1 <!doctype linuxdoc system> <!-- -*- text-mode -*- -->
4 <title>ca65 Users Guide
5 <author><url url="mailto:uz@cc65.org" name="Ullrich von Bassewitz">
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 CPA is an alias for CMP
438 DEA is an alias for DEC A
439 INA is an alias for INC A
440 SWA is an alias for XBA
441 TAD is an alias for TCD
442 TAS is an alias for TCS
443 TDA is an alias for TDC
444 TSA is an alias for TSC
448 <sect1>6502X mode<label id="6502X-mode"><p>
450 6502X mode is an extension to the normal 6502 mode. In this mode, several
451 mnemonics for illegal instructions of the NMOS 6502 CPUs are accepted. Since
452 these instructions are illegal, there are no official mnemonics for them. The
453 unofficial ones are taken from <url
454 url="http://www.oxyron.de/html/opcodes02.html">. Please note that only the
455 ones marked as "stable" are supported. The following table uses information
456 from the mentioned web page, for more information, see there.
459 <item><tt>ALR: A:=(A and #{imm})/2;</tt>
460 <item><tt>ANC: A:=A and #{imm};</tt> Generates opcode $0B.
461 <item><tt>ARR: A:=(A and #{imm})/2;</tt>
462 <item><tt>AXS: X:=A and X-#{imm};</tt>
463 <item><tt>DCP: {adr}:={adr}-1; A-{adr};</tt>
464 <item><tt>ISC: {adr}:={adr}+1; A:=A-{adr};</tt>
465 <item><tt>LAS: A,X,S:={adr} and S;</tt>
466 <item><tt>LAX: A,X:={adr};</tt>
467 <item><tt>RLA: {adr}:={adr}rol; A:=A and {adr};</tt>
468 <item><tt>RRA: {adr}:={adr}ror; A:=A adc {adr};</tt>
469 <item><tt>SAX: {adr}:=A and X;</tt>
470 <item><tt>SLO: {adr}:={adr}*2; A:=A or {adr};</tt>
471 <item><tt>SRE: {adr}:={adr}/2; A:=A xor {adr};</tt>
476 <sect1>sweet16 mode<label id="sweet16-mode"><p>
478 SWEET 16 is an interpreter for a pseudo 16 bit CPU written by Steve Wozniak
479 for the Apple ][ machines. It is available in the Apple ][ ROM. ca65 can
480 generate code for this pseudo CPU when switched into sweet16 mode. The
481 following is special in sweet16 mode:
485 <item>The '@' character denotes indirect addressing and is no longer available
486 for cheap local labels. If you need cheap local labels, you will have to
487 switch to another lead character using the <tt/<ref id=".LOCALCHAR"
488 name=".LOCALCHAR">/ command.
490 <item>Registers are specified using <tt/R0/ .. <tt/R15/. In sweet16 mode,
491 these identifiers are reserved words.
495 Please note that the assembler does neither supply the interpreter needed for
496 SWEET 16 code, nor the zero page locations needed for the SWEET 16 registers,
497 nor does it call the interpreter. All this must be done by your program. Apple
498 ][ programmers do probably know how to use sweet16 mode.
500 For more information about SWEET 16, see
501 <url url="http://www.6502.org/source/interpreters/sweet16.htm">.
504 <sect1>Number format<p>
506 For literal values, the assembler accepts the widely used number formats: A
507 preceding '$' or a trailing 'h' denotes a hex value, a preceding '%'
508 denotes a binary value, and a bare number is interpreted as a decimal. There
509 are currently no octal values and no floats.
512 <sect1>Conditional assembly<p>
514 Please note that when using the conditional directives (<tt/.IF/ and friends),
515 the input must consist of valid assembler tokens, even in <tt/.IF/ branches
516 that are not assembled. The reason for this behaviour is that the assembler
517 must still be able to detect the ending tokens (like <tt/.ENDIF/), so
518 conversion of the input stream into tokens still takes place. As a consequence
519 conditional assembly directives may <bf/not/ be used to prevent normal text
520 (used as a comment or similar) from being assembled. <p>
526 <sect1>Expression evaluation<p>
528 All expressions are evaluated with (at least) 32 bit precision. An
529 expression may contain constant values and any combination of internal and
530 external symbols. Expressions that cannot be evaluated at assembly time
531 are stored inside the object file for evaluation by the linker.
532 Expressions referencing imported symbols must always be evaluated by the
536 <sect1>Size of an expression result<p>
538 Sometimes, the assembler must know about the size of the value that is the
539 result of an expression. This is usually the case, if a decision has to be
540 made, to generate a zero page or an absolute memory references. In this
541 case, the assembler has to make some assumptions about the result of an
545 <item> If the result of an expression is constant, the actual value is
546 checked to see if it's a byte sized expression or not.
547 <item> If the expression is explicitly casted to a byte sized expression by
548 one of the '>', '<' or '^' operators, it is a byte expression.
549 <item> If this is not the case, and the expression contains a symbol,
550 explicitly declared as zero page symbol (by one of the .importzp or
551 .exportzp instructions), then the whole expression is assumed to be
553 <item> If the expression contains symbols that are not defined, and these
554 symbols are local symbols, the enclosing scopes are searched for a
555 symbol with the same name. If one exists and this symbol is defined,
556 its attributes are used to determine the result size.
557 <item> In all other cases the expression is assumed to be word sized.
560 Note: If the assembler is not able to evaluate the expression at assembly
561 time, the linker will evaluate it and check for range errors as soon as
565 <sect1>Boolean expressions<p>
567 In the context of a boolean expression, any non zero value is evaluated as
568 true, any other value to false. The result of a boolean expression is 1 if
569 it's true, and zero if it's false. There are boolean operators with extreme
570 low precedence with version 2.x (where x > 0). The <tt/.AND/ and <tt/.OR/
571 operators are shortcut operators. That is, if the result of the expression is
572 already known, after evaluating the left hand side, the right hand side is
576 <sect1>Constant expressions<p>
578 Sometimes an expression must evaluate to a constant without looking at any
579 further input. One such example is the <tt/<ref id=".IF" name=".IF">/ command
580 that decides if parts of the code are assembled or not. An expression used in
581 the <tt/.IF/ command cannot reference a symbol defined later, because the
582 decision about the <tt/.IF/ must be made at the point when it is read. If the
583 expression used in such a context contains only constant numerical values,
584 there is no problem. When unresolvable symbols are involved it may get harder
585 for the assembler to determine if the expression is actually constant, and it
586 is even possible to create expressions that aren't recognized as constant.
587 Simplifying the expressions will often help.
589 In cases where the result of the expression is not needed immediately, the
590 assembler will delay evaluation until all input is read, at which point all
591 symbols are known. So using arbitrary complex constant expressions is no
592 problem in most cases.
596 <sect1>Available operators<label id="operators"><p>
600 <bf/Operator/| <bf/Description/| <bf/Precedence/@<hline>
601 | Built-in string functions| 0@
603 | Built-in pseudo-variables| 1@
604 | Built-in pseudo-functions| 1@
605 +| Unary positive| 1@
606 -| Unary negative| 1@
608 .BITNOT| Unary bitwise not| 1@
610 .LOBYTE| Unary low-byte operator| 1@
612 .HIBYTE| Unary high-byte operator| 1@
614 .BANKBYTE| Unary bank-byte operator| 1@
616 *| Multiplication| 2@
618 .MOD| Modulo operator| 2@
620 .BITAND| Bitwise and| 2@
622 .BITXOR| Binary bitwise xor| 2@
624 .SHL| Shift-left operator| 2@
626 .SHR| Shift-right operator| 2@
628 +| Binary addition| 3@
629 -| Binary subtraction| 3@
631 .BITOR| Bitwise or| 3@
633 = | Compare operator (equal)| 4@
634 <>| Compare operator (not equal)| 4@
635 <| Compare operator (less)| 4@
636 >| Compare operator (greater)| 4@
637 <=| Compare operator (less or equal)| 4@
638 >=| Compare operator (greater or equal)| 4@
641 .AND| Boolean and| 5@
642 .XOR| Boolean xor| 5@
644 ||<newline>
648 .NOT| Boolean not| 7@<hline>
650 <caption>Available operators, sorted by precedence
653 To force a specific order of evaluation, parentheses may be used, as usual.
657 <sect>Symbols and labels<p>
659 A symbol or label is an identifier that starts with a letter and is followed
660 by letters and digits. Depending on some features enabled (see
661 <tt><ref id="at_in_identifiers" name="at_in_identifiers"></tt>,
662 <tt><ref id="dollar_in_identifiers" name="dollar_in_identifiers"></tt> and
663 <tt><ref id="leading_dot_in_identifiers" name="leading_dot_in_identifiers"></tt>)
664 other characters may be present. Use of identifiers consisting of a single
665 character will not work in all cases, because some of these identifiers are
666 reserved keywords (for example "A" is not a valid identifier for a label,
667 because it is the keyword for the accumulator).
669 The assembler allows you to use symbols instead of naked values to make
670 the source more readable. There are a lot of different ways to define and
671 use symbols and labels, giving a lot of flexibility.
673 <sect1>Numeric constants<p>
675 Numeric constants are defined using the equal sign or the label assignment
676 operator. After doing
682 may use the symbol "two" in every place where a number is expected, and it is
683 evaluated to the value 2 in this context. The label assignment operator is
684 almost identical, but causes the symbol to be marked as a label, so it may be
685 handled differently in a debugger:
691 The right side can of course be an expression:
698 <label id="variables">
699 <sect1>Numeric variables<p>
701 Within macros and other control structures (<tt><ref id=".REPEAT"
702 name=".REPEAT"></tt>, ...) it is sometimes useful to have some sort of
703 variable. This can be achieved by the <tt>.SET</tt> operator. It creates a
704 symbol that may get assigned a different value later:
708 lda #four ; Loads 4 into A
710 lda #four ; Loads 3 into A
713 Since the value of the symbol can change later, it must be possible to
714 evaluate it when used (no delayed evaluation as with normal symbols). So the
715 expression used as the value must be constant.
717 Following is an example for a macro that generates a different label each time
718 it is used. It uses the <tt><ref id=".SPRINTF" name=".SPRINTF"></tt> function
719 and a numeric variable named <tt>lcount</tt>.
722 .lcount .set 0 ; Initialize the counter
725 .ident (.sprintf ("L%04X", lcount)):
726 lcount .set lcount + 1
731 <sect1>Standard labels<p>
733 A label is defined by writing the name of the label at the start of the line
734 (before any instruction mnemonic, macro or pseudo directive), followed by a
735 colon. This will declare a symbol with the given name and the value of the
736 current program counter.
739 <sect1>Local labels and symbols<p>
741 Using the <tt><ref id=".PROC" name=".PROC"></tt> directive, it is possible to
742 create regions of code where the names of labels and symbols are local to this
743 region. They are not known outside of this region and cannot be accessed from
744 there. Such regions may be nested like PROCEDUREs in Pascal.
746 See the description of the <tt><ref id=".PROC" name=".PROC"></tt>
747 directive for more information.
750 <sect1>Cheap local labels<p>
752 Cheap local labels are defined like standard labels, but the name of the
753 label must begin with a special symbol (usually '@', but this can be
754 changed by the <tt><ref id=".LOCALCHAR" name=".LOCALCHAR"></tt>
757 Cheap local labels are visible only between two non cheap labels. As soon as a
758 standard symbol is encountered (this may also be a local symbol if inside a
759 region defined with the <tt><ref id=".PROC" name=".PROC"></tt> directive), the
760 cheap local symbol goes out of scope.
762 You may use cheap local labels as an easy way to reuse common label
763 names like "Loop". Here is an example:
766 Clear: lda #$00 ; Global label
768 @Loop: sta Mem,y ; Local label
772 Sub: ... ; New global label
773 bne @Loop ; ERROR: Unknown identifier!
776 <sect1>Unnamed labels<p>
778 If you really want to write messy code, there are also unnamed labels. These
779 labels do not have a name (you guessed that already, didn't you?). A colon is
780 used to mark the absence of the name.
782 Unnamed labels may be accessed by using the colon plus several minus or plus
783 characters as a label designator. Using the '-' characters will create a back
784 reference (use the n'th label backwards), using '+' will create a forward
785 reference (use the n'th label in forward direction). An example will help to
808 As you can see from the example, unnamed labels will make even short
809 sections of code hard to understand, because you have to count labels
810 to find branch targets (this is the reason why I for my part do
811 prefer the "cheap" local labels). Nevertheless, unnamed labels are
812 convenient in some situations, so it's your decision.
814 <em/Note:/ <ref id="scopes" name="Scopes"> organize named symbols, not
815 unnamed ones, so scopes don't have an effect on unnamed labels.
819 <sect1>Using macros to define labels and constants<p>
821 While there are drawbacks with this approach, it may be handy in a few rare
822 situations. Using <tt><ref id=".DEFINE" name=".DEFINE"></tt>, it is possible
823 to define symbols or constants that may be used elsewhere. One of the
824 advantages is that you can use it to define string constants (this is not
825 possible with the other symbol types).
827 Please note: <tt/.DEFINE/ style macros do token replacements on a low level,
828 so the names do not adhere to scoping, diagnostics may be misleading, there
829 are no symbols to look up in the map file, and there is no debug info.
830 Especially the first problem in the list can lead to very nasty programming
831 errors. Because of these problems, the general advice is, <bf/NOT/ do use
832 <tt/.DEFINE/ if you don't have to.
838 .DEFINE version "SOS V2.3"
840 four = two * two ; Ok
843 .PROC ; Start local scope
844 two = 3 ; Will give "2 = 3" - invalid!
849 <sect1>Symbols and <tt>.DEBUGINFO</tt><p>
851 If <tt><ref id=".DEBUGINFO" name=".DEBUGINFO"></tt> is enabled (or <ref
852 id="option-g" name="-g"> is given on the command line), global, local and
853 cheap local labels are written to the object file and will be available in the
854 symbol file via the linker. Unnamed labels are not written to the object file,
855 because they don't have a name which would allow to access them.
859 <sect>Scopes<label id="scopes"><p>
861 ca65 implements several sorts of scopes for symbols.
863 <sect1>Global scope<p>
865 All (non cheap local) symbols that are declared outside of any nested scopes
869 <sect1>Cheap locals<p>
871 A special scope is the scope for cheap local symbols. It lasts from one non
872 local symbol to the next one, without any provisions made by the programmer.
873 All other scopes differ in usage but use the same concept internally.
876 <sect1>Generic nested scopes<p>
878 A nested scoped for generic use is started with <tt/<ref id=".SCOPE"
879 name=".SCOPE">/ and closed with <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/.
880 The scope can have a name, in which case it is accessible from the outside by
881 using <ref id="scopesyntax" name="explicit scopes">. If the scope does not
882 have a name, all symbols created within the scope are local to the scope, and
883 aren't accessible from the outside.
885 A nested scope can access symbols from the local or from enclosing scopes by
886 name without using explicit scope names. In some cases there may be
887 ambiguities, for example if there is a reference to a local symbol that is not
888 yet defined, but a symbol with the same name exists in outer scopes:
900 In the example above, the <tt/lda/ instruction will load the value 3 into the
901 accumulator, because <tt/foo/ is redefined in the scope. However:
913 Here, <tt/lda/ will still load from <tt/$12,x/, but since it is unknown to the
914 assembler that <tt/foo/ is a zeropage symbol when translating the instruction,
915 absolute mode is used instead. In fact, the assembler will not use absolute
916 mode by default, but it will search through the enclosing scopes for a symbol
917 with the given name. If one is found, the address size of this symbol is used.
918 This may lead to errors:
930 In this case, when the assembler sees the symbol <tt/foo/ in the <tt/lda/
931 instruction, it will search for an already defined symbol <tt/foo/. It will
932 find <tt/foo/ in scope <tt/outer/, and a close look reveals that it is a
933 zeropage symbol. So the assembler will use zeropage addressing mode. If
934 <tt/foo/ is redefined later in scope <tt/inner/, the assembler tries to change
935 the address in the <tt/lda/ instruction already translated, but since the new
936 value needs absolute addressing mode, this fails, and an error message "Range
939 Of course the most simple solution for the problem is to move the definition
940 of <tt/foo/ in scope <tt/inner/ upwards, so it precedes its use. There may be
941 rare cases when this cannot be done. In these cases, you can use one of the
942 address size override operators:
954 This will cause the <tt/lda/ instruction to be translated using absolute
955 addressing mode, which means changing the symbol reference later does not
959 <sect1>Nested procedures<p>
961 A nested procedure is created by use of <tt/<ref id=".PROC" name=".PROC">/. It
962 differs from a <tt/<ref id=".SCOPE" name=".SCOPE">/ in that it must have a
963 name, and a it will introduce a symbol with this name in the enclosing scope.
972 is actually the same as
981 This is the reason why a procedure must have a name. If you want a scope
982 without a name, use <tt/<ref id=".SCOPE" name=".SCOPE">/.
984 <em/Note:/ As you can see from the example above, scopes and symbols live in
985 different namespaces. There can be a symbol named <tt/foo/ and a scope named
986 <tt/foo/ without any conflicts (but see the section titled <ref
987 id="scopesearch" name=""Scope search order"">).
990 <sect1>Structs, unions and enums<p>
992 Structs, unions and enums are explained in a <ref id="structs" name="separate
993 section">, I do only cover them here, because if they are declared with a
994 name, they open a nested scope, similar to <tt/<ref id=".SCOPE"
995 name=".SCOPE">/. However, when no name is specified, the behaviour is
996 different: In this case, no new scope will be opened, symbols declared within
997 a struct, union, or enum declaration will then be added to the enclosing scope
1001 <sect1>Explicit scope specification<label id="scopesyntax"><p>
1003 Accessing symbols from other scopes is possible by using an explicit scope
1004 specification, provided that the scope where the symbol lives in has a name.
1005 The namespace token (<tt/::/) is used to access other scopes:
1013 lda foo::bar ; Access foo in scope bar
1016 The only way to deny access to a scope from the outside is to declare a scope
1017 without a name (using the <tt/<ref id=".SCOPE" name=".SCOPE">/ command).
1019 A special syntax is used to specify the global scope: If a symbol or scope is
1020 preceded by the namespace token, the global scope is searched:
1027 lda #::bar ; Access the global bar (which is 3)
1032 <sect1>Scope search order<label id="scopesearch"><p>
1034 The assembler searches for a scope in a similar way as for a symbol. First, it
1035 looks in the current scope, and then it walks up the enclosing scopes until
1038 However, one important thing to note when using explicit scope syntax is, that
1039 a symbol may be accessed before it is defined, but a scope may <bf/not/ be
1040 used without a preceding definition. This means that in the following
1049 lda #foo::bar ; Will load 3, not 2!
1056 the reference to the scope <tt/foo/ will use the global scope, and not the
1057 local one, because the local one is not visible at the point where it is
1060 Things get more complex if a complete chain of scopes is specified:
1071 lda #outer::inner::bar ; 1
1083 When <tt/outer::inner::bar/ is referenced in the <tt/lda/ instruction, the
1084 assembler will first search in the local scope for a scope named <tt/outer/.
1085 Since none is found, the enclosing scope (<tt/another/) is checked. There is
1086 still no scope named <tt/outer/, so scope <tt/foo/ is checked, and finally
1087 scope <tt/outer/ is found. Within this scope, <tt/inner/ is searched, and in
1088 this scope, the assembler looks for a symbol named <tt/bar/.
1090 Please note that once the anchor scope is found, all following scopes
1091 (<tt/inner/ in this case) are expected to be found exactly in this scope. The
1092 assembler will search the scope tree only for the first scope (if it is not
1093 anchored in the root scope). Starting from there on, there is no flexibility,
1094 so if the scope named <tt/outer/ found by the assembler does not contain a
1095 scope named <tt/inner/, this would be an error, even if such a pair does exist
1096 (one level up in global scope).
1098 Ambiguities that may be introduced by this search algorithm may be removed by
1099 anchoring the scope specification in the global scope. In the example above,
1100 if you want to access the "other" symbol <tt/bar/, you would have to write:
1111 lda #::outer::inner::bar ; 2
1124 <sect>Address sizes and memory models<label id="address-sizes"><p>
1126 <sect1>Address sizes<p>
1128 ca65 assigns each segment and each symbol an address size. This is true, even
1129 if the symbol is not used as an address. You may also think of a value range
1130 of the symbol instead of an address size.
1132 Possible address sizes are:
1135 <item>Zeropage or direct (8 bits)
1136 <item>Absolute (16 bits)
1138 <item>Long (32 bits)
1141 Since the assembler uses default address sizes for the segments and symbols,
1142 it is usually not necessary to override the default behaviour. In cases, where
1143 it is necessary, the following keywords may be used to specify address sizes:
1146 <item>DIRECT, ZEROPAGE or ZP for zeropage addressing (8 bits).
1147 <item>ABSOLUTE, ABS or NEAR for absolute addressing (16 bits).
1148 <item>FAR for far addressing (24 bits).
1149 <item>LONG or DWORD for long addressing (32 bits).
1153 <sect1>Address sizes of segments<p>
1155 The assembler assigns an address size to each segment. Since the
1156 representation of a label within this segment is "segment start + offset",
1157 labels will inherit the address size of the segment they are declared in.
1159 The address size of a segment may be changed, by using an optional address
1160 size modifier. See the <tt/<ref id=".SEGMENT" name="segment directive">/ for
1161 an explanation on how this is done.
1164 <sect1>Address sizes of symbols<p>
1169 <sect1>Memory models<p>
1171 The default address size of a segment depends on the memory model used. Since
1172 labels inherit the address size from the segment they are declared in,
1173 changing the memory model is an easy way to change the address size of many
1179 <sect>Pseudo variables<label id="pseudo-variables"><p>
1181 Pseudo variables are readable in all cases, and in some special cases also
1184 <sect1><tt>*</tt><p>
1186 Reading this pseudo variable will return the program counter at the start
1187 of the current input line.
1189 Assignment to this variable is possible when <tt/<ref id=".FEATURE"
1190 name=".FEATURE pc_assignment">/ is used. Note: You should not use
1191 assignments to <tt/*/, use <tt/<ref id=".ORG" name=".ORG">/ instead.
1194 <sect1><tt>.ASIZE</tt><label id=".ASIZE"><p>
1196 Reading this pseudo variable will return the current size of the
1197 Accumulator in bits.
1199 For the 65816 instruction set .ASIZE will return either 8 or 16, depending
1200 on the current size of the operand in immediate accu addressing mode.
1202 For all other CPU instruction sets, .ASIZE will always return 8.
1207 ; Reverse Subtract with Accumulator
1220 See also: <tt><ref id=".ISIZE" name=".ISIZE"></tt>
1223 <sect1><tt>.CPU</tt><label id=".CPU"><p>
1225 Reading this pseudo variable will give a constant integer value that
1226 tells which CPU is currently enabled. It can also tell which instruction
1227 set the CPU is able to translate. The value read from the pseudo variable
1228 should be further examined by using one of the constants defined by the
1229 "cpu" macro package (see <tt/<ref id=".MACPACK" name=".MACPACK">/).
1231 It may be used to replace the .IFPxx pseudo instructions or to construct
1232 even more complex expressions.
1238 .if (.cpu .bitand CPU_ISET_65816)
1250 <sect1><tt>.ISIZE</tt><label id=".ISIZE"><p>
1252 Reading this pseudo variable will return the current size of the Index
1255 For the 65816 instruction set .ISIZE will return either 8 or 16, depending
1256 on the current size of the operand in immediate index addressing mode.
1258 For all other CPU instruction sets, .ISIZE will always return 8.
1260 See also: <tt><ref id=".ASIZE" name=".ASIZE"></tt>
1263 <sect1><tt>.PARAMCOUNT</tt><label id=".PARAMCOUNT"><p>
1265 This builtin pseudo variable is only available in macros. It is replaced by
1266 the actual number of parameters that were given in the macro invocation.
1271 .macro foo arg1, arg2, arg3
1272 .if .paramcount <> 3
1273 .error "Too few parameters for macro foo"
1279 See section <ref id="macros" name="Macros">.
1282 <sect1><tt>.TIME</tt><label id=".TIME"><p>
1284 Reading this pseudo variable will give a constant integer value that
1285 represents the current time in POSIX standard (as seconds since the
1288 It may be used to encode the time of translation somewhere in the created
1294 .dword .time ; Place time here
1298 <sect1><tt>.VERSION</tt><label id=".VERSION"><p>
1300 Reading this pseudo variable will give the assembler version according to
1301 the following formula:
1303 VER_MAJOR*$100 + VER_MINOR*$10
1305 It may be used to encode the assembler version or check the assembler for
1306 special features not available with older versions.
1310 Version 2.14 of the assembler will return $2E0 as numerical constant when
1311 reading the pseudo variable <tt/.VERSION/.
1315 <sect>Pseudo functions<label id="pseudo-functions"><p>
1317 Pseudo functions expect their arguments in parenthesis, and they have a result,
1318 either a string or an expression.
1321 <sect1><tt>.ADDRSIZE</tt><label id=".ADDRSIZE"><p>
1323 The <tt/.ADDRSIZE/ function is used to return the interal address size
1324 associated with a symbol. This can be helpful in macros when knowing the address
1325 size of symbol can help with custom instructions.
1331 .if .ADDRSIZE(foo) = 1
1332 ;do custom command based on zeropage addressing:
1334 .elseif .ADDRSIZE(foo) = 2
1335 ;do custom command based on absolute addressing:
1338 .elseif .ADDRSIZE(foo) = 0
1339 ; no address size defined for this symbol:
1340 .out .sprintf("Error, address size unknown for symbol %s", .string(foo))
1345 This command is new and must be enabled with the <tt/.FEATURE addrsize/ command.
1347 See: <tt><ref id=".FEATURE" name=".FEATURE"></tt>
1350 <sect1><tt>.BANK</tt><label id=".BANK"><p>
1352 The <tt/.BANK/ function is used to support systems with banked memory. The
1353 argument is an expression with exactly one segment reference - usually a
1354 label. The function result is the value of the <tt/bank/ attribute assigned
1355 to the run memory area of the segment. Please see the linker documentation
1356 for more information about memory areas and their attributes.
1358 The value of <tt/.BANK/ can be used to switch memory so that a memory bank
1359 containing specific data is available.
1361 The <tt/bank/ attribute is a 32 bit integer and so is the result of the
1362 <tt/.BANK/ function. You will have to use <tt><ref id=".LOBYTE"
1363 name=".LOBYTE"></tt> or similar functions to address just part of it.
1365 Please note that <tt/.BANK/ will always get evaluated in the link stage, so
1366 an expression containing <tt/.BANK/ can never be used where a constant known
1367 result is expected (for example with <tt/.RES/).
1384 .byte <.BANK (banked_func_1)
1387 .byte <.BANK (banked_func_2)
1393 <sect1><tt>.BANKBYTE</tt><label id=".BANKBYTE"><p>
1395 The function returns the bank byte (that is, bits 16-23) of its argument.
1396 It works identical to the '^' operator.
1398 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1399 <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>
1402 <sect1><tt>.BLANK</tt><label id=".BLANK"><p>
1404 Builtin function. The function evaluates its argument in braces and yields
1405 "false" if the argument is non blank (there is an argument), and "true" if
1406 there is no argument. The token list that makes up the function argument
1407 may optionally be enclosed in curly braces. This allows the inclusion of
1408 tokens that would otherwise terminate the list (the closing right
1409 parenthesis). The curly braces are not considered part of the list, a list
1410 just consisting of curly braces is considered to be empty.
1412 As an example, the <tt/.IFBLANK/ statement may be replaced by
1420 <sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
1422 Builtin string function. The function allows to concatenate a list of string
1423 constants separated by commas. The result is a string constant that is the
1424 concatenation of all arguments. This function is most useful in macros and
1425 when used together with the <tt/.STRING/ builtin function. The function may
1426 be used in any case where a string constant is expected.
1431 .include .concat ("myheader", ".", "inc")
1434 This is the same as the command
1437 .include "myheader.inc"
1441 <sect1><tt>.CONST</tt><label id=".CONST"><p>
1443 Builtin function. The function evaluates its argument in braces and
1444 yields "true" if the argument is a constant expression (that is, an
1445 expression that yields a constant value at assembly time) and "false"
1446 otherwise. As an example, the .IFCONST statement may be replaced by
1453 <sect1><tt>.HIBYTE</tt><label id=".HIBYTE"><p>
1455 The function returns the high byte (that is, bits 8-15) of its argument.
1456 It works identical to the '>' operator.
1458 See: <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>,
1459 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1462 <sect1><tt>.HIWORD</tt><label id=".HIWORD"><p>
1464 The function returns the high word (that is, bits 16-31) of its argument.
1466 See: <tt><ref id=".LOWORD" name=".LOWORD"></tt>
1469 <sect1><tt>.IDENT</tt><label id=".IDENT"><p>
1471 The function expects a string as its argument, and converts this argument
1472 into an identifier. If the string starts with the current <tt/<ref
1473 id=".LOCALCHAR" name=".LOCALCHAR">/, it will be converted into a cheap local
1474 identifier, otherwise it will be converted into a normal identifier.
1479 .macro makelabel arg1, arg2
1480 .ident (.concat (arg1, arg2)):
1483 makelabel "foo", "bar"
1485 .word foobar ; Valid label
1489 <sect1><tt>.LEFT</tt><label id=".LEFT"><p>
1491 Builtin function. Extracts the left part of a given token list.
1496 .LEFT (<int expr>, <token list>)
1499 The first integer expression gives the number of tokens to extract from
1500 the token list. The second argument is the token list itself. The token
1501 list may optionally be enclosed into curly braces. This allows the
1502 inclusion of tokens that would otherwise terminate the list (the closing
1503 right paren in the given case).
1507 To check in a macro if the given argument has a '#' as first token
1508 (immediate addressing mode), use something like this:
1513 .if (.match (.left (1, {arg}), #))
1515 ; ldax called with immediate operand
1523 See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
1524 name=".RIGHT"></tt> builtin functions.
1527 <sect1><tt>.LOBYTE</tt><label id=".LOBYTE"><p>
1529 The function returns the low byte (that is, bits 0-7) of its argument.
1530 It works identical to the '<' operator.
1532 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1533 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1536 <sect1><tt>.LOWORD</tt><label id=".LOWORD"><p>
1538 The function returns the low word (that is, bits 0-15) of its argument.
1540 See: <tt><ref id=".HIWORD" name=".HIWORD"></tt>
1543 <sect1><tt>.MATCH</tt><label id=".MATCH"><p>
1545 Builtin function. Matches two token lists against each other. This is
1546 most useful within macros, since macros are not stored as strings, but
1552 .MATCH(<token list #1>, <token list #2>)
1555 Both token list may contain arbitrary tokens with the exception of the
1556 terminator token (comma resp. right parenthesis) and
1563 The token lists may optionally be enclosed into curly braces. This allows
1564 the inclusion of tokens that would otherwise terminate the list (the closing
1565 right paren in the given case). Often a macro parameter is used for any of
1568 Please note that the function does only compare tokens, not token
1569 attributes. So any number is equal to any other number, regardless of the
1570 actual value. The same is true for strings. If you need to compare tokens
1571 <em/and/ token attributes, use the <tt><ref id=".XMATCH"
1572 name=".XMATCH"></tt> function.
1576 Assume the macro <tt/ASR/, that will shift right the accumulator by one,
1577 while honoring the sign bit. The builtin processor instructions will allow
1578 an optional "A" for accu addressing for instructions like <tt/ROL/ and
1579 <tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
1580 to check for this and print and error for invalid calls.
1585 .if (.not .blank(arg)) .and (.not .match ({arg}, a))
1586 .error "Syntax error"
1589 cmp #$80 ; Bit 7 into carry
1590 lsr a ; Shift carry into bit 7
1595 The macro will only accept no arguments, or one argument that must be the
1596 reserved keyword "A".
1598 See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
1601 <sect1><tt>.MAX</tt><label id=".MAX"><p>
1603 Builtin function. The result is the larger of two values.
1608 .MAX (<value #1>, <value #2>)
1614 ; Reserve space for the larger of two data blocks
1615 savearea: .max (.sizeof (foo), .sizeof (bar))
1618 See: <tt><ref id=".MIN" name=".MIN"></tt>
1621 <sect1><tt>.MID</tt><label id=".MID"><p>
1623 Builtin function. Takes a starting index, a count and a token list as
1624 arguments. Will return part of the token list.
1629 .MID (<int expr>, <int expr>, <token list>)
1632 The first integer expression gives the starting token in the list (the first
1633 token has index 0). The second integer expression gives the number of tokens
1634 to extract from the token list. The third argument is the token list itself.
1635 The token list may optionally be enclosed into curly braces. This allows the
1636 inclusion of tokens that would otherwise terminate the list (the closing
1637 right paren in the given case).
1641 To check in a macro if the given argument has a '<tt/#/' as first token
1642 (immediate addressing mode), use something like this:
1647 .if (.match (.mid (0, 1, {arg}), #))
1649 ; ldax called with immediate operand
1657 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
1658 name=".RIGHT"></tt> builtin functions.
1661 <sect1><tt>.MIN</tt><label id=".MIN"><p>
1663 Builtin function. The result is the smaller of two values.
1668 .MIN (<value #1>, <value #2>)
1674 ; Reserve space for some data, but 256 bytes minimum
1675 savearea: .min (.sizeof (foo), 256)
1678 See: <tt><ref id=".MAX" name=".MAX"></tt>
1681 <sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
1683 Builtin function. The function expects an identifier as argument in braces.
1684 The argument is evaluated, and the function yields "true" if the identifier
1685 is a symbol that has already been referenced somewhere in the source file up
1686 to the current position. Otherwise the function yields false. As an example,
1687 the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
1693 See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1696 <sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
1698 Builtin function. Extracts the right part of a given token list.
1703 .RIGHT (<int expr>, <token list>)
1706 The first integer expression gives the number of tokens to extract from the
1707 token list. The second argument is the token list itself. The token list
1708 may optionally be enclosed into curly braces. This allows the inclusion of
1709 tokens that would otherwise terminate the list (the closing right paren in
1712 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
1713 name=".MID"></tt> builtin functions.
1716 <sect1><tt>.SIZEOF</tt><label id=".SIZEOF"><p>
1718 <tt/.SIZEOF/ is a pseudo function that returns the size of its argument. The
1719 argument can be a struct/union, a struct member, a procedure, or a label. In
1720 case of a procedure or label, its size is defined by the amount of data
1721 placed in the segment where the label is relative to. If a line of code
1722 switches segments (for example in a macro) data placed in other segments
1723 does not count for the size.
1725 Please note that a symbol or scope must exist, before it is used together with
1726 <tt/.SIZEOF/ (this may get relaxed later, but will always be true for scopes).
1727 A scope has preference over a symbol with the same name, so if the last part
1728 of a name represents both, a scope and a symbol, the scope is chosen over the
1731 After the following code:
1734 .struct Point ; Struct size = 4
1739 P: .tag Point ; Declare a point
1740 @P: .tag Point ; Declare another point
1752 .data ; Segment switch!!!
1758 <tag><tt/.sizeof(Point)/</tag>
1759 will have the value 4, because this is the size of struct <tt/Point/.
1761 <tag><tt/.sizeof(Point::xcoord)/</tag>
1762 will have the value 2, because this is the size of the member <tt/xcoord/
1763 in struct <tt/Point/.
1765 <tag><tt/.sizeof(P)/</tag>
1766 will have the value 4, this is the size of the data declared on the same
1767 source line as the label <tt/P/, which is in the same segment that <tt/P/
1770 <tag><tt/.sizeof(@P)/</tag>
1771 will have the value 4, see above. The example demonstrates that <tt/.SIZEOF/
1772 does also work for cheap local symbols.
1774 <tag><tt/.sizeof(Code)/</tag>
1775 will have the value 3, since this is amount of data emitted into the code
1776 segment, the segment that was active when <tt/Code/ was entered. Note that
1777 this value includes the amount of data emitted in child scopes (in this
1778 case <tt/Code::Inner/).
1780 <tag><tt/.sizeof(Code::Inner)/</tag>
1781 will have the value 1 as expected.
1783 <tag><tt/.sizeof(Data)/</tag>
1784 will have the value 0. Data is emitted within the scope <tt/Data/, but since
1785 the segment is switched after entry, this data is emitted into another
1790 <sect1><tt>.STRAT</tt><label id=".STRAT"><p>
1792 Builtin function. The function accepts a string and an index as
1793 arguments and returns the value of the character at the given position
1794 as an integer value. The index is zero based.
1800 ; Check if the argument string starts with '#'
1801 .if (.strat (Arg, 0) = '#')
1808 <sect1><tt>.SPRINTF</tt><label id=".SPRINTF"><p>
1810 Builtin function. It expects a format string as first argument. The number
1811 and type of the following arguments depend on the format string. The format
1812 string is similar to the one of the C <tt/printf/ function. Missing things
1813 are: Length modifiers, variable width.
1815 The result of the function is a string.
1822 ; Generate an identifier:
1823 .ident (.sprintf ("%s%03d", "label", num)):
1827 <sect1><tt>.STRING</tt><label id=".STRING"><p>
1829 Builtin function. The function accepts an argument in braces and converts
1830 this argument into a string constant. The argument may be an identifier, or
1831 a constant numeric value.
1833 Since you can use a string in the first place, the use of the function may
1834 not be obvious. However, it is useful in macros, or more complex setups.
1839 ; Emulate other assemblers:
1841 .segment .string(name)
1846 <sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
1848 Builtin function. The function accepts a string argument in braces and
1849 evaluates to the length of the string.
1853 The following macro encodes a string as a pascal style string with
1854 a leading length byte.
1858 .byte .strlen(Arg), Arg
1863 <sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
1865 Builtin function. The function accepts a token list in braces. The function
1866 result is the number of tokens given as argument. The token list may
1867 optionally be enclosed into curly braces which are not considered part of
1868 the list and not counted. Enclosement in curly braces allows the inclusion
1869 of tokens that would otherwise terminate the list (the closing right paren
1874 The <tt/ldax/ macro accepts the '#' token to denote immediate addressing (as
1875 with the normal 6502 instructions). To translate it into two separate 8 bit
1876 load instructions, the '#' token has to get stripped from the argument:
1880 .if (.match (.mid (0, 1, {arg}), #))
1881 ; ldax called with immediate operand
1882 lda #<(.right (.tcount ({arg})-1, {arg}))
1883 ldx #>(.right (.tcount ({arg})-1, {arg}))
1891 <sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
1893 Builtin function. Matches two token lists against each other. This is
1894 most useful within macros, since macros are not stored as strings, but
1900 .XMATCH(<token list #1>, <token list #2>)
1903 Both token list may contain arbitrary tokens with the exception of the
1904 terminator token (comma resp. right parenthesis) and
1911 The token lists may optionally be enclosed into curly braces. This allows
1912 the inclusion of tokens that would otherwise terminate the list (the closing
1913 right paren in the given case). Often a macro parameter is used for any of
1916 The function compares tokens <em/and/ token values. If you need a function
1917 that just compares the type of tokens, have a look at the <tt><ref
1918 id=".MATCH" name=".MATCH"></tt> function.
1920 See: <tt><ref id=".MATCH" name=".MATCH"></tt>
1924 <sect>Control commands<label id="control-commands"><p>
1926 Here's a list of all control commands and a description, what they do:
1929 <sect1><tt>.A16</tt><label id=".A16"><p>
1931 Valid only in 65816 mode. Switch the accumulator to 16 bit.
1933 Note: This command will not emit any code, it will tell the assembler to
1934 create 16 bit operands for immediate accumulator addressing mode.
1936 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1939 <sect1><tt>.A8</tt><label id=".A8"><p>
1941 Valid only in 65816 mode. Switch the accumulator to 8 bit.
1943 Note: This command will not emit any code, it will tell the assembler to
1944 create 8 bit operands for immediate accu addressing mode.
1946 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1949 <sect1><tt>.ADDR</tt><label id=".ADDR"><p>
1951 Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
1952 may be used for better readability if the data words are address values. In
1953 65816 mode, the address is forced to be 16 bit wide to fit into the current
1954 segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
1955 must be followed by a sequence of (not necessarily constant) expressions.
1960 .addr $0D00, $AF13, _Clear
1963 See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
1967 <sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
1969 Align data to a given boundary. The command expects a constant integer
1970 argument in the range 1 ... 65536, plus an optional second argument
1971 in byte range. If there is a second argument, it is used as fill value,
1972 otherwise the value defined in the linker configuration file is used
1973 (the default for this value is zero).
1975 <tt/.ALIGN/ will insert fill bytes, and the number of fill bytes depend of
1976 the final address of the segment. <tt/.ALIGN/ cannot insert a variable
1977 number of bytes, since that would break address calculations within the
1978 module. So each <tt/.ALIGN/ expects the segment to be aligned to a multiple
1979 of the alignment, because that allows the number of fill bytes to be
1980 calculated in advance by the assembler. You are therefore required to
1981 specify a matching alignment for the segment in the linker config. The
1982 linker will output a warning if the alignment of the segment is less than
1983 what is necessary to have a correct alignment in the object file.
1991 Some unexpected behaviour might occur if there are multiple <tt/.ALIGN/
1992 commands with different arguments. To allow the assembler to calculate the
1993 number of fill bytes in advance, the alignment of the segment must be a
1994 multiple of each of the alignment factors. This may result in unexpectedly
1995 large alignments for the segment within the module.
2006 For the assembler to be able to align correctly, the segment must be aligned
2007 to the least common multiple of 15 and 18 which is 90. The assembler will
2008 calculate this automatically and will mark the segment with this value.
2010 Unfortunately, the combined alignment may get rather large without the user
2011 knowing about it, wasting space in the final executable. If we add another
2012 alignment to the example above
2023 the assembler will force a segment alignment to the least common multiple of
2024 15, 18 and 251 - which is 22590. To protect the user against errors, the
2025 assembler will issue a warning when the combined alignment exceeds 256. The
2026 command line option <tt><ref id="option--large-alignment"
2027 name="--large-alignment"></tt> will disable this warning.
2029 Please note that with alignments that are a power of two (which were the
2030 only alignments possible in older versions of the assembler), the problem is
2031 less severe, because the least common multiple of powers to the same base is
2032 always the larger one.
2036 <sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
2038 Define a string with a trailing zero.
2043 Msg: .asciiz "Hello world"
2046 This will put the string "Hello world" followed by a binary zero into
2047 the current segment. There may be more strings separated by commas, but
2048 the binary zero is only appended once (after the last one).
2051 <sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
2053 Add an assertion. The command is followed by an expression, an action
2054 specifier, and an optional message that is output in case the assertion
2055 fails. If no message was given, the string "Assertion failed" is used. The
2056 action specifier may be one of <tt/warning/, <tt/error/, <tt/ldwarning/ or
2057 <tt/lderror/. In the former two cases, the assertion is evaluated by the
2058 assembler if possible, and in any case, it's also passed to the linker in
2059 the object file (if one is generated). The linker will then evaluate the
2060 expression when segment placement has been done.
2065 .assert * = $8000, error, "Code not at $8000"
2068 The example assertion will check that the current location is at $8000,
2069 when the output file is written, and abort with an error if this is not
2070 the case. More complex expressions are possible. The action specifier
2071 <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
2072 an error message. In the latter case, generation of the output file is
2073 suppressed in both the assembler and linker.
2076 <sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
2078 Is followed by a plus or a minus character. When switched on (using a
2079 +), undefined symbols are automatically marked as import instead of
2080 giving errors. When switched off (which is the default so this does not
2081 make much sense), this does not happen and an error message is
2082 displayed. The state of the autoimport flag is evaluated when the
2083 complete source was translated, before outputting actual code, so it is
2084 <em/not/ possible to switch this feature on or off for separate sections
2085 of code. The last setting is used for all symbols.
2087 You should probably not use this switch because it delays error
2088 messages about undefined symbols until the link stage. The cc65
2089 compiler (which is supposed to produce correct assembler code in all
2090 circumstances, something which is not true for most assembler
2091 programmers) will insert this command to avoid importing each and every
2092 routine from the runtime library.
2097 .autoimport + ; Switch on auto import
2100 <sect1><tt>.BANKBYTES</tt><label id=".BANKBYTES"><p>
2102 Define byte sized data by extracting only the bank byte (that is, bits 16-23) from
2103 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2104 the operator '^' prepended to each expression in its list.
2109 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2111 TableLookupLo: .lobytes MyTable
2112 TableLookupHi: .hibytes MyTable
2113 TableLookupBank: .bankbytes MyTable
2116 which is equivalent to
2119 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2120 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2121 TableLookupBank: .byte ^TableItem0, ^TableItem1, ^TableItem2, ^TableItem3
2124 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2125 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
2126 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>
2129 <sect1><tt>.BSS</tt><label id=".BSS"><p>
2131 Switch to the BSS segment. The name of the BSS segment is always "BSS",
2132 so this is a shortcut for
2138 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2141 <sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
2143 Define byte sized data. Must be followed by a sequence of (byte ranged)
2144 expressions or strings.
2150 .byt "world", $0D, $00
2154 <sect1><tt>.CASE</tt><label id=".CASE"><p>
2156 Switch on or off case sensitivity on identifiers. The default is off
2157 (that is, identifiers are case sensitive), but may be changed by the
2158 -i switch on the command line.
2159 The command must be followed by a '+' or '-' character to switch the
2160 option on or off respectively.
2165 .case - ; Identifiers are not case sensitive
2169 <sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
2171 Apply a custom mapping for characters. The command is followed by two
2172 numbers. The first one is the index of the source character (range 1..255),
2173 the second one is the mapping (range 0..255). The mapping applies to all
2174 character and string constants when they generate output, and overrides a
2175 mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
2176 command line switch.
2181 .charmap $41, $61 ; Map 'A' to 'a'
2185 <sect1><tt>.CODE</tt><label id=".CODE"><p>
2187 Switch to the CODE segment. The name of the CODE segment is always
2188 "CODE", so this is a shortcut for
2194 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2197 <sect1><tt>.CONDES</tt><label id=".CONDES"><p>
2199 Export a symbol and mark it in a special way. The linker is able to build
2200 tables of all such symbols. This may be used to automatically create a list
2201 of functions needed to initialize linked library modules.
2203 Note: The linker has a feature to build a table of marked routines, but it
2204 is your code that must call these routines, so just declaring a symbol with
2205 <tt/.CONDES/ does nothing by itself.
2207 All symbols are exported as an absolute (16 bit) symbol. You don't need to
2208 use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
2209 is implied by <tt/.CONDES/.
2211 <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
2212 <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
2213 specifying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
2214 The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2215 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2216 name=".INTERRUPTOR"></tt> commands are actually shortcuts for <tt/.CONDES/
2217 with a type of <tt/constructor/ resp. <tt/destructor/ or <tt/interruptor/.
2219 After the type, an optional priority may be specified. Higher numeric values
2220 mean higher priority. If no priority is given, the default priority of 7 is
2221 used. Be careful when assigning priorities to your own module constructors
2222 so they won't interfere with the ones in the cc65 library.
2227 .condes ModuleInit, constructor
2228 .condes ModInit, 0, 16
2231 See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2232 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2233 name=".INTERRUPTOR"></tt> commands and the separate section <ref id="condes"
2234 name="Module constructors/destructors"> explaining the feature in more
2238 <sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
2240 Export a symbol and mark it as a module constructor. This may be used
2241 together with the linker to build a table of constructor subroutines that
2242 are called by the startup code.
2244 Note: The linker has a feature to build a table of marked routines, but it
2245 is your code that must call these routines, so just declaring a symbol as
2246 constructor does nothing by itself.
2248 A constructor is always exported as an absolute (16 bit) symbol. You don't
2249 need to use an additional <tt/.export/ statement, this is implied by
2250 <tt/.constructor/. It may have an optional priority that is separated by a
2251 comma. Higher numeric values mean a higher priority. If no priority is
2252 given, the default priority of 7 is used. Be careful when assigning
2253 priorities to your own module constructors so they won't interfere with the
2254 ones in the cc65 library.
2259 .constructor ModuleInit
2260 .constructor ModInit, 16
2263 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2264 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
2265 <ref id="condes" name="Module constructors/destructors"> explaining the
2266 feature in more detail.
2269 <sect1><tt>.DATA</tt><label id=".DATA"><p>
2271 Switch to the DATA segment. The name of the DATA segment is always
2272 "DATA", so this is a shortcut for
2278 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2281 <sect1><tt>.DBYT</tt><label id=".DBYT"><p>
2283 Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
2284 create word sized data in native 65XX format). Must be followed by a
2285 sequence of (word ranged) expressions.
2293 This will emit the bytes
2299 into the current segment in that order.
2302 <sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
2304 Switch on or off debug info generation. The default is off (that is,
2305 the object file will not contain debug infos), but may be changed by the
2306 -g switch on the command line.
2307 The command must be followed by a '+' or '-' character to switch the
2308 option on or off respectively.
2313 .debuginfo + ; Generate debug info
2317 <sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
2319 Start a define style macro definition. The command is followed by an
2320 identifier (the macro name) and optionally by a list of formal arguments
2323 Please note that <tt/.DEFINE/ shares most disadvantages with its C
2324 counterpart, so the general advice is, <bf/NOT/ do use <tt/.DEFINE/ if you
2327 See also the <tt><ref id=".UNDEFINE" name=".UNDEFINE"></tt> command and
2328 section <ref id="macros" name="Macros">.
2331 <sect1><tt>.DELMAC, .DELMACRO</tt><label id=".DELMACRO"><p>
2333 Delete a classic macro (defined with <tt><ref id=".MACRO"
2334 name=".MACRO"></tt>) . The command is followed by the name of an
2335 existing macro. Its definition will be deleted together with the name.
2336 If necessary, another macro with this name may be defined later.
2338 See: <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2339 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2340 <tt><ref id=".MACRO" name=".MACRO"></tt>
2342 See also section <ref id="macros" name="Macros">.
2345 <sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
2347 Builtin function. The function expects an identifier as argument in braces.
2348 The argument is evaluated, and the function yields "true" if the identifier
2349 is a symbol that is already defined somewhere in the source file up to the
2350 current position. Otherwise the function yields false. As an example, the
2351 <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
2358 <sect1><tt>.DEFINEDMACRO</tt><label id=".DEFINEDMACRO"><p>
2360 Builtin function. The function expects an identifier as argument in braces.
2361 The argument is evaluated, and the function yields "true" if the identifier
2362 has already been defined as the name of a macro. Otherwise the function yields
2371 .if .definedmacro(add)
2380 <sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
2382 Export a symbol and mark it as a module destructor. This may be used
2383 together with the linker to build a table of destructor subroutines that
2384 are called by the startup code.
2386 Note: The linker has a feature to build a table of marked routines, but it
2387 is your code that must call these routines, so just declaring a symbol as
2388 constructor does nothing by itself.
2390 A destructor is always exported as an absolute (16 bit) symbol. You don't
2391 need to use an additional <tt/.export/ statement, this is implied by
2392 <tt/.destructor/. It may have an optional priority that is separated by a
2393 comma. Higher numerical values mean a higher priority. If no priority is
2394 given, the default priority of 7 is used. Be careful when assigning
2395 priorities to your own module destructors so they won't interfere with the
2396 ones in the cc65 library.
2401 .destructor ModuleDone
2402 .destructor ModDone, 16
2405 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2406 id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
2407 section <ref id="condes" name="Module constructors/destructors"> explaining
2408 the feature in more detail.
2411 <sect1><tt>.DWORD</tt><label id=".DWORD"><p>
2413 Define dword sized data (4 bytes) Must be followed by a sequence of
2419 .dword $12344512, $12FA489
2423 <sect1><tt>.ELSE</tt><label id=".ELSE"><p>
2425 Conditional assembly: Reverse the current condition.
2428 <sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
2430 Conditional assembly: Reverse current condition and test a new one.
2433 <sect1><tt>.END</tt><label id=".END"><p>
2435 Forced end of assembly. Assembly stops at this point, even if the command
2436 is read from an include file.
2439 <sect1><tt>.ENDENUM</tt><label id=".ENDENUM"><p>
2441 End a <tt><ref id=".ENUM" name=".ENUM"></tt> declaration.
2444 <sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
2446 Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
2447 <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
2450 <sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
2452 Marks the end of a macro definition.
2454 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2455 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2456 <tt><ref id=".MACRO" name=".MACRO"></tt>
2458 See also section <ref id="macros" name="Macros">.
2461 <sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
2463 End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
2466 <sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
2468 End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
2471 <sect1><tt>.ENDSCOPE</tt><label id=".ENDSCOPE"><p>
2473 End of local lexical level (see <tt/<ref id=".SCOPE" name=".SCOPE">/).
2476 <sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
2478 Ends a struct definition. See the <tt/<ref id=".STRUCT" name=".STRUCT">/
2479 command and the separate section named <ref id="structs" name=""Structs
2483 <sect1><tt>.ENDUNION</tt><label id=".ENDUNION"><p>
2485 Ends a union definition. See the <tt/<ref id=".UNION" name=".UNION">/
2486 command and the separate section named <ref id="structs" name=""Structs
2490 <sect1><tt>.ENUM</tt><label id=".ENUM"><p>
2492 Start an enumeration. This directive is very similar to the C <tt/enum/
2493 keyword. If a name is given, a new scope is created for the enumeration,
2494 otherwise the enumeration members are placed in the enclosing scope.
2496 In the enumeration body, symbols are declared. The first symbol has a value
2497 of zero, and each following symbol will get the value of the preceding plus
2498 one. This behaviour may be overridden by an explicit assignment. Two symbols
2499 may have the same value.
2511 Above example will create a new scope named <tt/errorcodes/ with three
2512 symbols in it that get the values 0, 1 and 2 respectively. Another way
2513 to write this would have been:
2523 Please note that explicit scoping must be used to access the identifiers:
2526 .word errorcodes::no_error
2529 A more complex example:
2538 EWOULDBLOCK = EAGAIN
2542 In this example, the enumeration does not have a name, which means that the
2543 members will be visible in the enclosing scope and can be used in this scope
2544 without explicit scoping. The first member (<tt/EUNKNOWN/) has the value -1.
2545 The value for the following members is incremented by one, so <tt/EOK/ would
2546 be zero and so on. <tt/EWOULDBLOCK/ is an alias for <tt/EGAIN/, so it has an
2547 override for the value using an already defined symbol.
2550 <sect1><tt>.ERROR</tt><label id=".ERROR"><p>
2552 Force an assembly error. The assembler will output an error message
2553 preceded by "User error". Assembly is continued but no object file will
2556 This command may be used to check for initial conditions that must be
2557 set before assembling a source file.
2567 .error "Must define foo or bar!"
2571 See also: <tt><ref id=".FATAL" name=".FATAL"></tt>,
2572 <tt><ref id=".OUT" name=".OUT"></tt>,
2573 <tt><ref id=".WARNING" name=".WARNING"></tt>
2576 <sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
2578 Abort a macro expansion immediately. This command is often useful in
2581 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2582 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2583 <tt><ref id=".MACRO" name=".MACRO"></tt>
2585 See also section <ref id="macros" name="Macros">.
2588 <sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
2590 Make symbols accessible from other modules. Must be followed by a comma
2591 separated list of symbols to export, with each one optionally followed by an
2592 address specification and (also optional) an assignment. Using an additional
2593 assignment in the export statement allows to define and export a symbol in
2594 one statement. The default is to export the symbol with the address size it
2595 actually has. The assembler will issue a warning, if the symbol is exported
2596 with an address size smaller than the actual address size.
2603 .export foobar: far = foo * bar
2604 .export baz := foobar, zap: far = baz - bar
2607 As with constant definitions, using <tt/:=/ instead of <tt/=/ marks the
2610 See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
2613 <sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
2615 Make symbols accessible from other modules. Must be followed by a comma
2616 separated list of symbols to export. The exported symbols are explicitly
2617 marked as zero page symbols. An assignment may be included in the
2618 <tt/.EXPORTZP/ statement. This allows to define and export a symbol in one
2625 .exportzp baz := $02
2628 See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
2631 <sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
2633 Define far (24 bit) address data. The command must be followed by a
2634 sequence of (not necessarily constant) expressions.
2639 .faraddr DrawCircle, DrawRectangle, DrawHexagon
2642 See: <tt><ref id=".ADDR" name=".ADDR"></tt>
2645 <sect1><tt>.FATAL</tt><label id=".FATAL"><p>
2647 Force an assembly error and terminate assembly. The assembler will output an
2648 error message preceded by "User error" and will terminate assembly
2651 This command may be used to check for initial conditions that must be
2652 set before assembling a source file.
2662 .fatal "Must define foo or bar!"
2666 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
2667 <tt><ref id=".OUT" name=".OUT"></tt>,
2668 <tt><ref id=".WARNING" name=".WARNING"></tt>
2671 <sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
2673 This directive may be used to enable one or more compatibility features
2674 of the assembler. While the use of <tt/.FEATURE/ should be avoided when
2675 possible, it may be useful when porting sources written for other
2676 assemblers. There is no way to switch a feature off, once you have
2677 enabled it, so using
2683 will enable the feature until end of assembly is reached.
2685 The following features are available:
2689 <tag><tt>addrsize</tt><label id="addrsize"></tag>
2691 Enables the .ADDRSIZE pseudo function. This function is experimental and not enabled by default.
2693 See also: <tt><ref id=".ADDRSIZE" name=".ADDRSIZE"></tt>
2695 <tag><tt>at_in_identifiers</tt><label id="at_in_identifiers"></tag>
2697 Accept the at character (`@') as a valid character in identifiers. The
2698 at character is not allowed to start an identifier, even with this
2701 <tag><tt>c_comments</tt><label id="c_comments"></tag>
2703 Allow C like comments using <tt>/*</tt> and <tt>*/</tt> as left and right
2704 comment terminators. Note that C comments may not be nested. There's also a
2705 pitfall when using C like comments: All statements must be terminated by
2706 "end-of-line". Using C like comments, it is possible to hide the newline,
2707 which results in error messages. See the following non working example:
2710 lda #$00 /* This comment hides the newline
2714 <tag><tt>dollar_in_identifiers</tt><label id="dollar_in_identifiers"></tag>
2716 Accept the dollar sign (`$') as a valid character in identifiers. The
2717 dollar character is not allowed to start an identifier, even with this
2720 <tag><tt>dollar_is_pc</tt><label id="dollar_is_pc"></tag>
2722 The dollar sign may be used as an alias for the star (`*'), which
2723 gives the value of the current PC in expressions.
2724 Note: Assignment to the pseudo variable is not allowed.
2726 <tag><tt>force_range</tt><label id="force_range"></tag>
2728 Force expressions into their valid range for immediate addressing and
2729 storage operators like <tt><ref id=".BYTE" name=".BYTE"></tt> and
2730 <tt><ref id=".WORD" name=".WORD"></tt>. Be very careful with this one,
2731 since it will completely disable error checks.
2733 <tag><tt>labels_without_colons</tt><label id="labels_without_colons"></tag>
2735 Allow labels without a trailing colon. These labels are only accepted,
2736 if they start at the beginning of a line (no leading white space).
2738 <tag><tt>leading_dot_in_identifiers</tt><label id="leading_dot_in_identifiers"></tag>
2740 Accept the dot (`.') as the first character of an identifier. This may be
2741 used for example to create macro names that start with a dot emulating
2742 control directives of other assemblers. Note however, that none of the
2743 reserved keywords built into the assembler, that starts with a dot, may be
2744 overridden. When using this feature, you may also get into trouble if
2745 later versions of the assembler define new keywords starting with a dot.
2747 <tag><tt>loose_char_term</tt><label id="loose_char_term"></tag>
2749 Accept single quotes as well as double quotes as terminators for char
2752 <tag><tt>loose_string_term</tt><label id="loose_string_term"></tag>
2754 Accept single quotes as well as double quotes as terminators for string
2757 <tag><tt>missing_char_term</tt><label id="missing_char_term"></tag>
2759 Accept single quoted character constants where the terminating quote is
2764 <em/Note:/ This does not work in conjunction with <tt/.FEATURE
2765 loose_string_term/, since in this case the input would be ambiguous.
2767 <tag><tt>org_per_seg</tt><label id="org_per_seg"></tag>
2769 This feature makes relocatable/absolute mode local to the current segment.
2770 Using <tt><ref id=".ORG" name=".ORG"></tt> when <tt/org_per_seg/ is in
2771 effect will only enable absolute mode for the current segment. Dito for
2772 <tt><ref id=".RELOC" name=".RELOC"></tt>.
2774 <tag><tt>pc_assignment</tt><label id="pc_assignment"></tag>
2776 Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
2777 is enabled). Such an assignment is handled identical to the <tt><ref
2778 id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
2779 removing the lines with the assignments may also be an option when porting
2780 code written for older assemblers).
2782 <tag><tt>ubiquitous_idents</tt><label id="ubiquitous_idents"></tag>
2784 Allow the use of instructions names as names for macros and symbols. This
2785 makes it possible to "overload" instructions by defining a macro with the
2786 same name. This does also make it possible to introduce hard to find errors
2787 in your code, so be careful!
2789 <tag><tt>underline_in_numbers</tt><label id="underline_in_numbers"></tag>
2791 Allow underlines within numeric constants. These may be used for grouping
2792 the digits of numbers for easier reading.
2795 .feature underline_in_numbers
2796 .word %1100001110100101
2797 .word %1100_0011_1010_0101 ; Identical but easier to read
2802 It is also possible to specify features on the command line using the
2803 <tt><ref id="option--feature" name="--feature"></tt> command line option.
2804 This is useful when translating sources written for older assemblers, when
2805 you don't want to change the source code.
2807 As an example, to translate sources written for Andre Fachats xa65
2808 assembler, the features
2811 labels_without_colons, pc_assignment, loose_char_term
2814 may be helpful. They do not make ca65 completely compatible, so you may not
2815 be able to translate the sources without changes, even when enabling these
2816 features. However, I have found several sources that translate without
2817 problems when enabling these features on the command line.
2820 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
2822 Insert an option string into the object file. There are two forms of
2823 this command, one specifies the option by a keyword, the second
2824 specifies it as a number. Since usage of the second one needs knowledge
2825 of the internal encoding, its use is not recommended and I will only
2826 describe the first form here.
2828 The command is followed by one of the keywords
2836 a comma and a string. The option is written into the object file
2837 together with the string value. This is currently unidirectional and
2838 there is no way to actually use these options once they are in the
2844 .fileopt comment, "Code stolen from my brother"
2845 .fileopt compiler, "BASIC 2.0"
2846 .fopt author, "J. R. User"
2850 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
2852 Import an absolute symbol from another module. The command is followed by a
2853 comma separated list of symbols to import. The command is similar to <tt>
2854 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
2855 written to the generated object file, even if the symbol is never referenced
2856 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
2857 references for unused symbols).
2862 .forceimport needthisone, needthistoo
2865 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2868 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
2870 Declare symbols as global. Must be followed by a comma separated list of
2871 symbols to declare. Symbols from the list, that are defined somewhere in the
2872 source, are exported, all others are imported. Additional <tt><ref
2873 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
2874 name=".EXPORT"></tt> commands for the same symbol are allowed.
2883 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
2885 Declare symbols as global. Must be followed by a comma separated list of
2886 symbols to declare. Symbols from the list, that are defined somewhere in the
2887 source, are exported, all others are imported. Additional <tt><ref
2888 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
2889 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
2890 in the list are explicitly marked as zero page symbols.
2898 <sect1><tt>.HIBYTES</tt><label id=".HIBYTES"><p>
2900 Define byte sized data by extracting only the high byte (that is, bits 8-15) from
2901 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2902 the operator '>' prepended to each expression in its list.
2907 .lobytes $1234, $2345, $3456, $4567
2908 .hibytes $fedc, $edcb, $dcba, $cba9
2911 which is equivalent to
2914 .byte $34, $45, $56, $67
2915 .byte $fe, $ed, $dc, $cb
2921 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2923 TableLookupLo: .lobytes MyTable
2924 TableLookupHi: .hibytes MyTable
2927 which is equivalent to
2930 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2931 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2934 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2935 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>,
2936 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
2939 <sect1><tt>.I16</tt><label id=".I16"><p>
2941 Valid only in 65816 mode. Switch the index registers to 16 bit.
2943 Note: This command will not emit any code, it will tell the assembler to
2944 create 16 bit operands for immediate operands.
2946 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
2947 name=".SMART"></tt> commands.
2950 <sect1><tt>.I8</tt><label id=".I8"><p>
2952 Valid only in 65816 mode. Switch the index registers to 8 bit.
2954 Note: This command will not emit any code, it will tell the assembler to
2955 create 8 bit operands for immediate operands.
2957 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
2958 name=".SMART"></tt> commands.
2961 <sect1><tt>.IF</tt><label id=".IF"><p>
2963 Conditional assembly: Evaluate an expression and switch assembler output
2964 on or off depending on the expression. The expression must be a constant
2965 expression, that is, all operands must be defined.
2967 A expression value of zero evaluates to FALSE, any other value evaluates
2971 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
2973 Conditional assembly: Check if there are any remaining tokens in this line,
2974 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
2975 condition is not true, further lines are not assembled until an <tt><ref
2976 id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2977 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2979 This command is often used to check if a macro parameter was given. Since an
2980 empty macro parameter will evaluate to nothing, the condition will evaluate
2981 to TRUE if an empty parameter was given.
2995 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2998 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
3000 Conditional assembly: Evaluate an expression and switch assembler output
3001 on or off depending on the constness of the expression.
3003 A const expression evaluates to to TRUE, a non const expression (one
3004 containing an imported or currently undefined symbol) evaluates to
3007 See also: <tt><ref id=".CONST" name=".CONST"></tt>
3010 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
3012 Conditional assembly: Check if a symbol is defined. Must be followed by
3013 a symbol name. The condition is true if the the given symbol is already
3014 defined, and false otherwise.
3016 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
3019 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
3021 Conditional assembly: Check if there are any remaining tokens in this line,
3022 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
3023 condition is not true, further lines are not assembled until an <tt><ref
3024 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
3025 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
3027 This command is often used to check if a macro parameter was given.
3028 Since an empty macro parameter will evaluate to nothing, the condition
3029 will evaluate to FALSE if an empty parameter was given.
3042 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
3045 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
3047 Conditional assembly: Check if a symbol is defined. Must be followed by
3048 a symbol name. The condition is true if the the given symbol is not
3049 defined, and false otherwise.
3051 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
3054 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
3056 Conditional assembly: Check if a symbol is referenced. Must be followed
3057 by a symbol name. The condition is true if if the the given symbol was
3058 not referenced before, and false otherwise.
3060 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
3063 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
3065 Conditional assembly: Check if the assembler is currently in 6502 mode
3066 (see <tt><ref id=".P02" name=".P02"></tt> command).
3069 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
3071 Conditional assembly: Check if the assembler is currently in 65816 mode
3072 (see <tt><ref id=".P816" name=".P816"></tt> command).
3075 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
3077 Conditional assembly: Check if the assembler is currently in 65C02 mode
3078 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
3081 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
3083 Conditional assembly: Check if the assembler is currently in 65SC02 mode
3084 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
3087 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
3089 Conditional assembly: Check if a symbol is referenced. Must be followed
3090 by a symbol name. The condition is true if if the the given symbol was
3091 referenced before, and false otherwise.
3093 This command may be used to build subroutine libraries in include files
3094 (you may use separate object modules for this purpose too).
3099 .ifref ToHex ; If someone used this subroutine
3100 ToHex: tay ; Define subroutine
3106 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
3109 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
3111 Import a symbol from another module. The command is followed by a comma
3112 separated list of symbols to import, with each one optionally followed by
3113 an address specification.
3119 .import bar: zeropage
3122 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
3125 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
3127 Import a symbol from another module. The command is followed by a comma
3128 separated list of symbols to import. The symbols are explicitly imported
3129 as zero page symbols (that is, symbols with values in byte range).
3137 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
3140 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
3142 Include a file as binary data. The command expects a string argument
3143 that is the name of a file to include literally in the current segment.
3144 In addition to that, a start offset and a size value may be specified,
3145 separated by commas. If no size is specified, all of the file from the
3146 start offset to end-of-file is used. If no start position is specified
3147 either, zero is assumed (which means that the whole file is inserted).
3152 ; Include whole file
3153 .incbin "sprites.dat"
3155 ; Include file starting at offset 256
3156 .incbin "music.dat", $100
3158 ; Read 100 bytes starting at offset 200
3159 .incbin "graphics.dat", 200, 100
3163 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
3165 Include another file. Include files may be nested up to a depth of 16.
3174 <sect1><tt>.INTERRUPTOR</tt><label id=".INTERRUPTOR"><p>
3176 Export a symbol and mark it as an interruptor. This may be used together
3177 with the linker to build a table of interruptor subroutines that are called
3180 Note: The linker has a feature to build a table of marked routines, but it
3181 is your code that must call these routines, so just declaring a symbol as
3182 interruptor does nothing by itself.
3184 An interruptor is always exported as an absolute (16 bit) symbol. You don't
3185 need to use an additional <tt/.export/ statement, this is implied by
3186 <tt/.interruptor/. It may have an optional priority that is separated by a
3187 comma. Higher numeric values mean a higher priority. If no priority is
3188 given, the default priority of 7 is used. Be careful when assigning
3189 priorities to your own module constructors so they won't interfere with the
3190 ones in the cc65 library.
3195 .interruptor IrqHandler
3196 .interruptor Handler, 16
3199 See the <tt><ref id=".CONDES" name=".CONDES"></tt> command and the separate
3200 section <ref id="condes" name="Module constructors/destructors"> explaining
3201 the feature in more detail.
3204 <sect1><tt>.ISMNEM, .ISMNEMONIC</tt><label id=".ISMNEMONIC"><p>
3206 Builtin function. The function expects an identifier as argument in braces.
3207 The argument is evaluated, and the function yields "true" if the identifier
3208 is defined as an instruction mnemonic that is recognized by the assembler.
3212 .if .not .ismnemonic(ina)
3221 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
3223 Switch on or off line continuations using the backslash character
3224 before a newline. The option is off by default.
3225 Note: Line continuations do not work in a comment. A backslash at the
3226 end of a comment is treated as part of the comment and does not trigger
3228 The command must be followed by a '+' or '-' character to switch the
3229 option on or off respectively.
3234 .linecont + ; Allow line continuations
3237 #$20 ; This is legal now
3241 <sect1><tt>.LIST</tt><label id=".LIST"><p>
3243 Enable output to the listing. The command must be followed by a boolean
3244 switch ("on", "off", "+" or "-") and will enable or disable listing
3246 The option has no effect if the listing is not enabled by the command line
3247 switch -l. If -l is used, an internal counter is set to 1. Lines are output
3248 to the listing file, if the counter is greater than zero, and suppressed if
3249 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
3255 .list on ; Enable listing output
3259 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
3261 Set, how many bytes are shown in the listing for one source line. The
3262 default is 12, so the listing will show only the first 12 bytes for any
3263 source line that generates more than 12 bytes of code or data.
3264 The directive needs an argument, which is either "unlimited", or an
3265 integer constant in the range 4..255.
3270 .listbytes unlimited ; List all bytes
3271 .listbytes 12 ; List the first 12 bytes
3272 .incbin "data.bin" ; Include large binary file
3276 <sect1><tt>.LOBYTES</tt><label id=".LOBYTES"><p>
3278 Define byte sized data by extracting only the low byte (that is, bits 0-7) from
3279 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
3280 the operator '<' prepended to each expression in its list.
3285 .lobytes $1234, $2345, $3456, $4567
3286 .hibytes $fedc, $edcb, $dcba, $cba9
3289 which is equivalent to
3292 .byte $34, $45, $56, $67
3293 .byte $fe, $ed, $dc, $cb
3299 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
3301 TableLookupLo: .lobytes MyTable
3302 TableLookupHi: .hibytes MyTable
3305 which is equivalent to
3308 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
3309 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
3312 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
3313 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
3314 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
3317 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
3319 This command may only be used inside a macro definition. It declares a
3320 list of identifiers as local to the macro expansion.
3322 A problem when using macros are labels: Since they don't change their name,
3323 you get a "duplicate symbol" error if the macro is expanded the second time.
3324 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
3325 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
3328 Some other assemblers start a new lexical block inside a macro expansion.
3329 This has some drawbacks however, since that will not allow <em/any/ symbol
3330 to be visible outside a macro, a feature that is sometimes useful. The
3331 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
3332 to address the problem.
3334 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
3338 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
3340 Defines the character that start "cheap" local labels. You may use one
3341 of '@' and '?' as start character. The default is '@'.
3343 Cheap local labels are labels that are visible only between two non
3344 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
3345 using explicit lexical nesting.
3352 Clear: lda #$00 ; Global label
3353 ?Loop: sta Mem,y ; Local label
3357 Sub: ... ; New global label
3358 bne ?Loop ; ERROR: Unknown identifier!
3362 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
3364 Insert a predefined macro package. The command is followed by an
3365 identifier specifying the macro package to insert. Available macro
3369 atari Defines the scrcode macro.
3370 cbm Defines the scrcode macro.
3371 cpu Defines constants for the .CPU variable.
3372 generic Defines generic macroes like add, sub, and blt.
3373 longbranch Defines conditional long-jump macroes.
3376 Including a macro package twice, or including a macro package that
3377 redefines already existing macros will lead to an error.
3382 .macpack longbranch ; Include macro package
3384 cmp #$20 ; Set condition codes
3385 jne Label ; Jump long on condition
3388 Macro packages are explained in more detail in section <ref
3389 id="macropackages" name="Macro packages">.
3392 <sect1><tt>.MAC, .MACRO</tt><label id=".MACRO"><p>
3394 Start a classic macro definition. The command is followed by an identifier
3395 (the macro name) and optionally by a comma separated list of identifiers
3396 that are macro parameters. A macro definition is terminated by <tt><ref
3397 id=".ENDMACRO" name=".ENDMACRO"></tt>.
3402 .macro ldax arg ; Define macro ldax
3407 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
3408 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
3409 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>
3411 See also section <ref id="macros" name="Macros">.
3414 <sect1><tt>.ORG</tt><label id=".ORG"><p>
3416 Start a section of absolute code. The command is followed by a constant
3417 expression that gives the new PC counter location for which the code is
3418 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
3421 By default, absolute/relocatable mode is global (valid even when switching
3422 segments). Using <tt>.FEATURE <ref id="org_per_seg" name="org_per_seg"></tt>
3423 it can be made segment local.
3425 Please note that you <em/do not need/ <tt/.ORG/ in most cases. Placing
3426 code at a specific address is the job of the linker, not the assembler, so
3427 there is usually no reason to assemble code to a specific address.
3432 .org $7FF ; Emit code starting at $7FF
3436 <sect1><tt>.OUT</tt><label id=".OUT"><p>
3438 Output a string to the console without producing an error. This command
3439 is similar to <tt/.ERROR/, however, it does not force an assembler error
3440 that prevents the creation of an object file.
3445 .out "This code was written by the codebuster(tm)"
3448 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3449 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3450 <tt><ref id=".WARNING" name=".WARNING"></tt>
3453 <sect1><tt>.P02</tt><label id=".P02"><p>
3455 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
3456 instructions. This is the default if not overridden by the
3457 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
3459 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
3460 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3463 <sect1><tt>.P816</tt><label id=".P816"><p>
3465 Enable the 65816 instruction set. This is a superset of the 65SC02 and
3466 6502 instruction sets.
3468 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3469 name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
3472 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
3474 Set the page length for the listing. Must be followed by an integer
3475 constant. The value may be "unlimited", or in the range 32 to 127. The
3476 statement has no effect if no listing is generated. The default value is -1
3477 (unlimited) but may be overridden by the <tt/--pagelength/ command line
3478 option. Beware: Since ca65 is a one pass assembler, the listing is generated
3479 after assembly is complete, you cannot use multiple line lengths with one
3480 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
3485 .pagelength 66 ; Use 66 lines per listing page
3487 .pagelength unlimited ; Unlimited page length
3491 <sect1><tt>.PC02</tt><label id=".PC02"><p>
3493 Enable the 65C02 instructions set. This instruction set includes all
3494 6502 and 65SC02 instructions.
3496 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3497 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3500 <sect1><tt>.POPCPU</tt><label id=".POPCPU"><p>
3502 Pop the last CPU setting from the stack, and activate it.
3504 This command will switch back to the CPU that was last pushed onto the CPU
3505 stack using the <tt><ref id=".PUSHCPU" name=".PUSHCPU"></tt> command, and
3506 remove this entry from the stack.
3508 The assembler will print an error message if the CPU stack is empty when
3509 this command is issued.
3511 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".PUSHCPU"
3512 name=".PUSHCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3515 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
3517 Pop the last pushed segment from the stack, and set it.
3519 This command will switch back to the segment that was last pushed onto the
3520 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3521 command, and remove this entry from the stack.
3523 The assembler will print an error message if the segment stack is empty
3524 when this command is issued.
3526 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3529 <sect1><tt>.PROC</tt><label id=".PROC"><p>
3531 Start a nested lexical level with the given name and adds a symbol with this
3532 name to the enclosing scope. All new symbols from now on are in the local
3533 lexical level and are accessible from outside only via <ref id="scopesyntax"
3534 name="explicit scope specification">. Symbols defined outside this local
3535 level may be accessed as long as their names are not used for new symbols
3536 inside the level. Symbols names in other lexical levels do not clash, so you
3537 may use the same names for identifiers. The lexical level ends when the
3538 <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
3539 may be nested up to a depth of 16 (this is an artificial limit to protect
3540 against errors in the source).
3542 Note: Macro names are always in the global level and in a separate name
3543 space. There is no special reason for this, it's just that I've never
3544 had any need for local macro definitions.
3549 .proc Clear ; Define Clear subroutine, start new level
3551 L1: sta Mem,y ; L1 is local and does not cause a
3552 ; duplicate symbol error if used in other
3555 bne L1 ; Reference local symbol
3557 .endproc ; Leave lexical level
3560 See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
3564 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
3566 Enable the 65SC02 instructions set. This instruction set includes all
3569 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
3570 name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3573 <sect1><tt>.PUSHCPU</tt><label id=".PUSHCPU"><p>
3575 Push the currently active CPU onto a stack. The stack has a size of 8
3578 <tt/.PUSHCPU/ allows together with <tt><ref id=".POPCPU"
3579 name=".POPCPU"></tt> to switch to another CPU and to restore the old CPU
3580 later, without knowledge of the current CPU setting.
3582 The assembler will print an error message if the CPU stack is already full,
3583 when this command is issued.
3585 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".POPCPU"
3586 name=".POPCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3589 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
3591 Push the currently active segment onto a stack. The entries on the stack
3592 include the name of the segment and the segment type. The stack has a size
3595 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3596 to switch to another segment and to restore the old segment later, without
3597 even knowing the name and type of the current segment.
3599 The assembler will print an error message if the segment stack is already
3600 full, when this command is issued.
3602 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3605 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
3607 Switch back to relocatable mode. See the <tt><ref id=".ORG"
3608 name=".ORG"></tt> command.
3611 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
3613 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
3614 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
3615 a constant expression that tells how many times the commands in the body
3616 should get repeated. Optionally, a comma and an identifier may be specified.
3617 If this identifier is found in the body of the repeat statement, it is
3618 replaced by the current repeat count (starting with zero for the first time
3619 the body is repeated).
3621 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
3622 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
3623 level will be used, not the one from the outer level.
3627 The following macro will emit a string that is "encrypted" in that all
3628 characters of the string are XORed by the value $55.
3632 .repeat .strlen(Arg), I
3633 .byte .strat(Arg, I) ^ $55
3638 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
3641 <sect1><tt>.RES</tt><label id=".RES"><p>
3643 Reserve storage. The command is followed by one or two constant
3644 expressions. The first one is mandatory and defines, how many bytes of
3645 storage should be defined. The second, optional expression must by a
3646 constant byte value that will be used as value of the data. If there
3647 is no fill value given, the linker will use the value defined in the
3648 linker configuration file (default: zero).
3653 ; Reserve 12 bytes of memory with value $AA
3658 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
3660 Switch to the RODATA segment. The name of the RODATA segment is always
3661 "RODATA", so this is a shortcut for
3667 The RODATA segment is a segment that is used by the compiler for
3668 readonly data like string constants.
3670 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
3673 <sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
3675 Start a nested lexical level with the given name. All new symbols from now
3676 on are in the local lexical level and are accessible from outside only via
3677 <ref id="scopesyntax" name="explicit scope specification">. Symbols defined
3678 outside this local level may be accessed as long as their names are not used
3679 for new symbols inside the level. Symbols names in other lexical levels do
3680 not clash, so you may use the same names for identifiers. The lexical level
3681 ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
3682 read. Lexical levels may be nested up to a depth of 16 (this is an
3683 artificial limit to protect against errors in the source).
3685 Note: Macro names are always in the global level and in a separate name
3686 space. There is no special reason for this, it's just that I've never
3687 had any need for local macro definitions.
3692 .scope Error ; Start new scope named Error
3694 File = 1 ; File error
3695 Parse = 2 ; Parse error
3696 .endscope ; Close lexical level
3699 lda #Error::File ; Use symbol from scope Error
3702 See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
3706 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
3708 Switch to another segment. Code and data is always emitted into a
3709 segment, that is, a named section of data. The default segment is
3710 "CODE". There may be up to 254 different segments per object file
3711 (and up to 65534 per executable). There are shortcut commands for
3712 the most common segments ("ZEROPAGE", "CODE", "RODATA", "DATA", and "BSS").
3714 The command is followed by a string containing the segment name (there are
3715 some constraints for the name - as a rule of thumb use only those segment
3716 names that would also be valid identifiers). There may also be an optional
3717 address size separated by a colon. See the section covering <tt/<ref
3718 id="address-sizes" name="address sizes">/ for more information.
3720 The default address size for a segment depends on the memory model specified
3721 on the command line. The default is "absolute", which means that you don't
3722 have to use an address size modifier in most cases.
3724 "absolute" means that the is a segment with 16 bit (absolute) addressing.
3725 That is, the segment will reside somewhere in core memory outside the zero
3726 page. "zeropage" (8 bit) means that the segment will be placed in the zero
3727 page and direct (short) addressing is possible for data in this segment.
3729 Beware: Only labels in a segment with the zeropage attribute are marked
3730 as reachable by short addressing. The `*' (PC counter) operator will
3731 work as in other segments and will create absolute variable values.
3733 Please note that a segment cannot have two different address sizes. A
3734 segment specified as zeropage cannot be declared as being absolute later.
3739 .segment "ROM2" ; Switch to ROM2 segment
3740 .segment "ZP2": zeropage ; New direct segment
3741 .segment "ZP2" ; Ok, will use last attribute
3742 .segment "ZP2": absolute ; Error, redecl mismatch
3745 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
3746 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt>, <tt><ref
3747 id=".RODATA" name=".RODATA"></tt>, and <tt><ref id=".ZEROPAGE"
3748 name=".ZEROPAGE"></tt>
3751 <sect1><tt>.SET</tt><label id=".SET"><p>
3753 <tt/.SET/ is used to assign a value to a variable. See <ref id="variables"
3754 name="Numeric variables"> for a full description.
3757 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
3759 Switch the CPU instruction set. The command is followed by a string that
3760 specifies the CPU. Possible values are those that can also be supplied to
3761 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
3762 namely: 6502, 6502X, 65SC02, 65C02, 65816 and HuC6280.
3764 See: <tt><ref id=".CPU" name=".CPU"></tt>,
3765 <tt><ref id=".IFP02" name=".IFP02"></tt>,
3766 <tt><ref id=".IFP816" name=".IFP816"></tt>,
3767 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
3768 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
3769 <tt><ref id=".P02" name=".P02"></tt>,
3770 <tt><ref id=".P816" name=".P816"></tt>,
3771 <tt><ref id=".PC02" name=".PC02"></tt>,
3772 <tt><ref id=".PSC02" name=".PSC02"></tt>
3775 <sect1><tt>.SMART</tt><label id=".SMART"><p>
3777 Switch on or off smart mode. The command must be followed by a '+' or '-'
3778 character to switch the option on or off respectively. The default is off
3779 (that is, the assembler doesn't try to be smart), but this default may be
3780 changed by the -s switch on the command line.
3782 In smart mode the assembler will do the following:
3785 <item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
3786 and update the operand sizes accordingly. If the operand of such an
3787 instruction cannot be evaluated by the assembler (for example, because
3788 the operand is an imported symbol), a warning is issued. Beware: Since
3789 the assembler cannot trace the execution flow this may lead to false
3790 results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
3791 instructions to tell the assembler about the current settings.
3792 <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
3793 used within a procedure declared as <tt/far/, or if the procedure has
3794 no explicit address specification, but it is <tt/far/ because of the
3802 .smart - ; Stop being smart
3805 See: <tt><ref id=".A16" name=".A16"></tt>,
3806 <tt><ref id=".A8" name=".A8"></tt>,
3807 <tt><ref id=".I16" name=".I16"></tt>,
3808 <tt><ref id=".I8" name=".I8"></tt>
3811 <sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
3813 Starts a struct definition. Structs are covered in a separate section named
3814 <ref id="structs" name=""Structs and unions"">.
3816 See also: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>,
3817 <tt><ref id=".ENDUNION" name=".ENDUNION"></tt>,
3818 <tt><ref id=".UNION" name=".UNION"></tt>
3821 <sect1><tt>.TAG</tt><label id=".TAG"><p>
3823 Allocate space for a struct or union.
3834 .tag Point ; Allocate 4 bytes
3838 <sect1><tt>.UNDEF, .UNDEFINE</tt><label id=".UNDEFINE"><p>
3840 Delete a define style macro definition. The command is followed by an
3841 identifier which specifies the name of the macro to delete. Macro
3842 replacement is switched of when reading the token following the command
3843 (otherwise the macro name would be replaced by its replacement list).
3845 See also the <tt><ref id=".DEFINE" name=".DEFINE"></tt> command and
3846 section <ref id="macros" name="Macros">.
3849 <sect1><tt>.UNION</tt><label id=".UNION"><p>
3851 Starts a union definition. Unions are covered in a separate section named
3852 <ref id="structs" name=""Structs and unions"">.
3854 See also: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>,
3855 <tt><ref id=".ENDUNION" name=".ENDUNION"></tt>,
3856 <tt><ref id=".STRUCT" name=".STRUCT"></tt>
3859 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
3861 Force an assembly warning. The assembler will output a warning message
3862 preceded by "User warning". This warning will always be output, even if
3863 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
3864 command line option.
3866 This command may be used to output possible problems when assembling
3875 .warning "Forward jump in jne, cannot optimize!"
3885 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3886 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3887 <tt><ref id=".OUT" name=".OUT"></tt>
3890 <sect1><tt>.WORD</tt><label id=".WORD"><p>
3892 Define word sized data. Must be followed by a sequence of (word ranged,
3893 but not necessarily constant) expressions.
3898 .word $0D00, $AF13, _Clear
3902 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
3904 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
3905 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
3909 .segment "ZEROPAGE": zeropage
3912 Because of the "zeropage" attribute, labels declared in this segment are
3913 addressed using direct addressing mode if possible. You <em/must/ instruct
3914 the linker to place this segment somewhere in the address range 0..$FF
3915 otherwise you will get errors.
3917 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
3921 <sect>Macros<label id="macros"><p>
3924 <sect1>Introduction<p>
3926 Macros may be thought of as "parametrized super instructions". Macros are
3927 sequences of tokens that have a name. If that name is used in the source
3928 file, the macro is "expanded", that is, it is replaced by the tokens that
3929 were specified when the macro was defined.
3932 <sect1>Macros without parameters<p>
3934 In its simplest form, a macro does not have parameters. Here's an
3938 .macro asr ; Arithmetic shift right
3939 cmp #$80 ; Put bit 7 into carry
3940 ror ; Rotate right with carry
3944 The macro above consists of two real instructions, that are inserted into
3945 the code, whenever the macro is expanded. Macro expansion is simply done
3946 by using the name, like this:
3955 <sect1>Parametrized macros<p>
3957 When using macro parameters, macros can be even more useful:
3971 When calling the macro, you may give a parameter, and each occurrence of
3972 the name "addr" in the macro definition will be replaced by the given
3991 A macro may have more than one parameter, in this case, the parameters
3992 are separated by commas. You are free to give less parameters than the
3993 macro actually takes in the definition. You may also leave intermediate
3994 parameters empty. Empty parameters are replaced by empty space (that is,
3995 they are removed when the macro is expanded). If you have a look at our
3996 macro definition above, you will see, that replacing the "addr" parameter
3997 by nothing will lead to wrong code in most lines. To help you, writing
3998 macros with a variable parameter list, there are some control commands:
4000 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
4001 returns true, if there are any tokens on the remainder of the line. Since
4002 empty parameters are replaced by nothing, this may be used to test if a given
4003 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
4006 Look at this example:
4009 .macro ldaxy a, x, y
4022 This macro may be called as follows:
4025 ldaxy 1, 2, 3 ; Load all three registers
4027 ldaxy 1, , 3 ; Load only a and y
4029 ldaxy , , 3 ; Load y only
4032 There's another helper command for determining, which macro parameters are
4033 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt> This command is
4034 replaced by the parameter count given, <em/including/ intermediate empty macro
4038 ldaxy 1 ; .PARAMCOUNT = 1
4039 ldaxy 1,,3 ; .PARAMCOUNT = 3
4040 ldaxy 1,2 ; .PARAMCOUNT = 2
4041 ldaxy 1, ; .PARAMCOUNT = 2
4042 ldaxy 1,2,3 ; .PARAMCOUNT = 3
4045 Macro parameters may optionally be enclosed into curly braces. This allows the
4046 inclusion of tokens that would otherwise terminate the parameter (the comma in
4047 case of a macro parameter).
4050 .macro foo arg1, arg2
4054 foo ($00,x) ; Two parameters passed
4055 foo {($00,x)} ; One parameter passed
4058 In the first case, the macro is called with two parameters: '<tt/($00/'
4059 and 'x)'. The comma is not passed to the macro, since it is part of the
4060 calling sequence, not the parameters.
4062 In the second case, '($00,x)' is passed to the macro, this time
4063 including the comma.
4066 <sect1>Detecting parameter types<p>
4068 Sometimes it is nice to write a macro that acts differently depending on the
4069 type of the argument supplied. An example would be a macro that loads a 16 bit
4070 value from either an immediate operand, or from memory. The <tt/<ref
4071 id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
4072 functions will allow you to do exactly this:
4076 .if (.match (.left (1, {arg}), #))
4078 lda #<(.right (.tcount ({arg})-1, {arg}))
4079 ldx #>(.right (.tcount ({arg})-1, {arg}))
4081 ; assume absolute or zero page
4088 Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
4089 check if its argument begins with a hash mark. If so, two immediate loads are
4090 emitted, Otherwise a load from an absolute zero page memory location is
4091 assumed. Please note how the curly braces are used to enclose parameters to
4092 pseudo functions handling token lists. This is necessary, because the token
4093 lists may include commas or parens, which would be treated by the assembler
4096 The macro can be used as
4101 ldax #$1234 ; X=$12, A=$34
4103 ldax foo ; X=$56, A=$78
4107 <sect1>Recursive macros<p>
4109 Macros may be used recursively:
4112 .macro push r1, r2, r3
4121 There's also a special macro to help writing recursive macros: <tt><ref
4122 id=".EXITMACRO" name=".EXITMACRO"></tt> This command will stop macro expansion
4126 .macro push r1, r2, r3, r4, r5, r6, r7
4128 ; First parameter is empty
4134 push r2, r3, r4, r5, r6, r7
4138 When expanding this macro, the expansion will push all given parameters
4139 until an empty one is encountered. The macro may be called like this:
4142 push $20, $21, $32 ; Push 3 ZP locations
4143 push $21 ; Push one ZP location
4147 <sect1>Local symbols inside macros<p>
4149 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
4150 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
4151 Have a look at the inc16 macro above. Here is it again:
4165 If you have a closer look at the code, you will notice, that it could be
4166 written more efficiently, like this:
4177 But imagine what happens, if you use this macro twice? Since the label "Skip"
4178 has the same name both times, you get a "duplicate symbol" error. Without a
4179 way to circumvent this problem, macros are not as useful, as they could be.
4180 One possible solution is the command <tt><ref id=".LOCAL" name=".LOCAL"></tt>.
4181 It declares one or more symbols as local to the macro expansion. The names of
4182 local variables are replaced by a unique name in each separate macro
4183 expansion. So we can solve the problem above by using <tt/.LOCAL/:
4187 .local Skip ; Make Skip a local symbol
4191 Skip: ; Not visible outside
4195 Another solution is of course to start a new lexical block inside the macro
4196 that hides any labels:
4210 <sect1>C style macros<p>
4212 Starting with version 2.5 of the assembler, there is a second macro type
4213 available: C style macros using the <tt/.DEFINE/ directive. These macros are
4214 similar to the classic macro type described above, but behaviour is sometimes
4219 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
4220 span more than a line. You may use line continuation (see <tt><ref
4221 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
4222 more than one line for increased readability, but the macro itself
4223 may not contain an end-of-line token.
4225 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
4226 the name space with classic macros, but they are detected and replaced
4227 at the scanner level. While classic macros may be used in every place,
4228 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
4229 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
4230 they are more versatile in some situations.
4232 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
4233 parameters. While classic macros may have empty parameters, this is
4234 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
4235 For this macro type, the number of actual parameters must match
4236 exactly the number of formal parameters.
4238 To make this possible, formal parameters are enclosed in braces when
4239 defining the macro. If there are no parameters, the empty braces may
4242 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
4243 contain end-of-line tokens, there are things that cannot be done. They
4244 may not contain several processor instructions for example. So, while
4245 some things may be done with both macro types, each type has special
4246 usages. The types complement each other.
4250 Let's look at a few examples to make the advantages and disadvantages
4253 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
4254 following <tt/.DEFINE/:
4259 foo EQU $1234 ; This is accepted now
4262 You may use the directive to define string constants used elsewhere:
4265 ; Define the version number
4266 .define VERSION "12.3a"
4272 Macros with parameters may also be useful:
4275 .define DEBUG(message) .out message
4277 DEBUG "Assembling include file #3"
4280 Note that, while formal parameters have to be placed in braces, this is
4281 not true for the actual parameters. Beware: Since the assembler cannot
4282 detect the end of one parameter, only the first token is used. If you
4283 don't like that, use classic macros instead:
4286 .macro DEBUG message
4291 (This is an example where a problem can be solved with both macro types).
4294 <sect1>Characters in macros<p>
4296 When using the <ref id="option-t" name="-t"> option, characters are translated
4297 into the target character set of the specific machine. However, this happens
4298 as late as possible. This means that strings are translated if they are part
4299 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
4300 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
4301 used as part of an expression.
4303 This behaviour is very intuitive outside of macros but may be confusing when
4304 doing more complex macros. If you compare characters against numeric values,
4305 be sure to take the translation into account.
4308 <sect1>Deleting macros<p>
4310 Macros can be deleted. This will not work if the macro that should be deleted
4311 is currently expanded as in the following non working example:
4315 .delmacro notworking
4318 notworking ; Will not work
4321 The commands to delete classic and define style macros differ. Classic macros
4322 can be deleted by use of <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>, while
4323 for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros, <tt><ref
4324 id=".UNDEFINE" name=".UNDEFINE"></tt> must be used. Example:
4332 .byte value ; Emit one byte with value 1
4333 mac ; Emit another byte with value 2
4338 .byte value ; Error: Unknown identifier
4339 mac ; Error: Missing ":"
4342 A separate command for <tt>.DEFINE</tt> style macros was necessary, because
4343 the name of such a macro is replaced by its replacement list on a very low
4344 level. To get the actual name, macro replacement has to be switched off when
4345 reading the argument to <tt>.UNDEFINE</tt>. This does also mean that the
4346 argument to <tt>.UNDEFINE</tt> is not allowed to come from another
4347 <tt>.DEFINE</tt>. All this is not necessary for classic macros, so having two
4348 different commands increases flexibility.
4351 <sect>Macro packages<label id="macropackages"><p>
4353 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
4354 macro packages may be included with just one command. Available macro packages
4358 <sect1><tt>.MACPACK generic</tt><p>
4360 This macro package defines macroes that are useful in almost any program.
4361 Currently defined macroes are:
4364 .macro add Arg ; add without carry
4369 .macro sub Arg ; subtract without borrow
4374 .macro bge Arg ; branch on greater-than or equal
4378 .macro blt Arg ; branch on less-than
4382 .macro bgt Arg ; branch on greater-than
4389 .macro ble Arg ; branch on less-than or equal
4394 .macro bnz Arg ; branch on not zero
4398 .macro bze Arg ; branch on zero
4404 <sect1><tt>.MACPACK longbranch</tt><p>
4406 This macro package defines long conditional jumps. They are named like the
4407 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
4408 definition for the "<tt/jeq/" macro, the other macros are built using the same
4413 .if .def(Target) .and ((*+2)-(Target) <= 127)
4422 All macros expand to a short branch, if the label is already defined (back
4423 jump) and is reachable with a short jump. Otherwise the macro expands to a
4424 conditional branch with the branch condition inverted, followed by an absolute
4425 jump to the actual branch target.
4427 The package defines the following macros:
4430 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
4435 <sect1><tt>.MACPACK atari</tt><p>
4437 This macro package defines a macro named <tt/scrcode/. It takes a string
4438 as argument and places this string into memory translated into screen codes.
4441 <sect1><tt>.MACPACK cbm</tt><p>
4443 This macro package defines a macro named <tt/scrcode/. It takes a string
4444 as argument and places this string into memory translated into screen codes.
4447 <sect1><tt>.MACPACK cpu</tt><p>
4449 This macro package does not define any macros but constants used to examine
4450 the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
4451 each supported CPU a constant similar to
4462 is defined. These constants may be used to determine the exact type of the
4463 currently enabled CPU. In addition to that, for each CPU instruction set,
4464 another constant is defined:
4475 The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
4476 be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
4477 currently enabled CPU supports a specific instruction set. For example the
4478 65C02 supports all instructions of the 65SC02 CPU, so it has the
4479 <tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
4483 .if (.cpu .bitand CPU_ISET_65SC02)
4491 it is possible to determine if the
4497 instruction is supported, which is the case for the 65SC02, 65C02 and 65816
4498 CPUs (the latter two are upwards compatible to the 65SC02).
4501 <sect1><tt>.MACPACK module</tt><p>
4503 This macro package defines a macro named <tt/module_header/. It takes an
4504 identifier as argument and is used to define the header of a module both
4505 in the dynamic and static variant.
4509 <sect>Predefined constants<label id="predefined-constants"><p>
4511 For better orthogonality, the assembler defines similar symbols as the
4512 compiler, depending on the target system selected:
4515 <item><tt/__APPLE2__/ - Target system is <tt/apple2/ or <tt/apple2enh/
4516 <item><tt/__APPLE2ENH__/ - Target system is <tt/apple2enh/
4517 <item><tt/__ATARI5200__/ - Target system is <tt/atari5200/
4518 <item><tt/__ATARI__/ - Target system is <tt/atari/ or <tt/atarixl/
4519 <item><tt/__ATARIXL__/ - Target system is <tt/atarixl/
4520 <item><tt/__ATMOS__/ - Target system is <tt/atmos/
4521 <item><tt/__BBC__/ - Target system is <tt/bbc/
4522 <item><tt/__C128__/ - Target system is <tt/c128/
4523 <item><tt/__C16__/ - Target system is <tt/c16/ or <tt/plus4/
4524 <item><tt/__C64__/ - Target system is <tt/c64/
4525 <item><tt/__CBM__/ - Target is a Commodore system
4526 <item><tt/__CBM510__/ - Target system is <tt/cbm510/
4527 <item><tt/__CBM610__/ - Target system is <tt/cbm610/
4528 <item><tt/__GEOS__/ - Target is a GEOS system
4529 <item><tt/__GEOS_APPLE__/ - Target system is <tt/geos-apple/
4530 <item><tt/__GEOS_CBM__/ - Target system is <tt/geos-cbm/
4531 <item><tt/__LUNIX__/ - Target system is <tt/lunix/
4532 <item><tt/__LYNX__/ - Target system is <tt/lynx/
4533 <item><tt/__NES__/ - Target system is <tt/nes/
4534 <item><tt/__OSIC1P__/ - Target system is <tt/osic1p/
4535 <item><tt/__PET__/ - Target system is <tt/pet/
4536 <item><tt/__PLUS4__/ - Target system is <tt/plus4/
4537 <item><tt/__SIM6502__/ - Target system is <tt/sim6502/
4538 <item><tt/__SIM65C02__/ - Target system is <tt/sim65c02/
4539 <item><tt/__SUPERVISION__/ - Target system is <tt/supervision/
4540 <item><tt/__VIC20__/ - Target system is <tt/vic20/
4544 <sect>Structs and unions<label id="structs"><p>
4546 <sect1>Structs and unions Overview<p>
4548 Structs and unions are special forms of <ref id="scopes" name="scopes">. They
4549 are to some degree comparable to their C counterparts. Both have a list of
4550 members. Each member allocates storage and may optionally have a name, which,
4551 in case of a struct, is the offset from the beginning and, in case of a union,
4555 <sect1>Declaration<p>
4557 Here is an example for a very simple struct with two members and a total size
4567 A union shares the total space between all its members, its size is the same
4568 as that of the largest member. The offset of all members relative to the union
4578 A struct or union must not necessarily have a name. If it is anonymous, no
4579 local scope is opened, the identifiers used to name the members are placed
4580 into the current scope instead.
4582 A struct may contain unnamed members and definitions of local structs. The
4583 storage allocators may contain a multiplier, as in the example below:
4588 .word 2 ; Allocate two words
4595 <sect1>The <tt/.TAG/ keyword<p>
4597 Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to reserve space
4598 for an already defined struct or unions within another struct:
4612 Space for a struct or union may be allocated using the <ref id=".TAG"
4613 name=".TAG"> directive.
4619 Currently, members are just offsets from the start of the struct or union. To
4620 access a field of a struct, the member offset has to be added to the address
4621 of the struct itself:
4624 lda C+Circle::Radius ; Load circle radius into A
4627 This may change in a future version of the assembler.
4630 <sect1>Limitations<p>
4632 Structs and unions are currently implemented as nested symbol tables (in fact,
4633 they were a by-product of the improved scoping rules). Currently, the
4634 assembler has no idea of types. This means that the <ref id=".TAG"
4635 name=".TAG"> keyword will only allocate space. You won't be able to initialize
4636 variables declared with <ref id=".TAG" name=".TAG">, and adding an embedded
4637 structure to another structure with <ref id=".TAG" name=".TAG"> will not make
4638 this structure accessible by using the '::' operator.
4642 <sect>Module constructors/destructors<label id="condes"><p>
4644 <em>Note:</em> This section applies mostly to C programs, so the explanation
4645 below uses examples from the C libraries. However, the feature may also be
4646 useful for assembler programs.
4649 <sect1>Module constructors/destructors Overview<p>
4651 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4652 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4653 name=".INTERRUPTOR"></tt> keywords it is possible to export functions in a
4654 special way. The linker is able to generate tables with all functions of a
4655 specific type. Such a table will <em>only</em> include symbols from object
4656 files that are linked into a specific executable. This may be used to add
4657 initialization and cleanup code for library modules, or a table of interrupt
4660 The C heap functions are an example where module initialization code is used.
4661 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
4662 variables that contain the start and the end of the heap, pointers to the free
4663 list and so on. Since the end of the heap depends on the size and start of the
4664 stack, it must be initialized at runtime. However, initializing these
4665 variables for programs that do not use the heap are a waste of time and
4668 So the central module defines a function that contains initialization code and
4669 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
4670 this module is added to an executable by the linker, the initialization
4671 function will be placed into the table of constructors by the linker. The C
4672 startup code will call all constructors before <tt/main/ and all destructors
4673 after <tt/main/, so without any further work, the heap initialization code is
4674 called once the module is linked in.
4676 While it would be possible to add explicit calls to initialization functions
4677 in the startup code, the new approach has several advantages:
4681 If a module is not included, the initialization code is not linked in and not
4682 called. So you don't pay for things you don't need.
4685 Adding another library that needs initialization does not mean that the
4686 startup code has to be changed. Before we had module constructors and
4687 destructors, the startup code for all systems had to be adjusted to call the
4688 new initialization code.
4691 The feature saves memory: Each additional initialization function needs just
4692 two bytes in the table (a pointer to the function).
4697 <sect1>Calling order<p>
4699 The symbols are sorted in increasing priority order by the linker when using
4700 one of the builtin linker configurations, so the functions with lower
4701 priorities come first and are followed by those with higher priorities. The C
4702 library runtime subroutine that walks over the function tables calls the
4703 functions starting from the top of the table - which means that functions with
4704 a high priority are called first.
4706 So when using the C runtime, functions are called with high priority functions
4707 first, followed by low priority functions.
4712 When using these special symbols, please take care of the following:
4717 The linker will only generate function tables, it will not generate code to
4718 call these functions. If you're using the feature in some other than the
4719 existing C environments, you have to write code to call all functions in a
4720 linker generated table yourself. See the <tt/condes/ and <tt/callirq/ modules
4721 in the C runtime for an example on how to do this.
4724 The linker will only add addresses of functions that are in modules linked to
4725 the executable. This means that you have to be careful where to place the
4726 condes functions. If initialization or an irq handler is needed for a group of
4727 functions, be sure to place the function into a module that is linked in
4728 regardless of which function is called by the user.
4731 The linker will generate the tables only when requested to do so by the
4732 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
4733 be requested separately.
4736 Constructors and destructors may have priorities. These priorities determine
4737 the order of the functions in the table. If your initialization or cleanup code
4738 does depend on other initialization or cleanup code, you have to choose the
4739 priority for the functions accordingly.
4742 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4743 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4744 name=".INTERRUPTOR"></tt> statements, there is also a more generic command:
4745 <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to specify an
4746 additional type. Predefined types are 0 (constructor), 1 (destructor) and 2
4747 (interruptor). The linker generates a separate table for each type on request.
4752 <sect>Porting sources from other assemblers<p>
4754 Sometimes it is necessary to port code written for older assemblers to ca65.
4755 In some cases, this can be done without any changes to the source code by
4756 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
4757 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
4760 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
4761 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
4762 done by the linker. Most other assemblers generate absolute code, placement is
4763 done within the assembler and there is no external linker.
4765 In general it is not a good idea to write new code using the emulation
4766 features of the assembler, but there may be situations where even this rule is
4771 You need to use some of the ca65 emulation features to simulate the behaviour
4772 of such simple assemblers.
4775 <item>Prepare your sourcecode like this:
4778 ; if you want TASS style labels without colons
4779 .feature labels_without_colons
4781 ; if you want TASS style character constants
4782 ; ("a" instead of the default 'a')
4783 .feature loose_char_term
4785 .word *+2 ; the cbm load address
4790 notice that the two emulation features are mostly useful for porting
4791 sources originally written in/for TASS, they are not needed for the
4792 actual "simple assembler operation" and are not recommended if you are
4793 writing new code from scratch.
4795 <item>Replace all program counter assignments (which are not possible in ca65
4796 by default, and the respective emulation feature works different from what
4797 you'd expect) by another way to skip to memory locations, for example the
4798 <tt><ref id=".RES" name=".RES"></tt> directive.
4802 .res $2000-* ; reserve memory up to $2000
4805 Please note that other than the original TASS, ca65 can never move the program
4806 counter backwards - think of it as if you are assembling to disk with TASS.
4808 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
4809 rewritten to match ca65 syntax. Most importantly notice that due to the lack
4810 of <tt/.goto/, everything involving loops must be replaced by
4811 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
4813 <item>To assemble code to a different address than it is executed at, use the
4814 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
4815 <tt/.offs/-constructs.
4822 .reloc ; back to normal
4825 <item>Then assemble like this:
4828 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
4831 Note that you need to use the actual start address minus two, since two bytes
4832 are used for the cbm load address.
4839 ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
4840 Bassewitz. For usage of the binaries and/or sources the following
4841 conditions do apply:
4843 This software is provided 'as-is', without any expressed or implied
4844 warranty. In no event will the authors be held liable for any damages
4845 arising from the use of this software.
4847 Permission is granted to anyone to use this software for any purpose,
4848 including commercial applications, and to alter it and redistribute it
4849 freely, subject to the following restrictions:
4852 <item> The origin of this software must not be misrepresented; you must not
4853 claim that you wrote the original software. If you use this software
4854 in a product, an acknowledgment in the product documentation would be
4855 appreciated but is not required.
4856 <item> Altered source versions must be plainly marked as such, and must not
4857 be misrepresented as being the original software.
4858 <item> This notice may not be removed or altered from any source