1 <!doctype linuxdoc system> <!-- -*- text-mode -*- -->
4 <title>ca65 Users Guide
5 <author><url url="mailto:uz@cc65.org" name="Ullrich von Bassewitz">
9 ca65 is a powerful macro assembler for the 6502, 65C02, and 65816 CPUs. It is
10 used as a companion assembler for the cc65 crosscompiler, but it may also be
11 used as a standalone product.
14 <!-- Table of contents -->
17 <!-- Begin the document -->
21 ca65 is a replacement for the ra65 assembler that was part of the cc65 C
22 compiler, originally developed by John R. Dunning. I had some problems with
23 ra65 and the copyright does not permit some things which I wanted to be
24 possible, so I decided to write a completely new assembler/linker/archiver
25 suite for the cc65 compiler. ca65 is part of this suite.
27 Some parts of the assembler (code generation and some routines for symbol
28 table handling) are taken from an older crossassembler named a816 written
29 by me a long time ago.
32 <sect1>Design criteria<p>
34 Here's a list of the design criteria, that I considered important for the
39 <item> The assembler must support macros. Macros are not essential, but they
40 make some things easier, especially when you use the assembler in the
41 backend of a compiler.
42 <item> The assembler must support the newer 65C02 and 65816 CPUs. I have been
43 thinking about a 65816 backend for the C compiler, and even my old
44 a816 assembler had support for these CPUs, so this wasn't really a
46 <item> The assembler must produce relocatable code. This is necessary for the
47 compiler support, and it is more convenient.
48 <item> Conditional assembly must be supported. This is a must for bigger
49 projects written in assembler (like Elite128).
50 <item> The assembler must support segments, and it must support more than
51 three segments (this is the count, most other assemblers support).
52 Having more than one code segments helps developing code for systems
53 with a divided ROM area (like the C64).
54 <item> The linker must be able to resolve arbitrary expressions. It should
55 be able to get things like
62 <item> True lexical nesting for symbols. This is very convenient for larger
64 <item> "Cheap" local symbols without lexical nesting for those quick, late
66 <item> I liked the idea of "options" as Anre Fachats .o65 format has it, so I
67 introduced the concept into the object file format use by the new cc65
69 <item> The assembler will be a one pass assembler. There was no real need for
70 this decision, but I've written several multipass assemblers, and it
71 started to get boring. A one pass assembler needs much more elaborated
72 data structures, and because of that it's much more fun:-)
73 <item> Non-GPLed code that may be used in any project without restrictions or
74 fear of "GPL infecting" other code.
82 <sect1>Command line option overview<p>
84 The assembler accepts the following options:
87 ---------------------------------------------------------------------------
88 Usage: ca65 [options] file
90 -D name[=value] Define a symbol
91 -I dir Set an include directory search path
92 -U Mark unresolved symbols as import
93 -V Print the assembler version
94 -W n Set warning level n
96 -g Add debug info to object file
98 -i Ignore case of symbols
99 -l name Create a listing file if assembly was ok
100 -mm model Set the memory model
101 -o name Name the output file
103 -t sys Set the target system
104 -v Increase verbosity
107 --auto-import Mark unresolved symbols as import
108 --bin-include-dir dir Set a search path for binary includes
109 --cpu type Set cpu type
110 --create-dep name Create a make dependency file
111 --create-full-dep name Create a full make dependency file
113 --debug-info Add debug info to object file
114 --feature name Set an emulation feature
115 --help Help (this text)
116 --ignore-case Ignore case of symbols
117 --include-dir dir Set an include directory search path
118 --large-alignment Don't warn about large alignments
119 --listing name Create a listing file if assembly was ok
120 --list-bytes n Maximum number of bytes per listing line
121 --memory-model model Set the memory model
122 --pagelength n Set the page length for the listing
123 --relax-checks Relax some checks (see docs)
124 --smart Enable smart mode
125 --target sys Set the target system
126 --verbose Increase verbosity
127 --version Print the assembler version
128 ---------------------------------------------------------------------------
132 <sect1>Command line options in detail<p>
134 Here is a description of all the command line options:
138 <label id="option--bin-include-dir">
139 <tag><tt>--bin-include-dir dir</tt></tag>
141 Name a directory which is searched for binary include files. The option
142 may be used more than once to specify more than one directory to search. The
143 current directory is always searched first before considering any
144 additional directories. See also the section about <ref id="search-paths"
145 name="search paths">.
148 <label id="option--cpu">
149 <tag><tt>--cpu type</tt></tag>
151 Set the default for the CPU type. The option takes a parameter, which
154 6502, 65SC02, 65C02, 65816, sweet16, HuC6280
157 <label id="option-create-dep">
158 <tag><tt>--create-dep name</tt></tag>
160 Tells the assembler to generate a file containing the dependency list for
161 the assembled module in makefile syntax. The output is written to a file
162 with the given name. The output does not include files passed via debug
163 information to the assembler.
166 <label id="option-create-full-dep">
167 <tag><tt>--create-full-dep name</tt></tag>
169 Tells the assembler to generate a file containing the dependency list for
170 the assembled module in makefile syntax. The output is written to a file
171 with the given name. The output does include files passed via debug
172 information to the assembler.
175 <tag><tt>-d, --debug</tt></tag>
177 Enables debug mode, something that should not be needed for mere
181 <label id="option--feature">
182 <tag><tt>--feature name</tt></tag>
184 Enable an emulation feature. This is identical as using <tt/.FEATURE/
185 in the source with two exceptions: Feature names must be lower case, and
186 each feature must be specified by using an extra <tt/--feature/ option,
187 comma separated lists are not allowed.
189 See the discussion of the <tt><ref id=".FEATURE" name=".FEATURE"></tt>
190 command for a list of emulation features.
193 <label id="option-g">
194 <tag><tt>-g, --debug-info</tt></tag>
196 When this option (or the equivalent control command <tt/.DEBUGINFO/) is
197 used, the assembler will add a section to the object file that contains
198 all symbols (including local ones) together with the symbol values and
199 source file positions. The linker will put these additional symbols into
200 the VICE label file, so even local symbols can be seen in the VICE
204 <label id="option-h">
205 <tag><tt>-h, --help</tt></tag>
207 Print the short option summary shown above.
210 <label id="option-i">
211 <tag><tt>-i, --ignore-case</tt></tag>
213 This option makes the assembler case insensitive on identifiers and labels.
214 This option will override the default, but may itself be overridden by the
215 <tt><ref id=".CASE" name=".CASE"></tt> control command.
218 <label id="option-l">
219 <tag><tt>-l name, --listing name</tt></tag>
221 Generate an assembler listing with the given name. A listing file will
222 never be generated in case of assembly errors.
225 <label id="option--large-alignment">
226 <tag><tt>--large-alignment</tt></tag>
228 Disable warnings about a large combined alignment. See the discussion of the
229 <tt><ref id=".ALIGN" name=".ALIGN"></tt> directive for futher information.
232 <label id="option--list-bytes">
233 <tag><tt>--list-bytes n</tt></tag>
235 Set the maximum number of bytes printed in the listing for one line of
236 input. See the <tt><ref id=".LISTBYTES" name=".LISTBYTES"></tt> directive
237 for more information. The value zero can be used to encode an unlimited
238 number of printed bytes.
241 <label id="option-mm">
242 <tag><tt>-mm model, --memory-model model</tt></tag>
244 Define the default memory model. Possible model specifiers are near, far and
248 <label id="option-o">
249 <tag><tt>-o name</tt></tag>
251 The default output name is the name of the input file with the extension
252 replaced by ".o". If you don't like that, you may give another name with
253 the -o option. The output file will be placed in the same directory as
254 the source file, or, if -o is given, the full path in this name is used.
257 <label id="option--pagelength">
258 <tag><tt>--pagelength n</tt></tag>
260 sets the length of a listing page in lines. See the <tt><ref
261 id=".PAGELENGTH" name=".PAGELENGTH"></tt> directive for more information.
264 <label id="option--relax-checks">
265 <tag><tt>--relax-checks</tt></tag>
267 Relax some checks done by the assembler. This will allow code that is an
268 error in most cases and flagged as such by the assembler, but can be valid
269 in special situations.
273 <item>Short branches between two different segments.
274 <item>Byte sized address loads where the address is not a zeropage address.
278 <label id="option-s">
279 <tag><tt>-s, --smart-mode</tt></tag>
281 In smart mode (enabled by -s or the <tt><ref id=".SMART" name=".SMART"></tt>
282 pseudo instruction) the assembler will track usage of the <tt/REP/ and
283 <tt/SEP/ instructions in 65816 mode and update the operand sizes
284 accordingly. If the operand of such an instruction cannot be evaluated by
285 the assembler (for example, because the operand is an imported symbol), a
288 Beware: Since the assembler cannot trace the execution flow this may
289 lead to false results in some cases. If in doubt, use the .ixx and .axx
290 instructions to tell the assembler about the current settings. Smart
291 mode is off by default.
294 <label id="option-t">
295 <tag><tt>-t sys, --target sys</tt></tag>
297 Set the target system. This will enable translation of character strings and
298 character constants into the character set of the target platform. The
299 default for the target system is "none", which means that no translation
300 will take place. The assembler supports the same target systems as the
301 compiler, see there for a list.
303 Depending on the target, the default CPU type is also set. This can be
304 overriden by using the <tt/<ref id="option--cpu" name="--cpu">/ option.
307 <label id="option-v">
308 <tag><tt>-v, --verbose</tt></tag>
310 Increase the assembler verbosity. Usually only needed for debugging
311 purposes. You may use this option more than one time for even more
315 <label id="option-D">
316 <tag><tt>-D</tt></tag>
318 This option allows you to define symbols on the command line. Without a
319 value, the symbol is defined with the value zero. When giving a value,
320 you may use the '$' prefix for hexadecimal symbols. Please note
321 that for some operating systems, '$' has a special meaning, so
322 you may have to quote the expression.
325 <label id="option-I">
326 <tag><tt>-I dir, --include-dir dir</tt></tag>
328 Name a directory which is searched for include files. The option may be
329 used more than once to specify more than one directory to search. The
330 current directory is always searched first before considering any
331 additional directories. See also the section about <ref id="search-paths"
332 name="search paths">.
335 <label id="option-U">
336 <tag><tt>-U, --auto-import</tt></tag>
338 Mark symbols that are not defined in the sources as imported symbols. This
339 should be used with care since it delays error messages about typos and such
340 until the linker is run. The compiler uses the equivalent of this switch
341 (<tt><ref id=".AUTOIMPORT" name=".AUTOIMPORT"></tt>) to enable auto imported
342 symbols for the runtime library. However, the compiler is supposed to
343 generate code that runs through the assembler without problems, something
344 which is not always true for assembler programmers.
347 <label id="option-V">
348 <tag><tt>-V, --version</tt></tag>
350 Print the version number of the assembler. If you send any suggestions
351 or bugfixes, please include the version number.
354 <label id="option-W">
355 <tag><tt>-Wn</tt></tag>
357 Set the warning level for the assembler. Using -W2 the assembler will
358 even warn about such things like unused imported symbols. The default
359 warning level is 1, and it would probably be silly to set it to
367 <sect>Search paths<label id="search-paths"><p>
369 Normal include files are searched in the following places:
372 <item>The current file's directory.
373 <item>Any directory added with the <tt/<ref id="option-I" name="-I">/ option
375 <item>The value of the environment variable <tt/CA65_INC/ if it is defined.
376 <item>A subdirectory named <tt/asminc/ of the directory defined in the
377 environment variable <tt/CC65_HOME/, if it is defined.
378 <item>An optionally compiled-in directory.
381 Binary include files are searched in the following places:
384 <item>The current file's directory.
385 <item>Any directory added with the <tt/<ref id="option--bin-include-dir"
386 name="--bin-include-dir">/ option on the command line.
391 <sect>Input format<p>
393 <sect1>Assembler syntax<p>
395 The assembler accepts the standard 6502/65816 assembler syntax. One line may
396 contain a label (which is identified by a colon), and, in addition to the
397 label, an assembler mnemonic, a macro, or a control command (see section <ref
398 id="control-commands" name="Control Commands"> for supported control
399 commands). Alternatively, the line may contain a symbol definition using
400 the '=' token. Everything after a semicolon is handled as a comment (that is,
403 Here are some examples for valid input lines:
406 Label: ; A label and a comment
407 lda #$20 ; A 6502 instruction plus comment
408 L1: ldx #$20 ; Same with label
409 L2: .byte "Hello world" ; Label plus control command
410 mymac $20 ; Macro expansion
411 MySym = 3*L1 ; Symbol definition
412 MaSym = Label ; Another symbol
415 The assembler accepts
418 <item>all valid 6502 mnemonics when in 6502 mode (the default or after the
419 <tt><ref id=".P02" name=".P02"></tt> command was given).
420 <item>all valid 6502 mnemonics plus a set of illegal instructions when in
421 <ref id="6502X-mode" name="6502X mode">.
422 <item>all valid 65SC02 mnemonics when in 65SC02 mode (after the
423 <tt><ref id=".PSC02" name=".PSC02"></tt> command was given).
424 <item>all valid 65C02 mnemonics when in 65C02 mode (after the
425 <tt><ref id=".PC02" name=".PC02"></tt> command was given).
426 <item>all valid 65618 mnemonics when in 65816 mode (after the
427 <tt><ref id=".P816" name=".P816"></tt> command was given).
433 In 65816 mode, several aliases are accepted, in addition to the official
437 CPA is an alias for CMP
438 DEA is an alias for DEC A
439 INA is an alias for INC A
440 SWA is an alias for XBA
441 TAD is an alias for TCD
442 TAS is an alias for TCS
443 TDA is an alias for TDC
444 TSA is an alias for TSC
448 <sect1>6502X mode<label id="6502X-mode"><p>
450 6502X mode is an extension to the normal 6502 mode. In this mode, several
451 mnemonics for illegal instructions of the NMOS 6502 CPUs are accepted. Since
452 these instructions are illegal, there are no official mnemonics for them. The
453 unofficial ones are taken from <url
454 url="http://www.oxyron.de/html/opcodes02.html">. Please note that only the
455 ones marked as "stable" are supported. The following table uses information
456 from the mentioned web page, for more information, see there.
459 <item><tt>ALR: A:=(A and #{imm})/2;</tt>
460 <item><tt>ANC: A:=A and #{imm};</tt> Generates opcode $0B.
461 <item><tt>ARR: A:=(A and #{imm})/2;</tt>
462 <item><tt>AXS: X:=A and X-#{imm};</tt>
463 <item><tt>DCP: {adr}:={adr}-1; A-{adr};</tt>
464 <item><tt>ISC: {adr}:={adr}+1; A:=A-{adr};</tt>
465 <item><tt>LAS: A,X,S:={adr} and S;</tt>
466 <item><tt>LAX: A,X:={adr};</tt>
467 <item><tt>RLA: {adr}:={adr}rol; A:=A and {adr};</tt>
468 <item><tt>RRA: {adr}:={adr}ror; A:=A adc {adr};</tt>
469 <item><tt>SAX: {adr}:=A and X;</tt>
470 <item><tt>SLO: {adr}:={adr}*2; A:=A or {adr};</tt>
471 <item><tt>SRE: {adr}:={adr}/2; A:=A xor {adr};</tt>
476 <sect1>sweet16 mode<label id="sweet16-mode"><p>
478 SWEET 16 is an interpreter for a pseudo 16 bit CPU written by Steve Wozniak
479 for the Apple ][ machines. It is available in the Apple ][ ROM. ca65 can
480 generate code for this pseudo CPU when switched into sweet16 mode. The
481 following is special in sweet16 mode:
485 <item>The '@' character denotes indirect addressing and is no longer available
486 for cheap local labels. If you need cheap local labels, you will have to
487 switch to another lead character using the <tt/<ref id=".LOCALCHAR"
488 name=".LOCALCHAR">/ command.
490 <item>Registers are specified using <tt/R0/ .. <tt/R15/. In sweet16 mode,
491 these identifiers are reserved words.
495 Please note that the assembler does neither supply the interpreter needed for
496 SWEET 16 code, nor the zero page locations needed for the SWEET 16 registers,
497 nor does it call the interpreter. All this must be done by your program. Apple
498 ][ programmers do probably know how to use sweet16 mode.
500 For more information about SWEET 16, see
501 <url url="http://www.6502.org/source/interpreters/sweet16.htm">.
504 <sect1>Number format<p>
506 For literal values, the assembler accepts the widely used number formats: A
507 preceding '$' or a trailing 'h' denotes a hex value, a preceding '%'
508 denotes a binary value, and a bare number is interpreted as a decimal. There
509 are currently no octal values and no floats.
512 <sect1>Conditional assembly<p>
514 Please note that when using the conditional directives (<tt/.IF/ and friends),
515 the input must consist of valid assembler tokens, even in <tt/.IF/ branches
516 that are not assembled. The reason for this behaviour is that the assembler
517 must still be able to detect the ending tokens (like <tt/.ENDIF/), so
518 conversion of the input stream into tokens still takes place. As a consequence
519 conditional assembly directives may <bf/not/ be used to prevent normal text
520 (used as a comment or similar) from being assembled. <p>
526 <sect1>Expression evaluation<p>
528 All expressions are evaluated with (at least) 32 bit precision. An
529 expression may contain constant values and any combination of internal and
530 external symbols. Expressions that cannot be evaluated at assembly time
531 are stored inside the object file for evaluation by the linker.
532 Expressions referencing imported symbols must always be evaluated by the
536 <sect1>Size of an expression result<p>
538 Sometimes, the assembler must know about the size of the value that is the
539 result of an expression. This is usually the case, if a decision has to be
540 made, to generate a zero page or an absolute memory references. In this
541 case, the assembler has to make some assumptions about the result of an
545 <item> If the result of an expression is constant, the actual value is
546 checked to see if it's a byte sized expression or not.
547 <item> If the expression is explicitly casted to a byte sized expression by
548 one of the '>', '<' or '^' operators, it is a byte expression.
549 <item> If this is not the case, and the expression contains a symbol,
550 explicitly declared as zero page symbol (by one of the .importzp or
551 .exportzp instructions), then the whole expression is assumed to be
553 <item> If the expression contains symbols that are not defined, and these
554 symbols are local symbols, the enclosing scopes are searched for a
555 symbol with the same name. If one exists and this symbol is defined,
556 its attributes are used to determine the result size.
557 <item> In all other cases the expression is assumed to be word sized.
560 Note: If the assembler is not able to evaluate the expression at assembly
561 time, the linker will evaluate it and check for range errors as soon as
565 <sect1>Boolean expressions<p>
567 In the context of a boolean expression, any non zero value is evaluated as
568 true, any other value to false. The result of a boolean expression is 1 if
569 it's true, and zero if it's false. There are boolean operators with extreme
570 low precedence with version 2.x (where x > 0). The <tt/.AND/ and <tt/.OR/
571 operators are shortcut operators. That is, if the result of the expression is
572 already known, after evaluating the left hand side, the right hand side is
576 <sect1>Constant expressions<p>
578 Sometimes an expression must evaluate to a constant without looking at any
579 further input. One such example is the <tt/<ref id=".IF" name=".IF">/ command
580 that decides if parts of the code are assembled or not. An expression used in
581 the <tt/.IF/ command cannot reference a symbol defined later, because the
582 decision about the <tt/.IF/ must be made at the point when it is read. If the
583 expression used in such a context contains only constant numerical values,
584 there is no problem. When unresolvable symbols are involved it may get harder
585 for the assembler to determine if the expression is actually constant, and it
586 is even possible to create expressions that aren't recognized as constant.
587 Simplifying the expressions will often help.
589 In cases where the result of the expression is not needed immediately, the
590 assembler will delay evaluation until all input is read, at which point all
591 symbols are known. So using arbitrary complex constant expressions is no
592 problem in most cases.
596 <sect1>Available operators<label id="operators"><p>
600 <bf/Operator/| <bf/Description/| <bf/Precedence/@<hline>
601 | Built-in string functions| 0@
603 | Built-in pseudo-variables| 1@
604 | Built-in pseudo-functions| 1@
605 +| Unary positive| 1@
606 -| Unary negative| 1@
608 .BITNOT| Unary bitwise not| 1@
610 .LOBYTE| Unary low-byte operator| 1@
612 .HIBYTE| Unary high-byte operator| 1@
614 .BANKBYTE| Unary bank-byte operator| 1@
616 *| Multiplication| 2@
618 .MOD| Modulo operator| 2@
620 .BITAND| Bitwise and| 2@
622 .BITXOR| Binary bitwise xor| 2@
624 .SHL| Shift-left operator| 2@
626 .SHR| Shift-right operator| 2@
628 +| Binary addition| 3@
629 -| Binary subtraction| 3@
631 .BITOR| Bitwise or| 3@
633 = | Compare operator (equal)| 4@
634 <>| Compare operator (not equal)| 4@
635 <| Compare operator (less)| 4@
636 >| Compare operator (greater)| 4@
637 <=| Compare operator (less or equal)| 4@
638 >=| Compare operator (greater or equal)| 4@
641 .AND| Boolean and| 5@
642 .XOR| Boolean xor| 5@
644 ||<newline>
648 .NOT| Boolean not| 7@<hline>
650 <caption>Available operators, sorted by precedence
653 To force a specific order of evaluation, parentheses may be used, as usual.
657 <sect>Symbols and labels<p>
659 A symbol or label is an identifier that starts with a letter and is followed
660 by letters and digits. Depending on some features enabled (see
661 <tt><ref id="at_in_identifiers" name="at_in_identifiers"></tt>,
662 <tt><ref id="dollar_in_identifiers" name="dollar_in_identifiers"></tt> and
663 <tt><ref id="leading_dot_in_identifiers" name="leading_dot_in_identifiers"></tt>)
664 other characters may be present. Use of identifiers consisting of a single
665 character will not work in all cases, because some of these identifiers are
666 reserved keywords (for example "A" is not a valid identifier for a label,
667 because it is the keyword for the accumulator).
669 The assembler allows you to use symbols instead of naked values to make
670 the source more readable. There are a lot of different ways to define and
671 use symbols and labels, giving a lot of flexibility.
673 <sect1>Numeric constants<p>
675 Numeric constants are defined using the equal sign or the label assignment
676 operator. After doing
682 may use the symbol "two" in every place where a number is expected, and it is
683 evaluated to the value 2 in this context. The label assignment operator is
684 almost identical, but causes the symbol to be marked as a label, so it may be
685 handled differently in a debugger:
691 The right side can of course be an expression:
698 <label id="variables">
699 <sect1>Numeric variables<p>
701 Within macros and other control structures (<tt><ref id=".REPEAT"
702 name=".REPEAT"></tt>, ...) it is sometimes useful to have some sort of
703 variable. This can be achieved by the <tt>.SET</tt> operator. It creates a
704 symbol that may get assigned a different value later:
708 lda #four ; Loads 4 into A
710 lda #four ; Loads 3 into A
713 Since the value of the symbol can change later, it must be possible to
714 evaluate it when used (no delayed evaluation as with normal symbols). So the
715 expression used as the value must be constant.
717 Following is an example for a macro that generates a different label each time
718 it is used. It uses the <tt><ref id=".SPRINTF" name=".SPRINTF"></tt> function
719 and a numeric variable named <tt>lcount</tt>.
722 .lcount .set 0 ; Initialize the counter
725 .ident (.sprintf ("L%04X", lcount)):
726 lcount .set lcount + 1
731 <sect1>Standard labels<p>
733 A label is defined by writing the name of the label at the start of the line
734 (before any instruction mnemonic, macro or pseudo directive), followed by a
735 colon. This will declare a symbol with the given name and the value of the
736 current program counter.
739 <sect1>Local labels and symbols<p>
741 Using the <tt><ref id=".PROC" name=".PROC"></tt> directive, it is possible to
742 create regions of code where the names of labels and symbols are local to this
743 region. They are not known outside of this region and cannot be accessed from
744 there. Such regions may be nested like PROCEDUREs in Pascal.
746 See the description of the <tt><ref id=".PROC" name=".PROC"></tt>
747 directive for more information.
750 <sect1>Cheap local labels<p>
752 Cheap local labels are defined like standard labels, but the name of the
753 label must begin with a special symbol (usually '@', but this can be
754 changed by the <tt><ref id=".LOCALCHAR" name=".LOCALCHAR"></tt>
757 Cheap local labels are visible only between two non cheap labels. As soon as a
758 standard symbol is encountered (this may also be a local symbol if inside a
759 region defined with the <tt><ref id=".PROC" name=".PROC"></tt> directive), the
760 cheap local symbol goes out of scope.
762 You may use cheap local labels as an easy way to reuse common label
763 names like "Loop". Here is an example:
766 Clear: lda #$00 ; Global label
768 @Loop: sta Mem,y ; Local label
772 Sub: ... ; New global label
773 bne @Loop ; ERROR: Unknown identifier!
776 <sect1>Unnamed labels<p>
778 If you really want to write messy code, there are also unnamed labels. These
779 labels do not have a name (you guessed that already, didn't you?). A colon is
780 used to mark the absence of the name.
782 Unnamed labels may be accessed by using the colon plus several minus or plus
783 characters as a label designator. Using the '-' characters will create a back
784 reference (use the n'th label backwards), using '+' will create a forward
785 reference (use the n'th label in forward direction). An example will help to
808 As you can see from the example, unnamed labels will make even short
809 sections of code hard to understand, because you have to count labels
810 to find branch targets (this is the reason why I for my part do
811 prefer the "cheap" local labels). Nevertheless, unnamed labels are
812 convenient in some situations, so it's your decision.
814 <em/Note:/ <ref id="scopes" name="Scopes"> organize named symbols, not
815 unnamed ones, so scopes don't have an effect on unnamed labels.
819 <sect1>Using macros to define labels and constants<p>
821 While there are drawbacks with this approach, it may be handy in a few rare
822 situations. Using <tt><ref id=".DEFINE" name=".DEFINE"></tt>, it is possible
823 to define symbols or constants that may be used elsewhere. One of the
824 advantages is that you can use it to define string constants (this is not
825 possible with the other symbol types).
827 Please note: <tt/.DEFINE/ style macros do token replacements on a low level,
828 so the names do not adhere to scoping, diagnostics may be misleading, there
829 are no symbols to look up in the map file, and there is no debug info.
830 Especially the first problem in the list can lead to very nasty programming
831 errors. Because of these problems, the general advice is, <bf/NOT/ do use
832 <tt/.DEFINE/ if you don't have to.
838 .DEFINE version "SOS V2.3"
840 four = two * two ; Ok
843 .PROC ; Start local scope
844 two = 3 ; Will give "2 = 3" - invalid!
849 <sect1>Symbols and <tt>.DEBUGINFO</tt><p>
851 If <tt><ref id=".DEBUGINFO" name=".DEBUGINFO"></tt> is enabled (or <ref
852 id="option-g" name="-g"> is given on the command line), global, local and
853 cheap local labels are written to the object file and will be available in the
854 symbol file via the linker. Unnamed labels are not written to the object file,
855 because they don't have a name which would allow to access them.
859 <sect>Scopes<label id="scopes"><p>
861 ca65 implements several sorts of scopes for symbols.
863 <sect1>Global scope<p>
865 All (non cheap local) symbols that are declared outside of any nested scopes
869 <sect1>Cheap locals<p>
871 A special scope is the scope for cheap local symbols. It lasts from one non
872 local symbol to the next one, without any provisions made by the programmer.
873 All other scopes differ in usage but use the same concept internally.
876 <sect1>Generic nested scopes<p>
878 A nested scoped for generic use is started with <tt/<ref id=".SCOPE"
879 name=".SCOPE">/ and closed with <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/.
880 The scope can have a name, in which case it is accessible from the outside by
881 using <ref id="scopesyntax" name="explicit scopes">. If the scope does not
882 have a name, all symbols created within the scope are local to the scope, and
883 aren't accessible from the outside.
885 A nested scope can access symbols from the local or from enclosing scopes by
886 name without using explicit scope names. In some cases there may be
887 ambiguities, for example if there is a reference to a local symbol that is not
888 yet defined, but a symbol with the same name exists in outer scopes:
900 In the example above, the <tt/lda/ instruction will load the value 3 into the
901 accumulator, because <tt/foo/ is redefined in the scope. However:
913 Here, <tt/lda/ will still load from <tt/$12,x/, but since it is unknown to the
914 assembler that <tt/foo/ is a zeropage symbol when translating the instruction,
915 absolute mode is used instead. In fact, the assembler will not use absolute
916 mode by default, but it will search through the enclosing scopes for a symbol
917 with the given name. If one is found, the address size of this symbol is used.
918 This may lead to errors:
930 In this case, when the assembler sees the symbol <tt/foo/ in the <tt/lda/
931 instruction, it will search for an already defined symbol <tt/foo/. It will
932 find <tt/foo/ in scope <tt/outer/, and a close look reveals that it is a
933 zeropage symbol. So the assembler will use zeropage addressing mode. If
934 <tt/foo/ is redefined later in scope <tt/inner/, the assembler tries to change
935 the address in the <tt/lda/ instruction already translated, but since the new
936 value needs absolute addressing mode, this fails, and an error message "Range
939 Of course the most simple solution for the problem is to move the definition
940 of <tt/foo/ in scope <tt/inner/ upwards, so it precedes its use. There may be
941 rare cases when this cannot be done. In these cases, you can use one of the
942 address size override operators:
954 This will cause the <tt/lda/ instruction to be translated using absolute
955 addressing mode, which means changing the symbol reference later does not
959 <sect1>Nested procedures<p>
961 A nested procedure is created by use of <tt/<ref id=".PROC" name=".PROC">/. It
962 differs from a <tt/<ref id=".SCOPE" name=".SCOPE">/ in that it must have a
963 name, and a it will introduce a symbol with this name in the enclosing scope.
972 is actually the same as
981 This is the reason why a procedure must have a name. If you want a scope
982 without a name, use <tt/<ref id=".SCOPE" name=".SCOPE">/.
984 <em/Note:/ As you can see from the example above, scopes and symbols live in
985 different namespaces. There can be a symbol named <tt/foo/ and a scope named
986 <tt/foo/ without any conflicts (but see the section titled <ref
987 id="scopesearch" name=""Scope search order"">).
990 <sect1>Structs, unions and enums<p>
992 Structs, unions and enums are explained in a <ref id="structs" name="separate
993 section">, I do only cover them here, because if they are declared with a
994 name, they open a nested scope, similar to <tt/<ref id=".SCOPE"
995 name=".SCOPE">/. However, when no name is specified, the behaviour is
996 different: In this case, no new scope will be opened, symbols declared within
997 a struct, union, or enum declaration will then be added to the enclosing scope
1001 <sect1>Explicit scope specification<label id="scopesyntax"><p>
1003 Accessing symbols from other scopes is possible by using an explicit scope
1004 specification, provided that the scope where the symbol lives in has a name.
1005 The namespace token (<tt/::/) is used to access other scopes:
1013 lda foo::bar ; Access foo in scope bar
1016 The only way to deny access to a scope from the outside is to declare a scope
1017 without a name (using the <tt/<ref id=".SCOPE" name=".SCOPE">/ command).
1019 A special syntax is used to specify the global scope: If a symbol or scope is
1020 preceded by the namespace token, the global scope is searched:
1027 lda #::bar ; Access the global bar (which is 3)
1032 <sect1>Scope search order<label id="scopesearch"><p>
1034 The assembler searches for a scope in a similar way as for a symbol. First, it
1035 looks in the current scope, and then it walks up the enclosing scopes until
1038 However, one important thing to note when using explicit scope syntax is, that
1039 a symbol may be accessed before it is defined, but a scope may <bf/not/ be
1040 used without a preceding definition. This means that in the following
1049 lda #foo::bar ; Will load 3, not 2!
1056 the reference to the scope <tt/foo/ will use the global scope, and not the
1057 local one, because the local one is not visible at the point where it is
1060 Things get more complex if a complete chain of scopes is specified:
1071 lda #outer::inner::bar ; 1
1083 When <tt/outer::inner::bar/ is referenced in the <tt/lda/ instruction, the
1084 assembler will first search in the local scope for a scope named <tt/outer/.
1085 Since none is found, the enclosing scope (<tt/another/) is checked. There is
1086 still no scope named <tt/outer/, so scope <tt/foo/ is checked, and finally
1087 scope <tt/outer/ is found. Within this scope, <tt/inner/ is searched, and in
1088 this scope, the assembler looks for a symbol named <tt/bar/.
1090 Please note that once the anchor scope is found, all following scopes
1091 (<tt/inner/ in this case) are expected to be found exactly in this scope. The
1092 assembler will search the scope tree only for the first scope (if it is not
1093 anchored in the root scope). Starting from there on, there is no flexibility,
1094 so if the scope named <tt/outer/ found by the assembler does not contain a
1095 scope named <tt/inner/, this would be an error, even if such a pair does exist
1096 (one level up in global scope).
1098 Ambiguities that may be introduced by this search algorithm may be removed by
1099 anchoring the scope specification in the global scope. In the example above,
1100 if you want to access the "other" symbol <tt/bar/, you would have to write:
1111 lda #::outer::inner::bar ; 2
1124 <sect>Address sizes and memory models<label id="address-sizes"><p>
1126 <sect1>Address sizes<p>
1128 ca65 assigns each segment and each symbol an address size. This is true, even
1129 if the symbol is not used as an address. You may also think of a value range
1130 of the symbol instead of an address size.
1132 Possible address sizes are:
1135 <item>Zeropage or direct (8 bits)
1136 <item>Absolute (16 bits)
1138 <item>Long (32 bits)
1141 Since the assembler uses default address sizes for the segments and symbols,
1142 it is usually not necessary to override the default behaviour. In cases, where
1143 it is necessary, the following keywords may be used to specify address sizes:
1146 <item>DIRECT, ZEROPAGE or ZP for zeropage addressing (8 bits).
1147 <item>ABSOLUTE, ABS or NEAR for absolute addressing (16 bits).
1148 <item>FAR for far addressing (24 bits).
1149 <item>LONG or DWORD for long addressing (32 bits).
1153 <sect1>Address sizes of segments<p>
1155 The assembler assigns an address size to each segment. Since the
1156 representation of a label within this segment is "segment start + offset",
1157 labels will inherit the address size of the segment they are declared in.
1159 The address size of a segment may be changed, by using an optional address
1160 size modifier. See the <tt/<ref id=".SEGMENT" name="segment directive">/ for
1161 an explanation on how this is done.
1164 <sect1>Address sizes of symbols<p>
1169 <sect1>Memory models<p>
1171 The default address size of a segment depends on the memory model used. Since
1172 labels inherit the address size from the segment they are declared in,
1173 changing the memory model is an easy way to change the address size of many
1179 <sect>Pseudo variables<label id="pseudo-variables"><p>
1181 Pseudo variables are readable in all cases, and in some special cases also
1184 <sect1><tt>*</tt><p>
1186 Reading this pseudo variable will return the program counter at the start
1187 of the current input line.
1189 Assignment to this variable is possible when <tt/<ref id=".FEATURE"
1190 name=".FEATURE pc_assignment">/ is used. Note: You should not use
1191 assignments to <tt/*/, use <tt/<ref id=".ORG" name=".ORG">/ instead.
1194 <sect1><tt>.CPU</tt><label id=".CPU"><p>
1196 Reading this pseudo variable will give a constant integer value that
1197 tells which CPU is currently enabled. It can also tell which instruction
1198 set the CPU is able to translate. The value read from the pseudo variable
1199 should be further examined by using one of the constants defined by the
1200 "cpu" macro package (see <tt/<ref id=".MACPACK" name=".MACPACK">/).
1202 It may be used to replace the .IFPxx pseudo instructions or to construct
1203 even more complex expressions.
1209 .if (.cpu .bitand CPU_ISET_65816)
1221 <sect1><tt>.PARAMCOUNT</tt><label id=".PARAMCOUNT"><p>
1223 This builtin pseudo variable is only available in macros. It is replaced by
1224 the actual number of parameters that were given in the macro invocation.
1229 .macro foo arg1, arg2, arg3
1230 .if .paramcount <> 3
1231 .error "Too few parameters for macro foo"
1237 See section <ref id="macros" name="Macros">.
1240 <sect1><tt>.TIME</tt><label id=".TIME"><p>
1242 Reading this pseudo variable will give a constant integer value that
1243 represents the current time in POSIX standard (as seconds since the
1246 It may be used to encode the time of translation somewhere in the created
1252 .dword .time ; Place time here
1256 <sect1><tt>.VERSION</tt><label id=".VERSION"><p>
1258 Reading this pseudo variable will give the assembler version according to
1259 the following formula:
1261 VER_MAJOR*$100 + VER_MINOR*$10
1263 It may be used to encode the assembler version or check the assembler for
1264 special features not available with older versions.
1268 Version 2.14 of the assembler will return $2E0 as numerical constant when
1269 reading the pseudo variable <tt/.VERSION/.
1273 <sect>Pseudo functions<label id="pseudo-functions"><p>
1275 Pseudo functions expect their arguments in parenthesis, and they have a result,
1276 either a string or an expression.
1279 <sect1><tt>.ADDRSIZE</tt><label id=".ADDRSIZE"><p>
1281 The <tt/.ADDRSIZE/ function is used to return the interal address size
1282 associated with a symbol. This can be helpful in macros when knowing the address
1283 size of symbol can help with custom instructions.
1289 .if .ADDRSIZE(foo) = 1
1290 ;do custom command based on zeropage addressing:
1292 .elseif .ADDRSIZE(foo) = 2
1293 ;do custom command based on absolute addressing:
1296 .elseif .ADDRSIZE(foo) = 0
1297 ; no address size defined for this symbol:
1298 .out .sprintf("Error, address size unknown for symbol %s", .string(foo))
1303 This command is new and must be enabled with the <tt/.FEATURE addrsize/ command.
1305 See: <tt><ref id=".FEATURE" name=".FEATURE"></tt>
1308 <sect1><tt>.BANK</tt><label id=".BANK"><p>
1310 The <tt/.BANK/ function is used to support systems with banked memory. The
1311 argument is an expression with exactly one segment reference - usually a
1312 label. The function result is the value of the <tt/bank/ attribute assigned
1313 to the run memory area of the segment. Please see the linker documentation
1314 for more information about memory areas and their attributes.
1316 The value of <tt/.BANK/ can be used to switch memory so that a memory bank
1317 containing specific data is available.
1319 The <tt/bank/ attribute is a 32 bit integer and so is the result of the
1320 <tt/.BANK/ function. You will have to use <tt><ref id=".LOBYTE"
1321 name=".LOBYTE"></tt> or similar functions to address just part of it.
1323 Please note that <tt/.BANK/ will always get evaluated in the link stage, so
1324 an expression containing <tt/.BANK/ can never be used where a constant known
1325 result is expected (for example with <tt/.RES/).
1342 .byte <.BANK (banked_func_1)
1345 .byte <.BANK (banked_func_2)
1351 <sect1><tt>.BANKBYTE</tt><label id=".BANKBYTE"><p>
1353 The function returns the bank byte (that is, bits 16-23) of its argument.
1354 It works identical to the '^' operator.
1356 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1357 <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>
1360 <sect1><tt>.BLANK</tt><label id=".BLANK"><p>
1362 Builtin function. The function evaluates its argument in braces and yields
1363 "false" if the argument is non blank (there is an argument), and "true" if
1364 there is no argument. The token list that makes up the function argument
1365 may optionally be enclosed in curly braces. This allows the inclusion of
1366 tokens that would otherwise terminate the list (the closing right
1367 parenthesis). The curly braces are not considered part of the list, a list
1368 just consisting of curly braces is considered to be empty.
1370 As an example, the <tt/.IFBLANK/ statement may be replaced by
1378 <sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
1380 Builtin string function. The function allows to concatenate a list of string
1381 constants separated by commas. The result is a string constant that is the
1382 concatenation of all arguments. This function is most useful in macros and
1383 when used together with the <tt/.STRING/ builtin function. The function may
1384 be used in any case where a string constant is expected.
1389 .include .concat ("myheader", ".", "inc")
1392 This is the same as the command
1395 .include "myheader.inc"
1399 <sect1><tt>.CONST</tt><label id=".CONST"><p>
1401 Builtin function. The function evaluates its argument in braces and
1402 yields "true" if the argument is a constant expression (that is, an
1403 expression that yields a constant value at assembly time) and "false"
1404 otherwise. As an example, the .IFCONST statement may be replaced by
1411 <sect1><tt>.HIBYTE</tt><label id=".HIBYTE"><p>
1413 The function returns the high byte (that is, bits 8-15) of its argument.
1414 It works identical to the '>' operator.
1416 See: <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>,
1417 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1420 <sect1><tt>.HIWORD</tt><label id=".HIWORD"><p>
1422 The function returns the high word (that is, bits 16-31) of its argument.
1424 See: <tt><ref id=".LOWORD" name=".LOWORD"></tt>
1427 <sect1><tt>.IDENT</tt><label id=".IDENT"><p>
1429 The function expects a string as its argument, and converts this argument
1430 into an identifier. If the string starts with the current <tt/<ref
1431 id=".LOCALCHAR" name=".LOCALCHAR">/, it will be converted into a cheap local
1432 identifier, otherwise it will be converted into a normal identifier.
1437 .macro makelabel arg1, arg2
1438 .ident (.concat (arg1, arg2)):
1441 makelabel "foo", "bar"
1443 .word foobar ; Valid label
1447 <sect1><tt>.LEFT</tt><label id=".LEFT"><p>
1449 Builtin function. Extracts the left part of a given token list.
1454 .LEFT (<int expr>, <token list>)
1457 The first integer expression gives the number of tokens to extract from
1458 the token list. The second argument is the token list itself. The token
1459 list may optionally be enclosed into curly braces. This allows the
1460 inclusion of tokens that would otherwise terminate the list (the closing
1461 right paren in the given case).
1465 To check in a macro if the given argument has a '#' as first token
1466 (immediate addressing mode), use something like this:
1471 .if (.match (.left (1, {arg}), #))
1473 ; ldax called with immediate operand
1481 See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
1482 name=".RIGHT"></tt> builtin functions.
1485 <sect1><tt>.LOBYTE</tt><label id=".LOBYTE"><p>
1487 The function returns the low byte (that is, bits 0-7) of its argument.
1488 It works identical to the '<' operator.
1490 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1491 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1494 <sect1><tt>.LOWORD</tt><label id=".LOWORD"><p>
1496 The function returns the low word (that is, bits 0-15) of its argument.
1498 See: <tt><ref id=".HIWORD" name=".HIWORD"></tt>
1501 <sect1><tt>.MATCH</tt><label id=".MATCH"><p>
1503 Builtin function. Matches two token lists against each other. This is
1504 most useful within macros, since macros are not stored as strings, but
1510 .MATCH(<token list #1>, <token list #2>)
1513 Both token list may contain arbitrary tokens with the exception of the
1514 terminator token (comma resp. right parenthesis) and
1521 The token lists may optionally be enclosed into curly braces. This allows
1522 the inclusion of tokens that would otherwise terminate the list (the closing
1523 right paren in the given case). Often a macro parameter is used for any of
1526 Please note that the function does only compare tokens, not token
1527 attributes. So any number is equal to any other number, regardless of the
1528 actual value. The same is true for strings. If you need to compare tokens
1529 <em/and/ token attributes, use the <tt><ref id=".XMATCH"
1530 name=".XMATCH"></tt> function.
1534 Assume the macro <tt/ASR/, that will shift right the accumulator by one,
1535 while honoring the sign bit. The builtin processor instructions will allow
1536 an optional "A" for accu addressing for instructions like <tt/ROL/ and
1537 <tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
1538 to check for this and print and error for invalid calls.
1543 .if (.not .blank(arg)) .and (.not .match ({arg}, a))
1544 .error "Syntax error"
1547 cmp #$80 ; Bit 7 into carry
1548 lsr a ; Shift carry into bit 7
1553 The macro will only accept no arguments, or one argument that must be the
1554 reserved keyword "A".
1556 See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
1559 <sect1><tt>.MAX</tt><label id=".MAX"><p>
1561 Builtin function. The result is the larger of two values.
1566 .MAX (<value #1>, <value #2>)
1572 ; Reserve space for the larger of two data blocks
1573 savearea: .max (.sizeof (foo), .sizeof (bar))
1576 See: <tt><ref id=".MIN" name=".MIN"></tt>
1579 <sect1><tt>.MID</tt><label id=".MID"><p>
1581 Builtin function. Takes a starting index, a count and a token list as
1582 arguments. Will return part of the token list.
1587 .MID (<int expr>, <int expr>, <token list>)
1590 The first integer expression gives the starting token in the list (the first
1591 token has index 0). The second integer expression gives the number of tokens
1592 to extract from the token list. The third argument is the token list itself.
1593 The token list may optionally be enclosed into curly braces. This allows the
1594 inclusion of tokens that would otherwise terminate the list (the closing
1595 right paren in the given case).
1599 To check in a macro if the given argument has a '<tt/#/' as first token
1600 (immediate addressing mode), use something like this:
1605 .if (.match (.mid (0, 1, {arg}), #))
1607 ; ldax called with immediate operand
1615 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
1616 name=".RIGHT"></tt> builtin functions.
1619 <sect1><tt>.MIN</tt><label id=".MIN"><p>
1621 Builtin function. The result is the smaller of two values.
1626 .MIN (<value #1>, <value #2>)
1632 ; Reserve space for some data, but 256 bytes minimum
1633 savearea: .min (.sizeof (foo), 256)
1636 See: <tt><ref id=".MAX" name=".MAX"></tt>
1639 <sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
1641 Builtin function. The function expects an identifier as argument in braces.
1642 The argument is evaluated, and the function yields "true" if the identifier
1643 is a symbol that has already been referenced somewhere in the source file up
1644 to the current position. Otherwise the function yields false. As an example,
1645 the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
1651 See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1654 <sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
1656 Builtin function. Extracts the right part of a given token list.
1661 .RIGHT (<int expr>, <token list>)
1664 The first integer expression gives the number of tokens to extract from the
1665 token list. The second argument is the token list itself. The token list
1666 may optionally be enclosed into curly braces. This allows the inclusion of
1667 tokens that would otherwise terminate the list (the closing right paren in
1670 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
1671 name=".MID"></tt> builtin functions.
1674 <sect1><tt>.SIZEOF</tt><label id=".SIZEOF"><p>
1676 <tt/.SIZEOF/ is a pseudo function that returns the size of its argument. The
1677 argument can be a struct/union, a struct member, a procedure, or a label. In
1678 case of a procedure or label, its size is defined by the amount of data
1679 placed in the segment where the label is relative to. If a line of code
1680 switches segments (for example in a macro) data placed in other segments
1681 does not count for the size.
1683 Please note that a symbol or scope must exist, before it is used together with
1684 <tt/.SIZEOF/ (this may get relaxed later, but will always be true for scopes).
1685 A scope has preference over a symbol with the same name, so if the last part
1686 of a name represents both, a scope and a symbol, the scope is chosen over the
1689 After the following code:
1692 .struct Point ; Struct size = 4
1697 P: .tag Point ; Declare a point
1698 @P: .tag Point ; Declare another point
1710 .data ; Segment switch!!!
1716 <tag><tt/.sizeof(Point)/</tag>
1717 will have the value 4, because this is the size of struct <tt/Point/.
1719 <tag><tt/.sizeof(Point::xcoord)/</tag>
1720 will have the value 2, because this is the size of the member <tt/xcoord/
1721 in struct <tt/Point/.
1723 <tag><tt/.sizeof(P)/</tag>
1724 will have the value 4, this is the size of the data declared on the same
1725 source line as the label <tt/P/, which is in the same segment that <tt/P/
1728 <tag><tt/.sizeof(@P)/</tag>
1729 will have the value 4, see above. The example demonstrates that <tt/.SIZEOF/
1730 does also work for cheap local symbols.
1732 <tag><tt/.sizeof(Code)/</tag>
1733 will have the value 3, since this is amount of data emitted into the code
1734 segment, the segment that was active when <tt/Code/ was entered. Note that
1735 this value includes the amount of data emitted in child scopes (in this
1736 case <tt/Code::Inner/).
1738 <tag><tt/.sizeof(Code::Inner)/</tag>
1739 will have the value 1 as expected.
1741 <tag><tt/.sizeof(Data)/</tag>
1742 will have the value 0. Data is emitted within the scope <tt/Data/, but since
1743 the segment is switched after entry, this data is emitted into another
1748 <sect1><tt>.STRAT</tt><label id=".STRAT"><p>
1750 Builtin function. The function accepts a string and an index as
1751 arguments and returns the value of the character at the given position
1752 as an integer value. The index is zero based.
1758 ; Check if the argument string starts with '#'
1759 .if (.strat (Arg, 0) = '#')
1766 <sect1><tt>.SPRINTF</tt><label id=".SPRINTF"><p>
1768 Builtin function. It expects a format string as first argument. The number
1769 and type of the following arguments depend on the format string. The format
1770 string is similar to the one of the C <tt/printf/ function. Missing things
1771 are: Length modifiers, variable width.
1773 The result of the function is a string.
1780 ; Generate an identifier:
1781 .ident (.sprintf ("%s%03d", "label", num)):
1785 <sect1><tt>.STRING</tt><label id=".STRING"><p>
1787 Builtin function. The function accepts an argument in braces and converts
1788 this argument into a string constant. The argument may be an identifier, or
1789 a constant numeric value.
1791 Since you can use a string in the first place, the use of the function may
1792 not be obvious. However, it is useful in macros, or more complex setups.
1797 ; Emulate other assemblers:
1799 .segment .string(name)
1804 <sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
1806 Builtin function. The function accepts a string argument in braces and
1807 evaluates to the length of the string.
1811 The following macro encodes a string as a pascal style string with
1812 a leading length byte.
1816 .byte .strlen(Arg), Arg
1821 <sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
1823 Builtin function. The function accepts a token list in braces. The function
1824 result is the number of tokens given as argument. The token list may
1825 optionally be enclosed into curly braces which are not considered part of
1826 the list and not counted. Enclosement in curly braces allows the inclusion
1827 of tokens that would otherwise terminate the list (the closing right paren
1832 The <tt/ldax/ macro accepts the '#' token to denote immediate addressing (as
1833 with the normal 6502 instructions). To translate it into two separate 8 bit
1834 load instructions, the '#' token has to get stripped from the argument:
1838 .if (.match (.mid (0, 1, {arg}), #))
1839 ; ldax called with immediate operand
1840 lda #<(.right (.tcount ({arg})-1, {arg}))
1841 ldx #>(.right (.tcount ({arg})-1, {arg}))
1849 <sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
1851 Builtin function. Matches two token lists against each other. This is
1852 most useful within macros, since macros are not stored as strings, but
1858 .XMATCH(<token list #1>, <token list #2>)
1861 Both token list may contain arbitrary tokens with the exception of the
1862 terminator token (comma resp. right parenthesis) and
1869 The token lists may optionally be enclosed into curly braces. This allows
1870 the inclusion of tokens that would otherwise terminate the list (the closing
1871 right paren in the given case). Often a macro parameter is used for any of
1874 The function compares tokens <em/and/ token values. If you need a function
1875 that just compares the type of tokens, have a look at the <tt><ref
1876 id=".MATCH" name=".MATCH"></tt> function.
1878 See: <tt><ref id=".MATCH" name=".MATCH"></tt>
1882 <sect>Control commands<label id="control-commands"><p>
1884 Here's a list of all control commands and a description, what they do:
1887 <sect1><tt>.A16</tt><label id=".A16"><p>
1889 Valid only in 65816 mode. Switch the accumulator to 16 bit.
1891 Note: This command will not emit any code, it will tell the assembler to
1892 create 16 bit operands for immediate accumulator addressing mode.
1894 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1897 <sect1><tt>.A8</tt><label id=".A8"><p>
1899 Valid only in 65816 mode. Switch the accumulator to 8 bit.
1901 Note: This command will not emit any code, it will tell the assembler to
1902 create 8 bit operands for immediate accu addressing mode.
1904 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1907 <sect1><tt>.ADDR</tt><label id=".ADDR"><p>
1909 Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
1910 may be used for better readability if the data words are address values. In
1911 65816 mode, the address is forced to be 16 bit wide to fit into the current
1912 segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
1913 must be followed by a sequence of (not necessarily constant) expressions.
1918 .addr $0D00, $AF13, _Clear
1921 See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
1925 <sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
1927 Align data to a given boundary. The command expects a constant integer
1928 argument in the range 1 ... 65536, plus an optional second argument
1929 in byte range. If there is a second argument, it is used as fill value,
1930 otherwise the value defined in the linker configuration file is used
1931 (the default for this value is zero).
1933 <tt/.ALIGN/ will insert fill bytes, and the number of fill bytes depend of
1934 the final address of the segment. <tt/.ALIGN/ cannot insert a variable
1935 number of bytes, since that would break address calculations within the
1936 module. So each <tt/.ALIGN/ expects the segment to be aligned to a multiple
1937 of the alignment, because that allows the number of fill bytes to be
1938 calculated in advance by the assembler. You are therefore required to
1939 specify a matching alignment for the segment in the linker config. The
1940 linker will output a warning if the alignment of the segment is less than
1941 what is necessary to have a correct alignment in the object file.
1949 Some unexpected behaviour might occur if there are multiple <tt/.ALIGN/
1950 commands with different arguments. To allow the assembler to calculate the
1951 number of fill bytes in advance, the alignment of the segment must be a
1952 multiple of each of the alignment factors. This may result in unexpectedly
1953 large alignments for the segment within the module.
1964 For the assembler to be able to align correctly, the segment must be aligned
1965 to the least common multiple of 15 and 18 which is 90. The assembler will
1966 calculate this automatically and will mark the segment with this value.
1968 Unfortunately, the combined alignment may get rather large without the user
1969 knowing about it, wasting space in the final executable. If we add another
1970 alignment to the example above
1981 the assembler will force a segment alignment to the least common multiple of
1982 15, 18 and 251 - which is 22590. To protect the user against errors, the
1983 assembler will issue a warning when the combined alignment exceeds 256. The
1984 command line option <tt><ref id="option--large-alignment"
1985 name="--large-alignment"></tt> will disable this warning.
1987 Please note that with alignments that are a power of two (which were the
1988 only alignments possible in older versions of the assembler), the problem is
1989 less severe, because the least common multiple of powers to the same base is
1990 always the larger one.
1994 <sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
1996 Define a string with a trailing zero.
2001 Msg: .asciiz "Hello world"
2004 This will put the string "Hello world" followed by a binary zero into
2005 the current segment. There may be more strings separated by commas, but
2006 the binary zero is only appended once (after the last one).
2009 <sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
2011 Add an assertion. The command is followed by an expression, an action
2012 specifier, and an optional message that is output in case the assertion
2013 fails. If no message was given, the string "Assertion failed" is used. The
2014 action specifier may be one of <tt/warning/, <tt/error/, <tt/ldwarning/ or
2015 <tt/lderror/. In the former two cases, the assertion is evaluated by the
2016 assembler if possible, and in any case, it's also passed to the linker in
2017 the object file (if one is generated). The linker will then evaluate the
2018 expression when segment placement has been done.
2023 .assert * = $8000, error, "Code not at $8000"
2026 The example assertion will check that the current location is at $8000,
2027 when the output file is written, and abort with an error if this is not
2028 the case. More complex expressions are possible. The action specifier
2029 <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
2030 an error message. In the latter case, generation of the output file is
2031 suppressed in both the assembler and linker.
2034 <sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
2036 Is followed by a plus or a minus character. When switched on (using a
2037 +), undefined symbols are automatically marked as import instead of
2038 giving errors. When switched off (which is the default so this does not
2039 make much sense), this does not happen and an error message is
2040 displayed. The state of the autoimport flag is evaluated when the
2041 complete source was translated, before outputting actual code, so it is
2042 <em/not/ possible to switch this feature on or off for separate sections
2043 of code. The last setting is used for all symbols.
2045 You should probably not use this switch because it delays error
2046 messages about undefined symbols until the link stage. The cc65
2047 compiler (which is supposed to produce correct assembler code in all
2048 circumstances, something which is not true for most assembler
2049 programmers) will insert this command to avoid importing each and every
2050 routine from the runtime library.
2055 .autoimport + ; Switch on auto import
2058 <sect1><tt>.BANKBYTES</tt><label id=".BANKBYTES"><p>
2060 Define byte sized data by extracting only the bank byte (that is, bits 16-23) from
2061 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2062 the operator '^' prepended to each expression in its list.
2067 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2069 TableLookupLo: .lobytes MyTable
2070 TableLookupHi: .hibytes MyTable
2071 TableLookupBank: .bankbytes MyTable
2074 which is equivalent to
2077 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2078 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2079 TableLookupBank: .byte ^TableItem0, ^TableItem1, ^TableItem2, ^TableItem3
2082 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2083 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
2084 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>
2087 <sect1><tt>.BSS</tt><label id=".BSS"><p>
2089 Switch to the BSS segment. The name of the BSS segment is always "BSS",
2090 so this is a shortcut for
2096 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2099 <sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
2101 Define byte sized data. Must be followed by a sequence of (byte ranged)
2102 expressions or strings.
2108 .byt "world", $0D, $00
2112 <sect1><tt>.CASE</tt><label id=".CASE"><p>
2114 Switch on or off case sensitivity on identifiers. The default is off
2115 (that is, identifiers are case sensitive), but may be changed by the
2116 -i switch on the command line.
2117 The command must be followed by a '+' or '-' character to switch the
2118 option on or off respectively.
2123 .case - ; Identifiers are not case sensitive
2127 <sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
2129 Apply a custom mapping for characters. The command is followed by two
2130 numbers. The first one is the index of the source character (range 1..255),
2131 the second one is the mapping (range 0..255). The mapping applies to all
2132 character and string constants when they generate output, and overrides a
2133 mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
2134 command line switch.
2139 .charmap $41, $61 ; Map 'A' to 'a'
2143 <sect1><tt>.CODE</tt><label id=".CODE"><p>
2145 Switch to the CODE segment. The name of the CODE segment is always
2146 "CODE", so this is a shortcut for
2152 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2155 <sect1><tt>.CONDES</tt><label id=".CONDES"><p>
2157 Export a symbol and mark it in a special way. The linker is able to build
2158 tables of all such symbols. This may be used to automatically create a list
2159 of functions needed to initialize linked library modules.
2161 Note: The linker has a feature to build a table of marked routines, but it
2162 is your code that must call these routines, so just declaring a symbol with
2163 <tt/.CONDES/ does nothing by itself.
2165 All symbols are exported as an absolute (16 bit) symbol. You don't need to
2166 use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
2167 is implied by <tt/.CONDES/.
2169 <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
2170 <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
2171 specifying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
2172 The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2173 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2174 name=".INTERRUPTOR"></tt> commands are actually shortcuts for <tt/.CONDES/
2175 with a type of <tt/constructor/ resp. <tt/destructor/ or <tt/interruptor/.
2177 After the type, an optional priority may be specified. Higher numeric values
2178 mean higher priority. If no priority is given, the default priority of 7 is
2179 used. Be careful when assigning priorities to your own module constructors
2180 so they won't interfere with the ones in the cc65 library.
2185 .condes ModuleInit, constructor
2186 .condes ModInit, 0, 16
2189 See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2190 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2191 name=".INTERRUPTOR"></tt> commands and the separate section <ref id="condes"
2192 name="Module constructors/destructors"> explaining the feature in more
2196 <sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
2198 Export a symbol and mark it as a module constructor. This may be used
2199 together with the linker to build a table of constructor subroutines that
2200 are called by the startup code.
2202 Note: The linker has a feature to build a table of marked routines, but it
2203 is your code that must call these routines, so just declaring a symbol as
2204 constructor does nothing by itself.
2206 A constructor is always exported as an absolute (16 bit) symbol. You don't
2207 need to use an additional <tt/.export/ statement, this is implied by
2208 <tt/.constructor/. It may have an optional priority that is separated by a
2209 comma. Higher numeric values mean a higher priority. If no priority is
2210 given, the default priority of 7 is used. Be careful when assigning
2211 priorities to your own module constructors so they won't interfere with the
2212 ones in the cc65 library.
2217 .constructor ModuleInit
2218 .constructor ModInit, 16
2221 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2222 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
2223 <ref id="condes" name="Module constructors/destructors"> explaining the
2224 feature in more detail.
2227 <sect1><tt>.DATA</tt><label id=".DATA"><p>
2229 Switch to the DATA segment. The name of the DATA segment is always
2230 "DATA", so this is a shortcut for
2236 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2239 <sect1><tt>.DBYT</tt><label id=".DBYT"><p>
2241 Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
2242 create word sized data in native 65XX format). Must be followed by a
2243 sequence of (word ranged) expressions.
2251 This will emit the bytes
2257 into the current segment in that order.
2260 <sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
2262 Switch on or off debug info generation. The default is off (that is,
2263 the object file will not contain debug infos), but may be changed by the
2264 -g switch on the command line.
2265 The command must be followed by a '+' or '-' character to switch the
2266 option on or off respectively.
2271 .debuginfo + ; Generate debug info
2275 <sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
2277 Start a define style macro definition. The command is followed by an
2278 identifier (the macro name) and optionally by a list of formal arguments
2281 Please note that <tt/.DEFINE/ shares most disadvantages with its C
2282 counterpart, so the general advice is, <bf/NOT/ do use <tt/.DEFINE/ if you
2285 See also the <tt><ref id=".UNDEFINE" name=".UNDEFINE"></tt> command and
2286 section <ref id="macros" name="Macros">.
2289 <sect1><tt>.DELMAC, .DELMACRO</tt><label id=".DELMACRO"><p>
2291 Delete a classic macro (defined with <tt><ref id=".MACRO"
2292 name=".MACRO"></tt>) . The command is followed by the name of an
2293 existing macro. Its definition will be deleted together with the name.
2294 If necessary, another macro with this name may be defined later.
2296 See: <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2297 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2298 <tt><ref id=".MACRO" name=".MACRO"></tt>
2300 See also section <ref id="macros" name="Macros">.
2303 <sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
2305 Builtin function. The function expects an identifier as argument in braces.
2306 The argument is evaluated, and the function yields "true" if the identifier
2307 is a symbol that is already defined somewhere in the source file up to the
2308 current position. Otherwise the function yields false. As an example, the
2309 <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
2316 <sect1><tt>.DEFINEDMACRO</tt><label id=".DEFINEDMACRO"><p>
2318 Builtin function. The function expects an identifier as argument in braces.
2319 The argument is evaluated, and the function yields "true" if the identifier
2320 has already been defined as the name of a macro. Otherwise the function yields
2329 .if .definedmacro(add)
2338 <sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
2340 Export a symbol and mark it as a module destructor. This may be used
2341 together with the linker to build a table of destructor subroutines that
2342 are called by the startup code.
2344 Note: The linker has a feature to build a table of marked routines, but it
2345 is your code that must call these routines, so just declaring a symbol as
2346 constructor does nothing by itself.
2348 A destructor is always exported as an absolute (16 bit) symbol. You don't
2349 need to use an additional <tt/.export/ statement, this is implied by
2350 <tt/.destructor/. It may have an optional priority that is separated by a
2351 comma. Higher numerical values mean a higher priority. If no priority is
2352 given, the default priority of 7 is used. Be careful when assigning
2353 priorities to your own module destructors so they won't interfere with the
2354 ones in the cc65 library.
2359 .destructor ModuleDone
2360 .destructor ModDone, 16
2363 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2364 id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
2365 section <ref id="condes" name="Module constructors/destructors"> explaining
2366 the feature in more detail.
2369 <sect1><tt>.DWORD</tt><label id=".DWORD"><p>
2371 Define dword sized data (4 bytes) Must be followed by a sequence of
2377 .dword $12344512, $12FA489
2381 <sect1><tt>.ELSE</tt><label id=".ELSE"><p>
2383 Conditional assembly: Reverse the current condition.
2386 <sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
2388 Conditional assembly: Reverse current condition and test a new one.
2391 <sect1><tt>.END</tt><label id=".END"><p>
2393 Forced end of assembly. Assembly stops at this point, even if the command
2394 is read from an include file.
2397 <sect1><tt>.ENDENUM</tt><label id=".ENDENUM"><p>
2399 End a <tt><ref id=".ENUM" name=".ENUM"></tt> declaration.
2402 <sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
2404 Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
2405 <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
2408 <sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
2410 Marks the end of a macro definition.
2412 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2413 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2414 <tt><ref id=".MACRO" name=".MACRO"></tt>
2416 See also section <ref id="macros" name="Macros">.
2419 <sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
2421 End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
2424 <sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
2426 End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
2429 <sect1><tt>.ENDSCOPE</tt><label id=".ENDSCOPE"><p>
2431 End of local lexical level (see <tt/<ref id=".SCOPE" name=".SCOPE">/).
2434 <sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
2436 Ends a struct definition. See the <tt/<ref id=".STRUCT" name=".STRUCT">/
2437 command and the separate section named <ref id="structs" name=""Structs
2441 <sect1><tt>.ENDUNION</tt><label id=".ENDUNION"><p>
2443 Ends a union definition. See the <tt/<ref id=".UNION" name=".UNION">/
2444 command and the separate section named <ref id="structs" name=""Structs
2448 <sect1><tt>.ENUM</tt><label id=".ENUM"><p>
2450 Start an enumeration. This directive is very similar to the C <tt/enum/
2451 keyword. If a name is given, a new scope is created for the enumeration,
2452 otherwise the enumeration members are placed in the enclosing scope.
2454 In the enumeration body, symbols are declared. The first symbol has a value
2455 of zero, and each following symbol will get the value of the preceding plus
2456 one. This behaviour may be overridden by an explicit assignment. Two symbols
2457 may have the same value.
2469 Above example will create a new scope named <tt/errorcodes/ with three
2470 symbols in it that get the values 0, 1 and 2 respectively. Another way
2471 to write this would have been:
2481 Please note that explicit scoping must be used to access the identifiers:
2484 .word errorcodes::no_error
2487 A more complex example:
2496 EWOULDBLOCK = EAGAIN
2500 In this example, the enumeration does not have a name, which means that the
2501 members will be visible in the enclosing scope and can be used in this scope
2502 without explicit scoping. The first member (<tt/EUNKNOWN/) has the value -1.
2503 The value for the following members is incremented by one, so <tt/EOK/ would
2504 be zero and so on. <tt/EWOULDBLOCK/ is an alias for <tt/EGAIN/, so it has an
2505 override for the value using an already defined symbol.
2508 <sect1><tt>.ERROR</tt><label id=".ERROR"><p>
2510 Force an assembly error. The assembler will output an error message
2511 preceded by "User error". Assembly is continued but no object file will
2514 This command may be used to check for initial conditions that must be
2515 set before assembling a source file.
2525 .error "Must define foo or bar!"
2529 See also: <tt><ref id=".FATAL" name=".FATAL"></tt>,
2530 <tt><ref id=".OUT" name=".OUT"></tt>,
2531 <tt><ref id=".WARNING" name=".WARNING"></tt>
2534 <sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
2536 Abort a macro expansion immediately. This command is often useful in
2539 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2540 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2541 <tt><ref id=".MACRO" name=".MACRO"></tt>
2543 See also section <ref id="macros" name="Macros">.
2546 <sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
2548 Make symbols accessible from other modules. Must be followed by a comma
2549 separated list of symbols to export, with each one optionally followed by an
2550 address specification and (also optional) an assignment. Using an additional
2551 assignment in the export statement allows to define and export a symbol in
2552 one statement. The default is to export the symbol with the address size it
2553 actually has. The assembler will issue a warning, if the symbol is exported
2554 with an address size smaller than the actual address size.
2561 .export foobar: far = foo * bar
2562 .export baz := foobar, zap: far = baz - bar
2565 As with constant definitions, using <tt/:=/ instead of <tt/=/ marks the
2568 See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
2571 <sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
2573 Make symbols accessible from other modules. Must be followed by a comma
2574 separated list of symbols to export. The exported symbols are explicitly
2575 marked as zero page symbols. An assignment may be included in the
2576 <tt/.EXPORTZP/ statement. This allows to define and export a symbol in one
2583 .exportzp baz := $02
2586 See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
2589 <sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
2591 Define far (24 bit) address data. The command must be followed by a
2592 sequence of (not necessarily constant) expressions.
2597 .faraddr DrawCircle, DrawRectangle, DrawHexagon
2600 See: <tt><ref id=".ADDR" name=".ADDR"></tt>
2603 <sect1><tt>.FATAL</tt><label id=".FATAL"><p>
2605 Force an assembly error and terminate assembly. The assembler will output an
2606 error message preceded by "User error" and will terminate assembly
2609 This command may be used to check for initial conditions that must be
2610 set before assembling a source file.
2620 .fatal "Must define foo or bar!"
2624 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
2625 <tt><ref id=".OUT" name=".OUT"></tt>,
2626 <tt><ref id=".WARNING" name=".WARNING"></tt>
2629 <sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
2631 This directive may be used to enable one or more compatibility features
2632 of the assembler. While the use of <tt/.FEATURE/ should be avoided when
2633 possible, it may be useful when porting sources written for other
2634 assemblers. There is no way to switch a feature off, once you have
2635 enabled it, so using
2641 will enable the feature until end of assembly is reached.
2643 The following features are available:
2647 <tag><tt>addrsize</tt><label id="addrsize"></tag>
2649 Enables the .ADDRSIZE pseudo function. This function is experimental and not enabled by default.
2651 See also: <tt><ref id=".ADDRSIZE" name=".ADDRSIZE"></tt>
2653 <tag><tt>at_in_identifiers</tt><label id="at_in_identifiers"></tag>
2655 Accept the at character (`@') as a valid character in identifiers. The
2656 at character is not allowed to start an identifier, even with this
2659 <tag><tt>c_comments</tt><label id="c_comments"></tag>
2661 Allow C like comments using <tt>/*</tt> and <tt>*/</tt> as left and right
2662 comment terminators. Note that C comments may not be nested. There's also a
2663 pitfall when using C like comments: All statements must be terminated by
2664 "end-of-line". Using C like comments, it is possible to hide the newline,
2665 which results in error messages. See the following non working example:
2668 lda #$00 /* This comment hides the newline
2672 <tag><tt>dollar_in_identifiers</tt><label id="dollar_in_identifiers"></tag>
2674 Accept the dollar sign (`$') as a valid character in identifiers. The
2675 dollar character is not allowed to start an identifier, even with this
2678 <tag><tt>dollar_is_pc</tt><label id="dollar_is_pc"></tag>
2680 The dollar sign may be used as an alias for the star (`*'), which
2681 gives the value of the current PC in expressions.
2682 Note: Assignment to the pseudo variable is not allowed.
2684 <tag><tt>force_range</tt><label id="force_range"></tag>
2686 Force expressions into their valid range for immediate addressing and
2687 storage operators like <tt><ref id=".BYTE" name=".BYTE"></tt> and
2688 <tt><ref id=".WORD" name=".WORD"></tt>. Be very careful with this one,
2689 since it will completely disable error checks.
2691 <tag><tt>labels_without_colons</tt><label id="labels_without_colons"></tag>
2693 Allow labels without a trailing colon. These labels are only accepted,
2694 if they start at the beginning of a line (no leading white space).
2696 <tag><tt>leading_dot_in_identifiers</tt><label id="leading_dot_in_identifiers"></tag>
2698 Accept the dot (`.') as the first character of an identifier. This may be
2699 used for example to create macro names that start with a dot emulating
2700 control directives of other assemblers. Note however, that none of the
2701 reserved keywords built into the assembler, that starts with a dot, may be
2702 overridden. When using this feature, you may also get into trouble if
2703 later versions of the assembler define new keywords starting with a dot.
2705 <tag><tt>loose_char_term</tt><label id="loose_char_term"></tag>
2707 Accept single quotes as well as double quotes as terminators for char
2710 <tag><tt>loose_string_term</tt><label id="loose_string_term"></tag>
2712 Accept single quotes as well as double quotes as terminators for string
2715 <tag><tt>missing_char_term</tt><label id="missing_char_term"></tag>
2717 Accept single quoted character constants where the terminating quote is
2722 <em/Note:/ This does not work in conjunction with <tt/.FEATURE
2723 loose_string_term/, since in this case the input would be ambiguous.
2725 <tag><tt>org_per_seg</tt><label id="org_per_seg"></tag>
2727 This feature makes relocatable/absolute mode local to the current segment.
2728 Using <tt><ref id=".ORG" name=".ORG"></tt> when <tt/org_per_seg/ is in
2729 effect will only enable absolute mode for the current segment. Dito for
2730 <tt><ref id=".RELOC" name=".RELOC"></tt>.
2732 <tag><tt>pc_assignment</tt><label id="pc_assignment"></tag>
2734 Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
2735 is enabled). Such an assignment is handled identical to the <tt><ref
2736 id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
2737 removing the lines with the assignments may also be an option when porting
2738 code written for older assemblers).
2740 <tag><tt>ubiquitous_idents</tt><label id="ubiquitous_idents"></tag>
2742 Allow the use of instructions names as names for macros and symbols. This
2743 makes it possible to "overload" instructions by defining a macro with the
2744 same name. This does also make it possible to introduce hard to find errors
2745 in your code, so be careful!
2747 <tag><tt>underline_in_numbers</tt><label id="underline_in_numbers"></tag>
2749 Allow underlines within numeric constants. These may be used for grouping
2750 the digits of numbers for easier reading.
2753 .feature underline_in_numbers
2754 .word %1100001110100101
2755 .word %1100_0011_1010_0101 ; Identical but easier to read
2760 It is also possible to specify features on the command line using the
2761 <tt><ref id="option--feature" name="--feature"></tt> command line option.
2762 This is useful when translating sources written for older assemblers, when
2763 you don't want to change the source code.
2765 As an example, to translate sources written for Andre Fachats xa65
2766 assembler, the features
2769 labels_without_colons, pc_assignment, loose_char_term
2772 may be helpful. They do not make ca65 completely compatible, so you may not
2773 be able to translate the sources without changes, even when enabling these
2774 features. However, I have found several sources that translate without
2775 problems when enabling these features on the command line.
2778 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
2780 Insert an option string into the object file. There are two forms of
2781 this command, one specifies the option by a keyword, the second
2782 specifies it as a number. Since usage of the second one needs knowledge
2783 of the internal encoding, its use is not recommended and I will only
2784 describe the first form here.
2786 The command is followed by one of the keywords
2794 a comma and a string. The option is written into the object file
2795 together with the string value. This is currently unidirectional and
2796 there is no way to actually use these options once they are in the
2802 .fileopt comment, "Code stolen from my brother"
2803 .fileopt compiler, "BASIC 2.0"
2804 .fopt author, "J. R. User"
2808 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
2810 Import an absolute symbol from another module. The command is followed by a
2811 comma separated list of symbols to import. The command is similar to <tt>
2812 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
2813 written to the generated object file, even if the symbol is never referenced
2814 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
2815 references for unused symbols).
2820 .forceimport needthisone, needthistoo
2823 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2826 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
2828 Declare symbols as global. Must be followed by a comma separated list of
2829 symbols to declare. Symbols from the list, that are defined somewhere in the
2830 source, are exported, all others are imported. Additional <tt><ref
2831 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
2832 name=".EXPORT"></tt> commands for the same symbol are allowed.
2841 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
2843 Declare symbols as global. Must be followed by a comma separated list of
2844 symbols to declare. Symbols from the list, that are defined somewhere in the
2845 source, are exported, all others are imported. Additional <tt><ref
2846 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
2847 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
2848 in the list are explicitly marked as zero page symbols.
2856 <sect1><tt>.HIBYTES</tt><label id=".HIBYTES"><p>
2858 Define byte sized data by extracting only the high byte (that is, bits 8-15) from
2859 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2860 the operator '>' prepended to each expression in its list.
2865 .lobytes $1234, $2345, $3456, $4567
2866 .hibytes $fedc, $edcb, $dcba, $cba9
2869 which is equivalent to
2872 .byte $34, $45, $56, $67
2873 .byte $fe, $ed, $dc, $cb
2879 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2881 TableLookupLo: .lobytes MyTable
2882 TableLookupHi: .hibytes MyTable
2885 which is equivalent to
2888 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2889 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2892 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2893 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>,
2894 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
2897 <sect1><tt>.I16</tt><label id=".I16"><p>
2899 Valid only in 65816 mode. Switch the index registers to 16 bit.
2901 Note: This command will not emit any code, it will tell the assembler to
2902 create 16 bit operands for immediate operands.
2904 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
2905 name=".SMART"></tt> commands.
2908 <sect1><tt>.I8</tt><label id=".I8"><p>
2910 Valid only in 65816 mode. Switch the index registers to 8 bit.
2912 Note: This command will not emit any code, it will tell the assembler to
2913 create 8 bit operands for immediate operands.
2915 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
2916 name=".SMART"></tt> commands.
2919 <sect1><tt>.IF</tt><label id=".IF"><p>
2921 Conditional assembly: Evaluate an expression and switch assembler output
2922 on or off depending on the expression. The expression must be a constant
2923 expression, that is, all operands must be defined.
2925 A expression value of zero evaluates to FALSE, any other value evaluates
2929 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
2931 Conditional assembly: Check if there are any remaining tokens in this line,
2932 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
2933 condition is not true, further lines are not assembled until an <tt><ref
2934 id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2935 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2937 This command is often used to check if a macro parameter was given. Since an
2938 empty macro parameter will evaluate to nothing, the condition will evaluate
2939 to TRUE if an empty parameter was given.
2953 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2956 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
2958 Conditional assembly: Evaluate an expression and switch assembler output
2959 on or off depending on the constness of the expression.
2961 A const expression evaluates to to TRUE, a non const expression (one
2962 containing an imported or currently undefined symbol) evaluates to
2965 See also: <tt><ref id=".CONST" name=".CONST"></tt>
2968 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
2970 Conditional assembly: Check if a symbol is defined. Must be followed by
2971 a symbol name. The condition is true if the the given symbol is already
2972 defined, and false otherwise.
2974 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2977 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
2979 Conditional assembly: Check if there are any remaining tokens in this line,
2980 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
2981 condition is not true, further lines are not assembled until an <tt><ref
2982 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2983 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2985 This command is often used to check if a macro parameter was given.
2986 Since an empty macro parameter will evaluate to nothing, the condition
2987 will evaluate to FALSE if an empty parameter was given.
3000 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
3003 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
3005 Conditional assembly: Check if a symbol is defined. Must be followed by
3006 a symbol name. The condition is true if the the given symbol is not
3007 defined, and false otherwise.
3009 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
3012 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
3014 Conditional assembly: Check if a symbol is referenced. Must be followed
3015 by a symbol name. The condition is true if if the the given symbol was
3016 not referenced before, and false otherwise.
3018 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
3021 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
3023 Conditional assembly: Check if the assembler is currently in 6502 mode
3024 (see <tt><ref id=".P02" name=".P02"></tt> command).
3027 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
3029 Conditional assembly: Check if the assembler is currently in 65816 mode
3030 (see <tt><ref id=".P816" name=".P816"></tt> command).
3033 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
3035 Conditional assembly: Check if the assembler is currently in 65C02 mode
3036 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
3039 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
3041 Conditional assembly: Check if the assembler is currently in 65SC02 mode
3042 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
3045 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
3047 Conditional assembly: Check if a symbol is referenced. Must be followed
3048 by a symbol name. The condition is true if if the the given symbol was
3049 referenced before, and false otherwise.
3051 This command may be used to build subroutine libraries in include files
3052 (you may use separate object modules for this purpose too).
3057 .ifref ToHex ; If someone used this subroutine
3058 ToHex: tay ; Define subroutine
3064 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
3067 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
3069 Import a symbol from another module. The command is followed by a comma
3070 separated list of symbols to import, with each one optionally followed by
3071 an address specification.
3077 .import bar: zeropage
3080 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
3083 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
3085 Import a symbol from another module. The command is followed by a comma
3086 separated list of symbols to import. The symbols are explicitly imported
3087 as zero page symbols (that is, symbols with values in byte range).
3095 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
3098 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
3100 Include a file as binary data. The command expects a string argument
3101 that is the name of a file to include literally in the current segment.
3102 In addition to that, a start offset and a size value may be specified,
3103 separated by commas. If no size is specified, all of the file from the
3104 start offset to end-of-file is used. If no start position is specified
3105 either, zero is assumed (which means that the whole file is inserted).
3110 ; Include whole file
3111 .incbin "sprites.dat"
3113 ; Include file starting at offset 256
3114 .incbin "music.dat", $100
3116 ; Read 100 bytes starting at offset 200
3117 .incbin "graphics.dat", 200, 100
3121 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
3123 Include another file. Include files may be nested up to a depth of 16.
3132 <sect1><tt>.INTERRUPTOR</tt><label id=".INTERRUPTOR"><p>
3134 Export a symbol and mark it as an interruptor. This may be used together
3135 with the linker to build a table of interruptor subroutines that are called
3138 Note: The linker has a feature to build a table of marked routines, but it
3139 is your code that must call these routines, so just declaring a symbol as
3140 interruptor does nothing by itself.
3142 An interruptor is always exported as an absolute (16 bit) symbol. You don't
3143 need to use an additional <tt/.export/ statement, this is implied by
3144 <tt/.interruptor/. It may have an optional priority that is separated by a
3145 comma. Higher numeric values mean a higher priority. If no priority is
3146 given, the default priority of 7 is used. Be careful when assigning
3147 priorities to your own module constructors so they won't interfere with the
3148 ones in the cc65 library.
3153 .interruptor IrqHandler
3154 .interruptor Handler, 16
3157 See the <tt><ref id=".CONDES" name=".CONDES"></tt> command and the separate
3158 section <ref id="condes" name="Module constructors/destructors"> explaining
3159 the feature in more detail.
3162 <sect1><tt>.ISMNEM, .ISMNEMONIC</tt><label id=".ISMNEMONIC"><p>
3164 Builtin function. The function expects an identifier as argument in braces.
3165 The argument is evaluated, and the function yields "true" if the identifier
3166 is defined as an instruction mnemonic that is recognized by the assembler.
3170 .if .not .ismnemonic(ina)
3179 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
3181 Switch on or off line continuations using the backslash character
3182 before a newline. The option is off by default.
3183 Note: Line continuations do not work in a comment. A backslash at the
3184 end of a comment is treated as part of the comment and does not trigger
3186 The command must be followed by a '+' or '-' character to switch the
3187 option on or off respectively.
3192 .linecont + ; Allow line continuations
3195 #$20 ; This is legal now
3199 <sect1><tt>.LIST</tt><label id=".LIST"><p>
3201 Enable output to the listing. The command must be followed by a boolean
3202 switch ("on", "off", "+" or "-") and will enable or disable listing
3204 The option has no effect if the listing is not enabled by the command line
3205 switch -l. If -l is used, an internal counter is set to 1. Lines are output
3206 to the listing file, if the counter is greater than zero, and suppressed if
3207 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
3213 .list on ; Enable listing output
3217 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
3219 Set, how many bytes are shown in the listing for one source line. The
3220 default is 12, so the listing will show only the first 12 bytes for any
3221 source line that generates more than 12 bytes of code or data.
3222 The directive needs an argument, which is either "unlimited", or an
3223 integer constant in the range 4..255.
3228 .listbytes unlimited ; List all bytes
3229 .listbytes 12 ; List the first 12 bytes
3230 .incbin "data.bin" ; Include large binary file
3234 <sect1><tt>.LOBYTES</tt><label id=".LOBYTES"><p>
3236 Define byte sized data by extracting only the low byte (that is, bits 0-7) from
3237 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
3238 the operator '<' prepended to each expression in its list.
3243 .lobytes $1234, $2345, $3456, $4567
3244 .hibytes $fedc, $edcb, $dcba, $cba9
3247 which is equivalent to
3250 .byte $34, $45, $56, $67
3251 .byte $fe, $ed, $dc, $cb
3257 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
3259 TableLookupLo: .lobytes MyTable
3260 TableLookupHi: .hibytes MyTable
3263 which is equivalent to
3266 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
3267 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
3270 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
3271 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
3272 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
3275 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
3277 This command may only be used inside a macro definition. It declares a
3278 list of identifiers as local to the macro expansion.
3280 A problem when using macros are labels: Since they don't change their name,
3281 you get a "duplicate symbol" error if the macro is expanded the second time.
3282 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
3283 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
3286 Some other assemblers start a new lexical block inside a macro expansion.
3287 This has some drawbacks however, since that will not allow <em/any/ symbol
3288 to be visible outside a macro, a feature that is sometimes useful. The
3289 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
3290 to address the problem.
3292 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
3296 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
3298 Defines the character that start "cheap" local labels. You may use one
3299 of '@' and '?' as start character. The default is '@'.
3301 Cheap local labels are labels that are visible only between two non
3302 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
3303 using explicit lexical nesting.
3310 Clear: lda #$00 ; Global label
3311 ?Loop: sta Mem,y ; Local label
3315 Sub: ... ; New global label
3316 bne ?Loop ; ERROR: Unknown identifier!
3320 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
3322 Insert a predefined macro package. The command is followed by an
3323 identifier specifying the macro package to insert. Available macro
3327 atari Defines the scrcode macro.
3328 cbm Defines the scrcode macro.
3329 cpu Defines constants for the .CPU variable.
3330 generic Defines generic macroes like add, sub, and blt.
3331 longbranch Defines conditional long-jump macroes.
3334 Including a macro package twice, or including a macro package that
3335 redefines already existing macros will lead to an error.
3340 .macpack longbranch ; Include macro package
3342 cmp #$20 ; Set condition codes
3343 jne Label ; Jump long on condition
3346 Macro packages are explained in more detail in section <ref
3347 id="macropackages" name="Macro packages">.
3350 <sect1><tt>.MAC, .MACRO</tt><label id=".MACRO"><p>
3352 Start a classic macro definition. The command is followed by an identifier
3353 (the macro name) and optionally by a comma separated list of identifiers
3354 that are macro parameters. A macro definition is terminated by <tt><ref
3355 id=".ENDMACRO" name=".ENDMACRO"></tt>.
3360 .macro ldax arg ; Define macro ldax
3365 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
3366 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
3367 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>
3369 See also section <ref id="macros" name="Macros">.
3372 <sect1><tt>.ORG</tt><label id=".ORG"><p>
3374 Start a section of absolute code. The command is followed by a constant
3375 expression that gives the new PC counter location for which the code is
3376 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
3379 By default, absolute/relocatable mode is global (valid even when switching
3380 segments). Using <tt>.FEATURE <ref id="org_per_seg" name="org_per_seg"></tt>
3381 it can be made segment local.
3383 Please note that you <em/do not need/ <tt/.ORG/ in most cases. Placing
3384 code at a specific address is the job of the linker, not the assembler, so
3385 there is usually no reason to assemble code to a specific address.
3390 .org $7FF ; Emit code starting at $7FF
3394 <sect1><tt>.OUT</tt><label id=".OUT"><p>
3396 Output a string to the console without producing an error. This command
3397 is similar to <tt/.ERROR/, however, it does not force an assembler error
3398 that prevents the creation of an object file.
3403 .out "This code was written by the codebuster(tm)"
3406 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3407 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3408 <tt><ref id=".WARNING" name=".WARNING"></tt>
3411 <sect1><tt>.P02</tt><label id=".P02"><p>
3413 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
3414 instructions. This is the default if not overridden by the
3415 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
3417 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
3418 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3421 <sect1><tt>.P816</tt><label id=".P816"><p>
3423 Enable the 65816 instruction set. This is a superset of the 65SC02 and
3424 6502 instruction sets.
3426 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3427 name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
3430 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
3432 Set the page length for the listing. Must be followed by an integer
3433 constant. The value may be "unlimited", or in the range 32 to 127. The
3434 statement has no effect if no listing is generated. The default value is -1
3435 (unlimited) but may be overridden by the <tt/--pagelength/ command line
3436 option. Beware: Since ca65 is a one pass assembler, the listing is generated
3437 after assembly is complete, you cannot use multiple line lengths with one
3438 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
3443 .pagelength 66 ; Use 66 lines per listing page
3445 .pagelength unlimited ; Unlimited page length
3449 <sect1><tt>.PC02</tt><label id=".PC02"><p>
3451 Enable the 65C02 instructions set. This instruction set includes all
3452 6502 and 65SC02 instructions.
3454 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3455 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3458 <sect1><tt>.POPCPU</tt><label id=".POPCPU"><p>
3460 Pop the last CPU setting from the stack, and activate it.
3462 This command will switch back to the CPU that was last pushed onto the CPU
3463 stack using the <tt><ref id=".PUSHCPU" name=".PUSHCPU"></tt> command, and
3464 remove this entry from the stack.
3466 The assembler will print an error message if the CPU stack is empty when
3467 this command is issued.
3469 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".PUSHCPU"
3470 name=".PUSHCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3473 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
3475 Pop the last pushed segment from the stack, and set it.
3477 This command will switch back to the segment that was last pushed onto the
3478 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3479 command, and remove this entry from the stack.
3481 The assembler will print an error message if the segment stack is empty
3482 when this command is issued.
3484 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3487 <sect1><tt>.PROC</tt><label id=".PROC"><p>
3489 Start a nested lexical level with the given name and adds a symbol with this
3490 name to the enclosing scope. All new symbols from now on are in the local
3491 lexical level and are accessible from outside only via <ref id="scopesyntax"
3492 name="explicit scope specification">. Symbols defined outside this local
3493 level may be accessed as long as their names are not used for new symbols
3494 inside the level. Symbols names in other lexical levels do not clash, so you
3495 may use the same names for identifiers. The lexical level ends when the
3496 <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
3497 may be nested up to a depth of 16 (this is an artificial limit to protect
3498 against errors in the source).
3500 Note: Macro names are always in the global level and in a separate name
3501 space. There is no special reason for this, it's just that I've never
3502 had any need for local macro definitions.
3507 .proc Clear ; Define Clear subroutine, start new level
3509 L1: sta Mem,y ; L1 is local and does not cause a
3510 ; duplicate symbol error if used in other
3513 bne L1 ; Reference local symbol
3515 .endproc ; Leave lexical level
3518 See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
3522 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
3524 Enable the 65SC02 instructions set. This instruction set includes all
3527 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
3528 name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3531 <sect1><tt>.PUSHCPU</tt><label id=".PUSHCPU"><p>
3533 Push the currently active CPU onto a stack. The stack has a size of 8
3536 <tt/.PUSHCPU/ allows together with <tt><ref id=".POPCPU"
3537 name=".POPCPU"></tt> to switch to another CPU and to restore the old CPU
3538 later, without knowledge of the current CPU setting.
3540 The assembler will print an error message if the CPU stack is already full,
3541 when this command is issued.
3543 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".POPCPU"
3544 name=".POPCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3547 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
3549 Push the currently active segment onto a stack. The entries on the stack
3550 include the name of the segment and the segment type. The stack has a size
3553 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3554 to switch to another segment and to restore the old segment later, without
3555 even knowing the name and type of the current segment.
3557 The assembler will print an error message if the segment stack is already
3558 full, when this command is issued.
3560 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3563 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
3565 Switch back to relocatable mode. See the <tt><ref id=".ORG"
3566 name=".ORG"></tt> command.
3569 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
3571 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
3572 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
3573 a constant expression that tells how many times the commands in the body
3574 should get repeated. Optionally, a comma and an identifier may be specified.
3575 If this identifier is found in the body of the repeat statement, it is
3576 replaced by the current repeat count (starting with zero for the first time
3577 the body is repeated).
3579 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
3580 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
3581 level will be used, not the one from the outer level.
3585 The following macro will emit a string that is "encrypted" in that all
3586 characters of the string are XORed by the value $55.
3590 .repeat .strlen(Arg), I
3591 .byte .strat(Arg, I) ^ $55
3596 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
3599 <sect1><tt>.RES</tt><label id=".RES"><p>
3601 Reserve storage. The command is followed by one or two constant
3602 expressions. The first one is mandatory and defines, how many bytes of
3603 storage should be defined. The second, optional expression must by a
3604 constant byte value that will be used as value of the data. If there
3605 is no fill value given, the linker will use the value defined in the
3606 linker configuration file (default: zero).
3611 ; Reserve 12 bytes of memory with value $AA
3616 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
3618 Switch to the RODATA segment. The name of the RODATA segment is always
3619 "RODATA", so this is a shortcut for
3625 The RODATA segment is a segment that is used by the compiler for
3626 readonly data like string constants.
3628 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
3631 <sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
3633 Start a nested lexical level with the given name. All new symbols from now
3634 on are in the local lexical level and are accessible from outside only via
3635 <ref id="scopesyntax" name="explicit scope specification">. Symbols defined
3636 outside this local level may be accessed as long as their names are not used
3637 for new symbols inside the level. Symbols names in other lexical levels do
3638 not clash, so you may use the same names for identifiers. The lexical level
3639 ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
3640 read. Lexical levels may be nested up to a depth of 16 (this is an
3641 artificial limit to protect against errors in the source).
3643 Note: Macro names are always in the global level and in a separate name
3644 space. There is no special reason for this, it's just that I've never
3645 had any need for local macro definitions.
3650 .scope Error ; Start new scope named Error
3652 File = 1 ; File error
3653 Parse = 2 ; Parse error
3654 .endscope ; Close lexical level
3657 lda #Error::File ; Use symbol from scope Error
3660 See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
3664 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
3666 Switch to another segment. Code and data is always emitted into a
3667 segment, that is, a named section of data. The default segment is
3668 "CODE". There may be up to 254 different segments per object file
3669 (and up to 65534 per executable). There are shortcut commands for
3670 the most common segments ("ZEROPAGE", "CODE", "RODATA", "DATA", and "BSS").
3672 The command is followed by a string containing the segment name (there are
3673 some constraints for the name - as a rule of thumb use only those segment
3674 names that would also be valid identifiers). There may also be an optional
3675 address size separated by a colon. See the section covering <tt/<ref
3676 id="address-sizes" name="address sizes">/ for more information.
3678 The default address size for a segment depends on the memory model specified
3679 on the command line. The default is "absolute", which means that you don't
3680 have to use an address size modifier in most cases.
3682 "absolute" means that the is a segment with 16 bit (absolute) addressing.
3683 That is, the segment will reside somewhere in core memory outside the zero
3684 page. "zeropage" (8 bit) means that the segment will be placed in the zero
3685 page and direct (short) addressing is possible for data in this segment.
3687 Beware: Only labels in a segment with the zeropage attribute are marked
3688 as reachable by short addressing. The `*' (PC counter) operator will
3689 work as in other segments and will create absolute variable values.
3691 Please note that a segment cannot have two different address sizes. A
3692 segment specified as zeropage cannot be declared as being absolute later.
3697 .segment "ROM2" ; Switch to ROM2 segment
3698 .segment "ZP2": zeropage ; New direct segment
3699 .segment "ZP2" ; Ok, will use last attribute
3700 .segment "ZP2": absolute ; Error, redecl mismatch
3703 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
3704 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt>, <tt><ref
3705 id=".RODATA" name=".RODATA"></tt>, and <tt><ref id=".ZEROPAGE"
3706 name=".ZEROPAGE"></tt>
3709 <sect1><tt>.SET</tt><label id=".SET"><p>
3711 <tt/.SET/ is used to assign a value to a variable. See <ref id="variables"
3712 name="Numeric variables"> for a full description.
3715 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
3717 Switch the CPU instruction set. The command is followed by a string that
3718 specifies the CPU. Possible values are those that can also be supplied to
3719 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
3720 namely: 6502, 6502X, 65SC02, 65C02, 65816 and HuC6280.
3722 See: <tt><ref id=".CPU" name=".CPU"></tt>,
3723 <tt><ref id=".IFP02" name=".IFP02"></tt>,
3724 <tt><ref id=".IFP816" name=".IFP816"></tt>,
3725 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
3726 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
3727 <tt><ref id=".P02" name=".P02"></tt>,
3728 <tt><ref id=".P816" name=".P816"></tt>,
3729 <tt><ref id=".PC02" name=".PC02"></tt>,
3730 <tt><ref id=".PSC02" name=".PSC02"></tt>
3733 <sect1><tt>.SMART</tt><label id=".SMART"><p>
3735 Switch on or off smart mode. The command must be followed by a '+' or '-'
3736 character to switch the option on or off respectively. The default is off
3737 (that is, the assembler doesn't try to be smart), but this default may be
3738 changed by the -s switch on the command line.
3740 In smart mode the assembler will do the following:
3743 <item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
3744 and update the operand sizes accordingly. If the operand of such an
3745 instruction cannot be evaluated by the assembler (for example, because
3746 the operand is an imported symbol), a warning is issued. Beware: Since
3747 the assembler cannot trace the execution flow this may lead to false
3748 results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
3749 instructions to tell the assembler about the current settings.
3750 <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
3751 used within a procedure declared as <tt/far/, or if the procedure has
3752 no explicit address specification, but it is <tt/far/ because of the
3760 .smart - ; Stop being smart
3763 See: <tt><ref id=".A16" name=".A16"></tt>,
3764 <tt><ref id=".A8" name=".A8"></tt>,
3765 <tt><ref id=".I16" name=".I16"></tt>,
3766 <tt><ref id=".I8" name=".I8"></tt>
3769 <sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
3771 Starts a struct definition. Structs are covered in a separate section named
3772 <ref id="structs" name=""Structs and unions"">.
3774 See also: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>,
3775 <tt><ref id=".ENDUNION" name=".ENDUNION"></tt>,
3776 <tt><ref id=".UNION" name=".UNION"></tt>
3779 <sect1><tt>.TAG</tt><label id=".TAG"><p>
3781 Allocate space for a struct or union.
3792 .tag Point ; Allocate 4 bytes
3796 <sect1><tt>.UNDEF, .UNDEFINE</tt><label id=".UNDEFINE"><p>
3798 Delete a define style macro definition. The command is followed by an
3799 identifier which specifies the name of the macro to delete. Macro
3800 replacement is switched of when reading the token following the command
3801 (otherwise the macro name would be replaced by its replacement list).
3803 See also the <tt><ref id=".DEFINE" name=".DEFINE"></tt> command and
3804 section <ref id="macros" name="Macros">.
3807 <sect1><tt>.UNION</tt><label id=".UNION"><p>
3809 Starts a union definition. Unions are covered in a separate section named
3810 <ref id="structs" name=""Structs and unions"">.
3812 See also: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>,
3813 <tt><ref id=".ENDUNION" name=".ENDUNION"></tt>,
3814 <tt><ref id=".STRUCT" name=".STRUCT"></tt>
3817 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
3819 Force an assembly warning. The assembler will output a warning message
3820 preceded by "User warning". This warning will always be output, even if
3821 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
3822 command line option.
3824 This command may be used to output possible problems when assembling
3833 .warning "Forward jump in jne, cannot optimize!"
3843 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3844 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3845 <tt><ref id=".OUT" name=".OUT"></tt>
3848 <sect1><tt>.WORD</tt><label id=".WORD"><p>
3850 Define word sized data. Must be followed by a sequence of (word ranged,
3851 but not necessarily constant) expressions.
3856 .word $0D00, $AF13, _Clear
3860 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
3862 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
3863 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
3867 .segment "ZEROPAGE": zeropage
3870 Because of the "zeropage" attribute, labels declared in this segment are
3871 addressed using direct addressing mode if possible. You <em/must/ instruct
3872 the linker to place this segment somewhere in the address range 0..$FF
3873 otherwise you will get errors.
3875 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
3879 <sect>Macros<label id="macros"><p>
3882 <sect1>Introduction<p>
3884 Macros may be thought of as "parametrized super instructions". Macros are
3885 sequences of tokens that have a name. If that name is used in the source
3886 file, the macro is "expanded", that is, it is replaced by the tokens that
3887 were specified when the macro was defined.
3890 <sect1>Macros without parameters<p>
3892 In its simplest form, a macro does not have parameters. Here's an
3896 .macro asr ; Arithmetic shift right
3897 cmp #$80 ; Put bit 7 into carry
3898 ror ; Rotate right with carry
3902 The macro above consists of two real instructions, that are inserted into
3903 the code, whenever the macro is expanded. Macro expansion is simply done
3904 by using the name, like this:
3913 <sect1>Parametrized macros<p>
3915 When using macro parameters, macros can be even more useful:
3929 When calling the macro, you may give a parameter, and each occurrence of
3930 the name "addr" in the macro definition will be replaced by the given
3949 A macro may have more than one parameter, in this case, the parameters
3950 are separated by commas. You are free to give less parameters than the
3951 macro actually takes in the definition. You may also leave intermediate
3952 parameters empty. Empty parameters are replaced by empty space (that is,
3953 they are removed when the macro is expanded). If you have a look at our
3954 macro definition above, you will see, that replacing the "addr" parameter
3955 by nothing will lead to wrong code in most lines. To help you, writing
3956 macros with a variable parameter list, there are some control commands:
3958 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
3959 returns true, if there are any tokens on the remainder of the line. Since
3960 empty parameters are replaced by nothing, this may be used to test if a given
3961 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
3964 Look at this example:
3967 .macro ldaxy a, x, y
3980 This macro may be called as follows:
3983 ldaxy 1, 2, 3 ; Load all three registers
3985 ldaxy 1, , 3 ; Load only a and y
3987 ldaxy , , 3 ; Load y only
3990 There's another helper command for determining, which macro parameters are
3991 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt> This command is
3992 replaced by the parameter count given, <em/including/ intermediate empty macro
3996 ldaxy 1 ; .PARAMCOUNT = 1
3997 ldaxy 1,,3 ; .PARAMCOUNT = 3
3998 ldaxy 1,2 ; .PARAMCOUNT = 2
3999 ldaxy 1, ; .PARAMCOUNT = 2
4000 ldaxy 1,2,3 ; .PARAMCOUNT = 3
4003 Macro parameters may optionally be enclosed into curly braces. This allows the
4004 inclusion of tokens that would otherwise terminate the parameter (the comma in
4005 case of a macro parameter).
4008 .macro foo arg1, arg2
4012 foo ($00,x) ; Two parameters passed
4013 foo {($00,x)} ; One parameter passed
4016 In the first case, the macro is called with two parameters: '<tt/($00/'
4017 and 'x)'. The comma is not passed to the macro, since it is part of the
4018 calling sequence, not the parameters.
4020 In the second case, '($00,x)' is passed to the macro, this time
4021 including the comma.
4024 <sect1>Detecting parameter types<p>
4026 Sometimes it is nice to write a macro that acts differently depending on the
4027 type of the argument supplied. An example would be a macro that loads a 16 bit
4028 value from either an immediate operand, or from memory. The <tt/<ref
4029 id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
4030 functions will allow you to do exactly this:
4034 .if (.match (.left (1, {arg}), #))
4036 lda #<(.right (.tcount ({arg})-1, {arg}))
4037 ldx #>(.right (.tcount ({arg})-1, {arg}))
4039 ; assume absolute or zero page
4046 Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
4047 check if its argument begins with a hash mark. If so, two immediate loads are
4048 emitted, Otherwise a load from an absolute zero page memory location is
4049 assumed. Please note how the curly braces are used to enclose parameters to
4050 pseudo functions handling token lists. This is necessary, because the token
4051 lists may include commas or parens, which would be treated by the assembler
4054 The macro can be used as
4059 ldax #$1234 ; X=$12, A=$34
4061 ldax foo ; X=$56, A=$78
4065 <sect1>Recursive macros<p>
4067 Macros may be used recursively:
4070 .macro push r1, r2, r3
4079 There's also a special macro to help writing recursive macros: <tt><ref
4080 id=".EXITMACRO" name=".EXITMACRO"></tt> This command will stop macro expansion
4084 .macro push r1, r2, r3, r4, r5, r6, r7
4086 ; First parameter is empty
4092 push r2, r3, r4, r5, r6, r7
4096 When expanding this macro, the expansion will push all given parameters
4097 until an empty one is encountered. The macro may be called like this:
4100 push $20, $21, $32 ; Push 3 ZP locations
4101 push $21 ; Push one ZP location
4105 <sect1>Local symbols inside macros<p>
4107 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
4108 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
4109 Have a look at the inc16 macro above. Here is it again:
4123 If you have a closer look at the code, you will notice, that it could be
4124 written more efficiently, like this:
4135 But imagine what happens, if you use this macro twice? Since the label "Skip"
4136 has the same name both times, you get a "duplicate symbol" error. Without a
4137 way to circumvent this problem, macros are not as useful, as they could be.
4138 One possible solution is the command <tt><ref id=".LOCAL" name=".LOCAL"></tt>.
4139 It declares one or more symbols as local to the macro expansion. The names of
4140 local variables are replaced by a unique name in each separate macro
4141 expansion. So we can solve the problem above by using <tt/.LOCAL/:
4145 .local Skip ; Make Skip a local symbol
4149 Skip: ; Not visible outside
4153 Another solution is of course to start a new lexical block inside the macro
4154 that hides any labels:
4168 <sect1>C style macros<p>
4170 Starting with version 2.5 of the assembler, there is a second macro type
4171 available: C style macros using the <tt/.DEFINE/ directive. These macros are
4172 similar to the classic macro type described above, but behaviour is sometimes
4177 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
4178 span more than a line. You may use line continuation (see <tt><ref
4179 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
4180 more than one line for increased readability, but the macro itself
4181 may not contain an end-of-line token.
4183 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
4184 the name space with classic macros, but they are detected and replaced
4185 at the scanner level. While classic macros may be used in every place,
4186 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
4187 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
4188 they are more versatile in some situations.
4190 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
4191 parameters. While classic macros may have empty parameters, this is
4192 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
4193 For this macro type, the number of actual parameters must match
4194 exactly the number of formal parameters.
4196 To make this possible, formal parameters are enclosed in braces when
4197 defining the macro. If there are no parameters, the empty braces may
4200 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
4201 contain end-of-line tokens, there are things that cannot be done. They
4202 may not contain several processor instructions for example. So, while
4203 some things may be done with both macro types, each type has special
4204 usages. The types complement each other.
4208 Let's look at a few examples to make the advantages and disadvantages
4211 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
4212 following <tt/.DEFINE/:
4217 foo EQU $1234 ; This is accepted now
4220 You may use the directive to define string constants used elsewhere:
4223 ; Define the version number
4224 .define VERSION "12.3a"
4230 Macros with parameters may also be useful:
4233 .define DEBUG(message) .out message
4235 DEBUG "Assembling include file #3"
4238 Note that, while formal parameters have to be placed in braces, this is
4239 not true for the actual parameters. Beware: Since the assembler cannot
4240 detect the end of one parameter, only the first token is used. If you
4241 don't like that, use classic macros instead:
4244 .macro DEBUG message
4249 (This is an example where a problem can be solved with both macro types).
4252 <sect1>Characters in macros<p>
4254 When using the <ref id="option-t" name="-t"> option, characters are translated
4255 into the target character set of the specific machine. However, this happens
4256 as late as possible. This means that strings are translated if they are part
4257 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
4258 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
4259 used as part of an expression.
4261 This behaviour is very intuitive outside of macros but may be confusing when
4262 doing more complex macros. If you compare characters against numeric values,
4263 be sure to take the translation into account.
4266 <sect1>Deleting macros<p>
4268 Macros can be deleted. This will not work if the macro that should be deleted
4269 is currently expanded as in the following non working example:
4273 .delmacro notworking
4276 notworking ; Will not work
4279 The commands to delete classic and define style macros differ. Classic macros
4280 can be deleted by use of <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>, while
4281 for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros, <tt><ref
4282 id=".UNDEFINE" name=".UNDEFINE"></tt> must be used. Example:
4290 .byte value ; Emit one byte with value 1
4291 mac ; Emit another byte with value 2
4296 .byte value ; Error: Unknown identifier
4297 mac ; Error: Missing ":"
4300 A separate command for <tt>.DEFINE</tt> style macros was necessary, because
4301 the name of such a macro is replaced by its replacement list on a very low
4302 level. To get the actual name, macro replacement has to be switched off when
4303 reading the argument to <tt>.UNDEFINE</tt>. This does also mean that the
4304 argument to <tt>.UNDEFINE</tt> is not allowed to come from another
4305 <tt>.DEFINE</tt>. All this is not necessary for classic macros, so having two
4306 different commands increases flexibility.
4309 <sect>Macro packages<label id="macropackages"><p>
4311 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
4312 macro packages may be included with just one command. Available macro packages
4316 <sect1><tt>.MACPACK generic</tt><p>
4318 This macro package defines macroes that are useful in almost any program.
4319 Currently defined macroes are:
4322 .macro add Arg ; add without carry
4327 .macro sub Arg ; subtract without borrow
4332 .macro bge Arg ; branch on greater-than or equal
4336 .macro blt Arg ; branch on less-than
4340 .macro bgt Arg ; branch on greater-than
4347 .macro ble Arg ; branch on less-than or equal
4352 .macro bnz Arg ; branch on not zero
4356 .macro bze Arg ; branch on zero
4362 <sect1><tt>.MACPACK longbranch</tt><p>
4364 This macro package defines long conditional jumps. They are named like the
4365 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
4366 definition for the "<tt/jeq/" macro, the other macros are built using the same
4371 .if .def(Target) .and ((*+2)-(Target) <= 127)
4380 All macros expand to a short branch, if the label is already defined (back
4381 jump) and is reachable with a short jump. Otherwise the macro expands to a
4382 conditional branch with the branch condition inverted, followed by an absolute
4383 jump to the actual branch target.
4385 The package defines the following macros:
4388 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
4393 <sect1><tt>.MACPACK atari</tt><p>
4395 This macro package defines a macro named <tt/scrcode/. It takes a string
4396 as argument and places this string into memory translated into screen codes.
4399 <sect1><tt>.MACPACK cbm</tt><p>
4401 This macro package defines a macro named <tt/scrcode/. It takes a string
4402 as argument and places this string into memory translated into screen codes.
4405 <sect1><tt>.MACPACK cpu</tt><p>
4407 This macro package does not define any macros but constants used to examine
4408 the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
4409 each supported CPU a constant similar to
4420 is defined. These constants may be used to determine the exact type of the
4421 currently enabled CPU. In addition to that, for each CPU instruction set,
4422 another constant is defined:
4433 The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
4434 be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
4435 currently enabled CPU supports a specific instruction set. For example the
4436 65C02 supports all instructions of the 65SC02 CPU, so it has the
4437 <tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
4441 .if (.cpu .bitand CPU_ISET_65SC02)
4449 it is possible to determine if the
4455 instruction is supported, which is the case for the 65SC02, 65C02 and 65816
4456 CPUs (the latter two are upwards compatible to the 65SC02).
4459 <sect1><tt>.MACPACK module</tt><p>
4461 This macro package defines a macro named <tt/module_header/. It takes an
4462 identifier as argument and is used to define the header of a module both
4463 in the dynamic and static variant.
4467 <sect>Predefined constants<label id="predefined-constants"><p>
4469 For better orthogonality, the assembler defines similar symbols as the
4470 compiler, depending on the target system selected:
4473 <item><tt/__APPLE2__/ - Target system is <tt/apple2/ or <tt/apple2enh/
4474 <item><tt/__APPLE2ENH__/ - Target system is <tt/apple2enh/
4475 <item><tt/__ATARI5200__/ - Target system is <tt/atari5200/
4476 <item><tt/__ATARI__/ - Target system is <tt/atari/ or <tt/atarixl/
4477 <item><tt/__ATARIXL__/ - Target system is <tt/atarixl/
4478 <item><tt/__ATMOS__/ - Target system is <tt/atmos/
4479 <item><tt/__BBC__/ - Target system is <tt/bbc/
4480 <item><tt/__C128__/ - Target system is <tt/c128/
4481 <item><tt/__C16__/ - Target system is <tt/c16/ or <tt/plus4/
4482 <item><tt/__C64__/ - Target system is <tt/c64/
4483 <item><tt/__CBM__/ - Target is a Commodore system
4484 <item><tt/__CBM510__/ - Target system is <tt/cbm510/
4485 <item><tt/__CBM610__/ - Target system is <tt/cbm610/
4486 <item><tt/__GEOS__/ - Target is a GEOS system
4487 <item><tt/__GEOS_APPLE__/ - Target system is <tt/geos-apple/
4488 <item><tt/__GEOS_CBM__/ - Target system is <tt/geos-cbm/
4489 <item><tt/__LUNIX__/ - Target system is <tt/lunix/
4490 <item><tt/__LYNX__/ - Target system is <tt/lynx/
4491 <item><tt/__NES__/ - Target system is <tt/nes/
4492 <item><tt/__OSIC1P__/ - Target system is <tt/osic1p/
4493 <item><tt/__PET__/ - Target system is <tt/pet/
4494 <item><tt/__PLUS4__/ - Target system is <tt/plus4/
4495 <item><tt/__SIM6502__/ - Target system is <tt/sim6502/
4496 <item><tt/__SIM65C02__/ - Target system is <tt/sim65c02/
4497 <item><tt/__SUPERVISION__/ - Target system is <tt/supervision/
4498 <item><tt/__VIC20__/ - Target system is <tt/vic20/
4502 <sect>Structs and unions<label id="structs"><p>
4504 <sect1>Structs and unions Overview<p>
4506 Structs and unions are special forms of <ref id="scopes" name="scopes">. They
4507 are to some degree comparable to their C counterparts. Both have a list of
4508 members. Each member allocates storage and may optionally have a name, which,
4509 in case of a struct, is the offset from the beginning and, in case of a union,
4513 <sect1>Declaration<p>
4515 Here is an example for a very simple struct with two members and a total size
4525 A union shares the total space between all its members, its size is the same
4526 as that of the largest member. The offset of all members relative to the union
4536 A struct or union must not necessarily have a name. If it is anonymous, no
4537 local scope is opened, the identifiers used to name the members are placed
4538 into the current scope instead.
4540 A struct may contain unnamed members and definitions of local structs. The
4541 storage allocators may contain a multiplier, as in the example below:
4546 .word 2 ; Allocate two words
4553 <sect1>The <tt/.TAG/ keyword<p>
4555 Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to reserve space
4556 for an already defined struct or unions within another struct:
4570 Space for a struct or union may be allocated using the <ref id=".TAG"
4571 name=".TAG"> directive.
4577 Currently, members are just offsets from the start of the struct or union. To
4578 access a field of a struct, the member offset has to be added to the address
4579 of the struct itself:
4582 lda C+Circle::Radius ; Load circle radius into A
4585 This may change in a future version of the assembler.
4588 <sect1>Limitations<p>
4590 Structs and unions are currently implemented as nested symbol tables (in fact,
4591 they were a by-product of the improved scoping rules). Currently, the
4592 assembler has no idea of types. This means that the <ref id=".TAG"
4593 name=".TAG"> keyword will only allocate space. You won't be able to initialize
4594 variables declared with <ref id=".TAG" name=".TAG">, and adding an embedded
4595 structure to another structure with <ref id=".TAG" name=".TAG"> will not make
4596 this structure accessible by using the '::' operator.
4600 <sect>Module constructors/destructors<label id="condes"><p>
4602 <em>Note:</em> This section applies mostly to C programs, so the explanation
4603 below uses examples from the C libraries. However, the feature may also be
4604 useful for assembler programs.
4607 <sect1>Module constructors/destructors Overview<p>
4609 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4610 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4611 name=".INTERRUPTOR"></tt> keywords it is possible to export functions in a
4612 special way. The linker is able to generate tables with all functions of a
4613 specific type. Such a table will <em>only</em> include symbols from object
4614 files that are linked into a specific executable. This may be used to add
4615 initialization and cleanup code for library modules, or a table of interrupt
4618 The C heap functions are an example where module initialization code is used.
4619 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
4620 variables that contain the start and the end of the heap, pointers to the free
4621 list and so on. Since the end of the heap depends on the size and start of the
4622 stack, it must be initialized at runtime. However, initializing these
4623 variables for programs that do not use the heap are a waste of time and
4626 So the central module defines a function that contains initialization code and
4627 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
4628 this module is added to an executable by the linker, the initialization
4629 function will be placed into the table of constructors by the linker. The C
4630 startup code will call all constructors before <tt/main/ and all destructors
4631 after <tt/main/, so without any further work, the heap initialization code is
4632 called once the module is linked in.
4634 While it would be possible to add explicit calls to initialization functions
4635 in the startup code, the new approach has several advantages:
4639 If a module is not included, the initialization code is not linked in and not
4640 called. So you don't pay for things you don't need.
4643 Adding another library that needs initialization does not mean that the
4644 startup code has to be changed. Before we had module constructors and
4645 destructors, the startup code for all systems had to be adjusted to call the
4646 new initialization code.
4649 The feature saves memory: Each additional initialization function needs just
4650 two bytes in the table (a pointer to the function).
4655 <sect1>Calling order<p>
4657 The symbols are sorted in increasing priority order by the linker when using
4658 one of the builtin linker configurations, so the functions with lower
4659 priorities come first and are followed by those with higher priorities. The C
4660 library runtime subroutine that walks over the function tables calls the
4661 functions starting from the top of the table - which means that functions with
4662 a high priority are called first.
4664 So when using the C runtime, functions are called with high priority functions
4665 first, followed by low priority functions.
4670 When using these special symbols, please take care of the following:
4675 The linker will only generate function tables, it will not generate code to
4676 call these functions. If you're using the feature in some other than the
4677 existing C environments, you have to write code to call all functions in a
4678 linker generated table yourself. See the <tt/condes/ and <tt/callirq/ modules
4679 in the C runtime for an example on how to do this.
4682 The linker will only add addresses of functions that are in modules linked to
4683 the executable. This means that you have to be careful where to place the
4684 condes functions. If initialization or an irq handler is needed for a group of
4685 functions, be sure to place the function into a module that is linked in
4686 regardless of which function is called by the user.
4689 The linker will generate the tables only when requested to do so by the
4690 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
4691 be requested separately.
4694 Constructors and destructors may have priorities. These priorities determine
4695 the order of the functions in the table. If your initialization or cleanup code
4696 does depend on other initialization or cleanup code, you have to choose the
4697 priority for the functions accordingly.
4700 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4701 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4702 name=".INTERRUPTOR"></tt> statements, there is also a more generic command:
4703 <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to specify an
4704 additional type. Predefined types are 0 (constructor), 1 (destructor) and 2
4705 (interruptor). The linker generates a separate table for each type on request.
4710 <sect>Porting sources from other assemblers<p>
4712 Sometimes it is necessary to port code written for older assemblers to ca65.
4713 In some cases, this can be done without any changes to the source code by
4714 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
4715 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
4718 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
4719 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
4720 done by the linker. Most other assemblers generate absolute code, placement is
4721 done within the assembler and there is no external linker.
4723 In general it is not a good idea to write new code using the emulation
4724 features of the assembler, but there may be situations where even this rule is
4729 You need to use some of the ca65 emulation features to simulate the behaviour
4730 of such simple assemblers.
4733 <item>Prepare your sourcecode like this:
4736 ; if you want TASS style labels without colons
4737 .feature labels_without_colons
4739 ; if you want TASS style character constants
4740 ; ("a" instead of the default 'a')
4741 .feature loose_char_term
4743 .word *+2 ; the cbm load address
4748 notice that the two emulation features are mostly useful for porting
4749 sources originally written in/for TASS, they are not needed for the
4750 actual "simple assembler operation" and are not recommended if you are
4751 writing new code from scratch.
4753 <item>Replace all program counter assignments (which are not possible in ca65
4754 by default, and the respective emulation feature works different from what
4755 you'd expect) by another way to skip to memory locations, for example the
4756 <tt><ref id=".RES" name=".RES"></tt> directive.
4760 .res $2000-* ; reserve memory up to $2000
4763 Please note that other than the original TASS, ca65 can never move the program
4764 counter backwards - think of it as if you are assembling to disk with TASS.
4766 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
4767 rewritten to match ca65 syntax. Most importantly notice that due to the lack
4768 of <tt/.goto/, everything involving loops must be replaced by
4769 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
4771 <item>To assemble code to a different address than it is executed at, use the
4772 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
4773 <tt/.offs/-constructs.
4780 .reloc ; back to normal
4783 <item>Then assemble like this:
4786 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
4789 Note that you need to use the actual start address minus two, since two bytes
4790 are used for the cbm load address.
4797 ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
4798 Bassewitz. For usage of the binaries and/or sources the following
4799 conditions do apply:
4801 This software is provided 'as-is', without any expressed or implied
4802 warranty. In no event will the authors be held liable for any damages
4803 arising from the use of this software.
4805 Permission is granted to anyone to use this software for any purpose,
4806 including commercial applications, and to alter it and redistribute it
4807 freely, subject to the following restrictions:
4810 <item> The origin of this software must not be misrepresented; you must not
4811 claim that you wrote the original software. If you use this software
4812 in a product, an acknowledgment in the product documentation would be
4813 appreciated but is not required.
4814 <item> Altered source versions must be plainly marked as such, and must not
4815 be misrepresented as being the original software.
4816 <item> This notice may not be removed or altered from any source