1 <!doctype linuxdoc system> <!-- -*- text-mode -*- -->
4 <title>ca65 Users Guide
5 <author><url url="mailto:uz@cc65.org" name="Ullrich von Bassewitz">,<newline>
6 <url url="mailto:greg.king5@verizon.net" name="Greg King">
10 ca65 is a powerful macro assembler for the 6502, 65C02, and 65816 CPUs. It is
11 used as a companion assembler for the cc65 crosscompiler, but it may also be
12 used as a standalone product.
15 <!-- Table of contents -->
18 <!-- Begin the document -->
22 ca65 is a replacement for the ra65 assembler that was part of the cc65 C
23 compiler, originally developed by John R. Dunning. I had some problems with
24 ra65 and the copyright does not permit some things which I wanted to be
25 possible, so I decided to write a completely new assembler/linker/archiver
26 suite for the cc65 compiler. ca65 is part of this suite.
28 Some parts of the assembler (code generation and some routines for symbol
29 table handling) are taken from an older crossassembler named a816 written
30 by me a long time ago.
33 <sect1>Design criteria<p>
35 Here's a list of the design criteria, that I considered important for the
40 <item> The assembler must support macros. Macros are not essential, but they
41 make some things easier, especially when you use the assembler in the
42 backend of a compiler.
43 <item> The assembler must support the newer 65C02 and 65816 CPUs. I have been
44 thinking about a 65816 backend for the C compiler, and even my old
45 a816 assembler had support for these CPUs, so this wasn't really a
47 <item> The assembler must produce relocatable code. This is necessary for the
48 compiler support, and it is more convenient.
49 <item> Conditional assembly must be supported. This is a must for bigger
50 projects written in assembler (like Elite128).
51 <item> The assembler must support segments, and it must support more than
52 three segments (this is the count, most other assemblers support).
53 Having more than one code segments helps developing code for systems
54 with a divided ROM area (like the C64).
55 <item> The linker must be able to resolve arbitrary expressions. It should
56 be able to get things like
63 <item> True lexical nesting for symbols. This is very convenient for larger
65 <item> "Cheap" local symbols without lexical nesting for those quick, late
67 <item> I liked the idea of "options" as Anre Fachats .o65 format has it, so I
68 introduced the concept into the object file format use by the new cc65
70 <item> The assembler will be a one pass assembler. There was no real need for
71 this decision, but I've written several multipass assemblers, and it
72 started to get boring. A one pass assembler needs much more elaborated
73 data structures, and because of that it's much more fun:-)
74 <item> Non-GPLed code that may be used in any project without restrictions or
75 fear of "GPL infecting" other code.
83 <sect1>Command line option overview<p>
85 The assembler accepts the following options:
88 ---------------------------------------------------------------------------
89 Usage: ca65 [options] file
91 -D name[=value] Define a symbol
92 -I dir Set an include directory search path
93 -U Mark unresolved symbols as import
94 -V Print the assembler version
95 -W n Set warning level n
97 -g Add debug info to object file
99 -i Ignore case of symbols
100 -l name Create a listing file if assembly was ok
101 -mm model Set the memory model
102 -o name Name the output file
104 -t sys Set the target system
105 -v Increase verbosity
108 --auto-import Mark unresolved symbols as import
109 --bin-include-dir dir Set a search path for binary includes
110 --cpu type Set cpu type
111 --create-dep name Create a make dependency file
112 --create-full-dep name Create a full make dependency file
114 --debug-info Add debug info to object file
115 --feature name Set an emulation feature
116 --help Help (this text)
117 --ignore-case Ignore case of symbols
118 --include-dir dir Set an include directory search path
119 --large-alignment Don't warn about large alignments
120 --listing name Create a listing file if assembly was ok
121 --list-bytes n Maximum number of bytes per listing line
122 --memory-model model Set the memory model
123 --pagelength n Set the page length for the listing
124 --relax-checks Relax some checks (see docs)
125 --smart Enable smart mode
126 --target sys Set the target system
127 --verbose Increase verbosity
128 --version Print the assembler version
129 ---------------------------------------------------------------------------
133 <sect1>Command line options in detail<p>
135 Here is a description of all the command line options:
139 <label id="option--bin-include-dir">
140 <tag><tt>--bin-include-dir dir</tt></tag>
142 Name a directory which is searched for binary include files. The option
143 may be used more than once to specify more than one directory to search. The
144 current directory is always searched first before considering any
145 additional directories. See also the section about <ref id="search-paths"
146 name="search paths">.
149 <label id="option--cpu">
150 <tag><tt>--cpu type</tt></tag>
152 Set the default for the CPU type. The option takes a parameter, which
155 6502, 65SC02, 65C02, 65816, sweet16, HuC6280
158 <label id="option-create-dep">
159 <tag><tt>--create-dep name</tt></tag>
161 Tells the assembler to generate a file containing the dependency list for
162 the assembled module in makefile syntax. The output is written to a file
163 with the given name. The output does not include files passed via debug
164 information to the assembler.
167 <label id="option-create-full-dep">
168 <tag><tt>--create-full-dep name</tt></tag>
170 Tells the assembler to generate a file containing the dependency list for
171 the assembled module in makefile syntax. The output is written to a file
172 with the given name. The output does include files passed via debug
173 information to the assembler.
176 <tag><tt>-d, --debug</tt></tag>
178 Enables debug mode, something that should not be needed for mere
182 <label id="option--feature">
183 <tag><tt>--feature name</tt></tag>
185 Enable an emulation feature. This is identical as using <tt/.FEATURE/
186 in the source with two exceptions: Feature names must be lower case, and
187 each feature must be specified by using an extra <tt/--feature/ option,
188 comma separated lists are not allowed.
190 See the discussion of the <tt><ref id=".FEATURE" name=".FEATURE"></tt>
191 command for a list of emulation features.
194 <label id="option-g">
195 <tag><tt>-g, --debug-info</tt></tag>
197 When this option (or the equivalent control command <tt/.DEBUGINFO/) is
198 used, the assembler will add a section to the object file that contains
199 all symbols (including local ones) together with the symbol values and
200 source file positions. The linker will put these additional symbols into
201 the VICE label file, so even local symbols can be seen in the VICE
205 <label id="option-h">
206 <tag><tt>-h, --help</tt></tag>
208 Print the short option summary shown above.
211 <label id="option-i">
212 <tag><tt>-i, --ignore-case</tt></tag>
214 This option makes the assembler case insensitive on identifiers and labels.
215 This option will override the default, but may itself be overridden by the
216 <tt><ref id=".CASE" name=".CASE"></tt> control command.
219 <label id="option-l">
220 <tag><tt>-l name, --listing name</tt></tag>
222 Generate an assembler listing with the given name. A listing file will
223 never be generated in case of assembly errors.
226 <label id="option--large-alignment">
227 <tag><tt>--large-alignment</tt></tag>
229 Disable warnings about a large combined alignment. See the discussion of the
230 <tt><ref id=".ALIGN" name=".ALIGN"></tt> directive for futher information.
233 <label id="option--list-bytes">
234 <tag><tt>--list-bytes n</tt></tag>
236 Set the maximum number of bytes printed in the listing for one line of
237 input. See the <tt><ref id=".LISTBYTES" name=".LISTBYTES"></tt> directive
238 for more information. The value zero can be used to encode an unlimited
239 number of printed bytes.
242 <label id="option-mm">
243 <tag><tt>-mm model, --memory-model model</tt></tag>
245 Define the default memory model. Possible model specifiers are near, far and
249 <label id="option-o">
250 <tag><tt>-o name</tt></tag>
252 The default output name is the name of the input file with the extension
253 replaced by ".o". If you don't like that, you may give another name with
254 the -o option. The output file will be placed in the same directory as
255 the source file, or, if -o is given, the full path in this name is used.
258 <label id="option--pagelength">
259 <tag><tt>--pagelength n</tt></tag>
261 sets the length of a listing page in lines. See the <tt><ref
262 id=".PAGELENGTH" name=".PAGELENGTH"></tt> directive for more information.
265 <label id="option--relax-checks">
266 <tag><tt>--relax-checks</tt></tag>
268 Relax some checks done by the assembler. This will allow code that is an
269 error in most cases and flagged as such by the assembler, but can be valid
270 in special situations.
274 <item>Short branches between two different segments.
275 <item>Byte sized address loads where the address is not a zeropage address.
279 <label id="option-s">
280 <tag><tt>-s, --smart-mode</tt></tag>
282 In smart mode (enabled by -s or the <tt><ref id=".SMART" name=".SMART"></tt>
283 pseudo instruction) the assembler will track usage of the <tt/REP/ and
284 <tt/SEP/ instructions in 65816 mode and update the operand sizes
285 accordingly. If the operand of such an instruction cannot be evaluated by
286 the assembler (for example, because the operand is an imported symbol), a
289 Beware: Since the assembler cannot trace the execution flow this may
290 lead to false results in some cases. If in doubt, use the .ixx and .axx
291 instructions to tell the assembler about the current settings. Smart
292 mode is off by default.
295 <label id="option-t">
296 <tag><tt>-t sys, --target sys</tt></tag>
298 Set the target system. This will enable translation of character strings and
299 character constants into the character set of the target platform. The
300 default for the target system is "none", which means that no translation
301 will take place. The assembler supports the same target systems as the
302 compiler, see there for a list.
304 Depending on the target, the default CPU type is also set. This can be
305 overriden by using the <tt/<ref id="option--cpu" name="--cpu">/ option.
308 <label id="option-v">
309 <tag><tt>-v, --verbose</tt></tag>
311 Increase the assembler verbosity. Usually only needed for debugging
312 purposes. You may use this option more than one time for even more
316 <label id="option-D">
317 <tag><tt>-D</tt></tag>
319 This option allows you to define symbols on the command line. Without a
320 value, the symbol is defined with the value zero. When giving a value,
321 you may use the '$' prefix for hexadecimal symbols. Please note
322 that for some operating systems, '$' has a special meaning, so
323 you may have to quote the expression.
326 <label id="option-I">
327 <tag><tt>-I dir, --include-dir dir</tt></tag>
329 Name a directory which is searched for include files. The option may be
330 used more than once to specify more than one directory to search. The
331 current directory is always searched first before considering any
332 additional directories. See also the section about <ref id="search-paths"
333 name="search paths">.
336 <label id="option-U">
337 <tag><tt>-U, --auto-import</tt></tag>
339 Mark symbols that are not defined in the sources as imported symbols. This
340 should be used with care since it delays error messages about typos and such
341 until the linker is run. The compiler uses the equivalent of this switch
342 (<tt><ref id=".AUTOIMPORT" name=".AUTOIMPORT"></tt>) to enable auto imported
343 symbols for the runtime library. However, the compiler is supposed to
344 generate code that runs through the assembler without problems, something
345 which is not always true for assembler programmers.
348 <label id="option-V">
349 <tag><tt>-V, --version</tt></tag>
351 Print the version number of the assembler. If you send any suggestions
352 or bugfixes, please include the version number.
355 <label id="option-W">
356 <tag><tt>-Wn</tt></tag>
358 Set the warning level for the assembler. Using -W2 the assembler will
359 even warn about such things like unused imported symbols. The default
360 warning level is 1, and it would probably be silly to set it to
368 <sect>Search paths<label id="search-paths"><p>
370 Normal include files are searched in the following places:
373 <item>The current file's directory.
374 <item>Any directory added with the <tt/<ref id="option-I" name="-I">/ option
376 <item>The value of the environment variable <tt/CA65_INC/ if it is defined.
377 <item>A subdirectory named <tt/asminc/ of the directory defined in the
378 environment variable <tt/CC65_HOME/, if it is defined.
379 <item>An optionally compiled-in directory.
382 Binary include files are searched in the following places:
385 <item>The current file's directory.
386 <item>Any directory added with the <tt/<ref id="option--bin-include-dir"
387 name="--bin-include-dir">/ option on the command line.
392 <sect>Input format<p>
394 <sect1>Assembler syntax<p>
396 The assembler accepts the standard 6502/65816 assembler syntax. One line may
397 contain a label (which is identified by a colon), and, in addition to the
398 label, an assembler mnemonic, a macro, or a control command (see section <ref
399 id="control-commands" name="Control Commands"> for supported control
400 commands). Alternatively, the line may contain a symbol definition using
401 the '=' token. Everything after a semicolon is handled as a comment (that is,
404 Here are some examples for valid input lines:
407 Label: ; A label and a comment
408 lda #$20 ; A 6502 instruction plus comment
409 L1: ldx #$20 ; Same with label
410 L2: .byte "Hello world" ; Label plus control command
411 mymac $20 ; Macro expansion
412 MySym = 3*L1 ; Symbol definition
413 MaSym = Label ; Another symbol
416 The assembler accepts
419 <item>all valid 6502 mnemonics when in 6502 mode (the default or after the
420 <tt><ref id=".P02" name=".P02"></tt> command was given).
421 <item>all valid 6502 mnemonics plus a set of illegal instructions when in
422 <ref id="6502X-mode" name="6502X mode">.
423 <item>all valid 65SC02 mnemonics when in 65SC02 mode (after the
424 <tt><ref id=".PSC02" name=".PSC02"></tt> command was given).
425 <item>all valid 65C02 mnemonics when in 65C02 mode (after the
426 <tt><ref id=".PC02" name=".PC02"></tt> command was given).
427 <item>all valid 65618 mnemonics when in 65816 mode (after the
428 <tt><ref id=".P816" name=".P816"></tt> command was given).
434 In 65816 mode, several aliases are accepted, in addition to the official
438 CPA is an alias for CMP
439 DEA is an alias for DEC A
440 INA is an alias for INC A
441 SWA is an alias for XBA
442 TAD is an alias for TCD
443 TAS is an alias for TCS
444 TDA is an alias for TDC
445 TSA is an alias for TSC
449 <sect1>6502X mode<label id="6502X-mode"><p>
451 6502X mode is an extension to the normal 6502 mode. In this mode, several
452 mnemonics for illegal instructions of the NMOS 6502 CPUs are accepted. Since
453 these instructions are illegal, there are no official mnemonics for them. The
454 unofficial ones are taken from <url
455 url="http://www.oxyron.de/html/opcodes02.html">. Please note that only the
456 ones marked as "stable" are supported. The following table uses information
457 from the mentioned web page, for more information, see there.
460 <item><tt>ALR: A:=(A and #{imm})/2;</tt>
461 <item><tt>ANC: A:=A and #{imm};</tt> Generates opcode $0B.
462 <item><tt>ARR: A:=(A and #{imm})/2;</tt>
463 <item><tt>AXS: X:=A and X-#{imm};</tt>
464 <item><tt>DCP: {adr}:={adr}-1; A-{adr};</tt>
465 <item><tt>ISC: {adr}:={adr}+1; A:=A-{adr};</tt>
466 <item><tt>LAS: A,X,S:={adr} and S;</tt>
467 <item><tt>LAX: A,X:={adr};</tt>
468 <item><tt>RLA: {adr}:={adr}rol; A:=A and {adr};</tt>
469 <item><tt>RRA: {adr}:={adr}ror; A:=A adc {adr};</tt>
470 <item><tt>SAX: {adr}:=A and X;</tt>
471 <item><tt>SLO: {adr}:={adr}*2; A:=A or {adr};</tt>
472 <item><tt>SRE: {adr}:={adr}/2; A:=A xor {adr};</tt>
477 <sect1>sweet16 mode<label id="sweet16-mode"><p>
479 SWEET 16 is an interpreter for a pseudo 16 bit CPU written by Steve Wozniak
480 for the Apple ][ machines. It is available in the Apple ][ ROM. ca65 can
481 generate code for this pseudo CPU when switched into sweet16 mode. The
482 following is special in sweet16 mode:
486 <item>The '@' character denotes indirect addressing and is no longer available
487 for cheap local labels. If you need cheap local labels, you will have to
488 switch to another lead character using the <tt/<ref id=".LOCALCHAR"
489 name=".LOCALCHAR">/ command.
491 <item>Registers are specified using <tt/R0/ .. <tt/R15/. In sweet16 mode,
492 these identifiers are reserved words.
496 Please note that the assembler does neither supply the interpreter needed for
497 SWEET 16 code, nor the zero page locations needed for the SWEET 16 registers,
498 nor does it call the interpreter. All this must be done by your program. Apple
499 ][ programmers do probably know how to use sweet16 mode.
501 For more information about SWEET 16, see
502 <url url="http://www.6502.org/source/interpreters/sweet16.htm">.
505 <sect1>Number format<p>
507 For literal values, the assembler accepts the widely used number formats: A
508 preceding '$' or a trailing 'h' denotes a hex value, a preceding '%'
509 denotes a binary value, and a bare number is interpreted as a decimal. There
510 are currently no octal values and no floats.
513 <sect1>Conditional assembly<p>
515 Please note that when using the conditional directives (<tt/.IF/ and friends),
516 the input must consist of valid assembler tokens, even in <tt/.IF/ branches
517 that are not assembled. The reason for this behaviour is that the assembler
518 must still be able to detect the ending tokens (like <tt/.ENDIF/), so
519 conversion of the input stream into tokens still takes place. As a consequence
520 conditional assembly directives may <bf/not/ be used to prevent normal text
521 (used as a comment or similar) from being assembled. <p>
527 <sect1>Expression evaluation<p>
529 All expressions are evaluated with (at least) 32 bit precision. An
530 expression may contain constant values and any combination of internal and
531 external symbols. Expressions that cannot be evaluated at assembly time
532 are stored inside the object file for evaluation by the linker.
533 Expressions referencing imported symbols must always be evaluated by the
537 <sect1>Size of an expression result<p>
539 Sometimes, the assembler must know about the size of the value that is the
540 result of an expression. This is usually the case, if a decision has to be
541 made, to generate a zero page or an absolute memory references. In this
542 case, the assembler has to make some assumptions about the result of an
546 <item> If the result of an expression is constant, the actual value is
547 checked to see if it's a byte sized expression or not.
548 <item> If the expression is explicitly casted to a byte sized expression by
549 one of the '>', '<' or '^' operators, it is a byte expression.
550 <item> If this is not the case, and the expression contains a symbol,
551 explicitly declared as zero page symbol (by one of the .importzp or
552 .exportzp instructions), then the whole expression is assumed to be
554 <item> If the expression contains symbols that are not defined, and these
555 symbols are local symbols, the enclosing scopes are searched for a
556 symbol with the same name. If one exists and this symbol is defined,
557 its attributes are used to determine the result size.
558 <item> In all other cases the expression is assumed to be word sized.
561 Note: If the assembler is not able to evaluate the expression at assembly
562 time, the linker will evaluate it and check for range errors as soon as
566 <sect1>Boolean expressions<p>
568 In the context of a boolean expression, any non zero value is evaluated as
569 true, any other value to false. The result of a boolean expression is 1 if
570 it's true, and zero if it's false. There are boolean operators with extreme
571 low precedence with version 2.x (where x > 0). The <tt/.AND/ and <tt/.OR/
572 operators are shortcut operators. That is, if the result of the expression is
573 already known, after evaluating the left hand side, the right hand side is
577 <sect1>Constant expressions<p>
579 Sometimes an expression must evaluate to a constant without looking at any
580 further input. One such example is the <tt/<ref id=".IF" name=".IF">/ command
581 that decides if parts of the code are assembled or not. An expression used in
582 the <tt/.IF/ command cannot reference a symbol defined later, because the
583 decision about the <tt/.IF/ must be made at the point when it is read. If the
584 expression used in such a context contains only constant numerical values,
585 there is no problem. When unresolvable symbols are involved it may get harder
586 for the assembler to determine if the expression is actually constant, and it
587 is even possible to create expressions that aren't recognized as constant.
588 Simplifying the expressions will often help.
590 In cases where the result of the expression is not needed immediately, the
591 assembler will delay evaluation until all input is read, at which point all
592 symbols are known. So using arbitrary complex constant expressions is no
593 problem in most cases.
597 <sect1>Available operators<label id="operators"><p>
601 <bf/Operator/| <bf/Description/| <bf/Precedence/@<hline>
602 | Built-in string functions| 0@
604 | Built-in pseudo-variables| 1@
605 | Built-in pseudo-functions| 1@
606 +| Unary positive| 1@
607 -| Unary negative| 1@
609 .BITNOT| Unary bitwise not| 1@
611 .LOBYTE| Unary low-byte operator| 1@
613 .HIBYTE| Unary high-byte operator| 1@
615 .BANKBYTE| Unary bank-byte operator| 1@
617 *| Multiplication| 2@
619 .MOD| Modulo operator| 2@
621 .BITAND| Bitwise and| 2@
623 .BITXOR| Binary bitwise xor| 2@
625 .SHL| Shift-left operator| 2@
627 .SHR| Shift-right operator| 2@
629 +| Binary addition| 3@
630 -| Binary subtraction| 3@
632 .BITOR| Bitwise or| 3@
634 = | Compare operator (equal)| 4@
635 <>| Compare operator (not equal)| 4@
636 <| Compare operator (less)| 4@
637 >| Compare operator (greater)| 4@
638 <=| Compare operator (less or equal)| 4@
639 >=| Compare operator (greater or equal)| 4@
642 .AND| Boolean and| 5@
643 .XOR| Boolean xor| 5@
645 ||<newline>
649 .NOT| Boolean not| 7@<hline>
651 <caption>Available operators, sorted by precedence
654 To force a specific order of evaluation, parentheses may be used, as usual.
658 <sect>Symbols and labels<p>
660 A symbol or label is an identifier that starts with a letter and is followed
661 by letters and digits. Depending on some features enabled (see
662 <tt><ref id="at_in_identifiers" name="at_in_identifiers"></tt>,
663 <tt><ref id="dollar_in_identifiers" name="dollar_in_identifiers"></tt> and
664 <tt><ref id="leading_dot_in_identifiers" name="leading_dot_in_identifiers"></tt>)
665 other characters may be present. Use of identifiers consisting of a single
666 character will not work in all cases, because some of these identifiers are
667 reserved keywords (for example "A" is not a valid identifier for a label,
668 because it is the keyword for the accumulator).
670 The assembler allows you to use symbols instead of naked values to make
671 the source more readable. There are a lot of different ways to define and
672 use symbols and labels, giving a lot of flexibility.
674 <sect1>Numeric constants<p>
676 Numeric constants are defined using the equal sign or the label assignment
677 operator. After doing
683 may use the symbol "two" in every place where a number is expected, and it is
684 evaluated to the value 2 in this context. The label assignment operator is
685 almost identical, but causes the symbol to be marked as a label, so it may be
686 handled differently in a debugger:
692 The right side can of course be an expression:
699 <label id="variables">
700 <sect1>Numeric variables<p>
702 Within macros and other control structures (<tt><ref id=".REPEAT"
703 name=".REPEAT"></tt>, ...) it is sometimes useful to have some sort of
704 variable. This can be achieved by the <tt>.SET</tt> operator. It creates a
705 symbol that may get assigned a different value later:
709 lda #four ; Loads 4 into A
711 lda #four ; Loads 3 into A
714 Since the value of the symbol can change later, it must be possible to
715 evaluate it when used (no delayed evaluation as with normal symbols). So the
716 expression used as the value must be constant.
718 Following is an example for a macro that generates a different label each time
719 it is used. It uses the <tt><ref id=".SPRINTF" name=".SPRINTF"></tt> function
720 and a numeric variable named <tt>lcount</tt>.
723 .lcount .set 0 ; Initialize the counter
726 .ident (.sprintf ("L%04X", lcount)):
727 lcount .set lcount + 1
732 <sect1>Standard labels<p>
734 A label is defined by writing the name of the label at the start of the line
735 (before any instruction mnemonic, macro or pseudo directive), followed by a
736 colon. This will declare a symbol with the given name and the value of the
737 current program counter.
740 <sect1>Local labels and symbols<p>
742 Using the <tt><ref id=".PROC" name=".PROC"></tt> directive, it is possible to
743 create regions of code where the names of labels and symbols are local to this
744 region. They are not known outside of this region and cannot be accessed from
745 there. Such regions may be nested like PROCEDUREs in Pascal.
747 See the description of the <tt><ref id=".PROC" name=".PROC"></tt>
748 directive for more information.
751 <sect1>Cheap local labels<p>
753 Cheap local labels are defined like standard labels, but the name of the
754 label must begin with a special symbol (usually '@', but this can be
755 changed by the <tt><ref id=".LOCALCHAR" name=".LOCALCHAR"></tt>
758 Cheap local labels are visible only between two non cheap labels. As soon as a
759 standard symbol is encountered (this may also be a local symbol if inside a
760 region defined with the <tt><ref id=".PROC" name=".PROC"></tt> directive), the
761 cheap local symbol goes out of scope.
763 You may use cheap local labels as an easy way to reuse common label
764 names like "Loop". Here is an example:
767 Clear: lda #$00 ; Global label
769 @Loop: sta Mem,y ; Local label
773 Sub: ... ; New global label
774 bne @Loop ; ERROR: Unknown identifier!
777 <sect1>Unnamed labels<p>
779 If you really want to write messy code, there are also unnamed labels. These
780 labels do not have a name (you guessed that already, didn't you?). A colon is
781 used to mark the absence of the name.
783 Unnamed labels may be accessed by using the colon plus several minus or plus
784 characters as a label designator. Using the '-' characters will create a back
785 reference (use the n'th label backwards), using '+' will create a forward
786 reference (use the n'th label in forward direction). An example will help to
809 As you can see from the example, unnamed labels will make even short
810 sections of code hard to understand, because you have to count labels
811 to find branch targets (this is the reason why I for my part do
812 prefer the "cheap" local labels). Nevertheless, unnamed labels are
813 convenient in some situations, so it's your decision.
815 <em/Note:/ <ref id="scopes" name="Scopes"> organize named symbols, not
816 unnamed ones, so scopes don't have an effect on unnamed labels.
820 <sect1>Using macros to define labels and constants<p>
822 While there are drawbacks with this approach, it may be handy in a few rare
823 situations. Using <tt><ref id=".DEFINE" name=".DEFINE"></tt>, it is possible
824 to define symbols or constants that may be used elsewhere. One of the
825 advantages is that you can use it to define string constants (this is not
826 possible with the other symbol types).
828 Please note: <tt/.DEFINE/ style macros do token replacements on a low level,
829 so the names do not adhere to scoping, diagnostics may be misleading, there
830 are no symbols to look up in the map file, and there is no debug info.
831 Especially the first problem in the list can lead to very nasty programming
832 errors. Because of these problems, the general advice is, <bf/NOT/ do use
833 <tt/.DEFINE/ if you don't have to.
839 .DEFINE version "SOS V2.3"
841 four = two * two ; Ok
844 .PROC ; Start local scope
845 two = 3 ; Will give "2 = 3" - invalid!
850 <sect1>Symbols and <tt>.DEBUGINFO</tt><p>
852 If <tt><ref id=".DEBUGINFO" name=".DEBUGINFO"></tt> is enabled (or <ref
853 id="option-g" name="-g"> is given on the command line), global, local and
854 cheap local labels are written to the object file and will be available in the
855 symbol file via the linker. Unnamed labels are not written to the object file,
856 because they don't have a name which would allow to access them.
860 <sect>Scopes<label id="scopes"><p>
862 ca65 implements several sorts of scopes for symbols.
864 <sect1>Global scope<p>
866 All (non cheap local) symbols that are declared outside of any nested scopes
870 <sect1>Cheap locals<p>
872 A special scope is the scope for cheap local symbols. It lasts from one non
873 local symbol to the next one, without any provisions made by the programmer.
874 All other scopes differ in usage but use the same concept internally.
877 <sect1>Generic nested scopes<p>
879 A nested scoped for generic use is started with <tt/<ref id=".SCOPE"
880 name=".SCOPE">/ and closed with <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/.
881 The scope can have a name, in which case it is accessible from the outside by
882 using <ref id="scopesyntax" name="explicit scopes">. If the scope does not
883 have a name, all symbols created within the scope are local to the scope, and
884 aren't accessible from the outside.
886 A nested scope can access symbols from the local or from enclosing scopes by
887 name without using explicit scope names. In some cases there may be
888 ambiguities, for example if there is a reference to a local symbol that is not
889 yet defined, but a symbol with the same name exists in outer scopes:
901 In the example above, the <tt/lda/ instruction will load the value 3 into the
902 accumulator, because <tt/foo/ is redefined in the scope. However:
914 Here, <tt/lda/ will still load from <tt/$12,x/, but since it is unknown to the
915 assembler that <tt/foo/ is a zeropage symbol when translating the instruction,
916 absolute mode is used instead. In fact, the assembler will not use absolute
917 mode by default, but it will search through the enclosing scopes for a symbol
918 with the given name. If one is found, the address size of this symbol is used.
919 This may lead to errors:
931 In this case, when the assembler sees the symbol <tt/foo/ in the <tt/lda/
932 instruction, it will search for an already defined symbol <tt/foo/. It will
933 find <tt/foo/ in scope <tt/outer/, and a close look reveals that it is a
934 zeropage symbol. So the assembler will use zeropage addressing mode. If
935 <tt/foo/ is redefined later in scope <tt/inner/, the assembler tries to change
936 the address in the <tt/lda/ instruction already translated, but since the new
937 value needs absolute addressing mode, this fails, and an error message "Range
940 Of course the most simple solution for the problem is to move the definition
941 of <tt/foo/ in scope <tt/inner/ upwards, so it precedes its use. There may be
942 rare cases when this cannot be done. In these cases, you can use one of the
943 address size override operators:
955 This will cause the <tt/lda/ instruction to be translated using absolute
956 addressing mode, which means changing the symbol reference later does not
960 <sect1>Nested procedures<p>
962 A nested procedure is created by use of <tt/<ref id=".PROC" name=".PROC">/. It
963 differs from a <tt/<ref id=".SCOPE" name=".SCOPE">/ in that it must have a
964 name, and a it will introduce a symbol with this name in the enclosing scope.
973 is actually the same as
982 This is the reason why a procedure must have a name. If you want a scope
983 without a name, use <tt/<ref id=".SCOPE" name=".SCOPE">/.
985 <em/Note:/ As you can see from the example above, scopes and symbols live in
986 different namespaces. There can be a symbol named <tt/foo/ and a scope named
987 <tt/foo/ without any conflicts (but see the section titled <ref
988 id="scopesearch" name=""Scope search order"">).
991 <sect1>Structs, unions and enums<p>
993 Structs, unions and enums are explained in a <ref id="structs" name="separate
994 section">, I do only cover them here, because if they are declared with a
995 name, they open a nested scope, similar to <tt/<ref id=".SCOPE"
996 name=".SCOPE">/. However, when no name is specified, the behaviour is
997 different: In this case, no new scope will be opened, symbols declared within
998 a struct, union, or enum declaration will then be added to the enclosing scope
1002 <sect1>Explicit scope specification<label id="scopesyntax"><p>
1004 Accessing symbols from other scopes is possible by using an explicit scope
1005 specification, provided that the scope where the symbol lives in has a name.
1006 The namespace token (<tt/::/) is used to access other scopes:
1014 lda foo::bar ; Access foo in scope bar
1017 The only way to deny access to a scope from the outside is to declare a scope
1018 without a name (using the <tt/<ref id=".SCOPE" name=".SCOPE">/ command).
1020 A special syntax is used to specify the global scope: If a symbol or scope is
1021 preceded by the namespace token, the global scope is searched:
1028 lda #::bar ; Access the global bar (which is 3)
1033 <sect1>Scope search order<label id="scopesearch"><p>
1035 The assembler searches for a scope in a similar way as for a symbol. First, it
1036 looks in the current scope, and then it walks up the enclosing scopes until
1039 However, one important thing to note when using explicit scope syntax is, that
1040 a symbol may be accessed before it is defined, but a scope may <bf/not/ be
1041 used without a preceding definition. This means that in the following
1050 lda #foo::bar ; Will load 3, not 2!
1057 the reference to the scope <tt/foo/ will use the global scope, and not the
1058 local one, because the local one is not visible at the point where it is
1061 Things get more complex if a complete chain of scopes is specified:
1072 lda #outer::inner::bar ; 1
1084 When <tt/outer::inner::bar/ is referenced in the <tt/lda/ instruction, the
1085 assembler will first search in the local scope for a scope named <tt/outer/.
1086 Since none is found, the enclosing scope (<tt/another/) is checked. There is
1087 still no scope named <tt/outer/, so scope <tt/foo/ is checked, and finally
1088 scope <tt/outer/ is found. Within this scope, <tt/inner/ is searched, and in
1089 this scope, the assembler looks for a symbol named <tt/bar/.
1091 Please note that once the anchor scope is found, all following scopes
1092 (<tt/inner/ in this case) are expected to be found exactly in this scope. The
1093 assembler will search the scope tree only for the first scope (if it is not
1094 anchored in the root scope). Starting from there on, there is no flexibility,
1095 so if the scope named <tt/outer/ found by the assembler does not contain a
1096 scope named <tt/inner/, this would be an error, even if such a pair does exist
1097 (one level up in global scope).
1099 Ambiguities that may be introduced by this search algorithm may be removed by
1100 anchoring the scope specification in the global scope. In the example above,
1101 if you want to access the "other" symbol <tt/bar/, you would have to write:
1112 lda #::outer::inner::bar ; 2
1125 <sect>Address sizes and memory models<label id="address-sizes"><p>
1127 <sect1>Address sizes<p>
1129 ca65 assigns each segment and each symbol an address size. This is true, even
1130 if the symbol is not used as an address. You may also think of a value range
1131 of the symbol instead of an address size.
1133 Possible address sizes are:
1136 <item>Zeropage or direct (8 bits)
1137 <item>Absolute (16 bits)
1139 <item>Long (32 bits)
1142 Since the assembler uses default address sizes for the segments and symbols,
1143 it is usually not necessary to override the default behaviour. In cases, where
1144 it is necessary, the following keywords may be used to specify address sizes:
1147 <item>DIRECT, ZEROPAGE or ZP for zeropage addressing (8 bits).
1148 <item>ABSOLUTE, ABS or NEAR for absolute addressing (16 bits).
1149 <item>FAR for far addressing (24 bits).
1150 <item>LONG or DWORD for long addressing (32 bits).
1154 <sect1>Address sizes of segments<p>
1156 The assembler assigns an address size to each segment. Since the
1157 representation of a label within this segment is "segment start + offset",
1158 labels will inherit the address size of the segment they are declared in.
1160 The address size of a segment may be changed, by using an optional address
1161 size modifier. See the <tt/<ref id=".SEGMENT" name="segment directive">/ for
1162 an explanation on how this is done.
1165 <sect1>Address sizes of symbols<p>
1170 <sect1>Memory models<p>
1172 The default address size of a segment depends on the memory model used. Since
1173 labels inherit the address size from the segment they are declared in,
1174 changing the memory model is an easy way to change the address size of many
1180 <sect>Pseudo variables<label id="pseudo-variables"><p>
1182 Pseudo variables are readable in all cases, and in some special cases also
1185 <sect1><tt>*</tt><p>
1187 Reading this pseudo variable will return the program counter at the start
1188 of the current input line.
1190 Assignment to this variable is possible when <tt/<ref id=".FEATURE"
1191 name=".FEATURE pc_assignment">/ is used. Note: You should not use
1192 assignments to <tt/*/, use <tt/<ref id=".ORG" name=".ORG">/ instead.
1195 <sect1><tt>.ASIZE</tt><label id=".ASIZE"><p>
1197 Reading this pseudo variable will return the current size of the
1198 Accumulator in bits.
1200 For the 65816 instruction set .ASIZE will return either 8 or 16, depending
1201 on the current size of the operand in immediate accu addressing mode.
1203 For all other CPU instruction sets, .ASIZE will always return 8.
1208 ; Reverse Subtract with Accumulator
1221 See also: <tt><ref id=".ISIZE" name=".ISIZE"></tt>
1224 <sect1><tt>.CPU</tt><label id=".CPU"><p>
1226 Reading this pseudo variable will give a constant integer value that
1227 tells which CPU is currently enabled. It can also tell which instruction
1228 set the CPU is able to translate. The value read from the pseudo variable
1229 should be further examined by using one of the constants defined by the
1230 "cpu" macro package (see <tt/<ref id=".MACPACK" name=".MACPACK">/).
1232 It may be used to replace the .IFPxx pseudo instructions or to construct
1233 even more complex expressions.
1239 .if (.cpu .bitand CPU_ISET_65816)
1251 <sect1><tt>.ISIZE</tt><label id=".ISIZE"><p>
1253 Reading this pseudo variable will return the current size of the Index
1256 For the 65816 instruction set .ISIZE will return either 8 or 16, depending
1257 on the current size of the operand in immediate index addressing mode.
1259 For all other CPU instruction sets, .ISIZE will always return 8.
1261 See also: <tt><ref id=".ASIZE" name=".ASIZE"></tt>
1264 <sect1><tt>.PARAMCOUNT</tt><label id=".PARAMCOUNT"><p>
1266 This builtin pseudo variable is only available in macros. It is replaced by
1267 the actual number of parameters that were given in the macro invocation.
1272 .macro foo arg1, arg2, arg3
1273 .if .paramcount <> 3
1274 .error "Too few parameters for macro foo"
1280 See section <ref id="macros" name="Macros">.
1283 <sect1><tt>.TIME</tt><label id=".TIME"><p>
1285 Reading this pseudo variable will give a constant integer value that
1286 represents the current time in POSIX standard (as seconds since the
1289 It may be used to encode the time of translation somewhere in the created
1295 .dword .time ; Place time here
1299 <sect1><tt>.VERSION</tt><label id=".VERSION"><p>
1301 Reading this pseudo variable will give the assembler version according to
1302 the following formula:
1304 VER_MAJOR*$100 + VER_MINOR*$10
1306 It may be used to encode the assembler version or check the assembler for
1307 special features not available with older versions.
1311 Version 2.14 of the assembler will return $2E0 as numerical constant when
1312 reading the pseudo variable <tt/.VERSION/.
1316 <sect>Pseudo functions<label id="pseudo-functions"><p>
1318 Pseudo functions expect their arguments in parenthesis, and they have a result,
1319 either a string or an expression.
1322 <sect1><tt>.ADDRSIZE</tt><label id=".ADDRSIZE"><p>
1324 The <tt/.ADDRSIZE/ function is used to return the interal address size
1325 associated with a symbol. This can be helpful in macros when knowing the address
1326 size of symbol can help with custom instructions.
1332 .if .ADDRSIZE(foo) = 1
1333 ;do custom command based on zeropage addressing:
1335 .elseif .ADDRSIZE(foo) = 2
1336 ;do custom command based on absolute addressing:
1339 .elseif .ADDRSIZE(foo) = 0
1340 ; no address size defined for this symbol:
1341 .out .sprintf("Error, address size unknown for symbol %s", .string(foo))
1346 This command is new and must be enabled with the <tt/.FEATURE addrsize/ command.
1348 See: <tt><ref id=".FEATURE" name=".FEATURE"></tt>
1351 <sect1><tt>.BANK</tt><label id=".BANK"><p>
1353 The <tt/.BANK/ function is used to support systems with banked memory. The
1354 argument is an expression with exactly one segment reference - usually a
1355 label. The function result is the value of the <tt/bank/ attribute assigned
1356 to the run memory area of the segment. Please see the linker documentation
1357 for more information about memory areas and their attributes.
1359 The value of <tt/.BANK/ can be used to switch memory so that a memory bank
1360 containing specific data is available.
1362 The <tt/bank/ attribute is a 32 bit integer and so is the result of the
1363 <tt/.BANK/ function. You will have to use <tt><ref id=".LOBYTE"
1364 name=".LOBYTE"></tt> or similar functions to address just part of it.
1366 Please note that <tt/.BANK/ will always get evaluated in the link stage, so
1367 an expression containing <tt/.BANK/ can never be used where a constant known
1368 result is expected (for example with <tt/.RES/).
1385 .byte <.BANK (banked_func_1)
1388 .byte <.BANK (banked_func_2)
1394 <sect1><tt>.BANKBYTE</tt><label id=".BANKBYTE"><p>
1396 The function returns the bank byte (that is, bits 16-23) of its argument.
1397 It works identical to the '^' operator.
1399 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1400 <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>
1403 <sect1><tt>.BLANK</tt><label id=".BLANK"><p>
1405 Builtin function. The function evaluates its argument in braces and yields
1406 "false" if the argument is non blank (there is an argument), and "true" if
1407 there is no argument. The token list that makes up the function argument
1408 may optionally be enclosed in curly braces. This allows the inclusion of
1409 tokens that would otherwise terminate the list (the closing right
1410 parenthesis). The curly braces are not considered part of the list, a list
1411 just consisting of curly braces is considered to be empty.
1413 As an example, the <tt/.IFBLANK/ statement may be replaced by
1421 <sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
1423 Builtin string function. The function allows to concatenate a list of string
1424 constants separated by commas. The result is a string constant that is the
1425 concatenation of all arguments. This function is most useful in macros and
1426 when used together with the <tt/.STRING/ builtin function. The function may
1427 be used in any case where a string constant is expected.
1432 .include .concat ("myheader", ".", "inc")
1435 This is the same as the command
1438 .include "myheader.inc"
1442 <sect1><tt>.CONST</tt><label id=".CONST"><p>
1444 Builtin function. The function evaluates its argument in braces and
1445 yields "true" if the argument is a constant expression (that is, an
1446 expression that yields a constant value at assembly time) and "false"
1447 otherwise. As an example, the .IFCONST statement may be replaced by
1454 <sect1><tt>.HIBYTE</tt><label id=".HIBYTE"><p>
1456 The function returns the high byte (that is, bits 8-15) of its argument.
1457 It works identical to the '>' operator.
1459 See: <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>,
1460 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1463 <sect1><tt>.HIWORD</tt><label id=".HIWORD"><p>
1465 The function returns the high word (that is, bits 16-31) of its argument.
1467 See: <tt><ref id=".LOWORD" name=".LOWORD"></tt>
1470 <sect1><tt>.IDENT</tt><label id=".IDENT"><p>
1472 The function expects a string as its argument, and converts this argument
1473 into an identifier. If the string starts with the current <tt/<ref
1474 id=".LOCALCHAR" name=".LOCALCHAR">/, it will be converted into a cheap local
1475 identifier, otherwise it will be converted into a normal identifier.
1480 .macro makelabel arg1, arg2
1481 .ident (.concat (arg1, arg2)):
1484 makelabel "foo", "bar"
1486 .word foobar ; Valid label
1490 <sect1><tt>.LEFT</tt><label id=".LEFT"><p>
1492 Builtin function. Extracts the left part of a given token list.
1497 .LEFT (<int expr>, <token list>)
1500 The first integer expression gives the number of tokens to extract from
1501 the token list. The second argument is the token list itself. The token
1502 list may optionally be enclosed into curly braces. This allows the
1503 inclusion of tokens that would otherwise terminate the list (the closing
1504 right paren in the given case).
1508 To check in a macro if the given argument has a '#' as first token
1509 (immediate addressing mode), use something like this:
1514 .if (.match (.left (1, {arg}), #))
1516 ; ldax called with immediate operand
1524 See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
1525 name=".RIGHT"></tt> builtin functions.
1528 <sect1><tt>.LOBYTE</tt><label id=".LOBYTE"><p>
1530 The function returns the low byte (that is, bits 0-7) of its argument.
1531 It works identical to the '<' operator.
1533 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1534 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1537 <sect1><tt>.LOWORD</tt><label id=".LOWORD"><p>
1539 The function returns the low word (that is, bits 0-15) of its argument.
1541 See: <tt><ref id=".HIWORD" name=".HIWORD"></tt>
1544 <sect1><tt>.MATCH</tt><label id=".MATCH"><p>
1546 Builtin function. Matches two token lists against each other. This is
1547 most useful within macros, since macros are not stored as strings, but
1553 .MATCH(<token list #1>, <token list #2>)
1556 Both token list may contain arbitrary tokens with the exception of the
1557 terminator token (comma resp. right parenthesis) and
1564 The token lists may optionally be enclosed into curly braces. This allows
1565 the inclusion of tokens that would otherwise terminate the list (the closing
1566 right paren in the given case). Often a macro parameter is used for any of
1569 Please note that the function does only compare tokens, not token
1570 attributes. So any number is equal to any other number, regardless of the
1571 actual value. The same is true for strings. If you need to compare tokens
1572 <em/and/ token attributes, use the <tt><ref id=".XMATCH"
1573 name=".XMATCH"></tt> function.
1577 Assume the macro <tt/ASR/, that will shift right the accumulator by one,
1578 while honoring the sign bit. The builtin processor instructions will allow
1579 an optional "A" for accu addressing for instructions like <tt/ROL/ and
1580 <tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
1581 to check for this and print and error for invalid calls.
1586 .if (.not .blank(arg)) .and (.not .match ({arg}, a))
1587 .error "Syntax error"
1590 cmp #$80 ; Bit 7 into carry
1591 lsr a ; Shift carry into bit 7
1596 The macro will only accept no arguments, or one argument that must be the
1597 reserved keyword "A".
1599 See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
1602 <sect1><tt>.MAX</tt><label id=".MAX"><p>
1604 Builtin function. The result is the larger of two values.
1609 .MAX (<value #1>, <value #2>)
1615 ; Reserve space for the larger of two data blocks
1616 savearea: .max (.sizeof (foo), .sizeof (bar))
1619 See: <tt><ref id=".MIN" name=".MIN"></tt>
1622 <sect1><tt>.MID</tt><label id=".MID"><p>
1624 Builtin function. Takes a starting index, a count and a token list as
1625 arguments. Will return part of the token list.
1630 .MID (<int expr>, <int expr>, <token list>)
1633 The first integer expression gives the starting token in the list (the first
1634 token has index 0). The second integer expression gives the number of tokens
1635 to extract from the token list. The third argument is the token list itself.
1636 The token list may optionally be enclosed into curly braces. This allows the
1637 inclusion of tokens that would otherwise terminate the list (the closing
1638 right paren in the given case).
1642 To check in a macro if the given argument has a '<tt/#/' as first token
1643 (immediate addressing mode), use something like this:
1648 .if (.match (.mid (0, 1, {arg}), #))
1650 ; ldax called with immediate operand
1658 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
1659 name=".RIGHT"></tt> builtin functions.
1662 <sect1><tt>.MIN</tt><label id=".MIN"><p>
1664 Builtin function. The result is the smaller of two values.
1669 .MIN (<value #1>, <value #2>)
1675 ; Reserve space for some data, but 256 bytes minimum
1676 savearea: .min (.sizeof (foo), 256)
1679 See: <tt><ref id=".MAX" name=".MAX"></tt>
1682 <sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
1684 Builtin function. The function expects an identifier as argument in braces.
1685 The argument is evaluated, and the function yields "true" if the identifier
1686 is a symbol that has already been referenced somewhere in the source file up
1687 to the current position. Otherwise the function yields false. As an example,
1688 the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
1694 See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1697 <sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
1699 Builtin function. Extracts the right part of a given token list.
1704 .RIGHT (<int expr>, <token list>)
1707 The first integer expression gives the number of tokens to extract from the
1708 token list. The second argument is the token list itself. The token list
1709 may optionally be enclosed into curly braces. This allows the inclusion of
1710 tokens that would otherwise terminate the list (the closing right paren in
1713 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
1714 name=".MID"></tt> builtin functions.
1717 <sect1><tt>.SIZEOF</tt><label id=".SIZEOF"><p>
1719 <tt/.SIZEOF/ is a pseudo function that returns the size of its argument. The
1720 argument can be a struct/union, a struct member, a procedure, or a label. In
1721 case of a procedure or label, its size is defined by the amount of data
1722 placed in the segment where the label is relative to. If a line of code
1723 switches segments (for example in a macro) data placed in other segments
1724 does not count for the size.
1726 Please note that a symbol or scope must exist, before it is used together with
1727 <tt/.SIZEOF/ (this may get relaxed later, but will always be true for scopes).
1728 A scope has preference over a symbol with the same name, so if the last part
1729 of a name represents both, a scope and a symbol, the scope is chosen over the
1732 After the following code:
1735 .struct Point ; Struct size = 4
1740 P: .tag Point ; Declare a point
1741 @P: .tag Point ; Declare another point
1753 .data ; Segment switch!!!
1759 <tag><tt/.sizeof(Point)/</tag>
1760 will have the value 4, because this is the size of struct <tt/Point/.
1762 <tag><tt/.sizeof(Point::xcoord)/</tag>
1763 will have the value 2, because this is the size of the member <tt/xcoord/
1764 in struct <tt/Point/.
1766 <tag><tt/.sizeof(P)/</tag>
1767 will have the value 4, this is the size of the data declared on the same
1768 source line as the label <tt/P/, which is in the same segment that <tt/P/
1771 <tag><tt/.sizeof(@P)/</tag>
1772 will have the value 4, see above. The example demonstrates that <tt/.SIZEOF/
1773 does also work for cheap local symbols.
1775 <tag><tt/.sizeof(Code)/</tag>
1776 will have the value 3, since this is amount of data emitted into the code
1777 segment, the segment that was active when <tt/Code/ was entered. Note that
1778 this value includes the amount of data emitted in child scopes (in this
1779 case <tt/Code::Inner/).
1781 <tag><tt/.sizeof(Code::Inner)/</tag>
1782 will have the value 1 as expected.
1784 <tag><tt/.sizeof(Data)/</tag>
1785 will have the value 0. Data is emitted within the scope <tt/Data/, but since
1786 the segment is switched after entry, this data is emitted into another
1791 <sect1><tt>.STRAT</tt><label id=".STRAT"><p>
1793 Builtin function. The function accepts a string and an index as
1794 arguments and returns the value of the character at the given position
1795 as an integer value. The index is zero based.
1801 ; Check if the argument string starts with '#'
1802 .if (.strat (Arg, 0) = '#')
1809 <sect1><tt>.SPRINTF</tt><label id=".SPRINTF"><p>
1811 Builtin function. It expects a format string as first argument. The number
1812 and type of the following arguments depend on the format string. The format
1813 string is similar to the one of the C <tt/printf/ function. Missing things
1814 are: Length modifiers, variable width.
1816 The result of the function is a string.
1823 ; Generate an identifier:
1824 .ident (.sprintf ("%s%03d", "label", num)):
1828 <sect1><tt>.STRING</tt><label id=".STRING"><p>
1830 Builtin function. The function accepts an argument in braces and converts
1831 this argument into a string constant. The argument may be an identifier, or
1832 a constant numeric value.
1834 Since you can use a string in the first place, the use of the function may
1835 not be obvious. However, it is useful in macros, or more complex setups.
1840 ; Emulate other assemblers:
1842 .segment .string(name)
1847 <sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
1849 Builtin function. The function accepts a string argument in braces and
1850 evaluates to the length of the string.
1854 The following macro encodes a string as a pascal style string with
1855 a leading length byte.
1859 .byte .strlen(Arg), Arg
1864 <sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
1866 Builtin function. The function accepts a token list in braces. The function
1867 result is the number of tokens given as argument. The token list may
1868 optionally be enclosed into curly braces which are not considered part of
1869 the list and not counted. Enclosement in curly braces allows the inclusion
1870 of tokens that would otherwise terminate the list (the closing right paren
1875 The <tt/ldax/ macro accepts the '#' token to denote immediate addressing (as
1876 with the normal 6502 instructions). To translate it into two separate 8 bit
1877 load instructions, the '#' token has to get stripped from the argument:
1881 .if (.match (.mid (0, 1, {arg}), #))
1882 ; ldax called with immediate operand
1883 lda #<(.right (.tcount ({arg})-1, {arg}))
1884 ldx #>(.right (.tcount ({arg})-1, {arg}))
1892 <sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
1894 Builtin function. Matches two token lists against each other. This is
1895 most useful within macros, since macros are not stored as strings, but
1901 .XMATCH(<token list #1>, <token list #2>)
1904 Both token list may contain arbitrary tokens with the exception of the
1905 terminator token (comma resp. right parenthesis) and
1912 The token lists may optionally be enclosed into curly braces. This allows
1913 the inclusion of tokens that would otherwise terminate the list (the closing
1914 right paren in the given case). Often a macro parameter is used for any of
1917 The function compares tokens <em/and/ token values. If you need a function
1918 that just compares the type of tokens, have a look at the <tt><ref
1919 id=".MATCH" name=".MATCH"></tt> function.
1921 See: <tt><ref id=".MATCH" name=".MATCH"></tt>
1925 <sect>Control commands<label id="control-commands"><p>
1927 Here's a list of all control commands and a description, what they do:
1930 <sect1><tt>.A16</tt><label id=".A16"><p>
1932 Valid only in 65816 mode. Switch the accumulator to 16 bit.
1934 Note: This command will not emit any code, it will tell the assembler to
1935 create 16 bit operands for immediate accumulator addressing mode.
1937 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1940 <sect1><tt>.A8</tt><label id=".A8"><p>
1942 Valid only in 65816 mode. Switch the accumulator to 8 bit.
1944 Note: This command will not emit any code, it will tell the assembler to
1945 create 8 bit operands for immediate accu addressing mode.
1947 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1950 <sect1><tt>.ADDR</tt><label id=".ADDR"><p>
1952 Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
1953 may be used for better readability if the data words are address values. In
1954 65816 mode, the address is forced to be 16 bit wide to fit into the current
1955 segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
1956 must be followed by a sequence of (not necessarily constant) expressions.
1961 .addr $0D00, $AF13, _Clear
1964 See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
1968 <sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
1970 Align data to a given boundary. The command expects a constant integer
1971 argument in the range 1 ... 65536, plus an optional second argument
1972 in byte range. If there is a second argument, it is used as fill value,
1973 otherwise the value defined in the linker configuration file is used
1974 (the default for this value is zero).
1976 <tt/.ALIGN/ will insert fill bytes, and the number of fill bytes depend of
1977 the final address of the segment. <tt/.ALIGN/ cannot insert a variable
1978 number of bytes, since that would break address calculations within the
1979 module. So each <tt/.ALIGN/ expects the segment to be aligned to a multiple
1980 of the alignment, because that allows the number of fill bytes to be
1981 calculated in advance by the assembler. You are therefore required to
1982 specify a matching alignment for the segment in the linker config. The
1983 linker will output a warning if the alignment of the segment is less than
1984 what is necessary to have a correct alignment in the object file.
1992 Some unexpected behaviour might occur if there are multiple <tt/.ALIGN/
1993 commands with different arguments. To allow the assembler to calculate the
1994 number of fill bytes in advance, the alignment of the segment must be a
1995 multiple of each of the alignment factors. This may result in unexpectedly
1996 large alignments for the segment within the module.
2007 For the assembler to be able to align correctly, the segment must be aligned
2008 to the least common multiple of 15 and 18 which is 90. The assembler will
2009 calculate this automatically and will mark the segment with this value.
2011 Unfortunately, the combined alignment may get rather large without the user
2012 knowing about it, wasting space in the final executable. If we add another
2013 alignment to the example above
2024 the assembler will force a segment alignment to the least common multiple of
2025 15, 18 and 251 - which is 22590. To protect the user against errors, the
2026 assembler will issue a warning when the combined alignment exceeds 256. The
2027 command line option <tt><ref id="option--large-alignment"
2028 name="--large-alignment"></tt> will disable this warning.
2030 Please note that with alignments that are a power of two (which were the
2031 only alignments possible in older versions of the assembler), the problem is
2032 less severe, because the least common multiple of powers to the same base is
2033 always the larger one.
2037 <sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
2039 Define a string with a trailing zero.
2044 Msg: .asciiz "Hello world"
2047 This will put the string "Hello world" followed by a binary zero into
2048 the current segment. There may be more strings separated by commas, but
2049 the binary zero is only appended once (after the last one).
2052 <sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
2054 Add an assertion. The command is followed by an expression, an action
2055 specifier, and an optional message that is output in case the assertion
2056 fails. If no message was given, the string "Assertion failed" is used. The
2057 action specifier may be one of <tt/warning/, <tt/error/, <tt/ldwarning/ or
2058 <tt/lderror/. In the former two cases, the assertion is evaluated by the
2059 assembler if possible, and in any case, it's also passed to the linker in
2060 the object file (if one is generated). The linker will then evaluate the
2061 expression when segment placement has been done.
2066 .assert * = $8000, error, "Code not at $8000"
2069 The example assertion will check that the current location is at $8000,
2070 when the output file is written, and abort with an error if this is not
2071 the case. More complex expressions are possible. The action specifier
2072 <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
2073 an error message. In the latter case, generation of the output file is
2074 suppressed in both the assembler and linker.
2077 <sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
2079 Is followed by a plus or a minus character. When switched on (using a
2080 +), undefined symbols are automatically marked as import instead of
2081 giving errors. When switched off (which is the default so this does not
2082 make much sense), this does not happen and an error message is
2083 displayed. The state of the autoimport flag is evaluated when the
2084 complete source was translated, before outputting actual code, so it is
2085 <em/not/ possible to switch this feature on or off for separate sections
2086 of code. The last setting is used for all symbols.
2088 You should probably not use this switch because it delays error
2089 messages about undefined symbols until the link stage. The cc65
2090 compiler (which is supposed to produce correct assembler code in all
2091 circumstances, something which is not true for most assembler
2092 programmers) will insert this command to avoid importing each and every
2093 routine from the runtime library.
2098 .autoimport + ; Switch on auto import
2101 <sect1><tt>.BANKBYTES</tt><label id=".BANKBYTES"><p>
2103 Define byte sized data by extracting only the bank byte (that is, bits 16-23) from
2104 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2105 the operator '^' prepended to each expression in its list.
2110 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2112 TableLookupLo: .lobytes MyTable
2113 TableLookupHi: .hibytes MyTable
2114 TableLookupBank: .bankbytes MyTable
2117 which is equivalent to
2120 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2121 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2122 TableLookupBank: .byte ^TableItem0, ^TableItem1, ^TableItem2, ^TableItem3
2125 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2126 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
2127 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>
2130 <sect1><tt>.BSS</tt><label id=".BSS"><p>
2132 Switch to the BSS segment. The name of the BSS segment is always "BSS",
2133 so this is a shortcut for
2139 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2142 <sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
2144 Define byte sized data. Must be followed by a sequence of (byte ranged)
2145 expressions or strings.
2151 .byt "world", $0D, $00
2155 <sect1><tt>.CASE</tt><label id=".CASE"><p>
2157 Switch on or off case sensitivity on identifiers. The default is off
2158 (that is, identifiers are case sensitive), but may be changed by the
2159 -i switch on the command line.
2160 The command must be followed by a '+' or '-' character to switch the
2161 option on or off respectively.
2166 .case - ; Identifiers are not case sensitive
2170 <sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
2172 Apply a custom mapping for characters. The command is followed by two
2173 numbers. The first one is the index of the source character (range 1..255),
2174 the second one is the mapping (range 0..255). The mapping applies to all
2175 character and string constants when they generate output, and overrides a
2176 mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
2177 command line switch.
2182 .charmap $41, $61 ; Map 'A' to 'a'
2186 <sect1><tt>.CODE</tt><label id=".CODE"><p>
2188 Switch to the CODE segment. The name of the CODE segment is always
2189 "CODE", so this is a shortcut for
2195 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2198 <sect1><tt>.CONDES</tt><label id=".CONDES"><p>
2200 Export a symbol and mark it in a special way. The linker is able to build
2201 tables of all such symbols. This may be used to automatically create a list
2202 of functions needed to initialize linked library modules.
2204 Note: The linker has a feature to build a table of marked routines, but it
2205 is your code that must call these routines, so just declaring a symbol with
2206 <tt/.CONDES/ does nothing by itself.
2208 All symbols are exported as an absolute (16 bit) symbol. You don't need to
2209 use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
2210 is implied by <tt/.CONDES/.
2212 <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
2213 <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
2214 specifying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
2215 The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2216 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2217 name=".INTERRUPTOR"></tt> commands are actually shortcuts for <tt/.CONDES/
2218 with a type of <tt/constructor/ resp. <tt/destructor/ or <tt/interruptor/.
2220 After the type, an optional priority may be specified. Higher numeric values
2221 mean higher priority. If no priority is given, the default priority of 7 is
2222 used. Be careful when assigning priorities to your own module constructors
2223 so they won't interfere with the ones in the cc65 library.
2228 .condes ModuleInit, constructor
2229 .condes ModInit, 0, 16
2232 See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2233 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2234 name=".INTERRUPTOR"></tt> commands and the separate section <ref id="condes"
2235 name="Module constructors/destructors"> explaining the feature in more
2239 <sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
2241 Export a symbol and mark it as a module constructor. This may be used
2242 together with the linker to build a table of constructor subroutines that
2243 are called by the startup code.
2245 Note: The linker has a feature to build a table of marked routines, but it
2246 is your code that must call these routines, so just declaring a symbol as
2247 constructor does nothing by itself.
2249 A constructor is always exported as an absolute (16 bit) symbol. You don't
2250 need to use an additional <tt/.export/ statement, this is implied by
2251 <tt/.constructor/. It may have an optional priority that is separated by a
2252 comma. Higher numeric values mean a higher priority. If no priority is
2253 given, the default priority of 7 is used. Be careful when assigning
2254 priorities to your own module constructors so they won't interfere with the
2255 ones in the cc65 library.
2260 .constructor ModuleInit
2261 .constructor ModInit, 16
2264 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2265 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
2266 <ref id="condes" name="Module constructors/destructors"> explaining the
2267 feature in more detail.
2270 <sect1><tt>.DATA</tt><label id=".DATA"><p>
2272 Switch to the DATA segment. The name of the DATA segment is always
2273 "DATA", so this is a shortcut for
2279 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2282 <sect1><tt>.DBYT</tt><label id=".DBYT"><p>
2284 Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
2285 create word sized data in native 65XX format). Must be followed by a
2286 sequence of (word ranged) expressions.
2294 This will emit the bytes
2300 into the current segment in that order.
2303 <sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
2305 Switch on or off debug info generation. The default is off (that is,
2306 the object file will not contain debug infos), but may be changed by the
2307 -g switch on the command line.
2308 The command must be followed by a '+' or '-' character to switch the
2309 option on or off respectively.
2314 .debuginfo + ; Generate debug info
2318 <sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
2320 Start a define style macro definition. The command is followed by an
2321 identifier (the macro name) and optionally by a list of formal arguments
2324 Please note that <tt/.DEFINE/ shares most disadvantages with its C
2325 counterpart, so the general advice is, <bf/NOT/ do use <tt/.DEFINE/ if you
2328 See also the <tt><ref id=".UNDEFINE" name=".UNDEFINE"></tt> command and
2329 section <ref id="macros" name="Macros">.
2332 <sect1><tt>.DELMAC, .DELMACRO</tt><label id=".DELMACRO"><p>
2334 Delete a classic macro (defined with <tt><ref id=".MACRO"
2335 name=".MACRO"></tt>) . The command is followed by the name of an
2336 existing macro. Its definition will be deleted together with the name.
2337 If necessary, another macro with this name may be defined later.
2339 See: <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2340 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2341 <tt><ref id=".MACRO" name=".MACRO"></tt>
2343 See also section <ref id="macros" name="Macros">.
2346 <sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
2348 Builtin function. The function expects an identifier as argument in braces.
2349 The argument is evaluated, and the function yields "true" if the identifier
2350 is a symbol that is already defined somewhere in the source file up to the
2351 current position. Otherwise the function yields false. As an example, the
2352 <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
2359 <sect1><tt>.DEFINEDMACRO</tt><label id=".DEFINEDMACRO"><p>
2361 Builtin function. The function expects an identifier as argument in braces.
2362 The argument is evaluated, and the function yields "true" if the identifier
2363 has already been defined as the name of a macro. Otherwise the function yields
2372 .if .definedmacro(add)
2381 <sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
2383 Export a symbol and mark it as a module destructor. This may be used
2384 together with the linker to build a table of destructor subroutines that
2385 are called by the startup code.
2387 Note: The linker has a feature to build a table of marked routines, but it
2388 is your code that must call these routines, so just declaring a symbol as
2389 constructor does nothing by itself.
2391 A destructor is always exported as an absolute (16 bit) symbol. You don't
2392 need to use an additional <tt/.export/ statement, this is implied by
2393 <tt/.destructor/. It may have an optional priority that is separated by a
2394 comma. Higher numerical values mean a higher priority. If no priority is
2395 given, the default priority of 7 is used. Be careful when assigning
2396 priorities to your own module destructors so they won't interfere with the
2397 ones in the cc65 library.
2402 .destructor ModuleDone
2403 .destructor ModDone, 16
2406 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2407 id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
2408 section <ref id="condes" name="Module constructors/destructors"> explaining
2409 the feature in more detail.
2412 <sect1><tt>.DWORD</tt><label id=".DWORD"><p>
2414 Define dword sized data (4 bytes) Must be followed by a sequence of
2420 .dword $12344512, $12FA489
2424 <sect1><tt>.ELSE</tt><label id=".ELSE"><p>
2426 Conditional assembly: Reverse the current condition.
2429 <sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
2431 Conditional assembly: Reverse current condition and test a new one.
2434 <sect1><tt>.END</tt><label id=".END"><p>
2436 Forced end of assembly. Assembly stops at this point, even if the command
2437 is read from an include file.
2440 <sect1><tt>.ENDENUM</tt><label id=".ENDENUM"><p>
2442 End a <tt><ref id=".ENUM" name=".ENUM"></tt> declaration.
2445 <sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
2447 Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
2448 <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
2451 <sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
2453 Marks the end of a macro definition.
2455 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2456 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2457 <tt><ref id=".MACRO" name=".MACRO"></tt>
2459 See also section <ref id="macros" name="Macros">.
2462 <sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
2464 End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
2467 <sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
2469 End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
2472 <sect1><tt>.ENDSCOPE</tt><label id=".ENDSCOPE"><p>
2474 End of local lexical level (see <tt/<ref id=".SCOPE" name=".SCOPE">/).
2477 <sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
2479 Ends a struct definition. See the <tt/<ref id=".STRUCT" name=".STRUCT">/
2480 command and the separate section named <ref id="structs" name=""Structs
2484 <sect1><tt>.ENDUNION</tt><label id=".ENDUNION"><p>
2486 Ends a union definition. See the <tt/<ref id=".UNION" name=".UNION">/
2487 command and the separate section named <ref id="structs" name=""Structs
2491 <sect1><tt>.ENUM</tt><label id=".ENUM"><p>
2493 Start an enumeration. This directive is very similar to the C <tt/enum/
2494 keyword. If a name is given, a new scope is created for the enumeration,
2495 otherwise the enumeration members are placed in the enclosing scope.
2497 In the enumeration body, symbols are declared. The first symbol has a value
2498 of zero, and each following symbol will get the value of the preceding plus
2499 one. This behaviour may be overridden by an explicit assignment. Two symbols
2500 may have the same value.
2512 Above example will create a new scope named <tt/errorcodes/ with three
2513 symbols in it that get the values 0, 1 and 2 respectively. Another way
2514 to write this would have been:
2524 Please note that explicit scoping must be used to access the identifiers:
2527 .word errorcodes::no_error
2530 A more complex example:
2539 EWOULDBLOCK = EAGAIN
2543 In this example, the enumeration does not have a name, which means that the
2544 members will be visible in the enclosing scope and can be used in this scope
2545 without explicit scoping. The first member (<tt/EUNKNOWN/) has the value -1.
2546 The value for the following members is incremented by one, so <tt/EOK/ would
2547 be zero and so on. <tt/EWOULDBLOCK/ is an alias for <tt/EGAIN/, so it has an
2548 override for the value using an already defined symbol.
2551 <sect1><tt>.ERROR</tt><label id=".ERROR"><p>
2553 Force an assembly error. The assembler will output an error message
2554 preceded by "User error". Assembly is continued but no object file will
2557 This command may be used to check for initial conditions that must be
2558 set before assembling a source file.
2568 .error "Must define foo or bar!"
2572 See also: <tt><ref id=".FATAL" name=".FATAL"></tt>,
2573 <tt><ref id=".OUT" name=".OUT"></tt>,
2574 <tt><ref id=".WARNING" name=".WARNING"></tt>
2577 <sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
2579 Abort a macro expansion immediately. This command is often useful in
2582 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2583 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2584 <tt><ref id=".MACRO" name=".MACRO"></tt>
2586 See also section <ref id="macros" name="Macros">.
2589 <sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
2591 Make symbols accessible from other modules. Must be followed by a comma
2592 separated list of symbols to export, with each one optionally followed by an
2593 address specification and (also optional) an assignment. Using an additional
2594 assignment in the export statement allows to define and export a symbol in
2595 one statement. The default is to export the symbol with the address size it
2596 actually has. The assembler will issue a warning, if the symbol is exported
2597 with an address size smaller than the actual address size.
2604 .export foobar: far = foo * bar
2605 .export baz := foobar, zap: far = baz - bar
2608 As with constant definitions, using <tt/:=/ instead of <tt/=/ marks the
2611 See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
2614 <sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
2616 Make symbols accessible from other modules. Must be followed by a comma
2617 separated list of symbols to export. The exported symbols are explicitly
2618 marked as zero page symbols. An assignment may be included in the
2619 <tt/.EXPORTZP/ statement. This allows to define and export a symbol in one
2626 .exportzp baz := $02
2629 See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
2632 <sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
2634 Define far (24 bit) address data. The command must be followed by a
2635 sequence of (not necessarily constant) expressions.
2640 .faraddr DrawCircle, DrawRectangle, DrawHexagon
2643 See: <tt><ref id=".ADDR" name=".ADDR"></tt>
2646 <sect1><tt>.FATAL</tt><label id=".FATAL"><p>
2648 Force an assembly error and terminate assembly. The assembler will output an
2649 error message preceded by "User error" and will terminate assembly
2652 This command may be used to check for initial conditions that must be
2653 set before assembling a source file.
2663 .fatal "Must define foo or bar!"
2667 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
2668 <tt><ref id=".OUT" name=".OUT"></tt>,
2669 <tt><ref id=".WARNING" name=".WARNING"></tt>
2672 <sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
2674 This directive may be used to enable one or more compatibility features
2675 of the assembler. While the use of <tt/.FEATURE/ should be avoided when
2676 possible, it may be useful when porting sources written for other
2677 assemblers. There is no way to switch a feature off, once you have
2678 enabled it, so using
2684 will enable the feature until end of assembly is reached.
2686 The following features are available:
2690 <tag><tt>addrsize</tt><label id="addrsize"></tag>
2692 Enables the .ADDRSIZE pseudo function. This function is experimental and not enabled by default.
2694 See also: <tt><ref id=".ADDRSIZE" name=".ADDRSIZE"></tt>
2696 <tag><tt>at_in_identifiers</tt><label id="at_in_identifiers"></tag>
2698 Accept the at character (`@') as a valid character in identifiers. The
2699 at character is not allowed to start an identifier, even with this
2702 <tag><tt>c_comments</tt><label id="c_comments"></tag>
2704 Allow C like comments using <tt>/*</tt> and <tt>*/</tt> as left and right
2705 comment terminators. Note that C comments may not be nested. There's also a
2706 pitfall when using C like comments: All statements must be terminated by
2707 "end-of-line". Using C like comments, it is possible to hide the newline,
2708 which results in error messages. See the following non working example:
2711 lda #$00 /* This comment hides the newline
2715 <tag><tt>dollar_in_identifiers</tt><label id="dollar_in_identifiers"></tag>
2717 Accept the dollar sign (`$') as a valid character in identifiers. The
2718 dollar character is not allowed to start an identifier, even with this
2721 <tag><tt>dollar_is_pc</tt><label id="dollar_is_pc"></tag>
2723 The dollar sign may be used as an alias for the star (`*'), which
2724 gives the value of the current PC in expressions.
2725 Note: Assignment to the pseudo variable is not allowed.
2727 <tag><tt>force_range</tt><label id="force_range"></tag>
2729 Force expressions into their valid range for immediate addressing and
2730 storage operators like <tt><ref id=".BYTE" name=".BYTE"></tt> and
2731 <tt><ref id=".WORD" name=".WORD"></tt>. Be very careful with this one,
2732 since it will completely disable error checks.
2734 <tag><tt>labels_without_colons</tt><label id="labels_without_colons"></tag>
2736 Allow labels without a trailing colon. These labels are only accepted,
2737 if they start at the beginning of a line (no leading white space).
2739 <tag><tt>leading_dot_in_identifiers</tt><label id="leading_dot_in_identifiers"></tag>
2741 Accept the dot (`.') as the first character of an identifier. This may be
2742 used for example to create macro names that start with a dot emulating
2743 control directives of other assemblers. Note however, that none of the
2744 reserved keywords built into the assembler, that starts with a dot, may be
2745 overridden. When using this feature, you may also get into trouble if
2746 later versions of the assembler define new keywords starting with a dot.
2748 <tag><tt>loose_char_term</tt><label id="loose_char_term"></tag>
2750 Accept single quotes as well as double quotes as terminators for char
2753 <tag><tt>loose_string_term</tt><label id="loose_string_term"></tag>
2755 Accept single quotes as well as double quotes as terminators for string
2758 <tag><tt>missing_char_term</tt><label id="missing_char_term"></tag>
2760 Accept single quoted character constants where the terminating quote is
2765 <em/Note:/ This does not work in conjunction with <tt/.FEATURE
2766 loose_string_term/, since in this case the input would be ambiguous.
2768 <tag><tt>org_per_seg</tt><label id="org_per_seg"></tag>
2770 This feature makes relocatable/absolute mode local to the current segment.
2771 Using <tt><ref id=".ORG" name=".ORG"></tt> when <tt/org_per_seg/ is in
2772 effect will only enable absolute mode for the current segment. Dito for
2773 <tt><ref id=".RELOC" name=".RELOC"></tt>.
2775 <tag><tt>pc_assignment</tt><label id="pc_assignment"></tag>
2777 Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
2778 is enabled). Such an assignment is handled identical to the <tt><ref
2779 id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
2780 removing the lines with the assignments may also be an option when porting
2781 code written for older assemblers).
2783 <tag><tt>ubiquitous_idents</tt><label id="ubiquitous_idents"></tag>
2785 Allow the use of instructions names as names for macros and symbols. This
2786 makes it possible to "overload" instructions by defining a macro with the
2787 same name. This does also make it possible to introduce hard to find errors
2788 in your code, so be careful!
2790 <tag><tt>underline_in_numbers</tt><label id="underline_in_numbers"></tag>
2792 Allow underlines within numeric constants. These may be used for grouping
2793 the digits of numbers for easier reading.
2796 .feature underline_in_numbers
2797 .word %1100001110100101
2798 .word %1100_0011_1010_0101 ; Identical but easier to read
2803 It is also possible to specify features on the command line using the
2804 <tt><ref id="option--feature" name="--feature"></tt> command line option.
2805 This is useful when translating sources written for older assemblers, when
2806 you don't want to change the source code.
2808 As an example, to translate sources written for Andre Fachats xa65
2809 assembler, the features
2812 labels_without_colons, pc_assignment, loose_char_term
2815 may be helpful. They do not make ca65 completely compatible, so you may not
2816 be able to translate the sources without changes, even when enabling these
2817 features. However, I have found several sources that translate without
2818 problems when enabling these features on the command line.
2821 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
2823 Insert an option string into the object file. There are two forms of
2824 this command, one specifies the option by a keyword, the second
2825 specifies it as a number. Since usage of the second one needs knowledge
2826 of the internal encoding, its use is not recommended and I will only
2827 describe the first form here.
2829 The command is followed by one of the keywords
2837 a comma and a string. The option is written into the object file
2838 together with the string value. This is currently unidirectional and
2839 there is no way to actually use these options once they are in the
2845 .fileopt comment, "Code stolen from my brother"
2846 .fileopt compiler, "BASIC 2.0"
2847 .fopt author, "J. R. User"
2851 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
2853 Import an absolute symbol from another module. The command is followed by a
2854 comma separated list of symbols to import. The command is similar to <tt>
2855 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
2856 written to the generated object file, even if the symbol is never referenced
2857 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
2858 references for unused symbols).
2863 .forceimport needthisone, needthistoo
2866 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2869 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
2871 Declare symbols as global. Must be followed by a comma separated list of
2872 symbols to declare. Symbols from the list, that are defined somewhere in the
2873 source, are exported, all others are imported. Additional <tt><ref
2874 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
2875 name=".EXPORT"></tt> commands for the same symbol are allowed.
2884 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
2886 Declare symbols as global. Must be followed by a comma separated list of
2887 symbols to declare. Symbols from the list, that are defined somewhere in the
2888 source, are exported, all others are imported. Additional <tt><ref
2889 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
2890 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
2891 in the list are explicitly marked as zero page symbols.
2899 <sect1><tt>.HIBYTES</tt><label id=".HIBYTES"><p>
2901 Define byte sized data by extracting only the high byte (that is, bits 8-15) from
2902 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2903 the operator '>' prepended to each expression in its list.
2908 .lobytes $1234, $2345, $3456, $4567
2909 .hibytes $fedc, $edcb, $dcba, $cba9
2912 which is equivalent to
2915 .byte $34, $45, $56, $67
2916 .byte $fe, $ed, $dc, $cb
2922 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2924 TableLookupLo: .lobytes MyTable
2925 TableLookupHi: .hibytes MyTable
2928 which is equivalent to
2931 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2932 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2935 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2936 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>,
2937 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
2940 <sect1><tt>.I16</tt><label id=".I16"><p>
2942 Valid only in 65816 mode. Switch the index registers to 16 bit.
2944 Note: This command will not emit any code, it will tell the assembler to
2945 create 16 bit operands for immediate operands.
2947 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
2948 name=".SMART"></tt> commands.
2951 <sect1><tt>.I8</tt><label id=".I8"><p>
2953 Valid only in 65816 mode. Switch the index registers to 8 bit.
2955 Note: This command will not emit any code, it will tell the assembler to
2956 create 8 bit operands for immediate operands.
2958 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
2959 name=".SMART"></tt> commands.
2962 <sect1><tt>.IF</tt><label id=".IF"><p>
2964 Conditional assembly: Evaluate an expression and switch assembler output
2965 on or off depending on the expression. The expression must be a constant
2966 expression, that is, all operands must be defined.
2968 A expression value of zero evaluates to FALSE, any other value evaluates
2972 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
2974 Conditional assembly: Check if there are any remaining tokens in this line,
2975 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
2976 condition is not true, further lines are not assembled until an <tt><ref
2977 id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2978 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2980 This command is often used to check if a macro parameter was given. Since an
2981 empty macro parameter will evaluate to nothing, the condition will evaluate
2982 to TRUE if an empty parameter was given.
2996 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2999 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
3001 Conditional assembly: Evaluate an expression and switch assembler output
3002 on or off depending on the constness of the expression.
3004 A const expression evaluates to to TRUE, a non const expression (one
3005 containing an imported or currently undefined symbol) evaluates to
3008 See also: <tt><ref id=".CONST" name=".CONST"></tt>
3011 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
3013 Conditional assembly: Check if a symbol is defined. Must be followed by
3014 a symbol name. The condition is true if the the given symbol is already
3015 defined, and false otherwise.
3017 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
3020 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
3022 Conditional assembly: Check if there are any remaining tokens in this line,
3023 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
3024 condition is not true, further lines are not assembled until an <tt><ref
3025 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
3026 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
3028 This command is often used to check if a macro parameter was given.
3029 Since an empty macro parameter will evaluate to nothing, the condition
3030 will evaluate to FALSE if an empty parameter was given.
3043 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
3046 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
3048 Conditional assembly: Check if a symbol is defined. Must be followed by
3049 a symbol name. The condition is true if the the given symbol is not
3050 defined, and false otherwise.
3052 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
3055 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
3057 Conditional assembly: Check if a symbol is referenced. Must be followed
3058 by a symbol name. The condition is true if if the the given symbol was
3059 not referenced before, and false otherwise.
3061 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
3064 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
3066 Conditional assembly: Check if the assembler is currently in 6502 mode
3067 (see <tt><ref id=".P02" name=".P02"></tt> command).
3070 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
3072 Conditional assembly: Check if the assembler is currently in 65816 mode
3073 (see <tt><ref id=".P816" name=".P816"></tt> command).
3076 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
3078 Conditional assembly: Check if the assembler is currently in 65C02 mode
3079 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
3082 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
3084 Conditional assembly: Check if the assembler is currently in 65SC02 mode
3085 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
3088 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
3090 Conditional assembly: Check if a symbol is referenced. Must be followed
3091 by a symbol name. The condition is true if if the the given symbol was
3092 referenced before, and false otherwise.
3094 This command may be used to build subroutine libraries in include files
3095 (you may use separate object modules for this purpose too).
3100 .ifref ToHex ; If someone used this subroutine
3101 ToHex: tay ; Define subroutine
3107 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
3110 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
3112 Import a symbol from another module. The command is followed by a comma
3113 separated list of symbols to import, with each one optionally followed by
3114 an address specification.
3120 .import bar: zeropage
3123 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
3126 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
3128 Import a symbol from another module. The command is followed by a comma
3129 separated list of symbols to import. The symbols are explicitly imported
3130 as zero page symbols (that is, symbols with values in byte range).
3138 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
3141 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
3143 Include a file as binary data. The command expects a string argument
3144 that is the name of a file to include literally in the current segment.
3145 In addition to that, a start offset and a size value may be specified,
3146 separated by commas. If no size is specified, all of the file from the
3147 start offset to end-of-file is used. If no start position is specified
3148 either, zero is assumed (which means that the whole file is inserted).
3153 ; Include whole file
3154 .incbin "sprites.dat"
3156 ; Include file starting at offset 256
3157 .incbin "music.dat", $100
3159 ; Read 100 bytes starting at offset 200
3160 .incbin "graphics.dat", 200, 100
3164 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
3166 Include another file. Include files may be nested up to a depth of 16.
3175 <sect1><tt>.INTERRUPTOR</tt><label id=".INTERRUPTOR"><p>
3177 Export a symbol and mark it as an interruptor. This may be used together
3178 with the linker to build a table of interruptor subroutines that are called
3181 Note: The linker has a feature to build a table of marked routines, but it
3182 is your code that must call these routines, so just declaring a symbol as
3183 interruptor does nothing by itself.
3185 An interruptor is always exported as an absolute (16 bit) symbol. You don't
3186 need to use an additional <tt/.export/ statement, this is implied by
3187 <tt/.interruptor/. It may have an optional priority that is separated by a
3188 comma. Higher numeric values mean a higher priority. If no priority is
3189 given, the default priority of 7 is used. Be careful when assigning
3190 priorities to your own module constructors so they won't interfere with the
3191 ones in the cc65 library.
3196 .interruptor IrqHandler
3197 .interruptor Handler, 16
3200 See the <tt><ref id=".CONDES" name=".CONDES"></tt> command and the separate
3201 section <ref id="condes" name="Module constructors/destructors"> explaining
3202 the feature in more detail.
3205 <sect1><tt>.ISMNEM, .ISMNEMONIC</tt><label id=".ISMNEMONIC"><p>
3207 Builtin function. The function expects an identifier as argument in braces.
3208 The argument is evaluated, and the function yields "true" if the identifier
3209 is defined as an instruction mnemonic that is recognized by the assembler.
3213 .if .not .ismnemonic(ina)
3222 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
3224 Switch on or off line continuations using the backslash character
3225 before a newline. The option is off by default.
3226 Note: Line continuations do not work in a comment. A backslash at the
3227 end of a comment is treated as part of the comment and does not trigger
3229 The command must be followed by a '+' or '-' character to switch the
3230 option on or off respectively.
3235 .linecont + ; Allow line continuations
3238 #$20 ; This is legal now
3242 <sect1><tt>.LIST</tt><label id=".LIST"><p>
3244 Enable output to the listing. The command must be followed by a boolean
3245 switch ("on", "off", "+" or "-") and will enable or disable listing
3247 The option has no effect if the listing is not enabled by the command line
3248 switch -l. If -l is used, an internal counter is set to 1. Lines are output
3249 to the listing file, if the counter is greater than zero, and suppressed if
3250 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
3256 .list on ; Enable listing output
3260 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
3262 Set, how many bytes are shown in the listing for one source line. The
3263 default is 12, so the listing will show only the first 12 bytes for any
3264 source line that generates more than 12 bytes of code or data.
3265 The directive needs an argument, which is either "unlimited", or an
3266 integer constant in the range 4..255.
3271 .listbytes unlimited ; List all bytes
3272 .listbytes 12 ; List the first 12 bytes
3273 .incbin "data.bin" ; Include large binary file
3277 <sect1><tt>.LOBYTES</tt><label id=".LOBYTES"><p>
3279 Define byte sized data by extracting only the low byte (that is, bits 0-7) from
3280 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
3281 the operator '<' prepended to each expression in its list.
3286 .lobytes $1234, $2345, $3456, $4567
3287 .hibytes $fedc, $edcb, $dcba, $cba9
3290 which is equivalent to
3293 .byte $34, $45, $56, $67
3294 .byte $fe, $ed, $dc, $cb
3300 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
3302 TableLookupLo: .lobytes MyTable
3303 TableLookupHi: .hibytes MyTable
3306 which is equivalent to
3309 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
3310 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
3313 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
3314 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
3315 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
3318 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
3320 This command may only be used inside a macro definition. It declares a
3321 list of identifiers as local to the macro expansion.
3323 A problem when using macros are labels: Since they don't change their name,
3324 you get a "duplicate symbol" error if the macro is expanded the second time.
3325 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
3326 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
3329 Some other assemblers start a new lexical block inside a macro expansion.
3330 This has some drawbacks however, since that will not allow <em/any/ symbol
3331 to be visible outside a macro, a feature that is sometimes useful. The
3332 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
3333 to address the problem.
3335 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
3339 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
3341 Defines the character that start "cheap" local labels. You may use one
3342 of '@' and '?' as start character. The default is '@'.
3344 Cheap local labels are labels that are visible only between two non
3345 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
3346 using explicit lexical nesting.
3353 Clear: lda #$00 ; Global label
3354 ?Loop: sta Mem,y ; Local label
3358 Sub: ... ; New global label
3359 bne ?Loop ; ERROR: Unknown identifier!
3363 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
3365 Insert a predefined macro package. The command is followed by an
3366 identifier specifying the macro package to insert. Available macro
3370 atari Defines the scrcode macro.
3371 cbm Defines the scrcode macro.
3372 cpu Defines constants for the .CPU variable.
3373 generic Defines generic macroes like add, sub, and blt.
3374 longbranch Defines conditional long-jump macroes.
3377 Including a macro package twice, or including a macro package that
3378 redefines already existing macros will lead to an error.
3383 .macpack longbranch ; Include macro package
3385 cmp #$20 ; Set condition codes
3386 jne Label ; Jump long on condition
3389 Macro packages are explained in more detail in section <ref
3390 id="macropackages" name="Macro packages">.
3393 <sect1><tt>.MAC, .MACRO</tt><label id=".MACRO"><p>
3395 Start a classic macro definition. The command is followed by an identifier
3396 (the macro name) and optionally by a comma separated list of identifiers
3397 that are macro parameters. A macro definition is terminated by <tt><ref
3398 id=".ENDMACRO" name=".ENDMACRO"></tt>.
3403 .macro ldax arg ; Define macro ldax
3408 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
3409 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
3410 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>
3412 See also section <ref id="macros" name="Macros">.
3415 <sect1><tt>.ORG</tt><label id=".ORG"><p>
3417 Start a section of absolute code. The command is followed by a constant
3418 expression that gives the new PC counter location for which the code is
3419 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
3422 By default, absolute/relocatable mode is global (valid even when switching
3423 segments). Using <tt>.FEATURE <ref id="org_per_seg" name="org_per_seg"></tt>
3424 it can be made segment local.
3426 Please note that you <em/do not need/ <tt/.ORG/ in most cases. Placing
3427 code at a specific address is the job of the linker, not the assembler, so
3428 there is usually no reason to assemble code to a specific address.
3433 .org $7FF ; Emit code starting at $7FF
3437 <sect1><tt>.OUT</tt><label id=".OUT"><p>
3439 Output a string to the console without producing an error. This command
3440 is similar to <tt/.ERROR/, however, it does not force an assembler error
3441 that prevents the creation of an object file.
3446 .out "This code was written by the codebuster(tm)"
3449 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3450 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3451 <tt><ref id=".WARNING" name=".WARNING"></tt>
3454 <sect1><tt>.P02</tt><label id=".P02"><p>
3456 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
3457 instructions. This is the default if not overridden by the
3458 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
3460 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
3461 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3464 <sect1><tt>.P816</tt><label id=".P816"><p>
3466 Enable the 65816 instruction set. This is a superset of the 65SC02 and
3467 6502 instruction sets.
3469 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3470 name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
3473 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
3475 Set the page length for the listing. Must be followed by an integer
3476 constant. The value may be "unlimited", or in the range 32 to 127. The
3477 statement has no effect if no listing is generated. The default value is -1
3478 (unlimited) but may be overridden by the <tt/--pagelength/ command line
3479 option. Beware: Since ca65 is a one pass assembler, the listing is generated
3480 after assembly is complete, you cannot use multiple line lengths with one
3481 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
3486 .pagelength 66 ; Use 66 lines per listing page
3488 .pagelength unlimited ; Unlimited page length
3492 <sect1><tt>.PC02</tt><label id=".PC02"><p>
3494 Enable the 65C02 instructions set. This instruction set includes all
3495 6502 and 65SC02 instructions.
3497 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3498 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3501 <sect1><tt>.POPCPU</tt><label id=".POPCPU"><p>
3503 Pop the last CPU setting from the stack, and activate it.
3505 This command will switch back to the CPU that was last pushed onto the CPU
3506 stack using the <tt><ref id=".PUSHCPU" name=".PUSHCPU"></tt> command, and
3507 remove this entry from the stack.
3509 The assembler will print an error message if the CPU stack is empty when
3510 this command is issued.
3512 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".PUSHCPU"
3513 name=".PUSHCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3516 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
3518 Pop the last pushed segment from the stack, and set it.
3520 This command will switch back to the segment that was last pushed onto the
3521 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3522 command, and remove this entry from the stack.
3524 The assembler will print an error message if the segment stack is empty
3525 when this command is issued.
3527 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3530 <sect1><tt>.PROC</tt><label id=".PROC"><p>
3532 Start a nested lexical level with the given name and adds a symbol with this
3533 name to the enclosing scope. All new symbols from now on are in the local
3534 lexical level and are accessible from outside only via <ref id="scopesyntax"
3535 name="explicit scope specification">. Symbols defined outside this local
3536 level may be accessed as long as their names are not used for new symbols
3537 inside the level. Symbols names in other lexical levels do not clash, so you
3538 may use the same names for identifiers. The lexical level ends when the
3539 <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
3540 may be nested up to a depth of 16 (this is an artificial limit to protect
3541 against errors in the source).
3543 Note: Macro names are always in the global level and in a separate name
3544 space. There is no special reason for this, it's just that I've never
3545 had any need for local macro definitions.
3550 .proc Clear ; Define Clear subroutine, start new level
3552 L1: sta Mem,y ; L1 is local and does not cause a
3553 ; duplicate symbol error if used in other
3556 bne L1 ; Reference local symbol
3558 .endproc ; Leave lexical level
3561 See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
3565 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
3567 Enable the 65SC02 instructions set. This instruction set includes all
3570 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
3571 name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3574 <sect1><tt>.PUSHCPU</tt><label id=".PUSHCPU"><p>
3576 Push the currently active CPU onto a stack. The stack has a size of 8
3579 <tt/.PUSHCPU/ allows together with <tt><ref id=".POPCPU"
3580 name=".POPCPU"></tt> to switch to another CPU and to restore the old CPU
3581 later, without knowledge of the current CPU setting.
3583 The assembler will print an error message if the CPU stack is already full,
3584 when this command is issued.
3586 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".POPCPU"
3587 name=".POPCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3590 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
3592 Push the currently active segment onto a stack. The entries on the stack
3593 include the name of the segment and the segment type. The stack has a size
3596 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3597 to switch to another segment and to restore the old segment later, without
3598 even knowing the name and type of the current segment.
3600 The assembler will print an error message if the segment stack is already
3601 full, when this command is issued.
3603 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3606 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
3608 Switch back to relocatable mode. See the <tt><ref id=".ORG"
3609 name=".ORG"></tt> command.
3612 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
3614 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
3615 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
3616 a constant expression that tells how many times the commands in the body
3617 should get repeated. Optionally, a comma and an identifier may be specified.
3618 If this identifier is found in the body of the repeat statement, it is
3619 replaced by the current repeat count (starting with zero for the first time
3620 the body is repeated).
3622 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
3623 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
3624 level will be used, not the one from the outer level.
3628 The following macro will emit a string that is "encrypted" in that all
3629 characters of the string are XORed by the value $55.
3633 .repeat .strlen(Arg), I
3634 .byte .strat(Arg, I) ^ $55
3639 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
3642 <sect1><tt>.RES</tt><label id=".RES"><p>
3644 Reserve storage. The command is followed by one or two constant
3645 expressions. The first one is mandatory and defines, how many bytes of
3646 storage should be defined. The second, optional expression must by a
3647 constant byte value that will be used as value of the data. If there
3648 is no fill value given, the linker will use the value defined in the
3649 linker configuration file (default: zero).
3654 ; Reserve 12 bytes of memory with value $AA
3659 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
3661 Switch to the RODATA segment. The name of the RODATA segment is always
3662 "RODATA", so this is a shortcut for
3668 The RODATA segment is a segment that is used by the compiler for
3669 readonly data like string constants.
3671 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
3674 <sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
3676 Start a nested lexical level with the given name. All new symbols from now
3677 on are in the local lexical level and are accessible from outside only via
3678 <ref id="scopesyntax" name="explicit scope specification">. Symbols defined
3679 outside this local level may be accessed as long as their names are not used
3680 for new symbols inside the level. Symbols names in other lexical levels do
3681 not clash, so you may use the same names for identifiers. The lexical level
3682 ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
3683 read. Lexical levels may be nested up to a depth of 16 (this is an
3684 artificial limit to protect against errors in the source).
3686 Note: Macro names are always in the global level and in a separate name
3687 space. There is no special reason for this, it's just that I've never
3688 had any need for local macro definitions.
3693 .scope Error ; Start new scope named Error
3695 File = 1 ; File error
3696 Parse = 2 ; Parse error
3697 .endscope ; Close lexical level
3700 lda #Error::File ; Use symbol from scope Error
3703 See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
3707 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
3709 Switch to another segment. Code and data is always emitted into a
3710 segment, that is, a named section of data. The default segment is
3711 "CODE". There may be up to 254 different segments per object file
3712 (and up to 65534 per executable). There are shortcut commands for
3713 the most common segments ("ZEROPAGE", "CODE", "RODATA", "DATA", and "BSS").
3715 The command is followed by a string containing the segment name (there are
3716 some constraints for the name - as a rule of thumb use only those segment
3717 names that would also be valid identifiers). There may also be an optional
3718 address size separated by a colon. See the section covering <tt/<ref
3719 id="address-sizes" name="address sizes">/ for more information.
3721 The default address size for a segment depends on the memory model specified
3722 on the command line. The default is "absolute", which means that you don't
3723 have to use an address size modifier in most cases.
3725 "absolute" means that the is a segment with 16 bit (absolute) addressing.
3726 That is, the segment will reside somewhere in core memory outside the zero
3727 page. "zeropage" (8 bit) means that the segment will be placed in the zero
3728 page and direct (short) addressing is possible for data in this segment.
3730 Beware: Only labels in a segment with the zeropage attribute are marked
3731 as reachable by short addressing. The `*' (PC counter) operator will
3732 work as in other segments and will create absolute variable values.
3734 Please note that a segment cannot have two different address sizes. A
3735 segment specified as zeropage cannot be declared as being absolute later.
3740 .segment "ROM2" ; Switch to ROM2 segment
3741 .segment "ZP2": zeropage ; New direct segment
3742 .segment "ZP2" ; Ok, will use last attribute
3743 .segment "ZP2": absolute ; Error, redecl mismatch
3746 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
3747 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt>, <tt><ref
3748 id=".RODATA" name=".RODATA"></tt>, and <tt><ref id=".ZEROPAGE"
3749 name=".ZEROPAGE"></tt>
3752 <sect1><tt>.SET</tt><label id=".SET"><p>
3754 <tt/.SET/ is used to assign a value to a variable. See <ref id="variables"
3755 name="Numeric variables"> for a full description.
3758 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
3760 Switch the CPU instruction set. The command is followed by a string that
3761 specifies the CPU. Possible values are those that can also be supplied to
3762 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
3763 namely: 6502, 6502X, 65SC02, 65C02, 65816 and HuC6280.
3765 See: <tt><ref id=".CPU" name=".CPU"></tt>,
3766 <tt><ref id=".IFP02" name=".IFP02"></tt>,
3767 <tt><ref id=".IFP816" name=".IFP816"></tt>,
3768 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
3769 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
3770 <tt><ref id=".P02" name=".P02"></tt>,
3771 <tt><ref id=".P816" name=".P816"></tt>,
3772 <tt><ref id=".PC02" name=".PC02"></tt>,
3773 <tt><ref id=".PSC02" name=".PSC02"></tt>
3776 <sect1><tt>.SMART</tt><label id=".SMART"><p>
3778 Switch on or off smart mode. The command must be followed by a '+' or '-'
3779 character to switch the option on or off respectively. The default is off
3780 (that is, the assembler doesn't try to be smart), but this default may be
3781 changed by the -s switch on the command line.
3783 In smart mode the assembler will do the following:
3786 <item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
3787 and update the operand sizes accordingly. If the operand of such an
3788 instruction cannot be evaluated by the assembler (for example, because
3789 the operand is an imported symbol), a warning is issued. Beware: Since
3790 the assembler cannot trace the execution flow this may lead to false
3791 results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
3792 instructions to tell the assembler about the current settings.
3793 <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
3794 used within a procedure declared as <tt/far/, or if the procedure has
3795 no explicit address specification, but it is <tt/far/ because of the
3803 .smart - ; Stop being smart
3806 See: <tt><ref id=".A16" name=".A16"></tt>,
3807 <tt><ref id=".A8" name=".A8"></tt>,
3808 <tt><ref id=".I16" name=".I16"></tt>,
3809 <tt><ref id=".I8" name=".I8"></tt>
3812 <sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
3814 Starts a struct definition. Structs are covered in a separate section named
3815 <ref id="structs" name=""Structs and unions"">.
3817 See also: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>,
3818 <tt><ref id=".ENDUNION" name=".ENDUNION"></tt>,
3819 <tt><ref id=".UNION" name=".UNION"></tt>
3822 <sect1><tt>.TAG</tt><label id=".TAG"><p>
3824 Allocate space for a struct or union.
3835 .tag Point ; Allocate 4 bytes
3839 <sect1><tt>.UNDEF, .UNDEFINE</tt><label id=".UNDEFINE"><p>
3841 Delete a define style macro definition. The command is followed by an
3842 identifier which specifies the name of the macro to delete. Macro
3843 replacement is switched of when reading the token following the command
3844 (otherwise the macro name would be replaced by its replacement list).
3846 See also the <tt><ref id=".DEFINE" name=".DEFINE"></tt> command and
3847 section <ref id="macros" name="Macros">.
3850 <sect1><tt>.UNION</tt><label id=".UNION"><p>
3852 Starts a union definition. Unions are covered in a separate section named
3853 <ref id="structs" name=""Structs and unions"">.
3855 See also: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>,
3856 <tt><ref id=".ENDUNION" name=".ENDUNION"></tt>,
3857 <tt><ref id=".STRUCT" name=".STRUCT"></tt>
3860 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
3862 Force an assembly warning. The assembler will output a warning message
3863 preceded by "User warning". This warning will always be output, even if
3864 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
3865 command line option.
3867 This command may be used to output possible problems when assembling
3876 .warning "Forward jump in jne, cannot optimize!"
3886 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3887 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3888 <tt><ref id=".OUT" name=".OUT"></tt>
3891 <sect1><tt>.WORD</tt><label id=".WORD"><p>
3893 Define word sized data. Must be followed by a sequence of (word ranged,
3894 but not necessarily constant) expressions.
3899 .word $0D00, $AF13, _Clear
3903 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
3905 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
3906 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
3910 .segment "ZEROPAGE": zeropage
3913 Because of the "zeropage" attribute, labels declared in this segment are
3914 addressed using direct addressing mode if possible. You <em/must/ instruct
3915 the linker to place this segment somewhere in the address range 0..$FF
3916 otherwise you will get errors.
3918 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
3922 <sect>Macros<label id="macros"><p>
3925 <sect1>Introduction<p>
3927 Macros may be thought of as "parametrized super instructions". Macros are
3928 sequences of tokens that have a name. If that name is used in the source
3929 file, the macro is "expanded", that is, it is replaced by the tokens that
3930 were specified when the macro was defined.
3933 <sect1>Macros without parameters<p>
3935 In its simplest form, a macro does not have parameters. Here's an
3939 .macro asr ; Arithmetic shift right
3940 cmp #$80 ; Put bit 7 into carry
3941 ror ; Rotate right with carry
3945 The macro above consists of two real instructions, that are inserted into
3946 the code, whenever the macro is expanded. Macro expansion is simply done
3947 by using the name, like this:
3956 <sect1>Parametrized macros<p>
3958 When using macro parameters, macros can be even more useful:
3972 When calling the macro, you may give a parameter, and each occurrence of
3973 the name "addr" in the macro definition will be replaced by the given
3992 A macro may have more than one parameter, in this case, the parameters
3993 are separated by commas. You are free to give less parameters than the
3994 macro actually takes in the definition. You may also leave intermediate
3995 parameters empty. Empty parameters are replaced by empty space (that is,
3996 they are removed when the macro is expanded). If you have a look at our
3997 macro definition above, you will see, that replacing the "addr" parameter
3998 by nothing will lead to wrong code in most lines. To help you, writing
3999 macros with a variable parameter list, there are some control commands:
4001 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
4002 returns true, if there are any tokens on the remainder of the line. Since
4003 empty parameters are replaced by nothing, this may be used to test if a given
4004 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
4007 Look at this example:
4010 .macro ldaxy a, x, y
4023 That macro may be called as follows:
4026 ldaxy 1, 2, 3 ; Load all three registers
4028 ldaxy 1, , 3 ; Load only a and y
4030 ldaxy , , 3 ; Load y only
4033 There's another helper command for determining which macro parameters are
4034 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>. That command is
4035 replaced by the parameter count given, <em/including/ explicitly empty
4039 ldaxy 1 ; .PARAMCOUNT = 1
4040 ldaxy 1,,3 ; .PARAMCOUNT = 3
4041 ldaxy 1,2 ; .PARAMCOUNT = 2
4042 ldaxy 1, ; .PARAMCOUNT = 2
4043 ldaxy 1,2,3 ; .PARAMCOUNT = 3
4046 Macro parameters may optionally be enclosed into curly braces. This allows the
4047 inclusion of tokens that would otherwise terminate the parameter (the comma in
4048 case of a macro parameter).
4051 .macro foo arg1, arg2
4055 foo ($00,x) ; Two parameters passed
4056 foo {($00,x)} ; One parameter passed
4059 In the first case, the macro is called with two parameters: '<tt/($00/'
4060 and '<tt/x)/'. The comma is not passed to the macro, because it is part of the
4061 calling sequence, not the parameters.
4063 In the second case, '<tt/($00,x)/' is passed to the macro; this time,
4064 including the comma.
4067 <sect1>Detecting parameter types<p>
4069 Sometimes it is nice to write a macro that acts differently depending on the
4070 type of the argument supplied. An example would be a macro that loads a 16 bit
4071 value from either an immediate operand, or from memory. The <tt/<ref
4072 id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
4073 functions will allow you to do exactly this:
4077 .if (.match (.left (1, {arg}), #))
4079 lda #<(.right (.tcount ({arg})-1, {arg}))
4080 ldx #>(.right (.tcount ({arg})-1, {arg}))
4082 ; assume absolute or zero page
4089 Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
4090 check if its argument begins with a hash mark. If so, two immediate loads are
4091 emitted, Otherwise a load from an absolute zero page memory location is
4092 assumed. Please note how the curly braces are used to enclose parameters to
4093 pseudo functions handling token lists. This is necessary, because the token
4094 lists may include commas or parens, which would be treated by the assembler
4097 The macro can be used as
4102 ldax #$1234 ; X=$12, A=$34
4104 ldax foo ; X=$56, A=$78
4108 <sect1>Recursive macros<p>
4110 Macros may be used recursively:
4113 .macro push r1, r2, r3
4122 There's also a special macro command to help with writing recursive macros:
4123 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>. That command will stop macro
4124 expansion immediately:
4127 .macro push r1, r2, r3, r4, r5, r6, r7
4129 ; First parameter is empty
4135 push r2, r3, r4, r5, r6, r7
4139 When expanding that macro, the expansion will push all given parameters
4140 until an empty one is encountered. The macro may be called like this:
4143 push $20, $21, $32 ; Push 3 ZP locations
4144 push $21 ; Push one ZP location
4148 <sect1>Local symbols inside macros<p>
4150 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
4151 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
4152 Have a look at the inc16 macro above. Here is it again:
4166 If you have a closer look at the code, you will notice, that it could be
4167 written more efficiently, like this:
4178 But imagine what happens, if you use this macro twice? Since the label "Skip"
4179 has the same name both times, you get a "duplicate symbol" error. Without a
4180 way to circumvent this problem, macros are not as useful, as they could be.
4181 One possible solution is the command <tt><ref id=".LOCAL" name=".LOCAL"></tt>.
4182 It declares one or more symbols as local to the macro expansion. The names of
4183 local variables are replaced by a unique name in each separate macro
4184 expansion. So we can solve the problem above by using <tt/.LOCAL/:
4188 .local Skip ; Make Skip a local symbol
4192 Skip: ; Not visible outside
4196 Another solution is of course to start a new lexical block inside the macro
4197 that hides any labels:
4211 <sect1>C style macros<p>
4213 Starting with version 2.5 of the assembler, there is a second macro type
4214 available: C style macros using the <tt/.DEFINE/ directive. These macros are
4215 similar to the classic macro type described above, but behaviour is sometimes
4220 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
4221 span more than a line. You may use line continuation (see <tt><ref
4222 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
4223 more than one line for increased readability, but the macro itself
4224 may not contain an end-of-line token.
4226 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
4227 the name space with classic macros, but they are detected and replaced
4228 at the scanner level. While classic macros may be used in every place,
4229 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
4230 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
4231 they are more versatile in some situations.
4233 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
4234 parameters. While classic macros may have empty parameters, this is
4235 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
4236 For this macro type, the number of actual parameters must match
4237 exactly the number of formal parameters.
4239 To make this possible, formal parameters are enclosed in braces when
4240 defining the macro. If there are no parameters, the empty braces may
4243 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
4244 contain end-of-line tokens, there are things that cannot be done. They
4245 may not contain several processor instructions for example. So, while
4246 some things may be done with both macro types, each type has special
4247 usages. The types complement each other.
4251 Let's look at a few examples to make the advantages and disadvantages
4254 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
4255 following <tt/.DEFINE/:
4260 foo EQU $1234 ; This is accepted now
4263 You may use the directive to define string constants used elsewhere:
4266 ; Define the version number
4267 .define VERSION "12.3a"
4273 Macros with parameters may also be useful:
4276 .define DEBUG(message) .out message
4278 DEBUG "Assembling include file #3"
4281 Note that, while formal parameters have to be placed in braces, this is
4282 not true for the actual parameters. Beware: Since the assembler cannot
4283 detect the end of one parameter, only the first token is used. If you
4284 don't like that, use classic macros instead:
4287 .macro DEBUG message
4292 (That is an example where a problem can be solved with both macro types).
4295 <sect1>Characters in macros<p>
4297 When using the <ref id="option-t" name="-t"> option, characters are translated
4298 into the target character set of the specific machine. However, this happens
4299 as late as possible. This means that strings are translated if they are part
4300 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
4301 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
4302 used as part of an expression.
4304 This behaviour is very intuitive outside of macros but may be confusing when
4305 doing more complex macros. If you compare characters against numeric values,
4306 be sure to take the translation into account.
4309 <sect1>Deleting macros<p>
4311 Macros can be deleted. This will not work if the macro that should be deleted
4312 is currently expanded as in the following non-working example:
4316 .delmacro notworking
4319 notworking ; Will not work
4322 The commands to delete classic and define style macros differ. Classic macros
4323 can be deleted by use of <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>, while
4324 for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros, <tt><ref
4325 id=".UNDEFINE" name=".UNDEFINE"></tt> must be used. Example:
4333 .byte value ; Emit one byte with value 1
4334 mac ; Emit another byte with value 2
4339 .byte value ; Error: Unknown identifier
4340 mac ; Error: Missing ":"
4343 A separate command for <tt>.DEFINE</tt> style macros was necessary, because
4344 the name of such a macro is replaced by its replacement list on a very low
4345 level. To get the actual name, macro replacement has to be switched off when
4346 reading the argument to <tt>.UNDEFINE</tt>. This does also mean that the
4347 argument to <tt>.UNDEFINE</tt> is not allowed to come from another
4348 <tt>.DEFINE</tt>. All this is not necessary for classic macros, so having two
4349 different commands increases flexibility.
4353 <sect>Macro packages<label id="macropackages"><p>
4355 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
4356 macro packages may be included with just one command. Available macro packages
4360 <sect1><tt>.MACPACK generic</tt><p>
4362 This macro package defines macroes that are useful in almost any program.
4363 Currently defined macroes are:
4366 .macro add Arg ; add without carry
4371 .macro sub Arg ; subtract without borrow
4376 .macro bge Arg ; branch on greater-than or equal
4380 .macro blt Arg ; branch on less-than
4384 .macro bgt Arg ; branch on greater-than
4391 .macro ble Arg ; branch on less-than or equal
4396 .macro bnz Arg ; branch on not zero
4400 .macro bze Arg ; branch on zero
4406 <sect1><tt>.MACPACK longbranch</tt><p>
4408 This macro package defines long conditional jumps. They are named like the
4409 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
4410 definition for the "<tt/jeq/" macro, the other macros are built using the same
4415 .if .def(Target) .and ((*+2)-(Target) <= 127)
4424 All macros expand to a short branch, if the label is already defined (back
4425 jump) and is reachable with a short jump. Otherwise the macro expands to a
4426 conditional branch with the branch condition inverted, followed by an absolute
4427 jump to the actual branch target.
4429 The package defines the following macros:
4432 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
4437 <sect1><tt>.MACPACK atari</tt><p>
4439 This macro package defines a macro named <tt/scrcode/. It takes a string
4440 as argument and places this string into memory translated into screen codes.
4443 <sect1><tt>.MACPACK cbm</tt><p>
4445 This macro package defines a macro named <tt/scrcode/. It takes a string
4446 as argument and places this string into memory translated into screen codes.
4449 <sect1><tt>.MACPACK cpu</tt><p>
4451 This macro package does not define any macros but constants used to examine
4452 the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
4453 each supported CPU a constant similar to
4464 is defined. These constants may be used to determine the exact type of the
4465 currently enabled CPU. In addition to that, for each CPU instruction set,
4466 another constant is defined:
4477 The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
4478 be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
4479 currently enabled CPU supports a specific instruction set. For example the
4480 65C02 supports all instructions of the 65SC02 CPU, so it has the
4481 <tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
4485 .if (.cpu .bitand CPU_ISET_65SC02)
4493 it is possible to determine if the
4499 instruction is supported, which is the case for the 65SC02, 65C02 and 65816
4500 CPUs (the latter two are upwards compatible to the 65SC02).
4503 <sect1><tt>.MACPACK module</tt><p>
4505 This macro package defines a macro named <tt/module_header/. It takes an
4506 identifier as argument and is used to define the header of a module both
4507 in the dynamic and static variant.
4511 <sect>Predefined constants<label id="predefined-constants"><p>
4513 For better orthogonality, the assembler defines similar symbols as the
4514 compiler, depending on the target system selected:
4517 <item><tt/__APPLE2__/ - Target system is <tt/apple2/ or <tt/apple2enh/
4518 <item><tt/__APPLE2ENH__/ - Target system is <tt/apple2enh/
4519 <item><tt/__ATARI5200__/ - Target system is <tt/atari5200/
4520 <item><tt/__ATARI__/ - Target system is <tt/atari/ or <tt/atarixl/
4521 <item><tt/__ATARIXL__/ - Target system is <tt/atarixl/
4522 <item><tt/__ATMOS__/ - Target system is <tt/atmos/
4523 <item><tt/__BBC__/ - Target system is <tt/bbc/
4524 <item><tt/__C128__/ - Target system is <tt/c128/
4525 <item><tt/__C16__/ - Target system is <tt/c16/ or <tt/plus4/
4526 <item><tt/__C64__/ - Target system is <tt/c64/
4527 <item><tt/__CBM__/ - Target is a Commodore system
4528 <item><tt/__CBM510__/ - Target system is <tt/cbm510/
4529 <item><tt/__CBM610__/ - Target system is <tt/cbm610/
4530 <item><tt/__GEOS__/ - Target is a GEOS system
4531 <item><tt/__GEOS_APPLE__/ - Target system is <tt/geos-apple/
4532 <item><tt/__GEOS_CBM__/ - Target system is <tt/geos-cbm/
4533 <item><tt/__LUNIX__/ - Target system is <tt/lunix/
4534 <item><tt/__LYNX__/ - Target system is <tt/lynx/
4535 <item><tt/__NES__/ - Target system is <tt/nes/
4536 <item><tt/__OSIC1P__/ - Target system is <tt/osic1p/
4537 <item><tt/__PET__/ - Target system is <tt/pet/
4538 <item><tt/__PLUS4__/ - Target system is <tt/plus4/
4539 <item><tt/__SIM6502__/ - Target system is <tt/sim6502/
4540 <item><tt/__SIM65C02__/ - Target system is <tt/sim65c02/
4541 <item><tt/__SUPERVISION__/ - Target system is <tt/supervision/
4542 <item><tt/__VIC20__/ - Target system is <tt/vic20/
4546 <sect>Structs and unions<label id="structs"><p>
4548 <sect1>Structs and unions Overview<p>
4550 Structs and unions are special forms of <ref id="scopes" name="scopes">. They
4551 are to some degree comparable to their C counterparts. Both have a list of
4552 members. Each member allocates storage and may optionally have a name, which,
4553 in case of a struct, is the offset from the beginning and, in case of a union,
4557 <sect1>Declaration<p>
4559 Here is an example for a very simple struct with two members and a total size
4569 A union shares the total space between all its members, its size is the same
4570 as that of the largest member. The offset of all members relative to the union
4580 A struct or union must not necessarily have a name. If it is anonymous, no
4581 local scope is opened, the identifiers used to name the members are placed
4582 into the current scope instead.
4584 A struct may contain unnamed members and definitions of local structs. The
4585 storage allocators may contain a multiplier, as in the example below:
4590 .word 2 ; Allocate two words
4597 <sect1>The <tt/.TAG/ keyword<p>
4599 Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to reserve space
4600 for an already defined struct or unions within another struct:
4614 Space for a struct or union may be allocated using the <ref id=".TAG"
4615 name=".TAG"> directive.
4621 Currently, members are just offsets from the start of the struct or union. To
4622 access a field of a struct, the member offset has to be added to the address
4623 of the struct itself:
4626 lda C+Circle::Radius ; Load circle radius into A
4629 This may change in a future version of the assembler.
4632 <sect1>Limitations<p>
4634 Structs and unions are currently implemented as nested symbol tables (in fact,
4635 they were a by-product of the improved scoping rules). Currently, the
4636 assembler has no idea of types. This means that the <ref id=".TAG"
4637 name=".TAG"> keyword will only allocate space. You won't be able to initialize
4638 variables declared with <ref id=".TAG" name=".TAG">, and adding an embedded
4639 structure to another structure with <ref id=".TAG" name=".TAG"> will not make
4640 this structure accessible by using the '::' operator.
4644 <sect>Module constructors/destructors<label id="condes"><p>
4646 <em>Note:</em> This section applies mostly to C programs, so the explanation
4647 below uses examples from the C libraries. However, the feature may also be
4648 useful for assembler programs.
4651 <sect1>Module constructors/destructors Overview<p>
4653 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4654 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4655 name=".INTERRUPTOR"></tt> keywords it is possible to export functions in a
4656 special way. The linker is able to generate tables with all functions of a
4657 specific type. Such a table will <em>only</em> include symbols from object
4658 files that are linked into a specific executable. This may be used to add
4659 initialization and cleanup code for library modules, or a table of interrupt
4662 The C heap functions are an example where module initialization code is used.
4663 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
4664 variables that contain the start and the end of the heap, pointers to the free
4665 list and so on. Since the end of the heap depends on the size and start of the
4666 stack, it must be initialized at runtime. However, initializing these
4667 variables for programs that do not use the heap are a waste of time and
4670 So the central module defines a function that contains initialization code and
4671 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
4672 this module is added to an executable by the linker, the initialization
4673 function will be placed into the table of constructors by the linker. The C
4674 startup code will call all constructors before <tt/main/ and all destructors
4675 after <tt/main/, so without any further work, the heap initialization code is
4676 called once the module is linked in.
4678 While it would be possible to add explicit calls to initialization functions
4679 in the startup code, the new approach has several advantages:
4683 If a module is not included, the initialization code is not linked in and not
4684 called. So you don't pay for things you don't need.
4687 Adding another library that needs initialization does not mean that the
4688 startup code has to be changed. Before we had module constructors and
4689 destructors, the startup code for all systems had to be adjusted to call the
4690 new initialization code.
4693 The feature saves memory: Each additional initialization function needs just
4694 two bytes in the table (a pointer to the function).
4699 <sect1>Calling order<p>
4701 The symbols are sorted in increasing priority order by the linker when using
4702 one of the builtin linker configurations, so the functions with lower
4703 priorities come first and are followed by those with higher priorities. The C
4704 library runtime subroutine that walks over the function tables calls the
4705 functions starting from the top of the table - which means that functions with
4706 a high priority are called first.
4708 So when using the C runtime, functions are called with high priority functions
4709 first, followed by low priority functions.
4714 When using these special symbols, please take care of the following:
4719 The linker will only generate function tables, it will not generate code to
4720 call these functions. If you're using the feature in some other than the
4721 existing C environments, you have to write code to call all functions in a
4722 linker generated table yourself. See the <tt/condes/ and <tt/callirq/ modules
4723 in the C runtime for an example on how to do this.
4726 The linker will only add addresses of functions that are in modules linked to
4727 the executable. This means that you have to be careful where to place the
4728 condes functions. If initialization or an irq handler is needed for a group of
4729 functions, be sure to place the function into a module that is linked in
4730 regardless of which function is called by the user.
4733 The linker will generate the tables only when requested to do so by the
4734 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
4735 be requested separately.
4738 Constructors and destructors may have priorities. These priorities determine
4739 the order of the functions in the table. If your initialization or cleanup code
4740 does depend on other initialization or cleanup code, you have to choose the
4741 priority for the functions accordingly.
4744 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4745 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4746 name=".INTERRUPTOR"></tt> statements, there is also a more generic command:
4747 <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to specify an
4748 additional type. Predefined types are 0 (constructor), 1 (destructor) and 2
4749 (interruptor). The linker generates a separate table for each type on request.
4754 <sect>Porting sources from other assemblers<p>
4756 Sometimes it is necessary to port code written for older assemblers to ca65.
4757 In some cases, this can be done without any changes to the source code by
4758 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
4759 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
4762 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
4763 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
4764 done by the linker. Most other assemblers generate absolute code, placement is
4765 done within the assembler and there is no external linker.
4767 In general it is not a good idea to write new code using the emulation
4768 features of the assembler, but there may be situations where even this rule is
4773 You need to use some of the ca65 emulation features to simulate the behaviour
4774 of such simple assemblers.
4777 <item>Prepare your sourcecode like this:
4780 ; if you want TASS style labels without colons
4781 .feature labels_without_colons
4783 ; if you want TASS style character constants
4784 ; ("a" instead of the default 'a')
4785 .feature loose_char_term
4787 .word *+2 ; the cbm load address
4792 notice that the two emulation features are mostly useful for porting
4793 sources originally written in/for TASS, they are not needed for the
4794 actual "simple assembler operation" and are not recommended if you are
4795 writing new code from scratch.
4797 <item>Replace all program counter assignments (which are not possible in ca65
4798 by default, and the respective emulation feature works different from what
4799 you'd expect) by another way to skip to memory locations, for example the
4800 <tt><ref id=".RES" name=".RES"></tt> directive.
4804 .res $2000-* ; reserve memory up to $2000
4807 Please note that other than the original TASS, ca65 can never move the program
4808 counter backwards - think of it as if you are assembling to disk with TASS.
4810 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
4811 rewritten to match ca65 syntax. Most importantly notice that due to the lack
4812 of <tt/.goto/, everything involving loops must be replaced by
4813 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
4815 <item>To assemble code to a different address than it is executed at, use the
4816 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
4817 <tt/.offs/-constructs.
4824 .reloc ; back to normal
4827 <item>Then assemble like this:
4830 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
4833 Note that you need to use the actual start address minus two, since two bytes
4834 are used for the cbm load address.
4841 ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
4842 Bassewitz. For usage of the binaries and/or sources the following
4843 conditions do apply:
4845 This software is provided 'as-is', without any expressed or implied
4846 warranty. In no event will the authors be held liable for any damages
4847 arising from the use of this software.
4849 Permission is granted to anyone to use this software for any purpose,
4850 including commercial applications, and to alter it and redistribute it
4851 freely, subject to the following restrictions:
4854 <item> The origin of this software must not be misrepresented; you must not
4855 claim that you wrote the original software. If you use this software
4856 in a product, an acknowledgment in the product documentation would be
4857 appreciated but is not required.
4858 <item> Altered source versions must be plainly marked as such, and must not
4859 be misrepresented as being the original software.
4860 <item> This notice may not be removed or altered from any source