$00 ; Global label
773 @Loop: sta Mem,y ; Local label
777 Sub: ... ; New global label
778 bne @Loop ; ERROR: Unknown identifier!
781 <sect1>Unnamed labels<p>
783 If you really want to write messy code, there are also unnamed labels. These
784 labels do not have a name (you guessed that already, didn't you?). A colon is
785 used to mark the absence of the name.
787 Unnamed labels may be accessed by using the colon plus several minus or plus
788 characters as a label designator. Using the '-' characters will create a back
789 reference (use the n'th label backwards), using '+' will create a forward
790 reference (use the n'th label in forward direction). An example will help to
813 As you can see from the example, unnamed labels will make even short
814 sections of code hard to understand, because you have to count labels
815 to find branch targets (this is the reason why I for my part do
816 prefer the "cheap" local labels). Nevertheless, unnamed labels are
817 convenient in some situations, so it's your decision.
819 <bf/Note:/ <ref id="scopes" name="Scopes"> organize named symbols, not
820 unnamed ones, so scopes don't have an effect on unnamed labels.
824 <sect1>Using macros to define labels and constants<p>
826 While there are drawbacks with this approach, it may be handy in a few rare
827 situations. Using <tt><ref id=".DEFINE" name=".DEFINE"></tt>, it is possible
828 to define symbols or constants that may be used elsewhere. One of the
829 advantages is that you can use it to define string constants (this is not
830 possible with the other symbol types).
832 Please note: <tt/.DEFINE/ style macros do token replacements on a low level,
833 so the names do not adhere to scoping, diagnostics may be misleading, there
834 are no symbols to look up in the map file, and there is no debug info.
835 Especially the first problem in the list can lead to very nasty programming
836 errors. Because of these problems, the general advice is, <bf/NOT/ do use
837 <tt/.DEFINE/ if you don't have to.
843 .DEFINE version "SOS V2.3"
845 four = two * two ; Ok
848 .PROC ; Start local scope
849 two = 3 ; Will give "2 = 3" - invalid!
854 <sect1>Symbols and <tt>.DEBUGINFO</tt><p>
856 If <tt><ref id=".DEBUGINFO" name=".DEBUGINFO"></tt> is enabled (or <ref
857 id="option-g" name="-g"> is given on the command line), global, local and
858 cheap local labels are written to the object file and will be available in the
859 symbol file via the linker. Unnamed labels are not written to the object file,
860 because they don't have a name which would allow to access them.
864 <sect>Scopes<label id="scopes"><p>
866 ca65 implements several sorts of scopes for symbols.
868 <sect1>Global scope<p>
870 All (non cheap local) symbols that are declared outside of any nested scopes
874 <sect1>Cheap locals<p>
876 A special scope is the scope for cheap local symbols. It lasts from one non
877 local symbol to the next one, without any provisions made by the programmer.
878 All other scopes differ in usage but use the same concept internally.
881 <sect1>Generic nested scopes<p>
883 A nested scoped for generic use is started with <tt/<ref id=".SCOPE"
884 name=".SCOPE">/ and closed with <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/.
885 The scope can have a name, in which case it is accessible from the outside by
886 using <ref id="scopesyntax" name="explicit scopes">. If the scope does not
887 have a name, all symbols created within the scope are local to the scope, and
888 aren't accessible from the outside.
890 A nested scope can access symbols from the local or from enclosing scopes by
891 name without using explicit scope names. In some cases there may be
892 ambiguities, for example if there is a reference to a local symbol that is not
893 yet defined, but a symbol with the same name exists in outer scopes:
905 In the example above, the <tt/lda/ instruction will load the value 3 into the
906 accumulator, because <tt/foo/ is redefined in the scope. However:
918 Here, <tt/lda/ will still load from <tt/$12,x/, but since it is unknown to the
919 assembler that <tt/foo/ is a zeropage symbol when translating the instruction,
920 absolute mode is used instead. In fact, the assembler will not use absolute
921 mode by default, but it will search through the enclosing scopes for a symbol
922 with the given name. If one is found, the address size of this symbol is used.
923 This may lead to errors:
935 In this case, when the assembler sees the symbol <tt/foo/ in the <tt/lda/
936 instruction, it will search for an already defined symbol <tt/foo/. It will
937 find <tt/foo/ in scope <tt/outer/, and a close look reveals that it is a
938 zeropage symbol. So the assembler will use zeropage addressing mode. If
939 <tt/foo/ is redefined later in scope <tt/inner/, the assembler tries to change
940 the address in the <tt/lda/ instruction already translated, but since the new
941 value needs absolute addressing mode, this fails, and an error message "Range
944 Of course the most simple solution for the problem is to move the definition
945 of <tt/foo/ in scope <tt/inner/ upwards, so it precedes its use. There may be
946 rare cases when this cannot be done. In these cases, you can use one of the
947 address size override operators:
959 This will cause the <tt/lda/ instruction to be translated using absolute
960 addressing mode, which means changing the symbol reference later does not
964 <sect1>Nested procedures<p>
966 A nested procedure is created by use of <tt/<ref id=".PROC" name=".PROC">/. It
967 differs from a <tt/<ref id=".SCOPE" name=".SCOPE">/ in that it must have a
968 name, and a it will introduce a symbol with this name in the enclosing scope.
977 is actually the same as
986 This is the reason why a procedure must have a name. If you want a scope
987 without a name, use <tt/<ref id=".SCOPE" name=".SCOPE">/.
989 <bf/Note:/ As you can see from the example above, scopes and symbols live in
990 different namespaces. There can be a symbol named <tt/foo/ and a scope named
991 <tt/foo/ without any conflicts (but see the section titled <ref
992 id="scopesearch" name=""Scope search order"">).
995 <sect1>Structs, unions and enums<p>
997 Structs, unions and enums are explained in a <ref id="structs" name="separate
998 section">, I do only cover them here, because if they are declared with a
999 name, they open a nested scope, similar to <tt/<ref id=".SCOPE"
1000 name=".SCOPE">/. However, when no name is specified, the behaviour is
1001 different: In this case, no new scope will be opened, symbols declared within
1002 a struct, union, or enum declaration will then be added to the enclosing scope
1006 <sect1>Explicit scope specification<label id="scopesyntax"><p>
1008 Accessing symbols from other scopes is possible by using an explicit scope
1009 specification, provided that the scope where the symbol lives in has a name.
1010 The namespace token (<tt/::/) is used to access other scopes:
1018 lda foo::bar ; Access foo in scope bar
1021 The only way to deny access to a scope from the outside is to declare a scope
1022 without a name (using the <tt/<ref id=".SCOPE" name=".SCOPE">/ command).
1024 A special syntax is used to specify the global scope: If a symbol or scope is
1025 preceded by the namespace token, the global scope is searched:
1032 lda #::bar ; Access the global bar (which is 3)
1037 <sect1>Scope search order<label id="scopesearch"><p>
1039 The assembler searches for a scope in a similar way as for a symbol. First, it
1040 looks in the current scope, and then it walks up the enclosing scopes until
1043 However, one important thing to note when using explicit scope syntax is, that
1044 a symbol may be accessed before it is defined, but a scope may <bf/not/ be
1045 used without a preceding definition. This means that in the following
1054 lda #foo::bar ; Will load 3, not 2!
1061 the reference to the scope <tt/foo/ will use the global scope, and not the
1062 local one, because the local one is not visible at the point where it is
1065 Things get more complex if a complete chain of scopes is specified:
1076 lda #outer::inner::bar ; 1
1088 When <tt/outer::inner::bar/ is referenced in the <tt/lda/ instruction, the
1089 assembler will first search in the local scope for a scope named <tt/outer/.
1090 Since none is found, the enclosing scope (<tt/another/) is checked. There is
1091 still no scope named <tt/outer/, so scope <tt/foo/ is checked, and finally
1092 scope <tt/outer/ is found. Within this scope, <tt/inner/ is searched, and in
1093 this scope, the assembler looks for a symbol named <tt/bar/.
1095 Please note that once the anchor scope is found, all following scopes
1096 (<tt/inner/ in this case) are expected to be found exactly in this scope. The
1097 assembler will search the scope tree only for the first scope (if it is not
1098 anchored in the root scope). Starting from there on, there is no flexibility,
1099 so if the scope named <tt/outer/ found by the assembler does not contain a
1100 scope named <tt/inner/, this would be an error, even if such a pair does exist
1101 (one level up in global scope).
1103 Ambiguities that may be introduced by this search algorithm may be removed by
1104 anchoring the scope specification in the global scope. In the example above,
1105 if you want to access the "other" symbol <tt/bar/, you would have to write:
1116 lda #::outer::inner::bar ; 2
1129 <sect>Address sizes and memory models<label id="address-sizes"><p>
1131 <sect1>Address sizes<p>
1133 ca65 assigns each segment and each symbol an address size. This is true, even
1134 if the symbol is not used as an address. You may also think of a value range
1135 of the symbol instead of an address size.
1137 Possible address sizes are:
1140 <item>Zeropage or direct (8 bits)
1141 <item>Absolute (16 bits)
1143 <item>Long (32 bits)
1146 Since the assembler uses default address sizes for the segments and symbols,
1147 it is usually not necessary to override the default behaviour. In cases, where
1148 it is necessary, the following keywords may be used to specify address sizes:
1151 <item>DIRECT, ZEROPAGE or ZP for zeropage addressing (8 bits).
1152 <item>ABSOLUTE, ABS or NEAR for absolute addressing (16 bits).
1153 <item>FAR for far addressing (24 bits).
1154 <item>LONG or DWORD for long addressing (32 bits).
1158 <sect1>Address sizes of segments<p>
1160 The assembler assigns an address size to each segment. Since the
1161 representation of a label within this segment is "segment start + offset",
1162 labels will inherit the address size of the segment they are declared in.
1164 The address size of a segment may be changed, by using an optional address
1165 size modifier. See the <tt/<ref id=".SEGMENT" name="segment directive">/ for
1166 an explanation on how this is done.
1169 <sect1>Address sizes of symbols<p>
1174 <sect1>Memory models<p>
1176 The default address size of a segment depends on the memory model used. Since
1177 labels inherit the address size from the segment they are declared in,
1178 changing the memory model is an easy way to change the address size of many
1184 <sect>Pseudo variables<label id="pseudo-variables"><p>
1186 Pseudo variables are readable in all cases, and in some special cases also
1189 <sect1><tt>*</tt><p>
1191 Reading this pseudo variable will return the program counter at the start
1192 of the current input line.
1194 Assignment to this variable is possible when <tt/<ref id=".FEATURE"
1195 name=".FEATURE pc_assignment">/ is used. Note: You should not use
1196 assignments to <tt/*/, use <tt/<ref id=".ORG" name=".ORG">/ instead.
1199 <sect1><tt>.CPU</tt><label id=".CPU"><p>
1201 Reading this pseudo variable will give a constant integer value that
1202 tells which CPU is currently enabled. It can also tell which instruction
1203 set the CPU is able to translate. The value read from the pseudo variable
1204 should be further examined by using one of the constants defined by the
1205 "cpu" macro package (see <tt/<ref id=".MACPACK" name=".MACPACK">/).
1207 It may be used to replace the .IFPxx pseudo instructions or to construct
1208 even more complex expressions.
1214 .if (.cpu .bitand CPU_ISET_65816)
1226 <sect1><tt>.PARAMCOUNT</tt><label id=".PARAMCOUNT"><p>
1228 This builtin pseudo variable is only available in macros. It is replaced by
1229 the actual number of parameters that were given in the macro invocation.
1234 .macro foo arg1, arg2, arg3
1235 .if .paramcount <> 3
1236 .error "Too few parameters for macro foo"
1242 See section <ref id="macros" name="Macros">.
1245 <sect1><tt>.TIME</tt><label id=".TIME"><p>
1247 Reading this pseudo variable will give a constant integer value that
1248 represents the current time in POSIX standard (as seconds since the
1251 It may be used to encode the time of translation somewhere in the created
1257 .dword .time ; Place time here
1261 <sect1><tt>.VERSION</tt><label id=".VERSION"><p>
1263 Reading this pseudo variable will give the assembler version according to
1264 the following formula:
1266 VER_MAJOR*$100 + VER_MINOR*$10 + VER_PATCH
1268 It may be used to encode the assembler version or check the assembler for
1269 special features not available with older versions.
1273 Version 2.11.1 of the assembler will return $2B1 as numerical constant when
1274 reading the pseudo variable <tt/.VERSION/.
1278 <sect>Pseudo functions<label id="pseudo-functions"><p>
1280 Pseudo functions expect their arguments in parenthesis, and they have a result,
1281 either a string or an expression.
1284 <sect1><tt>.BANK</tt><label id=".BANK"><p>
1286 The <tt/.BANK/ function is used to support systems with banked memory. The
1287 argument is an expression with exactly one segment reference - usually a
1288 label. The function result is the value of the <tt/bank/ attribute assigned
1289 to the run memory area of the segment. Please see the linker documentation
1290 for more information about memory areas and their attributes.
1292 The value of <tt/.BANK/ can be used to switch memory so that a memory bank
1293 containing specific data is available.
1295 The <tt/bank/ attribute is a 32 bit integer and so is the result of the
1296 <tt/.BANK/ function. You will have to use <tt><ref id=".LOBYTE"
1297 name=".LOBYTE"></tt> or similar functions to address just part of it.
1299 Please note that <tt/.BANK/ will always get evaluated in the link stage, so
1300 an expression containing <tt/.BANK/ can never be used where a constant known
1301 result is expected (for example with <tt/.RES/).
1318 .byte <.BANK (banked_func_1)
1321 .byte <.BANK (banked_func_2)
1327 <sect1><tt>.BANKBYTE</tt><label id=".BANKBYTE"><p>
1329 The function returns the bank byte (that is, bits 16-23) of its argument.
1330 It works identical to the '^' operator.
1332 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1333 <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>
1336 <sect1><tt>.BLANK</tt><label id=".BLANK"><p>
1338 Builtin function. The function evaluates its argument in braces and yields
1339 "false" if the argument is non blank (there is an argument), and "true" if
1340 there is no argument. The token list that makes up the function argument
1341 may optionally be enclosed in curly braces. This allows the inclusion of
1342 tokens that would otherwise terminate the list (the closing right
1343 parenthesis). The curly braces are not considered part of the list, a list
1344 just consisting of curly braces is considered to be empty.
1346 As an example, the <tt/.IFBLANK/ statement may be replaced by
1354 <sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
1356 Builtin string function. The function allows to concatenate a list of string
1357 constants separated by commas. The result is a string constant that is the
1358 concatenation of all arguments. This function is most useful in macros and
1359 when used together with the <tt/.STRING/ builtin function. The function may
1360 be used in any case where a string constant is expected.
1365 .include .concat ("myheader", ".", "inc")
1368 This is the same as the command
1371 .include "myheader.inc"
1375 <sect1><tt>.CONST</tt><label id=".CONST"><p>
1377 Builtin function. The function evaluates its argument in braces and
1378 yields "true" if the argument is a constant expression (that is, an
1379 expression that yields a constant value at assembly time) and "false"
1380 otherwise. As an example, the .IFCONST statement may be replaced by
1387 <sect1><tt>.HIBYTE</tt><label id=".HIBYTE"><p>
1389 The function returns the high byte (that is, bits 8-15) of its argument.
1390 It works identical to the '>' operator.
1392 See: <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>,
1393 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1396 <sect1><tt>.HIWORD</tt><label id=".HIWORD"><p>
1398 The function returns the high word (that is, bits 16-31) of its argument.
1400 See: <tt><ref id=".LOWORD" name=".LOWORD"></tt>
1403 <sect1><tt>.IDENT</tt><label id=".IDENT"><p>
1405 The function expects a string as its argument, and converts this argument
1406 into an identifier. If the string starts with the current <tt/<ref
1407 id=".LOCALCHAR" name=".LOCALCHAR">/, it will be converted into a cheap local
1408 identifier, otherwise it will be converted into a normal identifier.
1413 .macro makelabel arg1, arg2
1414 .ident (.concat (arg1, arg2)):
1417 makelabel "foo", "bar"
1419 .word foobar ; Valid label
1423 <sect1><tt>.LEFT</tt><label id=".LEFT"><p>
1425 Builtin function. Extracts the left part of a given token list.
1430 .LEFT (<int expr>, <token list>)
1433 The first integer expression gives the number of tokens to extract from
1434 the token list. The second argument is the token list itself. The token
1435 list may optionally be enclosed into curly braces. This allows the
1436 inclusion of tokens that would otherwise terminate the list (the closing
1437 right paren in the given case).
1441 To check in a macro if the given argument has a '#' as first token
1442 (immediate addressing mode), use something like this:
1447 .if (.match (.left (1, {arg}), #))
1449 ; ldax called with immediate operand
1457 See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
1458 name=".RIGHT"></tt> builtin functions.
1461 <sect1><tt>.LOBYTE</tt><label id=".LOBYTE"><p>
1463 The function returns the low byte (that is, bits 0-7) of its argument.
1464 It works identical to the '<' operator.
1466 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1467 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1470 <sect1><tt>.LOWORD</tt><label id=".LOWORD"><p>
1472 The function returns the low word (that is, bits 0-15) of its argument.
1474 See: <tt><ref id=".HIWORD" name=".HIWORD"></tt>
1477 <sect1><tt>.MATCH</tt><label id=".MATCH"><p>
1479 Builtin function. Matches two token lists against each other. This is
1480 most useful within macros, since macros are not stored as strings, but
1486 .MATCH(<token list #1>, <token list #2>)
1489 Both token list may contain arbitrary tokens with the exception of the
1490 terminator token (comma resp. right parenthesis) and
1497 The token lists may optionally be enclosed into curly braces. This allows
1498 the inclusion of tokens that would otherwise terminate the list (the closing
1499 right paren in the given case). Often a macro parameter is used for any of
1502 Please note that the function does only compare tokens, not token
1503 attributes. So any number is equal to any other number, regardless of the
1504 actual value. The same is true for strings. If you need to compare tokens
1505 <em/and/ token attributes, use the <tt><ref id=".XMATCH"
1506 name=".XMATCH"></tt> function.
1510 Assume the macro <tt/ASR/, that will shift right the accumulator by one,
1511 while honoring the sign bit. The builtin processor instructions will allow
1512 an optional "A" for accu addressing for instructions like <tt/ROL/ and
1513 <tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
1514 to check for this and print and error for invalid calls.
1519 .if (.not .blank(arg)) .and (.not .match ({arg}, a))
1520 .error "Syntax error"
1523 cmp #$80 ; Bit 7 into carry
1524 lsr a ; Shift carry into bit 7
1529 The macro will only accept no arguments, or one argument that must be the
1530 reserved keyword "A".
1532 See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
1535 <sect1><tt>.MAX</tt><label id=".MAX"><p>
1537 Builtin function. The result is the larger of two values.
1542 .MAX (<value #1>, <value #2>)
1548 ; Reserve space for the larger of two data blocks
1549 savearea: .max (.sizeof (foo), .sizeof (bar))
1552 See: <tt><ref id=".MIN" name=".MIN"></tt>
1555 <sect1><tt>.MID</tt><label id=".MID"><p>
1557 Builtin function. Takes a starting index, a count and a token list as
1558 arguments. Will return part of the token list.
1563 .MID (<int expr>, <int expr>, <token list>)
1566 The first integer expression gives the starting token in the list (the first
1567 token has index 0). The second integer expression gives the number of tokens
1568 to extract from the token list. The third argument is the token list itself.
1569 The token list may optionally be enclosed into curly braces. This allows the
1570 inclusion of tokens that would otherwise terminate the list (the closing
1571 right paren in the given case).
1575 To check in a macro if the given argument has a '<tt/#/' as first token
1576 (immediate addressing mode), use something like this:
1581 .if (.match (.mid (0, 1, {arg}), #))
1583 ; ldax called with immediate operand
1591 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
1592 name=".RIGHT"></tt> builtin functions.
1595 <sect1><tt>.MIN</tt><label id=".MIN"><p>
1597 Builtin function. The result is the smaller of two values.
1602 .MIN (<value #1>, <value #2>)
1608 ; Reserve space for some data, but 256 bytes minimum
1609 savearea: .min (.sizeof (foo), 256)
1612 See: <tt><ref id=".MAX" name=".MAX"></tt>
1615 <sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
1617 Builtin function. The function expects an identifier as argument in braces.
1618 The argument is evaluated, and the function yields "true" if the identifier
1619 is a symbol that has already been referenced somewhere in the source file up
1620 to the current position. Otherwise the function yields false. As an example,
1621 the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
1627 See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1630 <sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
1632 Builtin function. Extracts the right part of a given token list.
1637 .RIGHT (<int expr>, <token list>)
1640 The first integer expression gives the number of tokens to extract from the
1641 token list. The second argument is the token list itself. The token list
1642 may optionally be enclosed into curly braces. This allows the inclusion of
1643 tokens that would otherwise terminate the list (the closing right paren in
1646 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
1647 name=".MID"></tt> builtin functions.
1650 <sect1><tt>.SIZEOF</tt><label id=".SIZEOF"><p>
1652 <tt/.SIZEOF/ is a pseudo function that returns the size of its argument. The
1653 argument can be a struct/union, a struct member, a procedure, or a label. In
1654 case of a procedure or label, its size is defined by the amount of data
1655 placed in the segment where the label is relative to. If a line of code
1656 switches segments (for example in a macro) data placed in other segments
1657 does not count for the size.
1659 Please note that a symbol or scope must exist, before it is used together with
1660 <tt/.SIZEOF/ (this may get relaxed later, but will always be true for scopes).
1661 A scope has preference over a symbol with the same name, so if the last part
1662 of a name represents both, a scope and a symbol, the scope is chosen over the
1665 After the following code:
1668 .struct Point ; Struct size = 4
1673 P: .tag Point ; Declare a point
1674 @P: .tag Point ; Declare another point
1686 .data ; Segment switch!!!
1692 <tag><tt/.sizeof(Point)/</tag>
1693 will have the value 4, because this is the size of struct <tt/Point/.
1695 <tag><tt/.sizeof(Point::xcoord)/</tag>
1696 will have the value 2, because this is the size of the member <tt/xcoord/
1697 in struct <tt/Point/.
1699 <tag><tt/.sizeof(P)/</tag>
1700 will have the value 4, this is the size of the data declared on the same
1701 source line as the label <tt/P/, which is in the same segment that <tt/P/
1704 <tag><tt/.sizeof(@P)/</tag>
1705 will have the value 4, see above. The example demonstrates that <tt/.SIZEOF/
1706 does also work for cheap local symbols.
1708 <tag><tt/.sizeof(Code)/</tag>
1709 will have the value 3, since this is amount of data emitted into the code
1710 segment, the segment that was active when <tt/Code/ was entered. Note that
1711 this value includes the amount of data emitted in child scopes (in this
1712 case <tt/Code::Inner/).
1714 <tag><tt/.sizeof(Code::Inner)/</tag>
1715 will have the value 1 as expected.
1717 <tag><tt/.sizeof(Data)/</tag>
1718 will have the value 0. Data is emitted within the scope <tt/Data/, but since
1719 the segment is switched after entry, this data is emitted into another
1724 <sect1><tt>.STRAT</tt><label id=".STRAT"><p>
1726 Builtin function. The function accepts a string and an index as
1727 arguments and returns the value of the character at the given position
1728 as an integer value. The index is zero based.
1734 ; Check if the argument string starts with '#'
1735 .if (.strat (Arg, 0) = '#')
1742 <sect1><tt>.SPRINTF</tt><label id=".SPRINTF"><p>
1744 Builtin function. It expects a format string as first argument. The number
1745 and type of the following arguments depend on the format string. The format
1746 string is similar to the one of the C <tt/printf/ function. Missing things
1747 are: Length modifiers, variable width.
1749 The result of the function is a string.
1756 ; Generate an identifier:
1757 .ident (.sprintf ("%s%03d", "label", num)):
1761 <sect1><tt>.STRING</tt><label id=".STRING"><p>
1763 Builtin function. The function accepts an argument in braces and converts
1764 this argument into a string constant. The argument may be an identifier, or
1765 a constant numeric value.
1767 Since you can use a string in the first place, the use of the function may
1768 not be obvious. However, it is useful in macros, or more complex setups.
1773 ; Emulate other assemblers:
1775 .segment .string(name)
1780 <sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
1782 Builtin function. The function accepts a string argument in braces and
1783 evaluates to the length of the string.
1787 The following macro encodes a string as a pascal style string with
1788 a leading length byte.
1792 .byte .strlen(Arg), Arg
1797 <sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
1799 Builtin function. The function accepts a token list in braces. The function
1800 result is the number of tokens given as argument. The token list may
1801 optionally be enclosed into curly braces which are not considered part of
1802 the list and not counted. Enclosement in curly braces allows the inclusion
1803 of tokens that would otherwise terminate the list (the closing right paren
1808 The <tt/ldax/ macro accepts the '#' token to denote immediate addressing (as
1809 with the normal 6502 instructions). To translate it into two separate 8 bit
1810 load instructions, the '#' token has to get stripped from the argument:
1814 .if (.match (.mid (0, 1, {arg}), #))
1815 ; ldax called with immediate operand
1816 lda #<(.right (.tcount ({arg})-1, {arg}))
1817 ldx #>(.right (.tcount ({arg})-1, {arg}))
1825 <sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
1827 Builtin function. Matches two token lists against each other. This is
1828 most useful within macros, since macros are not stored as strings, but
1834 .XMATCH(<token list #1>, <token list #2>)
1837 Both token list may contain arbitrary tokens with the exception of the
1838 terminator token (comma resp. right parenthesis) and
1845 The token lists may optionally be enclosed into curly braces. This allows
1846 the inclusion of tokens that would otherwise terminate the list (the closing
1847 right paren in the given case). Often a macro parameter is used for any of
1850 The function compares tokens <em/and/ token values. If you need a function
1851 that just compares the type of tokens, have a look at the <tt><ref
1852 id=".MATCH" name=".MATCH"></tt> function.
1854 See: <tt><ref id=".MATCH" name=".MATCH"></tt>
1858 <sect>Control commands<label id="control-commands"><p>
1860 Here's a list of all control commands and a description, what they do:
1863 <sect1><tt>.A16</tt><label id=".A16"><p>
1865 Valid only in 65816 mode. Switch the accumulator to 16 bit.
1867 Note: This command will not emit any code, it will tell the assembler to
1868 create 16 bit operands for immediate accumulator addressing mode.
1870 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1873 <sect1><tt>.A8</tt><label id=".A8"><p>
1875 Valid only in 65816 mode. Switch the accumulator to 8 bit.
1877 Note: This command will not emit any code, it will tell the assembler to
1878 create 8 bit operands for immediate accu addressing mode.
1880 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1883 <sect1><tt>.ADDR</tt><label id=".ADDR"><p>
1885 Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
1886 may be used for better readability if the data words are address values. In
1887 65816 mode, the address is forced to be 16 bit wide to fit into the current
1888 segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
1889 must be followed by a sequence of (not necessarily constant) expressions.
1894 .addr $0D00, $AF13, _Clear
1897 See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
1901 <sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
1903 Align data to a given boundary. The command expects a constant integer
1904 argument in the range 1 ... 65536, plus an optional second argument
1905 in byte range. If there is a second argument, it is used as fill value,
1906 otherwise the value defined in the linker configuration file is used
1907 (the default for this value is zero).
1909 <tt/.ALIGN/ will insert fill bytes, and the number of fill bytes depend of
1910 the final address of the segment. <tt/.ALIGN/ cannot insert a variable
1911 number of bytes, since that would break address calculations within the
1912 module. So each <tt/.ALIGN/ expects the segment to be aligned to a multiple
1913 of the alignment, because that allows the number of fill bytes to be
1914 calculated in advance by the assembler. You are therefore required to
1915 specify a matching alignment for the segment in the linker config. The
1916 linker will output a warning if the alignment of the segment is less than
1917 what is necessary to have a correct alignment in the object file.
1925 Some unexpected behaviour might occur if there are multiple <tt/.ALIGN/
1926 commands with different arguments. To allow the assembler to calculate the
1927 number of fill bytes in advance, the alignment of the segment must be a
1928 multiple of each of the alignment factors. This may result in unexpectedly
1929 large alignments for the segment within the module.
1940 For the assembler to be able to align correctly, the segment must be aligned
1941 to the least common multiple of 15 and 18 which is 90. The assembler will
1942 calculate this automatically and will mark the segment with this value.
1944 Unfortunately, the combined alignment may get rather large without the user
1945 knowing about it, wasting space in the final executable. If we add another
1946 alignment to the example above
1957 the assembler will force a segment alignment to the least common multiple of
1958 15, 18 and 251 - which is 22590. To protect the user against errors, the
1959 assembler will issue a warning when the combined alignment exceeds 256. The
1960 command line option <tt><ref id="option--large-alignment"
1961 name="--large-alignment"></tt> will disable this warning.
1963 Please note that with alignments that are a power of two (which were the
1964 only alignments possible in older versions of the assembler), the problem is
1965 less severe, because the least common multiple of powers to the same base is
1966 always the larger one.
1970 <sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
1972 Define a string with a trailing zero.
1977 Msg: .asciiz "Hello world"
1980 This will put the string "Hello world" followed by a binary zero into
1981 the current segment. There may be more strings separated by commas, but
1982 the binary zero is only appended once (after the last one).
1985 <sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
1987 Add an assertion. The command is followed by an expression, an action
1988 specifier, and an optional message that is output in case the assertion
1989 fails. If no message was given, the string "Assertion failed" is used. The
1990 action specifier may be one of <tt/warning/, <tt/error/, <tt/ldwarning/ or
1991 <tt/lderror/. In the former two cases, the assertion is evaluated by the
1992 assembler if possible, and in any case, it's also passed to the linker in
1993 the object file (if one is generated). The linker will then evaluate the
1994 expression when segment placement has been done.
1999 .assert * = $8000, error, "Code not at $8000"
2002 The example assertion will check that the current location is at $8000,
2003 when the output file is written, and abort with an error if this is not
2004 the case. More complex expressions are possible. The action specifier
2005 <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
2006 an error message. In the latter case, generation of the output file is
2007 suppressed in both the assembler and linker.
2010 <sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
2012 Is followed by a plus or a minus character. When switched on (using a
2013 +), undefined symbols are automatically marked as import instead of
2014 giving errors. When switched off (which is the default so this does not
2015 make much sense), this does not happen and an error message is
2016 displayed. The state of the autoimport flag is evaluated when the
2017 complete source was translated, before outputting actual code, so it is
2018 <em/not/ possible to switch this feature on or off for separate sections
2019 of code. The last setting is used for all symbols.
2021 You should probably not use this switch because it delays error
2022 messages about undefined symbols until the link stage. The cc65
2023 compiler (which is supposed to produce correct assembler code in all
2024 circumstances, something which is not true for most assembler
2025 programmers) will insert this command to avoid importing each and every
2026 routine from the runtime library.
2031 .autoimport + ; Switch on auto import
2034 <sect1><tt>.BANKBYTES</tt><label id=".BANKBYTES"><p>
2036 Define byte sized data by extracting only the bank byte (that is, bits 16-23) from
2037 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2038 the operator '^' prepended to each expression in its list.
2043 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2045 TableLookupLo: .lobytes MyTable
2046 TableLookupHi: .hibytes MyTable
2047 TableLookupBank: .bankbytes MyTable
2050 which is equivalent to
2053 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2054 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2055 TableLookupBank: .byte ^TableItem0, ^TableItem1, ^TableItem2, ^TableItem3
2058 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2059 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
2060 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>
2063 <sect1><tt>.BSS</tt><label id=".BSS"><p>
2065 Switch to the BSS segment. The name of the BSS segment is always "BSS",
2066 so this is a shortcut for
2072 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2075 <sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
2077 Define byte sized data. Must be followed by a sequence of (byte ranged)
2078 expressions or strings.
2084 .byt "world", $0D, $00
2088 <sect1><tt>.CASE</tt><label id=".CASE"><p>
2090 Switch on or off case sensitivity on identifiers. The default is off
2091 (that is, identifiers are case sensitive), but may be changed by the
2092 -i switch on the command line.
2093 The command must be followed by a '+' or '-' character to switch the
2094 option on or off respectively.
2099 .case - ; Identifiers are not case sensitive
2103 <sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
2105 Apply a custom mapping for characters. The command is followed by two
2106 numbers. The first one is the index of the source character (range 1..255),
2107 the second one is the mapping (range 0..255). The mapping applies to all
2108 character and string constants when they generate output, and overrides a
2109 mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
2110 command line switch.
2115 .charmap $41, $61 ; Map 'A' to 'a'
2119 <sect1><tt>.CODE</tt><label id=".CODE"><p>
2121 Switch to the CODE segment. The name of the CODE segment is always
2122 "CODE", so this is a shortcut for
2128 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2131 <sect1><tt>.CONDES</tt><label id=".CONDES"><p>
2133 Export a symbol and mark it in a special way. The linker is able to build
2134 tables of all such symbols. This may be used to automatically create a list
2135 of functions needed to initialize linked library modules.
2137 Note: The linker has a feature to build a table of marked routines, but it
2138 is your code that must call these routines, so just declaring a symbol with
2139 <tt/.CONDES/ does nothing by itself.
2141 All symbols are exported as an absolute (16 bit) symbol. You don't need to
2142 use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
2143 is implied by <tt/.CONDES/.
2145 <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
2146 <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
2147 specifying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
2148 The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2149 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2150 name=".INTERRUPTOR"></tt> commands are actually shortcuts for <tt/.CONDES/
2151 with a type of <tt/constructor/ resp. <tt/destructor/ or <tt/interruptor/.
2153 After the type, an optional priority may be specified. Higher numeric values
2154 mean higher priority. If no priority is given, the default priority of 7 is
2155 used. Be careful when assigning priorities to your own module constructors
2156 so they won't interfere with the ones in the cc65 library.
2161 .condes ModuleInit, constructor
2162 .condes ModInit, 0, 16
2165 See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2166 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2167 name=".INTERRUPTOR"></tt> commands and the separate section <ref id="condes"
2168 name="Module constructors/destructors"> explaining the feature in more
2172 <sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
2174 Export a symbol and mark it as a module constructor. This may be used
2175 together with the linker to build a table of constructor subroutines that
2176 are called by the startup code.
2178 Note: The linker has a feature to build a table of marked routines, but it
2179 is your code that must call these routines, so just declaring a symbol as
2180 constructor does nothing by itself.
2182 A constructor is always exported as an absolute (16 bit) symbol. You don't
2183 need to use an additional <tt/.export/ statement, this is implied by
2184 <tt/.constructor/. It may have an optional priority that is separated by a
2185 comma. Higher numeric values mean a higher priority. If no priority is
2186 given, the default priority of 7 is used. Be careful when assigning
2187 priorities to your own module constructors so they won't interfere with the
2188 ones in the cc65 library.
2193 .constructor ModuleInit
2194 .constructor ModInit, 16
2197 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2198 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
2199 <ref id="condes" name="Module constructors/destructors"> explaining the
2200 feature in more detail.
2203 <sect1><tt>.DATA</tt><label id=".DATA"><p>
2205 Switch to the DATA segment. The name of the DATA segment is always
2206 "DATA", so this is a shortcut for
2212 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2215 <sect1><tt>.DBYT</tt><label id=".DBYT"><p>
2217 Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
2218 create word sized data in native 65XX format). Must be followed by a
2219 sequence of (word ranged) expressions.
2227 This will emit the bytes
2233 into the current segment in that order.
2236 <sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
2238 Switch on or off debug info generation. The default is off (that is,
2239 the object file will not contain debug infos), but may be changed by the
2240 -g switch on the command line.
2241 The command must be followed by a '+' or '-' character to switch the
2242 option on or off respectively.
2247 .debuginfo + ; Generate debug info
2251 <sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
2253 Start a define style macro definition. The command is followed by an
2254 identifier (the macro name) and optionally by a list of formal arguments
2257 Please note that <tt/.DEFINE/ shares most disadvantages with its C
2258 counterpart, so the general advice is, <bf/NOT/ do use <tt/.DEFINE/ if you
2261 See also the <tt><ref id=".UNDEFINE" name=".UNDEFINE"></tt> command and
2262 section <ref id="macros" name="Macros">.
2265 <sect1><tt>.DELMAC, .DELMACRO</tt><label id=".DELMACRO"><p>
2267 Delete a classic macro (defined with <tt><ref id=".MACRO"
2268 name=".MACRO"></tt>) . The command is followed by the name of an
2269 existing macro. Its definition will be deleted together with the name.
2270 If necessary, another macro with this name may be defined later.
2272 See: <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2273 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2274 <tt><ref id=".MACRO" name=".MACRO"></tt>
2276 See also section <ref id="macros" name="Macros">.
2279 <sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
2281 Builtin function. The function expects an identifier as argument in braces.
2282 The argument is evaluated, and the function yields "true" if the identifier
2283 is a symbol that is already defined somewhere in the source file up to the
2284 current position. Otherwise the function yields false. As an example, the
2285 <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
2292 <sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
2294 Export a symbol and mark it as a module destructor. This may be used
2295 together with the linker to build a table of destructor subroutines that
2296 are called by the startup code.
2298 Note: The linker has a feature to build a table of marked routines, but it
2299 is your code that must call these routines, so just declaring a symbol as
2300 constructor does nothing by itself.
2302 A destructor is always exported as an absolute (16 bit) symbol. You don't
2303 need to use an additional <tt/.export/ statement, this is implied by
2304 <tt/.destructor/. It may have an optional priority that is separated by a
2305 comma. Higher numerical values mean a higher priority. If no priority is
2306 given, the default priority of 7 is used. Be careful when assigning
2307 priorities to your own module destructors so they won't interfere with the
2308 ones in the cc65 library.
2313 .destructor ModuleDone
2314 .destructor ModDone, 16
2317 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2318 id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
2319 section <ref id="condes" name="Module constructors/destructors"> explaining
2320 the feature in more detail.
2323 <sect1><tt>.DWORD</tt><label id=".DWORD"><p>
2325 Define dword sized data (4 bytes) Must be followed by a sequence of
2331 .dword $12344512, $12FA489
2335 <sect1><tt>.ELSE</tt><label id=".ELSE"><p>
2337 Conditional assembly: Reverse the current condition.
2340 <sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
2342 Conditional assembly: Reverse current condition and test a new one.
2345 <sect1><tt>.END</tt><label id=".END"><p>
2347 Forced end of assembly. Assembly stops at this point, even if the command
2348 is read from an include file.
2351 <sect1><tt>.ENDENUM</tt><label id=".ENDENUM"><p>
2353 End a <tt><ref id=".ENUM" name=".ENUM"></tt> declaration.
2356 <sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
2358 Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
2359 <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
2362 <sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
2364 Marks the end of a macro definition.
2366 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2367 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2368 <tt><ref id=".MACRO" name=".MACRO"></tt>
2370 See also section <ref id="macros" name="Macros">.
2373 <sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
2375 End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
2378 <sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
2380 End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
2383 <sect1><tt>.ENDSCOPE</tt><label id=".ENDSCOPE"><p>
2385 End of local lexical level (see <tt/<ref id=".SCOPE" name=".SCOPE">/).
2388 <sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
2390 Ends a struct definition. See the <tt/<ref id=".STRUCT" name=".STRUCT">/
2391 command and the separate section named <ref id="structs" name=""Structs
2395 <sect1><tt>.ENDUNION</tt><label id=".ENDUNION"><p>
2397 Ends a union definition. See the <tt/<ref id=".UNION" name=".UNION">/
2398 command and the separate section named <ref id="structs" name=""Structs
2402 <sect1><tt>.ENUM</tt><label id=".ENUM"><p>
2404 Start an enumeration. This directive is very similar to the C <tt/enum/
2405 keyword. If a name is given, a new scope is created for the enumeration,
2406 otherwise the enumeration members are placed in the enclosing scope.
2408 In the enumeration body, symbols are declared. The first symbol has a value
2409 of zero, and each following symbol will get the value of the preceding plus
2410 one. This behaviour may be overridden by an explicit assignment. Two symbols
2411 may have the same value.
2423 Above example will create a new scope named <tt/errorcodes/ with three
2424 symbols in it that get the values 0, 1 and 2 respectively. Another way
2425 to write this would have been:
2435 Please note that explicit scoping must be used to access the identifiers:
2438 .word errorcodes::no_error
2441 A more complex example:
2450 EWOULDBLOCK = EAGAIN
2454 In this example, the enumeration does not have a name, which means that the
2455 members will be visible in the enclosing scope and can be used in this scope
2456 without explicit scoping. The first member (<tt/EUNKNOWN/) has the value -1.
2457 The value for the following members is incremented by one, so <tt/EOK/ would
2458 be zero and so on. <tt/EWOULDBLOCK/ is an alias for <tt/EGAIN/, so it has an
2459 override for the value using an already defined symbol.
2462 <sect1><tt>.ERROR</tt><label id=".ERROR"><p>
2464 Force an assembly error. The assembler will output an error message
2465 preceded by "User error". Assembly is continued but no object file will
2468 This command may be used to check for initial conditions that must be
2469 set before assembling a source file.
2479 .error "Must define foo or bar!"
2483 See also: <tt><ref id=".FATAL" name=".FATAL"></tt>,
2484 <tt><ref id=".OUT" name=".OUT"></tt>,
2485 <tt><ref id=".WARNING" name=".WARNING"></tt>
2488 <sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
2490 Abort a macro expansion immediately. This command is often useful in
2493 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2494 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2495 <tt><ref id=".MACRO" name=".MACRO"></tt>
2497 See also section <ref id="macros" name="Macros">.
2500 <sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
2502 Make symbols accessible from other modules. Must be followed by a comma
2503 separated list of symbols to export, with each one optionally followed by an
2504 address specification and (also optional) an assignment. Using an additional
2505 assignment in the export statement allows to define and export a symbol in
2506 one statement. The default is to export the symbol with the address size it
2507 actually has. The assembler will issue a warning, if the symbol is exported
2508 with an address size smaller than the actual address size.
2515 .export foobar: far = foo * bar
2516 .export baz := foobar, zap: far = baz - bar
2519 As with constant definitions, using <tt/:=/ instead of <tt/=/ marks the
2522 See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
2525 <sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
2527 Make symbols accessible from other modules. Must be followed by a comma
2528 separated list of symbols to export. The exported symbols are explicitly
2529 marked as zero page symbols. An assignment may be included in the
2530 <tt/.EXPORTZP/ statement. This allows to define and export a symbol in one
2537 .exportzp baz := $02
2540 See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
2543 <sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
2545 Define far (24 bit) address data. The command must be followed by a
2546 sequence of (not necessarily constant) expressions.
2551 .faraddr DrawCircle, DrawRectangle, DrawHexagon
2554 See: <tt><ref id=".ADDR" name=".ADDR"></tt>
2557 <sect1><tt>.FATAL</tt><label id=".FATAL"><p>
2559 Force an assembly error and terminate assembly. The assembler will output an
2560 error message preceded by "User error" and will terminate assembly
2563 This command may be used to check for initial conditions that must be
2564 set before assembling a source file.
2574 .fatal "Must define foo or bar!"
2578 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
2579 <tt><ref id=".OUT" name=".OUT"></tt>,
2580 <tt><ref id=".WARNING" name=".WARNING"></tt>
2583 <sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
2585 This directive may be used to enable one or more compatibility features
2586 of the assembler. While the use of <tt/.FEATURE/ should be avoided when
2587 possible, it may be useful when porting sources written for other
2588 assemblers. There is no way to switch a feature off, once you have
2589 enabled it, so using
2595 will enable the feature until end of assembly is reached.
2597 The following features are available:
2601 <tag><tt>at_in_identifiers</tt><label id="at_in_identifiers"></tag>
2603 Accept the at character (`@') as a valid character in identifiers. The
2604 at character is not allowed to start an identifier, even with this
2607 <tag><tt>c_comments</tt><label id="c_comments"></tag>
2609 Allow C like comments using <tt>/*</tt> and <tt>*/</tt> as left and right
2610 comment terminators. Note that C comments may not be nested. There's also a
2611 pitfall when using C like comments: All statements must be terminated by
2612 "end-of-line". Using C like comments, it is possible to hide the newline,
2613 which results in error messages. See the following non working example:
2616 lda #$00 /* This comment hides the newline
2620 <tag><tt>dollar_in_identifiers</tt><label id="dollar_in_identifiers"></tag>
2622 Accept the dollar sign (`$') as a valid character in identifiers. The
2623 dollar character is not allowed to start an identifier, even with this
2626 <tag><tt>dollar_is_pc</tt><label id="dollar_is_pc"></tag>
2628 The dollar sign may be used as an alias for the star (`*'), which
2629 gives the value of the current PC in expressions.
2630 Note: Assignment to the pseudo variable is not allowed.
2632 <tag><tt>force_range</tt><label id="force_range"></tag>
2634 Force expressions into their valid range for immediate addressing and
2635 storage operators like <tt><ref id=".BYTE" name=".BYTE"></tt> and
2636 <tt><ref id=".WORD" name=".WORD"></tt>. Be very careful with this one,
2637 since it will completely disable error checks.
2639 <tag><tt>labels_without_colons</tt><label id="labels_without_colons"></tag>
2641 Allow labels without a trailing colon. These labels are only accepted,
2642 if they start at the beginning of a line (no leading white space).
2644 <tag><tt>leading_dot_in_identifiers</tt><label id="leading_dot_in_identifiers"></tag>
2646 Accept the dot (`.') as the first character of an identifier. This may be
2647 used for example to create macro names that start with a dot emulating
2648 control directives of other assemblers. Note however, that none of the
2649 reserved keywords built into the assembler, that starts with a dot, may be
2650 overridden. When using this feature, you may also get into trouble if
2651 later versions of the assembler define new keywords starting with a dot.
2653 <tag><tt>loose_char_term</tt><label id="loose_char_term"></tag>
2655 Accept single quotes as well as double quotes as terminators for char
2658 <tag><tt>loose_string_term</tt><label id="loose_string_term"></tag>
2660 Accept single quotes as well as double quotes as terminators for string
2663 <tag><tt>missing_char_term</tt><label id="missing_char_term"></tag>
2665 Accept single quoted character constants where the terminating quote is
2670 <bf/Note:/ This does not work in conjunction with <tt/.FEATURE
2671 loose_string_term/, since in this case the input would be ambiguous.
2673 <tag><tt>org_per_seg</tt><label id="org_per_seg"></tag>
2675 This feature makes relocatable/absolute mode local to the current segment.
2676 Using <tt><ref id=".ORG" name=".ORG"></tt> when <tt/org_per_seg/ is in
2677 effect will only enable absolute mode for the current segment. Dito for
2678 <tt><ref id=".RELOC" name=".RELOC"></tt>.
2680 <tag><tt>pc_assignment</tt><label id="pc_assignment"></tag>
2682 Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
2683 is enabled). Such an assignment is handled identical to the <tt><ref
2684 id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
2685 removing the lines with the assignments may also be an option when porting
2686 code written for older assemblers).
2688 <tag><tt>ubiquitous_idents</tt><label id="ubiquitous_idents"></tag>
2690 Allow the use of instructions names as names for macros and symbols. This
2691 makes it possible to "overload" instructions by defining a macro with the
2692 same name. This does also make it possible to introduce hard to find errors
2693 in your code, so be careful!
2695 <tag><tt>underline_in_numbers</tt><label id="underline_in_numbers"></tag>
2697 Allow underlines within numeric constants. These may be used for grouping
2698 the digits of numbers for easier reading.
2701 .feature underline_in_numbers
2702 .word %1100001110100101
2703 .word %1100_0011_1010_0101 ; Identical but easier to read
2708 It is also possible to specify features on the command line using the
2709 <tt><ref id="option--feature" name="--feature"></tt> command line option.
2710 This is useful when translating sources written for older assemblers, when
2711 you don't want to change the source code.
2713 As an example, to translate sources written for Andre Fachats xa65
2714 assembler, the features
2717 labels_without_colons, pc_assignment, loose_char_term
2720 may be helpful. They do not make ca65 completely compatible, so you may not
2721 be able to translate the sources without changes, even when enabling these
2722 features. However, I have found several sources that translate without
2723 problems when enabling these features on the command line.
2726 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
2728 Insert an option string into the object file. There are two forms of
2729 this command, one specifies the option by a keyword, the second
2730 specifies it as a number. Since usage of the second one needs knowledge
2731 of the internal encoding, its use is not recommended and I will only
2732 describe the first form here.
2734 The command is followed by one of the keywords
2742 a comma and a string. The option is written into the object file
2743 together with the string value. This is currently unidirectional and
2744 there is no way to actually use these options once they are in the
2750 .fileopt comment, "Code stolen from my brother"
2751 .fileopt compiler, "BASIC 2.0"
2752 .fopt author, "J. R. User"
2756 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
2758 Import an absolute symbol from another module. The command is followed by a
2759 comma separated list of symbols to import. The command is similar to <tt>
2760 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
2761 written to the generated object file, even if the symbol is never referenced
2762 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
2763 references for unused symbols).
2768 .forceimport needthisone, needthistoo
2771 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2774 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
2776 Declare symbols as global. Must be followed by a comma separated list of
2777 symbols to declare. Symbols from the list, that are defined somewhere in the
2778 source, are exported, all others are imported. Additional <tt><ref
2779 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
2780 name=".EXPORT"></tt> commands for the same symbol are allowed.
2789 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
2791 Declare symbols as global. Must be followed by a comma separated list of
2792 symbols to declare. Symbols from the list, that are defined somewhere in the
2793 source, are exported, all others are imported. Additional <tt><ref
2794 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
2795 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
2796 in the list are explicitly marked as zero page symbols.
2804 <sect1><tt>.HIBYTES</tt><label id=".HIBYTES"><p>
2806 Define byte sized data by extracting only the high byte (that is, bits 8-15) from
2807 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2808 the operator '>' prepended to each expression in its list.
2813 .lobytes $1234, $2345, $3456, $4567
2814 .hibytes $fedc, $edcb, $dcba, $cba9
2817 which is equivalent to
2820 .byte $34, $45, $56, $67
2821 .byte $fe, $ed, $dc, $cb
2827 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2829 TableLookupLo: .lobytes MyTable
2830 TableLookupHi: .hibytes MyTable
2833 which is equivalent to
2836 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2837 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2840 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2841 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>,
2842 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
2845 <sect1><tt>.I16</tt><label id=".I16"><p>
2847 Valid only in 65816 mode. Switch the index registers to 16 bit.
2849 Note: This command will not emit any code, it will tell the assembler to
2850 create 16 bit operands for immediate operands.
2852 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
2853 name=".SMART"></tt> commands.
2856 <sect1><tt>.I8</tt><label id=".I8"><p>
2858 Valid only in 65816 mode. Switch the index registers to 8 bit.
2860 Note: This command will not emit any code, it will tell the assembler to
2861 create 8 bit operands for immediate operands.
2863 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
2864 name=".SMART"></tt> commands.
2867 <sect1><tt>.IF</tt><label id=".IF"><p>
2869 Conditional assembly: Evaluate an expression and switch assembler output
2870 on or off depending on the expression. The expression must be a constant
2871 expression, that is, all operands must be defined.
2873 A expression value of zero evaluates to FALSE, any other value evaluates
2877 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
2879 Conditional assembly: Check if there are any remaining tokens in this line,
2880 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
2881 condition is not true, further lines are not assembled until an <tt><ref
2882 id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2883 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2885 This command is often used to check if a macro parameter was given. Since an
2886 empty macro parameter will evaluate to nothing, the condition will evaluate
2887 to TRUE if an empty parameter was given.
2901 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2904 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
2906 Conditional assembly: Evaluate an expression and switch assembler output
2907 on or off depending on the constness of the expression.
2909 A const expression evaluates to to TRUE, a non const expression (one
2910 containing an imported or currently undefined symbol) evaluates to
2913 See also: <tt><ref id=".CONST" name=".CONST"></tt>
2916 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
2918 Conditional assembly: Check if a symbol is defined. Must be followed by
2919 a symbol name. The condition is true if the the given symbol is already
2920 defined, and false otherwise.
2922 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2925 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
2927 Conditional assembly: Check if there are any remaining tokens in this line,
2928 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
2929 condition is not true, further lines are not assembled until an <tt><ref
2930 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2931 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2933 This command is often used to check if a macro parameter was given.
2934 Since an empty macro parameter will evaluate to nothing, the condition
2935 will evaluate to FALSE if an empty parameter was given.
2948 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2951 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
2953 Conditional assembly: Check if a symbol is defined. Must be followed by
2954 a symbol name. The condition is true if the the given symbol is not
2955 defined, and false otherwise.
2957 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2960 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
2962 Conditional assembly: Check if a symbol is referenced. Must be followed
2963 by a symbol name. The condition is true if if the the given symbol was
2964 not referenced before, and false otherwise.
2966 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2969 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
2971 Conditional assembly: Check if the assembler is currently in 6502 mode
2972 (see <tt><ref id=".P02" name=".P02"></tt> command).
2975 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
2977 Conditional assembly: Check if the assembler is currently in 65816 mode
2978 (see <tt><ref id=".P816" name=".P816"></tt> command).
2981 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
2983 Conditional assembly: Check if the assembler is currently in 65C02 mode
2984 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
2987 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
2989 Conditional assembly: Check if the assembler is currently in 65SC02 mode
2990 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
2993 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
2995 Conditional assembly: Check if a symbol is referenced. Must be followed
2996 by a symbol name. The condition is true if if the the given symbol was
2997 referenced before, and false otherwise.
2999 This command may be used to build subroutine libraries in include files
3000 (you may use separate object modules for this purpose too).
3005 .ifref ToHex ; If someone used this subroutine
3006 ToHex: tay ; Define subroutine
3012 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
3015 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
3017 Import a symbol from another module. The command is followed by a comma
3018 separated list of symbols to import, with each one optionally followed by
3019 an address specification.
3025 .import bar: zeropage
3028 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
3031 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
3033 Import a symbol from another module. The command is followed by a comma
3034 separated list of symbols to import. The symbols are explicitly imported
3035 as zero page symbols (that is, symbols with values in byte range).
3043 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
3046 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
3048 Include a file as binary data. The command expects a string argument
3049 that is the name of a file to include literally in the current segment.
3050 In addition to that, a start offset and a size value may be specified,
3051 separated by commas. If no size is specified, all of the file from the
3052 start offset to end-of-file is used. If no start position is specified
3053 either, zero is assumed (which means that the whole file is inserted).
3058 ; Include whole file
3059 .incbin "sprites.dat"
3061 ; Include file starting at offset 256
3062 .incbin "music.dat", $100
3064 ; Read 100 bytes starting at offset 200
3065 .incbin "graphics.dat", 200, 100
3069 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
3071 Include another file. Include files may be nested up to a depth of 16.
3080 <sect1><tt>.INTERRUPTOR</tt><label id=".INTERRUPTOR"><p>
3082 Export a symbol and mark it as an interruptor. This may be used together
3083 with the linker to build a table of interruptor subroutines that are called
3086 Note: The linker has a feature to build a table of marked routines, but it
3087 is your code that must call these routines, so just declaring a symbol as
3088 interruptor does nothing by itself.
3090 An interruptor is always exported as an absolute (16 bit) symbol. You don't
3091 need to use an additional <tt/.export/ statement, this is implied by
3092 <tt/.interruptor/. It may have an optional priority that is separated by a
3093 comma. Higher numeric values mean a higher priority. If no priority is
3094 given, the default priority of 7 is used. Be careful when assigning
3095 priorities to your own module constructors so they won't interfere with the
3096 ones in the cc65 library.
3101 .interruptor IrqHandler
3102 .interruptor Handler, 16
3105 See the <tt><ref id=".CONDES" name=".CONDES"></tt> command and the separate
3106 section <ref id="condes" name="Module constructors/destructors"> explaining
3107 the feature in more detail.
3110 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
3112 Switch on or off line continuations using the backslash character
3113 before a newline. The option is off by default.
3114 Note: Line continuations do not work in a comment. A backslash at the
3115 end of a comment is treated as part of the comment and does not trigger
3117 The command must be followed by a '+' or '-' character to switch the
3118 option on or off respectively.
3123 .linecont + ; Allow line continuations
3126 #$20 ; This is legal now
3130 <sect1><tt>.LIST</tt><label id=".LIST"><p>
3132 Enable output to the listing. The command must be followed by a boolean
3133 switch ("on", "off", "+" or "-") and will enable or disable listing
3135 The option has no effect if the listing is not enabled by the command line
3136 switch -l. If -l is used, an internal counter is set to 1. Lines are output
3137 to the listing file, if the counter is greater than zero, and suppressed if
3138 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
3144 .list on ; Enable listing output
3148 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
3150 Set, how many bytes are shown in the listing for one source line. The
3151 default is 12, so the listing will show only the first 12 bytes for any
3152 source line that generates more than 12 bytes of code or data.
3153 The directive needs an argument, which is either "unlimited", or an
3154 integer constant in the range 4..255.
3159 .listbytes unlimited ; List all bytes
3160 .listbytes 12 ; List the first 12 bytes
3161 .incbin "data.bin" ; Include large binary file
3165 <sect1><tt>.LOBYTES</tt><label id=".LOBYTES"><p>
3167 Define byte sized data by extracting only the low byte (that is, bits 0-7) from
3168 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
3169 the operator '<' prepended to each expression in its list.
3174 .lobytes $1234, $2345, $3456, $4567
3175 .hibytes $fedc, $edcb, $dcba, $cba9
3178 which is equivalent to
3181 .byte $34, $45, $56, $67
3182 .byte $fe, $ed, $dc, $cb
3188 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
3190 TableLookupLo: .lobytes MyTable
3191 TableLookupHi: .hibytes MyTable
3194 which is equivalent to
3197 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
3198 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
3201 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
3202 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
3203 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
3206 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
3208 This command may only be used inside a macro definition. It declares a
3209 list of identifiers as local to the macro expansion.
3211 A problem when using macros are labels: Since they don't change their name,
3212 you get a "duplicate symbol" error if the macro is expanded the second time.
3213 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
3214 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
3217 Some other assemblers start a new lexical block inside a macro expansion.
3218 This has some drawbacks however, since that will not allow <em/any/ symbol
3219 to be visible outside a macro, a feature that is sometimes useful. The
3220 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
3221 to address the problem.
3223 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
3227 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
3229 Defines the character that start "cheap" local labels. You may use one
3230 of '@' and '?' as start character. The default is '@'.
3232 Cheap local labels are labels that are visible only between two non
3233 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
3234 using explicit lexical nesting.
3241 Clear: lda #$00 ; Global label
3242 ?Loop: sta Mem,y ; Local label
3246 Sub: ... ; New global label
3247 bne ?Loop ; ERROR: Unknown identifier!
3251 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
3253 Insert a predefined macro package. The command is followed by an
3254 identifier specifying the macro package to insert. Available macro
3258 atari Defines the scrcode macro.
3259 cbm Defines the scrcode macro.
3260 cpu Defines constants for the .CPU variable.
3261 generic Defines generic macros like add and sub.
3262 longbranch Defines conditional long jump macros.
3265 Including a macro package twice, or including a macro package that
3266 redefines already existing macros will lead to an error.
3271 .macpack longbranch ; Include macro package
3273 cmp #$20 ; Set condition codes
3274 jne Label ; Jump long on condition
3277 Macro packages are explained in more detail in section <ref
3278 id="macropackages" name="Macro packages">.
3281 <sect1><tt>.MAC, .MACRO</tt><label id=".MACRO"><p>
3283 Start a classic macro definition. The command is followed by an identifier
3284 (the macro name) and optionally by a comma separated list of identifiers
3285 that are macro parameters. A macro definition is terminated by <tt><ref
3286 id=".ENDMACRO" name=".ENDMACRO"></tt>.
3291 .macro ldax arg ; Define macro ldax
3296 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
3297 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
3298 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>
3300 See also section <ref id="macros" name="Macros">.
3303 <sect1><tt>.ORG</tt><label id=".ORG"><p>
3305 Start a section of absolute code. The command is followed by a constant
3306 expression that gives the new PC counter location for which the code is
3307 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
3310 By default, absolute/relocatable mode is global (valid even when switching
3311 segments). Using <tt>.FEATURE <ref id="org_per_seg" name="org_per_seg"></tt>
3312 it can be made segment local.
3314 Please note that you <em/do not need/ <tt/.ORG/ in most cases. Placing
3315 code at a specific address is the job of the linker, not the assembler, so
3316 there is usually no reason to assemble code to a specific address.
3321 .org $7FF ; Emit code starting at $7FF
3325 <sect1><tt>.OUT</tt><label id=".OUT"><p>
3327 Output a string to the console without producing an error. This command
3328 is similar to <tt/.ERROR/, however, it does not force an assembler error
3329 that prevents the creation of an object file.
3334 .out "This code was written by the codebuster(tm)"
3337 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3338 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3339 <tt><ref id=".WARNING" name=".WARNING"></tt>
3342 <sect1><tt>.P02</tt><label id=".P02"><p>
3344 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
3345 instructions. This is the default if not overridden by the
3346 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
3348 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
3349 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3352 <sect1><tt>.P816</tt><label id=".P816"><p>
3354 Enable the 65816 instruction set. This is a superset of the 65SC02 and
3355 6502 instruction sets.
3357 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3358 name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
3361 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
3363 Set the page length for the listing. Must be followed by an integer
3364 constant. The value may be "unlimited", or in the range 32 to 127. The
3365 statement has no effect if no listing is generated. The default value is -1
3366 (unlimited) but may be overridden by the <tt/--pagelength/ command line
3367 option. Beware: Since ca65 is a one pass assembler, the listing is generated
3368 after assembly is complete, you cannot use multiple line lengths with one
3369 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
3374 .pagelength 66 ; Use 66 lines per listing page
3376 .pagelength unlimited ; Unlimited page length
3380 <sect1><tt>.PC02</tt><label id=".PC02"><p>
3382 Enable the 65C02 instructions set. This instruction set includes all
3383 6502 and 65SC02 instructions.
3385 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3386 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3389 <sect1><tt>.POPCPU</tt><label id=".POPCPU"><p>
3391 Pop the last CPU setting from the stack, and activate it.
3393 This command will switch back to the CPU that was last pushed onto the CPU
3394 stack using the <tt><ref id=".PUSHCPU" name=".PUSHCPU"></tt> command, and
3395 remove this entry from the stack.
3397 The assembler will print an error message if the CPU stack is empty when
3398 this command is issued.
3400 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".PUSHCPU"
3401 name=".PUSHCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3404 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
3406 Pop the last pushed segment from the stack, and set it.
3408 This command will switch back to the segment that was last pushed onto the
3409 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3410 command, and remove this entry from the stack.
3412 The assembler will print an error message if the segment stack is empty
3413 when this command is issued.
3415 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3418 <sect1><tt>.PROC</tt><label id=".PROC"><p>
3420 Start a nested lexical level with the given name and adds a symbol with this
3421 name to the enclosing scope. All new symbols from now on are in the local
3422 lexical level and are accessible from outside only via <ref id="scopesyntax"
3423 name="explicit scope specification">. Symbols defined outside this local
3424 level may be accessed as long as their names are not used for new symbols
3425 inside the level. Symbols names in other lexical levels do not clash, so you
3426 may use the same names for identifiers. The lexical level ends when the
3427 <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
3428 may be nested up to a depth of 16 (this is an artificial limit to protect
3429 against errors in the source).
3431 Note: Macro names are always in the global level and in a separate name
3432 space. There is no special reason for this, it's just that I've never
3433 had any need for local macro definitions.
3438 .proc Clear ; Define Clear subroutine, start new level
3440 L1: sta Mem,y ; L1 is local and does not cause a
3441 ; duplicate symbol error if used in other
3444 bne L1 ; Reference local symbol
3446 .endproc ; Leave lexical level
3449 See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
3453 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
3455 Enable the 65SC02 instructions set. This instruction set includes all
3458 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
3459 name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3462 <sect1><tt>.PUSHCPU</tt><label id=".PUSHCPU"><p>
3464 Push the currently active CPU onto a stack. The stack has a size of 8
3467 <tt/.PUSHCPU/ allows together with <tt><ref id=".POPCPU"
3468 name=".POPCPU"></tt> to switch to another CPU and to restore the old CPU
3469 later, without knowledge of the current CPU setting.
3471 The assembler will print an error message if the CPU stack is already full,
3472 when this command is issued.
3474 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".POPCPU"
3475 name=".POPCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3478 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
3480 Push the currently active segment onto a stack. The entries on the stack
3481 include the name of the segment and the segment type. The stack has a size
3484 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3485 to switch to another segment and to restore the old segment later, without
3486 even knowing the name and type of the current segment.
3488 The assembler will print an error message if the segment stack is already
3489 full, when this command is issued.
3491 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3494 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
3496 Switch back to relocatable mode. See the <tt><ref id=".ORG"
3497 name=".ORG"></tt> command.
3500 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
3502 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
3503 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
3504 a constant expression that tells how many times the commands in the body
3505 should get repeated. Optionally, a comma and an identifier may be specified.
3506 If this identifier is found in the body of the repeat statement, it is
3507 replaced by the current repeat count (starting with zero for the first time
3508 the body is repeated).
3510 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
3511 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
3512 level will be used, not the one from the outer level.
3516 The following macro will emit a string that is "encrypted" in that all
3517 characters of the string are XORed by the value $55.
3521 .repeat .strlen(Arg), I
3522 .byte .strat(Arg, I) ^ $55
3527 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
3530 <sect1><tt>.RES</tt><label id=".RES"><p>
3532 Reserve storage. The command is followed by one or two constant
3533 expressions. The first one is mandatory and defines, how many bytes of
3534 storage should be defined. The second, optional expression must by a
3535 constant byte value that will be used as value of the data. If there
3536 is no fill value given, the linker will use the value defined in the
3537 linker configuration file (default: zero).
3542 ; Reserve 12 bytes of memory with value $AA
3547 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
3549 Switch to the RODATA segment. The name of the RODATA segment is always
3550 "RODATA", so this is a shortcut for
3556 The RODATA segment is a segment that is used by the compiler for
3557 readonly data like string constants.
3559 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
3562 <sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
3564 Start a nested lexical level with the given name. All new symbols from now
3565 on are in the local lexical level and are accessible from outside only via
3566 <ref id="scopesyntax" name="explicit scope specification">. Symbols defined
3567 outside this local level may be accessed as long as their names are not used
3568 for new symbols inside the level. Symbols names in other lexical levels do
3569 not clash, so you may use the same names for identifiers. The lexical level
3570 ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
3571 read. Lexical levels may be nested up to a depth of 16 (this is an
3572 artificial limit to protect against errors in the source).
3574 Note: Macro names are always in the global level and in a separate name
3575 space. There is no special reason for this, it's just that I've never
3576 had any need for local macro definitions.
3581 .scope Error ; Start new scope named Error
3583 File = 1 ; File error
3584 Parse = 2 ; Parse error
3585 .endscope ; Close lexical level
3588 lda #Error::File ; Use symbol from scope Error
3591 See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
3595 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
3597 Switch to another segment. Code and data is always emitted into a
3598 segment, that is, a named section of data. The default segment is
3599 "CODE". There may be up to 254 different segments per object file
3600 (and up to 65534 per executable). There are shortcut commands for
3601 the most common segments ("CODE", "DATA" and "BSS").
3603 The command is followed by a string containing the segment name (there are
3604 some constraints for the name - as a rule of thumb use only those segment
3605 names that would also be valid identifiers). There may also be an optional
3606 address size separated by a colon. See the section covering <tt/<ref
3607 id="address-sizes" name="address sizes">/ for more information.
3609 The default address size for a segment depends on the memory model specified
3610 on the command line. The default is "absolute", which means that you don't
3611 have to use an address size modifier in most cases.
3613 "absolute" means that the is a segment with 16 bit (absolute) addressing.
3614 That is, the segment will reside somewhere in core memory outside the zero
3615 page. "zeropage" (8 bit) means that the segment will be placed in the zero
3616 page and direct (short) addressing is possible for data in this segment.
3618 Beware: Only labels in a segment with the zeropage attribute are marked
3619 as reachable by short addressing. The `*' (PC counter) operator will
3620 work as in other segments and will create absolute variable values.
3622 Please note that a segment cannot have two different address sizes. A
3623 segment specified as zeropage cannot be declared as being absolute later.
3628 .segment "ROM2" ; Switch to ROM2 segment
3629 .segment "ZP2": zeropage ; New direct segment
3630 .segment "ZP2" ; Ok, will use last attribute
3631 .segment "ZP2": absolute ; Error, redecl mismatch
3634 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
3635 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt> and <tt><ref
3636 id=".RODATA" name=".RODATA"></tt>
3639 <sect1><tt>.SET</tt><label id=".SET"><p>
3641 <tt/.SET/ is used to assign a value to a variable. See <ref id="variables"
3642 name="Numeric variables"> for a full description.
3645 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
3647 Switch the CPU instruction set. The command is followed by a string that
3648 specifies the CPU. Possible values are those that can also be supplied to
3649 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
3650 namely: 6502, 6502X, 65SC02, 65C02, 65816 and HuC6280.
3652 See: <tt><ref id=".CPU" name=".CPU"></tt>,
3653 <tt><ref id=".IFP02" name=".IFP02"></tt>,
3654 <tt><ref id=".IFP816" name=".IFP816"></tt>,
3655 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
3656 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
3657 <tt><ref id=".P02" name=".P02"></tt>,
3658 <tt><ref id=".P816" name=".P816"></tt>,
3659 <tt><ref id=".PC02" name=".PC02"></tt>,
3660 <tt><ref id=".PSC02" name=".PSC02"></tt>
3663 <sect1><tt>.SMART</tt><label id=".SMART"><p>
3665 Switch on or off smart mode. The command must be followed by a '+' or '-'
3666 character to switch the option on or off respectively. The default is off
3667 (that is, the assembler doesn't try to be smart), but this default may be
3668 changed by the -s switch on the command line.
3670 In smart mode the assembler will do the following:
3673 <item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
3674 and update the operand sizes accordingly. If the operand of such an
3675 instruction cannot be evaluated by the assembler (for example, because
3676 the operand is an imported symbol), a warning is issued. Beware: Since
3677 the assembler cannot trace the execution flow this may lead to false
3678 results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
3679 instructions to tell the assembler about the current settings.
3680 <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
3681 used within a procedure declared as <tt/far/, or if the procedure has
3682 no explicit address specification, but it is <tt/far/ because of the
3690 .smart - ; Stop being smart
3693 See: <tt><ref id=".A16" name=".A16"></tt>,
3694 <tt><ref id=".A8" name=".A8"></tt>,
3695 <tt><ref id=".I16" name=".I16"></tt>,
3696 <tt><ref id=".I8" name=".I8"></tt>
3699 <sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
3701 Starts a struct definition. Structs are covered in a separate section named
3702 <ref id="structs" name=""Structs and unions"">.
3704 See also: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>,
3705 <tt><ref id=".ENDUNION" name=".ENDUNION"></tt>,
3706 <tt><ref id=".UNION" name=".UNION"></tt>
3709 <sect1><tt>.TAG</tt><label id=".TAG"><p>
3711 Allocate space for a struct or union.
3722 .tag Point ; Allocate 4 bytes
3726 <sect1><tt>.UNDEF, .UNDEFINE</tt><label id=".UNDEFINE"><p>
3728 Delete a define style macro definition. The command is followed by an
3729 identifier which specifies the name of the macro to delete. Macro
3730 replacement is switched of when reading the token following the command
3731 (otherwise the macro name would be replaced by its replacement list).
3733 See also the <tt><ref id=".DEFINE" name=".DEFINE"></tt> command and
3734 section <ref id="macros" name="Macros">.
3737 <sect1><tt>.UNION</tt><label id=".UNION"><p>
3739 Starts a union definition. Unions are covered in a separate section named
3740 <ref id="structs" name=""Structs and unions"">.
3742 See also: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>,
3743 <tt><ref id=".ENDUNION" name=".ENDUNION"></tt>,
3744 <tt><ref id=".STRUCT" name=".STRUCT"></tt>
3747 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
3749 Force an assembly warning. The assembler will output a warning message
3750 preceded by "User warning". This warning will always be output, even if
3751 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
3752 command line option.
3754 This command may be used to output possible problems when assembling
3763 .warning "Forward jump in jne, cannot optimize!"
3773 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3774 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3775 <tt><ref id=".OUT" name=".OUT"></tt>
3778 <sect1><tt>.WORD</tt><label id=".WORD"><p>
3780 Define word sized data. Must be followed by a sequence of (word ranged,
3781 but not necessarily constant) expressions.
3786 .word $0D00, $AF13, _Clear
3790 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
3792 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
3793 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
3797 .segment "ZEROPAGE", zeropage
3800 Because of the "zeropage" attribute, labels declared in this segment are
3801 addressed using direct addressing mode if possible. You <em/must/ instruct
3802 the linker to place this segment somewhere in the address range 0..$FF
3803 otherwise you will get errors.
3805 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
3809 <sect>Macros<label id="macros"><p>
3812 <sect1>Introduction<p>
3814 Macros may be thought of as "parametrized super instructions". Macros are
3815 sequences of tokens that have a name. If that name is used in the source
3816 file, the macro is "expanded", that is, it is replaced by the tokens that
3817 were specified when the macro was defined.
3820 <sect1>Macros without parameters<p>
3822 In its simplest form, a macro does not have parameters. Here's an
3826 .macro asr ; Arithmetic shift right
3827 cmp #$80 ; Put bit 7 into carry
3828 ror ; Rotate right with carry
3832 The macro above consists of two real instructions, that are inserted into
3833 the code, whenever the macro is expanded. Macro expansion is simply done
3834 by using the name, like this:
3843 <sect1>Parametrized macros<p>
3845 When using macro parameters, macros can be even more useful:
3859 When calling the macro, you may give a parameter, and each occurrence of
3860 the name "addr" in the macro definition will be replaced by the given
3879 A macro may have more than one parameter, in this case, the parameters
3880 are separated by commas. You are free to give less parameters than the
3881 macro actually takes in the definition. You may also leave intermediate
3882 parameters empty. Empty parameters are replaced by empty space (that is,
3883 they are removed when the macro is expanded). If you have a look at our
3884 macro definition above, you will see, that replacing the "addr" parameter
3885 by nothing will lead to wrong code in most lines. To help you, writing
3886 macros with a variable parameter list, there are some control commands:
3888 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
3889 returns true, if there are any tokens on the remainder of the line. Since
3890 empty parameters are replaced by nothing, this may be used to test if a given
3891 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
3894 Look at this example:
3897 .macro ldaxy a, x, y
3910 This macro may be called as follows:
3913 ldaxy 1, 2, 3 ; Load all three registers
3915 ldaxy 1, , 3 ; Load only a and y
3917 ldaxy , , 3 ; Load y only
3920 There's another helper command for determining, which macro parameters are
3921 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt> This command is
3922 replaced by the parameter count given, <em/including/ intermediate empty macro
3926 ldaxy 1 ; .PARAMCOUNT = 1
3927 ldaxy 1,,3 ; .PARAMCOUNT = 3
3928 ldaxy 1,2 ; .PARAMCOUNT = 2
3929 ldaxy 1, ; .PARAMCOUNT = 2
3930 ldaxy 1,2,3 ; .PARAMCOUNT = 3
3933 Macro parameters may optionally be enclosed into curly braces. This allows the
3934 inclusion of tokens that would otherwise terminate the parameter (the comma in
3935 case of a macro parameter).
3938 .macro foo arg1, arg2
3942 foo ($00,x) ; Two parameters passed
3943 foo {($00,x)} ; One parameter passed
3946 In the first case, the macro is called with two parameters: '<tt/($00/'
3947 and 'x)'. The comma is not passed to the macro, since it is part of the
3948 calling sequence, not the parameters.
3950 In the second case, '($00,x)' is passed to the macro, this time
3951 including the comma.
3954 <sect1>Detecting parameter types<p>
3956 Sometimes it is nice to write a macro that acts differently depending on the
3957 type of the argument supplied. An example would be a macro that loads a 16 bit
3958 value from either an immediate operand, or from memory. The <tt/<ref
3959 id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
3960 functions will allow you to do exactly this:
3964 .if (.match (.left (1, {arg}), #))
3966 lda #<(.right (.tcount ({arg})-1, {arg}))
3967 ldx #>(.right (.tcount ({arg})-1, {arg}))
3969 ; assume absolute or zero page
3976 Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
3977 check if its argument begins with a hash mark. If so, two immediate loads are
3978 emitted, Otherwise a load from an absolute zero page memory location is
3979 assumed. Please note how the curly braces are used to enclose parameters to
3980 pseudo functions handling token lists. This is necessary, because the token
3981 lists may include commas or parens, which would be treated by the assembler
3984 The macro can be used as
3989 ldax #$1234 ; X=$12, A=$34
3991 ldax foo ; X=$56, A=$78
3995 <sect1>Recursive macros<p>
3997 Macros may be used recursively:
4000 .macro push r1, r2, r3
4009 There's also a special macro to help writing recursive macros: <tt><ref
4010 id=".EXITMACRO" name=".EXITMACRO"></tt> This command will stop macro expansion
4014 .macro push r1, r2, r3, r4, r5, r6, r7
4016 ; First parameter is empty
4022 push r2, r3, r4, r5, r6, r7
4026 When expanding this macro, the expansion will push all given parameters
4027 until an empty one is encountered. The macro may be called like this:
4030 push $20, $21, $32 ; Push 3 ZP locations
4031 push $21 ; Push one ZP location
4035 <sect1>Local symbols inside macros<p>
4037 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
4038 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
4039 Have a look at the inc16 macro above. Here is it again:
4053 If you have a closer look at the code, you will notice, that it could be
4054 written more efficiently, like this:
4065 But imagine what happens, if you use this macro twice? Since the label "Skip"
4066 has the same name both times, you get a "duplicate symbol" error. Without a
4067 way to circumvent this problem, macros are not as useful, as they could be.
4068 One possible solution is the command <tt><ref id=".LOCAL" name=".LOCAL"></tt>.
4069 It declares one or more symbols as local to the macro expansion. The names of
4070 local variables are replaced by a unique name in each separate macro
4071 expansion. So we can solve the problem above by using <tt/.LOCAL/:
4075 .local Skip ; Make Skip a local symbol
4079 Skip: ; Not visible outside
4083 Another solution is of course to start a new lexical block inside the macro
4084 that hides any labels:
4098 <sect1>C style macros<p>
4100 Starting with version 2.5 of the assembler, there is a second macro type
4101 available: C style macros using the <tt/.DEFINE/ directive. These macros are
4102 similar to the classic macro type described above, but behaviour is sometimes
4107 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
4108 span more than a line. You may use line continuation (see <tt><ref
4109 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
4110 more than one line for increased readability, but the macro itself
4111 may not contain an end-of-line token.
4113 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
4114 the name space with classic macros, but they are detected and replaced
4115 at the scanner level. While classic macros may be used in every place,
4116 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
4117 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
4118 they are more versatile in some situations.
4120 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
4121 parameters. While classic macros may have empty parameters, this is
4122 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
4123 For this macro type, the number of actual parameters must match
4124 exactly the number of formal parameters.
4126 To make this possible, formal parameters are enclosed in braces when
4127 defining the macro. If there are no parameters, the empty braces may
4130 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
4131 contain end-of-line tokens, there are things that cannot be done. They
4132 may not contain several processor instructions for example. So, while
4133 some things may be done with both macro types, each type has special
4134 usages. The types complement each other.
4138 Let's look at a few examples to make the advantages and disadvantages
4141 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
4142 following <tt/.DEFINE/:
4147 foo EQU $1234 ; This is accepted now
4150 You may use the directive to define string constants used elsewhere:
4153 ; Define the version number
4154 .define VERSION "12.3a"
4160 Macros with parameters may also be useful:
4163 .define DEBUG(message) .out message
4165 DEBUG "Assembling include file #3"
4168 Note that, while formal parameters have to be placed in braces, this is
4169 not true for the actual parameters. Beware: Since the assembler cannot
4170 detect the end of one parameter, only the first token is used. If you
4171 don't like that, use classic macros instead:
4174 .macro DEBUG message
4179 (This is an example where a problem can be solved with both macro types).
4182 <sect1>Characters in macros<p>
4184 When using the <ref id="option-t" name="-t"> option, characters are translated
4185 into the target character set of the specific machine. However, this happens
4186 as late as possible. This means that strings are translated if they are part
4187 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
4188 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
4189 used as part of an expression.
4191 This behaviour is very intuitive outside of macros but may be confusing when
4192 doing more complex macros. If you compare characters against numeric values,
4193 be sure to take the translation into account.
4196 <sect1>Deleting macros<p>
4198 Macros can be deleted. This will not work if the macro that should be deleted
4199 is currently expanded as in the following non working example:
4203 .delmacro notworking
4206 notworking ; Will not work
4209 The commands to delete classic and define style macros differ. Classic macros
4210 can be deleted by use of <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>, while
4211 for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros, <tt><ref
4212 id=".UNDEFINE" name=".UNDEFINE"></tt> must be used. Example:
4220 .byte value ; Emit one byte with value 1
4221 mac ; Emit another byte with value 2
4226 .byte value ; Error: Unknown identifier
4227 mac ; Error: Missing ":"
4230 A separate command for <tt>.DEFINE</tt> style macros was necessary, because
4231 the name of such a macro is replaced by its replacement list on a very low
4232 level. To get the actual name, macro replacement has to be switched off when
4233 reading the argument to <tt>.UNDEFINE</tt>. This does also mean that the
4234 argument to <tt>.UNDEFINE</tt> is not allowed to come from another
4235 <tt>.DEFINE</tt>. All this is not necessary for classic macros, so having two
4236 different commands increases flexibility.
4239 <sect>Macro packages<label id="macropackages"><p>
4241 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
4242 macro packages may be included with just one command. Available macro packages
4246 <sect1><tt>.MACPACK generic</tt><p>
4248 This macro package defines macros that are useful in almost any program.
4249 Currently defined macros are:
4293 <sect1><tt>.MACPACK longbranch</tt><p>
4295 This macro package defines long conditional jumps. They are named like the
4296 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
4297 definition for the "<tt/jeq/" macro, the other macros are built using the same
4302 .if .def(Target) .and ((*+2)-(Target) <= 127)
4311 All macros expand to a short branch, if the label is already defined (back
4312 jump) and is reachable with a short jump. Otherwise the macro expands to a
4313 conditional branch with the branch condition inverted, followed by an absolute
4314 jump to the actual branch target.
4316 The package defines the following macros:
4319 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
4324 <sect1><tt>.MACPACK atari</tt><p>
4326 The atari macro package will define a macro named <tt/scrcode/. It takes a
4327 string as argument and places this string into memory translated into screen
4331 <sect1><tt>.MACPACK cbm</tt><p>
4333 The cbm macro package will define a macro named <tt/scrcode/. It takes a
4334 string as argument and places this string into memory translated into screen
4338 <sect1><tt>.MACPACK cpu</tt><p>
4340 This macro package does not define any macros but constants used to examine
4341 the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
4342 each supported CPU a constant similar to
4353 is defined. These constants may be used to determine the exact type of the
4354 currently enabled CPU. In addition to that, for each CPU instruction set,
4355 another constant is defined:
4366 The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
4367 be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
4368 currently enabled CPU supports a specific instruction set. For example the
4369 65C02 supports all instructions of the 65SC02 CPU, so it has the
4370 <tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
4374 .if (.cpu .bitand CPU_ISET_65SC02)
4382 it is possible to determine if the
4388 instruction is supported, which is the case for the 65SC02, 65C02 and 65816
4389 CPUs (the latter two are upwards compatible to the 65SC02).
4393 <sect>Predefined constants<label id="predefined-constants"><p>
4395 For better orthogonality, the assembler defines similar symbols as the
4396 compiler, depending on the target system selected:
4399 <item><tt/__APPLE2__/ - Target system is <tt/apple2/ or <tt/apple2enh/
4400 <item><tt/__APPLE2ENH__/ - Target system is <tt/apple2enh/
4401 <item><tt/__ATARI__/ - Target system is <tt/atari/ or <tt/atarixl/
4402 <item><tt/__ATARIXL__/ - Target system is <tt/atarixl/
4403 <item><tt/__ATMOS__/ - Target system is <tt/atmos/
4404 <item><tt/__BBC__/ - Target system is <tt/bbc/
4405 <item><tt/__C128__/ - Target system is <tt/c128/
4406 <item><tt/__C16__/ - Target system is <tt/c16/ or <tt/plus4/
4407 <item><tt/__C64__/ - Target system is <tt/c64/
4408 <item><tt/__CBM__/ - Target is a Commodore system
4409 <item><tt/__CBM510__/ - Target system is <tt/cbm510/
4410 <item><tt/__CBM610__/ - Target system is <tt/cbm610/
4411 <item><tt/__GEOS__/ - Target is a GEOS system
4412 <item><tt/__GEOS_APPLE__/ - Target system is <tt/geos-apple/
4413 <item><tt/__GEOS_CBM__/ - Target system is <tt/geos-cbm/
4414 <item><tt/__LUNIX__/ - Target system is <tt/lunix/
4415 <item><tt/__LYNX__/ - Target system is <tt/lynx/
4416 <item><tt/__NES__/ - Target system is <tt/nes/
4417 <item><tt/__PET__/ - Target system is <tt/pet/
4418 <item><tt/__PLUS4__/ - Target system is <tt/plus4/
4419 <item><tt/__SIM6502__/ - Target system is <tt/sim6502/
4420 <item><tt/__SIM65C02__/ - Target system is <tt/sim65c02/
4421 <item><tt/__SUPERVISION__/ - Target system is <tt/supervision/
4422 <item><tt/__VIC20__/ - Target system is <tt/vic20/
4426 <sect>Structs and unions<label id="structs"><p>
4428 <sect1>Structs and unions Overview<p>
4430 Structs and unions are special forms of <ref id="scopes" name="scopes">. They
4431 are to some degree comparable to their C counterparts. Both have a list of
4432 members. Each member allocates storage and may optionally have a name, which,
4433 in case of a struct, is the offset from the beginning and, in case of a union,
4437 <sect1>Declaration<p>
4439 Here is an example for a very simple struct with two members and a total size
4449 A union shares the total space between all its members, its size is the same
4450 as that of the largest member. The offset of all members relative to the union
4460 A struct or union must not necessarily have a name. If it is anonymous, no
4461 local scope is opened, the identifiers used to name the members are placed
4462 into the current scope instead.
4464 A struct may contain unnamed members and definitions of local structs. The
4465 storage allocators may contain a multiplier, as in the example below:
4470 .word 2 ; Allocate two words
4477 <sect1>The <tt/.TAG/ keyword<p>
4479 Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to reserve space
4480 for an already defined struct or unions within another struct:
4494 Space for a struct or union may be allocated using the <ref id=".TAG"
4495 name=".TAG"> directive.
4501 Currently, members are just offsets from the start of the struct or union. To
4502 access a field of a struct, the member offset has to be added to the address
4503 of the struct itself:
4506 lda C+Circle::Radius ; Load circle radius into A
4509 This may change in a future version of the assembler.
4512 <sect1>Limitations<p>
4514 Structs and unions are currently implemented as nested symbol tables (in fact,
4515 they were a by-product of the improved scoping rules). Currently, the
4516 assembler has no idea of types. This means that the <ref id=".TAG"
4517 name=".TAG"> keyword will only allocate space. You won't be able to initialize
4518 variables declared with <ref id=".TAG" name=".TAG">, and adding an embedded
4519 structure to another structure with <ref id=".TAG" name=".TAG"> will not make
4520 this structure accessible by using the '::' operator.
4524 <sect>Module constructors/destructors<label id="condes"><p>
4526 <em>Note:</em> This section applies mostly to C programs, so the explanation
4527 below uses examples from the C libraries. However, the feature may also be
4528 useful for assembler programs.
4531 <sect1>Module constructors/destructors Overview<p>
4533 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4534 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4535 name=".INTERRUPTOR"></tt> keywords it is possible to export functions in a
4536 special way. The linker is able to generate tables with all functions of a
4537 specific type. Such a table will <em>only</em> include symbols from object
4538 files that are linked into a specific executable. This may be used to add
4539 initialization and cleanup code for library modules, or a table of interrupt
4542 The C heap functions are an example where module initialization code is used.
4543 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
4544 variables that contain the start and the end of the heap, pointers to the free
4545 list and so on. Since the end of the heap depends on the size and start of the
4546 stack, it must be initialized at runtime. However, initializing these
4547 variables for programs that do not use the heap are a waste of time and
4550 So the central module defines a function that contains initialization code and
4551 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
4552 this module is added to an executable by the linker, the initialization
4553 function will be placed into the table of constructors by the linker. The C
4554 startup code will call all constructors before <tt/main/ and all destructors
4555 after <tt/main/, so without any further work, the heap initialization code is
4556 called once the module is linked in.
4558 While it would be possible to add explicit calls to initialization functions
4559 in the startup code, the new approach has several advantages:
4563 If a module is not included, the initialization code is not linked in and not
4564 called. So you don't pay for things you don't need.
4567 Adding another library that needs initialization does not mean that the
4568 startup code has to be changed. Before we had module constructors and
4569 destructors, the startup code for all systems had to be adjusted to call the
4570 new initialization code.
4573 The feature saves memory: Each additional initialization function needs just
4574 two bytes in the table (a pointer to the function).
4579 <sect1>Calling order<p>
4581 The symbols are sorted in increasing priority order by the linker when using
4582 one of the builtin linker configurations, so the functions with lower
4583 priorities come first and are followed by those with higher priorities. The C
4584 library runtime subroutine that walks over the function tables calls the
4585 functions starting from the top of the table - which means that functions with
4586 a high priority are called first.
4588 So when using the C runtime, functions are called with high priority functions
4589 first, followed by low priority functions.
4594 When using these special symbols, please take care of the following:
4599 The linker will only generate function tables, it will not generate code to
4600 call these functions. If you're using the feature in some other than the
4601 existing C environments, you have to write code to call all functions in a
4602 linker generated table yourself. See the <tt/condes/ and <tt/callirq/ modules
4603 in the C runtime for an example on how to do this.
4606 The linker will only add addresses of functions that are in modules linked to
4607 the executable. This means that you have to be careful where to place the
4608 condes functions. If initialization or an irq handler is needed for a group of
4609 functions, be sure to place the function into a module that is linked in
4610 regardless of which function is called by the user.
4613 The linker will generate the tables only when requested to do so by the
4614 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
4615 be requested separately.
4618 Constructors and destructors may have priorities. These priorities determine
4619 the order of the functions in the table. If your initialization or cleanup code
4620 does depend on other initialization or cleanup code, you have to choose the
4621 priority for the functions accordingly.
4624 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4625 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4626 name=".INTERRUPTOR"></tt> statements, there is also a more generic command:
4627 <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to specify an
4628 additional type. Predefined types are 0 (constructor), 1 (destructor) and 2
4629 (interruptor). The linker generates a separate table for each type on request.
4634 <sect>Porting sources from other assemblers<p>
4636 Sometimes it is necessary to port code written for older assemblers to ca65.
4637 In some cases, this can be done without any changes to the source code by
4638 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
4639 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
4642 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
4643 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
4644 done by the linker. Most other assemblers generate absolute code, placement is
4645 done within the assembler and there is no external linker.
4647 In general it is not a good idea to write new code using the emulation
4648 features of the assembler, but there may be situations where even this rule is
4653 You need to use some of the ca65 emulation features to simulate the behaviour
4654 of such simple assemblers.
4657 <item>Prepare your sourcecode like this:
4660 ; if you want TASS style labels without colons
4661 .feature labels_without_colons
4663 ; if you want TASS style character constants
4664 ; ("a" instead of the default 'a')
4665 .feature loose_char_term
4667 .word *+2 ; the cbm load address
4672 notice that the two emulation features are mostly useful for porting
4673 sources originally written in/for TASS, they are not needed for the
4674 actual "simple assembler operation" and are not recommended if you are
4675 writing new code from scratch.
4677 <item>Replace all program counter assignments (which are not possible in ca65
4678 by default, and the respective emulation feature works different from what
4679 you'd expect) by another way to skip to memory locations, for example the
4680 <tt><ref id=".RES" name=".RES"></tt> directive.
4684 .res $2000-* ; reserve memory up to $2000
4687 Please note that other than the original TASS, ca65 can never move the program
4688 counter backwards - think of it as if you are assembling to disk with TASS.
4690 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
4691 rewritten to match ca65 syntax. Most importantly notice that due to the lack
4692 of <tt/.goto/, everything involving loops must be replaced by
4693 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
4695 <item>To assemble code to a different address than it is executed at, use the
4696 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
4697 <tt/.offs/-constructs.
4704 .reloc ; back to normal
4707 <item>Then assemble like this:
4710 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
4713 Note that you need to use the actual start address minus two, since two bytes
4714 are used for the cbm load address.
4721 ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
4722 Bassewitz. For usage of the binaries and/or sources the following
4723 conditions do apply:
4725 This software is provided 'as-is', without any expressed or implied
4726 warranty. In no event will the authors be held liable for any damages
4727 arising from the use of this software.
4729 Permission is granted to anyone to use this software for any purpose,
4730 including commercial applications, and to alter it and redistribute it
4731 freely, subject to the following restrictions:
4734 <item> The origin of this software must not be misrepresented; you must not
4735 claim that you wrote the original software. If you use this software
4736 in a product, an acknowledgment in the product documentation would be
4737 appreciated but is not required.
4738 <item> Altered source versions must be plainly marked as such, and must not
4739 be misrepresented as being the original software.
4740 <item> This notice may not be removed or altered from any source