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 BGE is an alias for BCS
438 BLT is an alias for BCC
439 CPA is an alias for CMP
440 DEA is an alias for DEC A
441 INA is an alias for INC A
442 SWA is an alias for XBA
443 TAD is an alias for TCD
444 TAS is an alias for TCS
445 TDA is an alias for TDC
446 TSA is an alias for TSC
451 <sect1>6502X mode<label id="6502X-mode"><p>
453 6502X mode is an extension to the normal 6502 mode. In this mode, several
454 mnemonics for illegal instructions of the NMOS 6502 CPUs are accepted. Since
455 these instructions are illegal, there are no official mnemonics for them. The
456 unofficial ones are taken from <url
457 url="http://www.oxyron.de/html/opcodes02.html">. Please note that only the
458 ones marked as "stable" are supported. The following table uses information
459 from the mentioned web page, for more information, see there.
462 <item><tt>ALR: A:=(A and #{imm})/2;</tt>
463 <item><tt>ANC: A:=A and #{imm};</tt> Generates opcode $0B.
464 <item><tt>ARR: A:=(A and #{imm})/2;</tt>
465 <item><tt>AXS: X:=A and X-#{imm};</tt>
466 <item><tt>DCP: {adr}:={adr}-1; A-{adr};</tt>
467 <item><tt>ISC: {adr}:={adr}+1; A:=A-{adr};</tt>
468 <item><tt>LAS: A,X,S:={adr} and S;</tt>
469 <item><tt>LAX: A,X:={adr};</tt>
470 <item><tt>RLA: {adr}:={adr}rol; A:=A and {adr};</tt>
471 <item><tt>RRA: {adr}:={adr}ror; A:=A adc {adr};</tt>
472 <item><tt>SAX: {adr}:=A and X;</tt>
473 <item><tt>SLO: {adr}:={adr}*2; A:=A or {adr};</tt>
474 <item><tt>SRE: {adr}:={adr}/2; A:=A xor {adr};</tt>
479 <sect1>sweet16 mode<label id="sweet16-mode"><p>
481 SWEET 16 is an interpreter for a pseudo 16 bit CPU written by Steve Wozniak
482 for the Apple ][ machines. It is available in the Apple ][ ROM. ca65 can
483 generate code for this pseudo CPU when switched into sweet16 mode. The
484 following is special in sweet16 mode:
488 <item>The '@' character denotes indirect addressing and is no longer available
489 for cheap local labels. If you need cheap local labels, you will have to
490 switch to another lead character using the <tt/<ref id=".LOCALCHAR"
491 name=".LOCALCHAR">/ command.
493 <item>Registers are specified using <tt/R0/ .. <tt/R15/. In sweet16 mode,
494 these identifiers are reserved words.
498 Please note that the assembler does neither supply the interpreter needed for
499 SWEET 16 code, nor the zero page locations needed for the SWEET 16 registers,
500 nor does it call the interpreter. All this must be done by your program. Apple
501 ][ programmers do probably know how to use sweet16 mode.
503 For more information about SWEET 16, see
504 <url url="http://www.6502.org/source/interpreters/sweet16.htm">.
507 <sect1>Number format<p>
509 For literal values, the assembler accepts the widely used number formats: A
510 preceding '$' or a trailing 'h' denotes a hex value, a preceding '%'
511 denotes a binary value, and a bare number is interpreted as a decimal. There
512 are currently no octal values and no floats.
515 <sect1>Conditional assembly<p>
517 Please note that when using the conditional directives (<tt/.IF/ and friends),
518 the input must consist of valid assembler tokens, even in <tt/.IF/ branches
519 that are not assembled. The reason for this behaviour is that the assembler
520 must still be able to detect the ending tokens (like <tt/.ENDIF/), so
521 conversion of the input stream into tokens still takes place. As a consequence
522 conditional assembly directives may <bf/not/ be used to prevent normal text
523 (used as a comment or similar) from being assembled. <p>
529 <sect1>Expression evaluation<p>
531 All expressions are evaluated with (at least) 32 bit precision. An
532 expression may contain constant values and any combination of internal and
533 external symbols. Expressions that cannot be evaluated at assembly time
534 are stored inside the object file for evaluation by the linker.
535 Expressions referencing imported symbols must always be evaluated by the
539 <sect1>Size of an expression result<p>
541 Sometimes, the assembler must know about the size of the value that is the
542 result of an expression. This is usually the case, if a decision has to be
543 made, to generate a zero page or an absolute memory references. In this
544 case, the assembler has to make some assumptions about the result of an
548 <item> If the result of an expression is constant, the actual value is
549 checked to see if it's a byte sized expression or not.
550 <item> If the expression is explicitly casted to a byte sized expression by
551 one of the '>', '<' or '^' operators, it is a byte expression.
552 <item> If this is not the case, and the expression contains a symbol,
553 explicitly declared as zero page symbol (by one of the .importzp or
554 .exportzp instructions), then the whole expression is assumed to be
556 <item> If the expression contains symbols that are not defined, and these
557 symbols are local symbols, the enclosing scopes are searched for a
558 symbol with the same name. If one exists and this symbol is defined,
559 its attributes are used to determine the result size.
560 <item> In all other cases the expression is assumed to be word sized.
563 Note: If the assembler is not able to evaluate the expression at assembly
564 time, the linker will evaluate it and check for range errors as soon as
568 <sect1>Boolean expressions<p>
570 In the context of a boolean expression, any non zero value is evaluated as
571 true, any other value to false. The result of a boolean expression is 1 if
572 it's true, and zero if it's false. There are boolean operators with extreme
573 low precedence with version 2.x (where x > 0). The <tt/.AND/ and <tt/.OR/
574 operators are shortcut operators. That is, if the result of the expression is
575 already known, after evaluating the left hand side, the right hand side is
579 <sect1>Constant expressions<p>
581 Sometimes an expression must evaluate to a constant without looking at any
582 further input. One such example is the <tt/<ref id=".IF" name=".IF">/ command
583 that decides if parts of the code are assembled or not. An expression used in
584 the <tt/.IF/ command cannot reference a symbol defined later, because the
585 decision about the <tt/.IF/ must be made at the point when it is read. If the
586 expression used in such a context contains only constant numerical values,
587 there is no problem. When unresolvable symbols are involved it may get harder
588 for the assembler to determine if the expression is actually constant, and it
589 is even possible to create expressions that aren't recognized as constant.
590 Simplifying the expressions will often help.
592 In cases where the result of the expression is not needed immediately, the
593 assembler will delay evaluation until all input is read, at which point all
594 symbols are known. So using arbitrary complex constant expressions is no
595 problem in most cases.
599 <sect1>Available operators<label id="operators"><p>
603 <bf/Operator/| <bf/Description/| <bf/Precedence/@<hline>
604 | Built-in string functions| 0@
606 | Built-in pseudo-variables| 1@
607 | Built-in pseudo-functions| 1@
608 +| Unary positive| 1@
609 -| Unary negative| 1@
611 .BITNOT| Unary bitwise not| 1@
613 .LOBYTE| Unary low-byte operator| 1@
615 .HIBYTE| Unary high-byte operator| 1@
617 .BANKBYTE| Unary bank-byte operator| 1@
619 *| Multiplication| 2@
621 .MOD| Modulo operator| 2@
623 .BITAND| Bitwise and| 2@
625 .BITXOR| Binary bitwise xor| 2@
627 .SHL| Shift-left operator| 2@
629 .SHR| Shift-right operator| 2@
631 +| Binary addition| 3@
632 -| Binary subtraction| 3@
634 .BITOR| Bitwise or| 3@
636 = | Compare operator (equal)| 4@
637 <>| Compare operator (not equal)| 4@
638 <| Compare operator (less)| 4@
639 >| Compare operator (greater)| 4@
640 <=| Compare operator (less or equal)| 4@
641 >=| Compare operator (greater or equal)| 4@
644 .AND| Boolean and| 5@
645 .XOR| Boolean xor| 5@
647 ||<newline>
651 .NOT| Boolean not| 7@<hline>
653 <caption>Available operators, sorted by precedence
656 To force a specific order of evaluation, parentheses may be used, as usual.
660 <sect>Symbols and labels<p>
662 A symbol or label is an identifier that starts with a letter and is followed
663 by letters and digits. Depending on some features enabled (see
664 <tt><ref id="at_in_identifiers" name="at_in_identifiers"></tt>,
665 <tt><ref id="dollar_in_identifiers" name="dollar_in_identifiers"></tt> and
666 <tt><ref id="leading_dot_in_identifiers" name="leading_dot_in_identifiers"></tt>)
667 other characters may be present. Use of identifiers consisting of a single
668 character will not work in all cases, because some of these identifiers are
669 reserved keywords (for example "A" is not a valid identifier for a label,
670 because it is the keyword for the accumulator).
672 The assembler allows you to use symbols instead of naked values to make
673 the source more readable. There are a lot of different ways to define and
674 use symbols and labels, giving a lot of flexibility.
676 <sect1>Numeric constants<p>
678 Numeric constants are defined using the equal sign or the label assignment
679 operator. After doing
685 may use the symbol "two" in every place where a number is expected, and it is
686 evaluated to the value 2 in this context. The label assignment operator is
687 almost identical, but causes the symbol to be marked as a label, so it may be
688 handled differently in a debugger:
694 The right side can of course be an expression:
701 <label id="variables">
702 <sect1>Numeric variables<p>
704 Within macros and other control structures (<tt><ref id=".REPEAT"
705 name=".REPEAT"></tt>, ...) it is sometimes useful to have some sort of
706 variable. This can be achieved by the <tt>.SET</tt> operator. It creates a
707 symbol that may get assigned a different value later:
711 lda #four ; Loads 4 into A
713 lda #four ; Loads 3 into A
716 Since the value of the symbol can change later, it must be possible to
717 evaluate it when used (no delayed evaluation as with normal symbols). So the
718 expression used as the value must be constant.
720 Following is an example for a macro that generates a different label each time
721 it is used. It uses the <tt><ref id=".SPRINTF" name=".SPRINTF"></tt> function
722 and a numeric variable named <tt>lcount</tt>.
725 .lcount .set 0 ; Initialize the counter
728 .ident (.sprintf ("L%04X", lcount)):
729 lcount .set lcount + 1
734 <sect1>Standard labels<p>
736 A label is defined by writing the name of the label at the start of the line
737 (before any instruction mnemonic, macro or pseudo directive), followed by a
738 colon. This will declare a symbol with the given name and the value of the
739 current program counter.
742 <sect1>Local labels and symbols<p>
744 Using the <tt><ref id=".PROC" name=".PROC"></tt> directive, it is possible to
745 create regions of code where the names of labels and symbols are local to this
746 region. They are not known outside of this region and cannot be accessed from
747 there. Such regions may be nested like PROCEDUREs in Pascal.
749 See the description of the <tt><ref id=".PROC" name=".PROC"></tt>
750 directive for more information.
753 <sect1>Cheap local labels<p>
755 Cheap local labels are defined like standard labels, but the name of the
756 label must begin with a special symbol (usually '@', but this can be
757 changed by the <tt><ref id=".LOCALCHAR" name=".LOCALCHAR"></tt>
760 Cheap local labels are visible only between two non cheap labels. As soon as a
761 standard symbol is encountered (this may also be a local symbol if inside a
762 region defined with the <tt><ref id=".PROC" name=".PROC"></tt> directive), the
763 cheap local symbol goes out of scope.
765 You may use cheap local labels as an easy way to reuse common label
766 names like "Loop". Here is an example:
769 Clear: lda #$00 ; Global label
771 @Loop: sta Mem,y ; Local label
775 Sub: ... ; New global label
776 bne @Loop ; ERROR: Unknown identifier!
779 <sect1>Unnamed labels<p>
781 If you really want to write messy code, there are also unnamed labels. These
782 labels do not have a name (you guessed that already, didn't you?). A colon is
783 used to mark the absence of the name.
785 Unnamed labels may be accessed by using the colon plus several minus or plus
786 characters as a label designator. Using the '-' characters will create a back
787 reference (use the n'th label backwards), using '+' will create a forward
788 reference (use the n'th label in forward direction). An example will help to
811 As you can see from the example, unnamed labels will make even short
812 sections of code hard to understand, because you have to count labels
813 to find branch targets (this is the reason why I for my part do
814 prefer the "cheap" local labels). Nevertheless, unnamed labels are
815 convenient in some situations, so it's your decision.
817 <em/Note:/ <ref id="scopes" name="Scopes"> organize named symbols, not
818 unnamed ones, so scopes don't have an effect on unnamed labels.
822 <sect1>Using macros to define labels and constants<p>
824 While there are drawbacks with this approach, it may be handy in a few rare
825 situations. Using <tt><ref id=".DEFINE" name=".DEFINE"></tt>, it is possible
826 to define symbols or constants that may be used elsewhere. One of the
827 advantages is that you can use it to define string constants (this is not
828 possible with the other symbol types).
830 Please note: <tt/.DEFINE/ style macros do token replacements on a low level,
831 so the names do not adhere to scoping, diagnostics may be misleading, there
832 are no symbols to look up in the map file, and there is no debug info.
833 Especially the first problem in the list can lead to very nasty programming
834 errors. Because of these problems, the general advice is, <bf/NOT/ do use
835 <tt/.DEFINE/ if you don't have to.
841 .DEFINE version "SOS V2.3"
843 four = two * two ; Ok
846 .PROC ; Start local scope
847 two = 3 ; Will give "2 = 3" - invalid!
852 <sect1>Symbols and <tt>.DEBUGINFO</tt><p>
854 If <tt><ref id=".DEBUGINFO" name=".DEBUGINFO"></tt> is enabled (or <ref
855 id="option-g" name="-g"> is given on the command line), global, local and
856 cheap local labels are written to the object file and will be available in the
857 symbol file via the linker. Unnamed labels are not written to the object file,
858 because they don't have a name which would allow to access them.
862 <sect>Scopes<label id="scopes"><p>
864 ca65 implements several sorts of scopes for symbols.
866 <sect1>Global scope<p>
868 All (non cheap local) symbols that are declared outside of any nested scopes
872 <sect1>Cheap locals<p>
874 A special scope is the scope for cheap local symbols. It lasts from one non
875 local symbol to the next one, without any provisions made by the programmer.
876 All other scopes differ in usage but use the same concept internally.
879 <sect1>Generic nested scopes<p>
881 A nested scoped for generic use is started with <tt/<ref id=".SCOPE"
882 name=".SCOPE">/ and closed with <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/.
883 The scope can have a name, in which case it is accessible from the outside by
884 using <ref id="scopesyntax" name="explicit scopes">. If the scope does not
885 have a name, all symbols created within the scope are local to the scope, and
886 aren't accessible from the outside.
888 A nested scope can access symbols from the local or from enclosing scopes by
889 name without using explicit scope names. In some cases there may be
890 ambiguities, for example if there is a reference to a local symbol that is not
891 yet defined, but a symbol with the same name exists in outer scopes:
903 In the example above, the <tt/lda/ instruction will load the value 3 into the
904 accumulator, because <tt/foo/ is redefined in the scope. However:
916 Here, <tt/lda/ will still load from <tt/$12,x/, but since it is unknown to the
917 assembler that <tt/foo/ is a zeropage symbol when translating the instruction,
918 absolute mode is used instead. In fact, the assembler will not use absolute
919 mode by default, but it will search through the enclosing scopes for a symbol
920 with the given name. If one is found, the address size of this symbol is used.
921 This may lead to errors:
933 In this case, when the assembler sees the symbol <tt/foo/ in the <tt/lda/
934 instruction, it will search for an already defined symbol <tt/foo/. It will
935 find <tt/foo/ in scope <tt/outer/, and a close look reveals that it is a
936 zeropage symbol. So the assembler will use zeropage addressing mode. If
937 <tt/foo/ is redefined later in scope <tt/inner/, the assembler tries to change
938 the address in the <tt/lda/ instruction already translated, but since the new
939 value needs absolute addressing mode, this fails, and an error message "Range
942 Of course the most simple solution for the problem is to move the definition
943 of <tt/foo/ in scope <tt/inner/ upwards, so it precedes its use. There may be
944 rare cases when this cannot be done. In these cases, you can use one of the
945 address size override operators:
957 This will cause the <tt/lda/ instruction to be translated using absolute
958 addressing mode, which means changing the symbol reference later does not
962 <sect1>Nested procedures<p>
964 A nested procedure is created by use of <tt/<ref id=".PROC" name=".PROC">/. It
965 differs from a <tt/<ref id=".SCOPE" name=".SCOPE">/ in that it must have a
966 name, and a it will introduce a symbol with this name in the enclosing scope.
975 is actually the same as
984 This is the reason why a procedure must have a name. If you want a scope
985 without a name, use <tt/<ref id=".SCOPE" name=".SCOPE">/.
987 <em/Note:/ As you can see from the example above, scopes and symbols live in
988 different namespaces. There can be a symbol named <tt/foo/ and a scope named
989 <tt/foo/ without any conflicts (but see the section titled <ref
990 id="scopesearch" name=""Scope search order"">).
993 <sect1>Structs, unions and enums<p>
995 Structs, unions and enums are explained in a <ref id="structs" name="separate
996 section">, I do only cover them here, because if they are declared with a
997 name, they open a nested scope, similar to <tt/<ref id=".SCOPE"
998 name=".SCOPE">/. However, when no name is specified, the behaviour is
999 different: In this case, no new scope will be opened, symbols declared within
1000 a struct, union, or enum declaration will then be added to the enclosing scope
1004 <sect1>Explicit scope specification<label id="scopesyntax"><p>
1006 Accessing symbols from other scopes is possible by using an explicit scope
1007 specification, provided that the scope where the symbol lives in has a name.
1008 The namespace token (<tt/::/) is used to access other scopes:
1016 lda foo::bar ; Access foo in scope bar
1019 The only way to deny access to a scope from the outside is to declare a scope
1020 without a name (using the <tt/<ref id=".SCOPE" name=".SCOPE">/ command).
1022 A special syntax is used to specify the global scope: If a symbol or scope is
1023 preceded by the namespace token, the global scope is searched:
1030 lda #::bar ; Access the global bar (which is 3)
1035 <sect1>Scope search order<label id="scopesearch"><p>
1037 The assembler searches for a scope in a similar way as for a symbol. First, it
1038 looks in the current scope, and then it walks up the enclosing scopes until
1041 However, one important thing to note when using explicit scope syntax is, that
1042 a symbol may be accessed before it is defined, but a scope may <bf/not/ be
1043 used without a preceding definition. This means that in the following
1052 lda #foo::bar ; Will load 3, not 2!
1059 the reference to the scope <tt/foo/ will use the global scope, and not the
1060 local one, because the local one is not visible at the point where it is
1063 Things get more complex if a complete chain of scopes is specified:
1074 lda #outer::inner::bar ; 1
1086 When <tt/outer::inner::bar/ is referenced in the <tt/lda/ instruction, the
1087 assembler will first search in the local scope for a scope named <tt/outer/.
1088 Since none is found, the enclosing scope (<tt/another/) is checked. There is
1089 still no scope named <tt/outer/, so scope <tt/foo/ is checked, and finally
1090 scope <tt/outer/ is found. Within this scope, <tt/inner/ is searched, and in
1091 this scope, the assembler looks for a symbol named <tt/bar/.
1093 Please note that once the anchor scope is found, all following scopes
1094 (<tt/inner/ in this case) are expected to be found exactly in this scope. The
1095 assembler will search the scope tree only for the first scope (if it is not
1096 anchored in the root scope). Starting from there on, there is no flexibility,
1097 so if the scope named <tt/outer/ found by the assembler does not contain a
1098 scope named <tt/inner/, this would be an error, even if such a pair does exist
1099 (one level up in global scope).
1101 Ambiguities that may be introduced by this search algorithm may be removed by
1102 anchoring the scope specification in the global scope. In the example above,
1103 if you want to access the "other" symbol <tt/bar/, you would have to write:
1114 lda #::outer::inner::bar ; 2
1127 <sect>Address sizes and memory models<label id="address-sizes"><p>
1129 <sect1>Address sizes<p>
1131 ca65 assigns each segment and each symbol an address size. This is true, even
1132 if the symbol is not used as an address. You may also think of a value range
1133 of the symbol instead of an address size.
1135 Possible address sizes are:
1138 <item>Zeropage or direct (8 bits)
1139 <item>Absolute (16 bits)
1141 <item>Long (32 bits)
1144 Since the assembler uses default address sizes for the segments and symbols,
1145 it is usually not necessary to override the default behaviour. In cases, where
1146 it is necessary, the following keywords may be used to specify address sizes:
1149 <item>DIRECT, ZEROPAGE or ZP for zeropage addressing (8 bits).
1150 <item>ABSOLUTE, ABS or NEAR for absolute addressing (16 bits).
1151 <item>FAR for far addressing (24 bits).
1152 <item>LONG or DWORD for long addressing (32 bits).
1156 <sect1>Address sizes of segments<p>
1158 The assembler assigns an address size to each segment. Since the
1159 representation of a label within this segment is "segment start + offset",
1160 labels will inherit the address size of the segment they are declared in.
1162 The address size of a segment may be changed, by using an optional address
1163 size modifier. See the <tt/<ref id=".SEGMENT" name="segment directive">/ for
1164 an explanation on how this is done.
1167 <sect1>Address sizes of symbols<p>
1172 <sect1>Memory models<p>
1174 The default address size of a segment depends on the memory model used. Since
1175 labels inherit the address size from the segment they are declared in,
1176 changing the memory model is an easy way to change the address size of many
1182 <sect>Pseudo variables<label id="pseudo-variables"><p>
1184 Pseudo variables are readable in all cases, and in some special cases also
1187 <sect1><tt>*</tt><p>
1189 Reading this pseudo variable will return the program counter at the start
1190 of the current input line.
1192 Assignment to this variable is possible when <tt/<ref id=".FEATURE"
1193 name=".FEATURE pc_assignment">/ is used. Note: You should not use
1194 assignments to <tt/*/, use <tt/<ref id=".ORG" name=".ORG">/ instead.
1197 <sect1><tt>.CPU</tt><label id=".CPU"><p>
1199 Reading this pseudo variable will give a constant integer value that
1200 tells which CPU is currently enabled. It can also tell which instruction
1201 set the CPU is able to translate. The value read from the pseudo variable
1202 should be further examined by using one of the constants defined by the
1203 "cpu" macro package (see <tt/<ref id=".MACPACK" name=".MACPACK">/).
1205 It may be used to replace the .IFPxx pseudo instructions or to construct
1206 even more complex expressions.
1212 .if (.cpu .bitand CPU_ISET_65816)
1224 <sect1><tt>.PARAMCOUNT</tt><label id=".PARAMCOUNT"><p>
1226 This builtin pseudo variable is only available in macros. It is replaced by
1227 the actual number of parameters that were given in the macro invocation.
1232 .macro foo arg1, arg2, arg3
1233 .if .paramcount <> 3
1234 .error "Too few parameters for macro foo"
1240 See section <ref id="macros" name="Macros">.
1243 <sect1><tt>.TIME</tt><label id=".TIME"><p>
1245 Reading this pseudo variable will give a constant integer value that
1246 represents the current time in POSIX standard (as seconds since the
1249 It may be used to encode the time of translation somewhere in the created
1255 .dword .time ; Place time here
1259 <sect1><tt>.VERSION</tt><label id=".VERSION"><p>
1261 Reading this pseudo variable will give the assembler version according to
1262 the following formula:
1264 VER_MAJOR*$100 + VER_MINOR*$10
1266 It may be used to encode the assembler version or check the assembler for
1267 special features not available with older versions.
1271 Version 2.14 of the assembler will return $2E0 as numerical constant when
1272 reading the pseudo variable <tt/.VERSION/.
1276 <sect>Pseudo functions<label id="pseudo-functions"><p>
1278 Pseudo functions expect their arguments in parenthesis, and they have a result,
1279 either a string or an expression.
1282 <sect1><tt>.ADDRSIZE</tt><label id=".ADDRSIZE"><p>
1284 The <tt/.ADDRSIZE/ function is used to return the interal address size
1285 associated with a symbol. This can be helpful in macros when knowing the address
1286 size of symbol can help with custom instructions.
1292 .if .ADDRSIZE(foo) = 1
1293 ;do custom command based on zeropage addressing:
1295 .elseif .ADDRSIZE(foo) = 2
1296 ;do custom command based on absolute addressing:
1299 .elseif .ADDRSIZE(foo) = 0
1300 ; no address size defined for this symbol:
1301 .out .sprintf("Error, address size unknown for symbol %s", .string(foo))
1306 This command is new and must be enabled with the <tt/.FEATURE addrsize/ command.
1308 See: <tt><ref id=".FEATURE" name=".FEATURE"></tt>
1311 <sect1><tt>.BANK</tt><label id=".BANK"><p>
1313 The <tt/.BANK/ function is used to support systems with banked memory. The
1314 argument is an expression with exactly one segment reference - usually a
1315 label. The function result is the value of the <tt/bank/ attribute assigned
1316 to the run memory area of the segment. Please see the linker documentation
1317 for more information about memory areas and their attributes.
1319 The value of <tt/.BANK/ can be used to switch memory so that a memory bank
1320 containing specific data is available.
1322 The <tt/bank/ attribute is a 32 bit integer and so is the result of the
1323 <tt/.BANK/ function. You will have to use <tt><ref id=".LOBYTE"
1324 name=".LOBYTE"></tt> or similar functions to address just part of it.
1326 Please note that <tt/.BANK/ will always get evaluated in the link stage, so
1327 an expression containing <tt/.BANK/ can never be used where a constant known
1328 result is expected (for example with <tt/.RES/).
1345 .byte <.BANK (banked_func_1)
1348 .byte <.BANK (banked_func_2)
1354 <sect1><tt>.BANKBYTE</tt><label id=".BANKBYTE"><p>
1356 The function returns the bank byte (that is, bits 16-23) of its argument.
1357 It works identical to the '^' operator.
1359 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1360 <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>
1363 <sect1><tt>.BLANK</tt><label id=".BLANK"><p>
1365 Builtin function. The function evaluates its argument in braces and yields
1366 "false" if the argument is non blank (there is an argument), and "true" if
1367 there is no argument. The token list that makes up the function argument
1368 may optionally be enclosed in curly braces. This allows the inclusion of
1369 tokens that would otherwise terminate the list (the closing right
1370 parenthesis). The curly braces are not considered part of the list, a list
1371 just consisting of curly braces is considered to be empty.
1373 As an example, the <tt/.IFBLANK/ statement may be replaced by
1381 <sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
1383 Builtin string function. The function allows to concatenate a list of string
1384 constants separated by commas. The result is a string constant that is the
1385 concatenation of all arguments. This function is most useful in macros and
1386 when used together with the <tt/.STRING/ builtin function. The function may
1387 be used in any case where a string constant is expected.
1392 .include .concat ("myheader", ".", "inc")
1395 This is the same as the command
1398 .include "myheader.inc"
1402 <sect1><tt>.CONST</tt><label id=".CONST"><p>
1404 Builtin function. The function evaluates its argument in braces and
1405 yields "true" if the argument is a constant expression (that is, an
1406 expression that yields a constant value at assembly time) and "false"
1407 otherwise. As an example, the .IFCONST statement may be replaced by
1414 <sect1><tt>.HIBYTE</tt><label id=".HIBYTE"><p>
1416 The function returns the high byte (that is, bits 8-15) of its argument.
1417 It works identical to the '>' operator.
1419 See: <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>,
1420 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1423 <sect1><tt>.HIWORD</tt><label id=".HIWORD"><p>
1425 The function returns the high word (that is, bits 16-31) of its argument.
1427 See: <tt><ref id=".LOWORD" name=".LOWORD"></tt>
1430 <sect1><tt>.IDENT</tt><label id=".IDENT"><p>
1432 The function expects a string as its argument, and converts this argument
1433 into an identifier. If the string starts with the current <tt/<ref
1434 id=".LOCALCHAR" name=".LOCALCHAR">/, it will be converted into a cheap local
1435 identifier, otherwise it will be converted into a normal identifier.
1440 .macro makelabel arg1, arg2
1441 .ident (.concat (arg1, arg2)):
1444 makelabel "foo", "bar"
1446 .word foobar ; Valid label
1450 <sect1><tt>.LEFT</tt><label id=".LEFT"><p>
1452 Builtin function. Extracts the left part of a given token list.
1457 .LEFT (<int expr>, <token list>)
1460 The first integer expression gives the number of tokens to extract from
1461 the token list. The second argument is the token list itself. The token
1462 list may optionally be enclosed into curly braces. This allows the
1463 inclusion of tokens that would otherwise terminate the list (the closing
1464 right paren in the given case).
1468 To check in a macro if the given argument has a '#' as first token
1469 (immediate addressing mode), use something like this:
1474 .if (.match (.left (1, {arg}), #))
1476 ; ldax called with immediate operand
1484 See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
1485 name=".RIGHT"></tt> builtin functions.
1488 <sect1><tt>.LOBYTE</tt><label id=".LOBYTE"><p>
1490 The function returns the low byte (that is, bits 0-7) of its argument.
1491 It works identical to the '<' operator.
1493 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1494 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1497 <sect1><tt>.LOWORD</tt><label id=".LOWORD"><p>
1499 The function returns the low word (that is, bits 0-15) of its argument.
1501 See: <tt><ref id=".HIWORD" name=".HIWORD"></tt>
1504 <sect1><tt>.MATCH</tt><label id=".MATCH"><p>
1506 Builtin function. Matches two token lists against each other. This is
1507 most useful within macros, since macros are not stored as strings, but
1513 .MATCH(<token list #1>, <token list #2>)
1516 Both token list may contain arbitrary tokens with the exception of the
1517 terminator token (comma resp. right parenthesis) and
1524 The token lists may optionally be enclosed into curly braces. This allows
1525 the inclusion of tokens that would otherwise terminate the list (the closing
1526 right paren in the given case). Often a macro parameter is used for any of
1529 Please note that the function does only compare tokens, not token
1530 attributes. So any number is equal to any other number, regardless of the
1531 actual value. The same is true for strings. If you need to compare tokens
1532 <em/and/ token attributes, use the <tt><ref id=".XMATCH"
1533 name=".XMATCH"></tt> function.
1537 Assume the macro <tt/ASR/, that will shift right the accumulator by one,
1538 while honoring the sign bit. The builtin processor instructions will allow
1539 an optional "A" for accu addressing for instructions like <tt/ROL/ and
1540 <tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
1541 to check for this and print and error for invalid calls.
1546 .if (.not .blank(arg)) .and (.not .match ({arg}, a))
1547 .error "Syntax error"
1550 cmp #$80 ; Bit 7 into carry
1551 lsr a ; Shift carry into bit 7
1556 The macro will only accept no arguments, or one argument that must be the
1557 reserved keyword "A".
1559 See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
1562 <sect1><tt>.MAX</tt><label id=".MAX"><p>
1564 Builtin function. The result is the larger of two values.
1569 .MAX (<value #1>, <value #2>)
1575 ; Reserve space for the larger of two data blocks
1576 savearea: .max (.sizeof (foo), .sizeof (bar))
1579 See: <tt><ref id=".MIN" name=".MIN"></tt>
1582 <sect1><tt>.MID</tt><label id=".MID"><p>
1584 Builtin function. Takes a starting index, a count and a token list as
1585 arguments. Will return part of the token list.
1590 .MID (<int expr>, <int expr>, <token list>)
1593 The first integer expression gives the starting token in the list (the first
1594 token has index 0). The second integer expression gives the number of tokens
1595 to extract from the token list. The third argument is the token list itself.
1596 The token list may optionally be enclosed into curly braces. This allows the
1597 inclusion of tokens that would otherwise terminate the list (the closing
1598 right paren in the given case).
1602 To check in a macro if the given argument has a '<tt/#/' as first token
1603 (immediate addressing mode), use something like this:
1608 .if (.match (.mid (0, 1, {arg}), #))
1610 ; ldax called with immediate operand
1618 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
1619 name=".RIGHT"></tt> builtin functions.
1622 <sect1><tt>.MIN</tt><label id=".MIN"><p>
1624 Builtin function. The result is the smaller of two values.
1629 .MIN (<value #1>, <value #2>)
1635 ; Reserve space for some data, but 256 bytes minimum
1636 savearea: .min (.sizeof (foo), 256)
1639 See: <tt><ref id=".MAX" name=".MAX"></tt>
1642 <sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
1644 Builtin function. The function expects an identifier as argument in braces.
1645 The argument is evaluated, and the function yields "true" if the identifier
1646 is a symbol that has already been referenced somewhere in the source file up
1647 to the current position. Otherwise the function yields false. As an example,
1648 the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
1654 See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1657 <sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
1659 Builtin function. Extracts the right part of a given token list.
1664 .RIGHT (<int expr>, <token list>)
1667 The first integer expression gives the number of tokens to extract from the
1668 token list. The second argument is the token list itself. The token list
1669 may optionally be enclosed into curly braces. This allows the inclusion of
1670 tokens that would otherwise terminate the list (the closing right paren in
1673 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
1674 name=".MID"></tt> builtin functions.
1677 <sect1><tt>.SIZEOF</tt><label id=".SIZEOF"><p>
1679 <tt/.SIZEOF/ is a pseudo function that returns the size of its argument. The
1680 argument can be a struct/union, a struct member, a procedure, or a label. In
1681 case of a procedure or label, its size is defined by the amount of data
1682 placed in the segment where the label is relative to. If a line of code
1683 switches segments (for example in a macro) data placed in other segments
1684 does not count for the size.
1686 Please note that a symbol or scope must exist, before it is used together with
1687 <tt/.SIZEOF/ (this may get relaxed later, but will always be true for scopes).
1688 A scope has preference over a symbol with the same name, so if the last part
1689 of a name represents both, a scope and a symbol, the scope is chosen over the
1692 After the following code:
1695 .struct Point ; Struct size = 4
1700 P: .tag Point ; Declare a point
1701 @P: .tag Point ; Declare another point
1713 .data ; Segment switch!!!
1719 <tag><tt/.sizeof(Point)/</tag>
1720 will have the value 4, because this is the size of struct <tt/Point/.
1722 <tag><tt/.sizeof(Point::xcoord)/</tag>
1723 will have the value 2, because this is the size of the member <tt/xcoord/
1724 in struct <tt/Point/.
1726 <tag><tt/.sizeof(P)/</tag>
1727 will have the value 4, this is the size of the data declared on the same
1728 source line as the label <tt/P/, which is in the same segment that <tt/P/
1731 <tag><tt/.sizeof(@P)/</tag>
1732 will have the value 4, see above. The example demonstrates that <tt/.SIZEOF/
1733 does also work for cheap local symbols.
1735 <tag><tt/.sizeof(Code)/</tag>
1736 will have the value 3, since this is amount of data emitted into the code
1737 segment, the segment that was active when <tt/Code/ was entered. Note that
1738 this value includes the amount of data emitted in child scopes (in this
1739 case <tt/Code::Inner/).
1741 <tag><tt/.sizeof(Code::Inner)/</tag>
1742 will have the value 1 as expected.
1744 <tag><tt/.sizeof(Data)/</tag>
1745 will have the value 0. Data is emitted within the scope <tt/Data/, but since
1746 the segment is switched after entry, this data is emitted into another
1751 <sect1><tt>.STRAT</tt><label id=".STRAT"><p>
1753 Builtin function. The function accepts a string and an index as
1754 arguments and returns the value of the character at the given position
1755 as an integer value. The index is zero based.
1761 ; Check if the argument string starts with '#'
1762 .if (.strat (Arg, 0) = '#')
1769 <sect1><tt>.SPRINTF</tt><label id=".SPRINTF"><p>
1771 Builtin function. It expects a format string as first argument. The number
1772 and type of the following arguments depend on the format string. The format
1773 string is similar to the one of the C <tt/printf/ function. Missing things
1774 are: Length modifiers, variable width.
1776 The result of the function is a string.
1783 ; Generate an identifier:
1784 .ident (.sprintf ("%s%03d", "label", num)):
1788 <sect1><tt>.STRING</tt><label id=".STRING"><p>
1790 Builtin function. The function accepts an argument in braces and converts
1791 this argument into a string constant. The argument may be an identifier, or
1792 a constant numeric value.
1794 Since you can use a string in the first place, the use of the function may
1795 not be obvious. However, it is useful in macros, or more complex setups.
1800 ; Emulate other assemblers:
1802 .segment .string(name)
1807 <sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
1809 Builtin function. The function accepts a string argument in braces and
1810 evaluates to the length of the string.
1814 The following macro encodes a string as a pascal style string with
1815 a leading length byte.
1819 .byte .strlen(Arg), Arg
1824 <sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
1826 Builtin function. The function accepts a token list in braces. The function
1827 result is the number of tokens given as argument. The token list may
1828 optionally be enclosed into curly braces which are not considered part of
1829 the list and not counted. Enclosement in curly braces allows the inclusion
1830 of tokens that would otherwise terminate the list (the closing right paren
1835 The <tt/ldax/ macro accepts the '#' token to denote immediate addressing (as
1836 with the normal 6502 instructions). To translate it into two separate 8 bit
1837 load instructions, the '#' token has to get stripped from the argument:
1841 .if (.match (.mid (0, 1, {arg}), #))
1842 ; ldax called with immediate operand
1843 lda #<(.right (.tcount ({arg})-1, {arg}))
1844 ldx #>(.right (.tcount ({arg})-1, {arg}))
1852 <sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
1854 Builtin function. Matches two token lists against each other. This is
1855 most useful within macros, since macros are not stored as strings, but
1861 .XMATCH(<token list #1>, <token list #2>)
1864 Both token list may contain arbitrary tokens with the exception of the
1865 terminator token (comma resp. right parenthesis) and
1872 The token lists may optionally be enclosed into curly braces. This allows
1873 the inclusion of tokens that would otherwise terminate the list (the closing
1874 right paren in the given case). Often a macro parameter is used for any of
1877 The function compares tokens <em/and/ token values. If you need a function
1878 that just compares the type of tokens, have a look at the <tt><ref
1879 id=".MATCH" name=".MATCH"></tt> function.
1881 See: <tt><ref id=".MATCH" name=".MATCH"></tt>
1885 <sect>Control commands<label id="control-commands"><p>
1887 Here's a list of all control commands and a description, what they do:
1890 <sect1><tt>.A16</tt><label id=".A16"><p>
1892 Valid only in 65816 mode. Switch the accumulator to 16 bit.
1894 Note: This command will not emit any code, it will tell the assembler to
1895 create 16 bit operands for immediate accumulator addressing mode.
1897 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1900 <sect1><tt>.A8</tt><label id=".A8"><p>
1902 Valid only in 65816 mode. Switch the accumulator to 8 bit.
1904 Note: This command will not emit any code, it will tell the assembler to
1905 create 8 bit operands for immediate accu addressing mode.
1907 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1910 <sect1><tt>.ADDR</tt><label id=".ADDR"><p>
1912 Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
1913 may be used for better readability if the data words are address values. In
1914 65816 mode, the address is forced to be 16 bit wide to fit into the current
1915 segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
1916 must be followed by a sequence of (not necessarily constant) expressions.
1921 .addr $0D00, $AF13, _Clear
1924 See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
1928 <sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
1930 Align data to a given boundary. The command expects a constant integer
1931 argument in the range 1 ... 65536, plus an optional second argument
1932 in byte range. If there is a second argument, it is used as fill value,
1933 otherwise the value defined in the linker configuration file is used
1934 (the default for this value is zero).
1936 <tt/.ALIGN/ will insert fill bytes, and the number of fill bytes depend of
1937 the final address of the segment. <tt/.ALIGN/ cannot insert a variable
1938 number of bytes, since that would break address calculations within the
1939 module. So each <tt/.ALIGN/ expects the segment to be aligned to a multiple
1940 of the alignment, because that allows the number of fill bytes to be
1941 calculated in advance by the assembler. You are therefore required to
1942 specify a matching alignment for the segment in the linker config. The
1943 linker will output a warning if the alignment of the segment is less than
1944 what is necessary to have a correct alignment in the object file.
1952 Some unexpected behaviour might occur if there are multiple <tt/.ALIGN/
1953 commands with different arguments. To allow the assembler to calculate the
1954 number of fill bytes in advance, the alignment of the segment must be a
1955 multiple of each of the alignment factors. This may result in unexpectedly
1956 large alignments for the segment within the module.
1967 For the assembler to be able to align correctly, the segment must be aligned
1968 to the least common multiple of 15 and 18 which is 90. The assembler will
1969 calculate this automatically and will mark the segment with this value.
1971 Unfortunately, the combined alignment may get rather large without the user
1972 knowing about it, wasting space in the final executable. If we add another
1973 alignment to the example above
1984 the assembler will force a segment alignment to the least common multiple of
1985 15, 18 and 251 - which is 22590. To protect the user against errors, the
1986 assembler will issue a warning when the combined alignment exceeds 256. The
1987 command line option <tt><ref id="option--large-alignment"
1988 name="--large-alignment"></tt> will disable this warning.
1990 Please note that with alignments that are a power of two (which were the
1991 only alignments possible in older versions of the assembler), the problem is
1992 less severe, because the least common multiple of powers to the same base is
1993 always the larger one.
1997 <sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
1999 Define a string with a trailing zero.
2004 Msg: .asciiz "Hello world"
2007 This will put the string "Hello world" followed by a binary zero into
2008 the current segment. There may be more strings separated by commas, but
2009 the binary zero is only appended once (after the last one).
2012 <sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
2014 Add an assertion. The command is followed by an expression, an action
2015 specifier, and an optional message that is output in case the assertion
2016 fails. If no message was given, the string "Assertion failed" is used. The
2017 action specifier may be one of <tt/warning/, <tt/error/, <tt/ldwarning/ or
2018 <tt/lderror/. In the former two cases, the assertion is evaluated by the
2019 assembler if possible, and in any case, it's also passed to the linker in
2020 the object file (if one is generated). The linker will then evaluate the
2021 expression when segment placement has been done.
2026 .assert * = $8000, error, "Code not at $8000"
2029 The example assertion will check that the current location is at $8000,
2030 when the output file is written, and abort with an error if this is not
2031 the case. More complex expressions are possible. The action specifier
2032 <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
2033 an error message. In the latter case, generation of the output file is
2034 suppressed in both the assembler and linker.
2037 <sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
2039 Is followed by a plus or a minus character. When switched on (using a
2040 +), undefined symbols are automatically marked as import instead of
2041 giving errors. When switched off (which is the default so this does not
2042 make much sense), this does not happen and an error message is
2043 displayed. The state of the autoimport flag is evaluated when the
2044 complete source was translated, before outputting actual code, so it is
2045 <em/not/ possible to switch this feature on or off for separate sections
2046 of code. The last setting is used for all symbols.
2048 You should probably not use this switch because it delays error
2049 messages about undefined symbols until the link stage. The cc65
2050 compiler (which is supposed to produce correct assembler code in all
2051 circumstances, something which is not true for most assembler
2052 programmers) will insert this command to avoid importing each and every
2053 routine from the runtime library.
2058 .autoimport + ; Switch on auto import
2061 <sect1><tt>.BANKBYTES</tt><label id=".BANKBYTES"><p>
2063 Define byte sized data by extracting only the bank byte (that is, bits 16-23) from
2064 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2065 the operator '^' prepended to each expression in its list.
2070 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2072 TableLookupLo: .lobytes MyTable
2073 TableLookupHi: .hibytes MyTable
2074 TableLookupBank: .bankbytes MyTable
2077 which is equivalent to
2080 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2081 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2082 TableLookupBank: .byte ^TableItem0, ^TableItem1, ^TableItem2, ^TableItem3
2085 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2086 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
2087 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>
2090 <sect1><tt>.BSS</tt><label id=".BSS"><p>
2092 Switch to the BSS segment. The name of the BSS segment is always "BSS",
2093 so this is a shortcut for
2099 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2102 <sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
2104 Define byte sized data. Must be followed by a sequence of (byte ranged)
2105 expressions or strings.
2111 .byt "world", $0D, $00
2115 <sect1><tt>.CASE</tt><label id=".CASE"><p>
2117 Switch on or off case sensitivity on identifiers. The default is off
2118 (that is, identifiers are case sensitive), but may be changed by the
2119 -i switch on the command line.
2120 The command must be followed by a '+' or '-' character to switch the
2121 option on or off respectively.
2126 .case - ; Identifiers are not case sensitive
2130 <sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
2132 Apply a custom mapping for characters. The command is followed by two
2133 numbers. The first one is the index of the source character (range 1..255),
2134 the second one is the mapping (range 0..255). The mapping applies to all
2135 character and string constants when they generate output, and overrides a
2136 mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
2137 command line switch.
2142 .charmap $41, $61 ; Map 'A' to 'a'
2146 <sect1><tt>.CODE</tt><label id=".CODE"><p>
2148 Switch to the CODE segment. The name of the CODE segment is always
2149 "CODE", so this is a shortcut for
2155 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2158 <sect1><tt>.CONDES</tt><label id=".CONDES"><p>
2160 Export a symbol and mark it in a special way. The linker is able to build
2161 tables of all such symbols. This may be used to automatically create a list
2162 of functions needed to initialize linked library modules.
2164 Note: The linker has a feature to build a table of marked routines, but it
2165 is your code that must call these routines, so just declaring a symbol with
2166 <tt/.CONDES/ does nothing by itself.
2168 All symbols are exported as an absolute (16 bit) symbol. You don't need to
2169 use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
2170 is implied by <tt/.CONDES/.
2172 <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
2173 <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
2174 specifying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
2175 The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2176 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2177 name=".INTERRUPTOR"></tt> commands are actually shortcuts for <tt/.CONDES/
2178 with a type of <tt/constructor/ resp. <tt/destructor/ or <tt/interruptor/.
2180 After the type, an optional priority may be specified. Higher numeric values
2181 mean higher priority. If no priority is given, the default priority of 7 is
2182 used. Be careful when assigning priorities to your own module constructors
2183 so they won't interfere with the ones in the cc65 library.
2188 .condes ModuleInit, constructor
2189 .condes ModInit, 0, 16
2192 See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
2193 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
2194 name=".INTERRUPTOR"></tt> commands and the separate section <ref id="condes"
2195 name="Module constructors/destructors"> explaining the feature in more
2199 <sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
2201 Export a symbol and mark it as a module constructor. This may be used
2202 together with the linker to build a table of constructor subroutines that
2203 are called by the startup code.
2205 Note: The linker has a feature to build a table of marked routines, but it
2206 is your code that must call these routines, so just declaring a symbol as
2207 constructor does nothing by itself.
2209 A constructor is always exported as an absolute (16 bit) symbol. You don't
2210 need to use an additional <tt/.export/ statement, this is implied by
2211 <tt/.constructor/. It may have an optional priority that is separated by a
2212 comma. Higher numeric values mean a higher priority. If no priority is
2213 given, the default priority of 7 is used. Be careful when assigning
2214 priorities to your own module constructors so they won't interfere with the
2215 ones in the cc65 library.
2220 .constructor ModuleInit
2221 .constructor ModInit, 16
2224 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2225 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
2226 <ref id="condes" name="Module constructors/destructors"> explaining the
2227 feature in more detail.
2230 <sect1><tt>.DATA</tt><label id=".DATA"><p>
2232 Switch to the DATA segment. The name of the DATA segment is always
2233 "DATA", so this is a shortcut for
2239 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2242 <sect1><tt>.DBYT</tt><label id=".DBYT"><p>
2244 Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
2245 create word sized data in native 65XX format). Must be followed by a
2246 sequence of (word ranged) expressions.
2254 This will emit the bytes
2260 into the current segment in that order.
2263 <sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
2265 Switch on or off debug info generation. The default is off (that is,
2266 the object file will not contain debug infos), but may be changed by the
2267 -g switch on the command line.
2268 The command must be followed by a '+' or '-' character to switch the
2269 option on or off respectively.
2274 .debuginfo + ; Generate debug info
2278 <sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
2280 Start a define style macro definition. The command is followed by an
2281 identifier (the macro name) and optionally by a list of formal arguments
2284 Please note that <tt/.DEFINE/ shares most disadvantages with its C
2285 counterpart, so the general advice is, <bf/NOT/ do use <tt/.DEFINE/ if you
2288 See also the <tt><ref id=".UNDEFINE" name=".UNDEFINE"></tt> command and
2289 section <ref id="macros" name="Macros">.
2292 <sect1><tt>.DELMAC, .DELMACRO</tt><label id=".DELMACRO"><p>
2294 Delete a classic macro (defined with <tt><ref id=".MACRO"
2295 name=".MACRO"></tt>) . The command is followed by the name of an
2296 existing macro. Its definition will be deleted together with the name.
2297 If necessary, another macro with this name may be defined later.
2299 See: <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2300 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2301 <tt><ref id=".MACRO" name=".MACRO"></tt>
2303 See also section <ref id="macros" name="Macros">.
2306 <sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
2308 Builtin function. The function expects an identifier as argument in braces.
2309 The argument is evaluated, and the function yields "true" if the identifier
2310 is a symbol that is already defined somewhere in the source file up to the
2311 current position. Otherwise the function yields false. As an example, the
2312 <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
2319 <sect1><tt>.DEFINEDINSTR</tt><label id=".DEFINEDINSTR"><p>
2321 Builtin function. The function expects an identifier as argument in braces.
2322 The argument is evaluated, and the function yields "true" if the identifier
2323 is defined as an instruction mnemonic that is recognized by the assembler.
2327 .if .not .definedinstr(ina)
2337 <sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
2339 Export a symbol and mark it as a module destructor. This may be used
2340 together with the linker to build a table of destructor subroutines that
2341 are called by the startup code.
2343 Note: The linker has a feature to build a table of marked routines, but it
2344 is your code that must call these routines, so just declaring a symbol as
2345 constructor does nothing by itself.
2347 A destructor is always exported as an absolute (16 bit) symbol. You don't
2348 need to use an additional <tt/.export/ statement, this is implied by
2349 <tt/.destructor/. It may have an optional priority that is separated by a
2350 comma. Higher numerical values mean a higher priority. If no priority is
2351 given, the default priority of 7 is used. Be careful when assigning
2352 priorities to your own module destructors so they won't interfere with the
2353 ones in the cc65 library.
2358 .destructor ModuleDone
2359 .destructor ModDone, 16
2362 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
2363 id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
2364 section <ref id="condes" name="Module constructors/destructors"> explaining
2365 the feature in more detail.
2368 <sect1><tt>.DWORD</tt><label id=".DWORD"><p>
2370 Define dword sized data (4 bytes) Must be followed by a sequence of
2376 .dword $12344512, $12FA489
2380 <sect1><tt>.ELSE</tt><label id=".ELSE"><p>
2382 Conditional assembly: Reverse the current condition.
2385 <sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
2387 Conditional assembly: Reverse current condition and test a new one.
2390 <sect1><tt>.END</tt><label id=".END"><p>
2392 Forced end of assembly. Assembly stops at this point, even if the command
2393 is read from an include file.
2396 <sect1><tt>.ENDENUM</tt><label id=".ENDENUM"><p>
2398 End a <tt><ref id=".ENUM" name=".ENUM"></tt> declaration.
2401 <sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
2403 Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
2404 <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
2407 <sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
2409 Marks the end of a macro definition.
2411 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2412 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>,
2413 <tt><ref id=".MACRO" name=".MACRO"></tt>
2415 See also section <ref id="macros" name="Macros">.
2418 <sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
2420 End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
2423 <sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
2425 End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
2428 <sect1><tt>.ENDSCOPE</tt><label id=".ENDSCOPE"><p>
2430 End of local lexical level (see <tt/<ref id=".SCOPE" name=".SCOPE">/).
2433 <sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
2435 Ends a struct definition. See the <tt/<ref id=".STRUCT" name=".STRUCT">/
2436 command and the separate section named <ref id="structs" name=""Structs
2440 <sect1><tt>.ENDUNION</tt><label id=".ENDUNION"><p>
2442 Ends a union definition. See the <tt/<ref id=".UNION" name=".UNION">/
2443 command and the separate section named <ref id="structs" name=""Structs
2447 <sect1><tt>.ENUM</tt><label id=".ENUM"><p>
2449 Start an enumeration. This directive is very similar to the C <tt/enum/
2450 keyword. If a name is given, a new scope is created for the enumeration,
2451 otherwise the enumeration members are placed in the enclosing scope.
2453 In the enumeration body, symbols are declared. The first symbol has a value
2454 of zero, and each following symbol will get the value of the preceding plus
2455 one. This behaviour may be overridden by an explicit assignment. Two symbols
2456 may have the same value.
2468 Above example will create a new scope named <tt/errorcodes/ with three
2469 symbols in it that get the values 0, 1 and 2 respectively. Another way
2470 to write this would have been:
2480 Please note that explicit scoping must be used to access the identifiers:
2483 .word errorcodes::no_error
2486 A more complex example:
2495 EWOULDBLOCK = EAGAIN
2499 In this example, the enumeration does not have a name, which means that the
2500 members will be visible in the enclosing scope and can be used in this scope
2501 without explicit scoping. The first member (<tt/EUNKNOWN/) has the value -1.
2502 The value for the following members is incremented by one, so <tt/EOK/ would
2503 be zero and so on. <tt/EWOULDBLOCK/ is an alias for <tt/EGAIN/, so it has an
2504 override for the value using an already defined symbol.
2507 <sect1><tt>.ERROR</tt><label id=".ERROR"><p>
2509 Force an assembly error. The assembler will output an error message
2510 preceded by "User error". Assembly is continued but no object file will
2513 This command may be used to check for initial conditions that must be
2514 set before assembling a source file.
2524 .error "Must define foo or bar!"
2528 See also: <tt><ref id=".FATAL" name=".FATAL"></tt>,
2529 <tt><ref id=".OUT" name=".OUT"></tt>,
2530 <tt><ref id=".WARNING" name=".WARNING"></tt>
2533 <sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
2535 Abort a macro expansion immediately. This command is often useful in
2538 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
2539 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
2540 <tt><ref id=".MACRO" name=".MACRO"></tt>
2542 See also section <ref id="macros" name="Macros">.
2545 <sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
2547 Make symbols accessible from other modules. Must be followed by a comma
2548 separated list of symbols to export, with each one optionally followed by an
2549 address specification and (also optional) an assignment. Using an additional
2550 assignment in the export statement allows to define and export a symbol in
2551 one statement. The default is to export the symbol with the address size it
2552 actually has. The assembler will issue a warning, if the symbol is exported
2553 with an address size smaller than the actual address size.
2560 .export foobar: far = foo * bar
2561 .export baz := foobar, zap: far = baz - bar
2564 As with constant definitions, using <tt/:=/ instead of <tt/=/ marks the
2567 See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
2570 <sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
2572 Make symbols accessible from other modules. Must be followed by a comma
2573 separated list of symbols to export. The exported symbols are explicitly
2574 marked as zero page symbols. An assignment may be included in the
2575 <tt/.EXPORTZP/ statement. This allows to define and export a symbol in one
2582 .exportzp baz := $02
2585 See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
2588 <sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
2590 Define far (24 bit) address data. The command must be followed by a
2591 sequence of (not necessarily constant) expressions.
2596 .faraddr DrawCircle, DrawRectangle, DrawHexagon
2599 See: <tt><ref id=".ADDR" name=".ADDR"></tt>
2602 <sect1><tt>.FATAL</tt><label id=".FATAL"><p>
2604 Force an assembly error and terminate assembly. The assembler will output an
2605 error message preceded by "User error" and will terminate assembly
2608 This command may be used to check for initial conditions that must be
2609 set before assembling a source file.
2619 .fatal "Must define foo or bar!"
2623 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
2624 <tt><ref id=".OUT" name=".OUT"></tt>,
2625 <tt><ref id=".WARNING" name=".WARNING"></tt>
2628 <sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
2630 This directive may be used to enable one or more compatibility features
2631 of the assembler. While the use of <tt/.FEATURE/ should be avoided when
2632 possible, it may be useful when porting sources written for other
2633 assemblers. There is no way to switch a feature off, once you have
2634 enabled it, so using
2640 will enable the feature until end of assembly is reached.
2642 The following features are available:
2646 <tag><tt>addrsize</tt><label id="addrsize"></tag>
2648 Enables the .ADDRSIZE pseudo function. This function is experimental and not enabled by default.
2650 See also: <tt><ref id=".ADDRSIZE" name=".ADDRSIZE"></tt>
2652 <tag><tt>at_in_identifiers</tt><label id="at_in_identifiers"></tag>
2654 Accept the at character (`@') as a valid character in identifiers. The
2655 at character is not allowed to start an identifier, even with this
2658 <tag><tt>c_comments</tt><label id="c_comments"></tag>
2660 Allow C like comments using <tt>/*</tt> and <tt>*/</tt> as left and right
2661 comment terminators. Note that C comments may not be nested. There's also a
2662 pitfall when using C like comments: All statements must be terminated by
2663 "end-of-line". Using C like comments, it is possible to hide the newline,
2664 which results in error messages. See the following non working example:
2667 lda #$00 /* This comment hides the newline
2671 <tag><tt>dollar_in_identifiers</tt><label id="dollar_in_identifiers"></tag>
2673 Accept the dollar sign (`$') as a valid character in identifiers. The
2674 dollar character is not allowed to start an identifier, even with this
2677 <tag><tt>dollar_is_pc</tt><label id="dollar_is_pc"></tag>
2679 The dollar sign may be used as an alias for the star (`*'), which
2680 gives the value of the current PC in expressions.
2681 Note: Assignment to the pseudo variable is not allowed.
2683 <tag><tt>force_range</tt><label id="force_range"></tag>
2685 Force expressions into their valid range for immediate addressing and
2686 storage operators like <tt><ref id=".BYTE" name=".BYTE"></tt> and
2687 <tt><ref id=".WORD" name=".WORD"></tt>. Be very careful with this one,
2688 since it will completely disable error checks.
2690 <tag><tt>labels_without_colons</tt><label id="labels_without_colons"></tag>
2692 Allow labels without a trailing colon. These labels are only accepted,
2693 if they start at the beginning of a line (no leading white space).
2695 <tag><tt>leading_dot_in_identifiers</tt><label id="leading_dot_in_identifiers"></tag>
2697 Accept the dot (`.') as the first character of an identifier. This may be
2698 used for example to create macro names that start with a dot emulating
2699 control directives of other assemblers. Note however, that none of the
2700 reserved keywords built into the assembler, that starts with a dot, may be
2701 overridden. When using this feature, you may also get into trouble if
2702 later versions of the assembler define new keywords starting with a dot.
2704 <tag><tt>loose_char_term</tt><label id="loose_char_term"></tag>
2706 Accept single quotes as well as double quotes as terminators for char
2709 <tag><tt>loose_string_term</tt><label id="loose_string_term"></tag>
2711 Accept single quotes as well as double quotes as terminators for string
2714 <tag><tt>missing_char_term</tt><label id="missing_char_term"></tag>
2716 Accept single quoted character constants where the terminating quote is
2721 <em/Note:/ This does not work in conjunction with <tt/.FEATURE
2722 loose_string_term/, since in this case the input would be ambiguous.
2724 <tag><tt>org_per_seg</tt><label id="org_per_seg"></tag>
2726 This feature makes relocatable/absolute mode local to the current segment.
2727 Using <tt><ref id=".ORG" name=".ORG"></tt> when <tt/org_per_seg/ is in
2728 effect will only enable absolute mode for the current segment. Dito for
2729 <tt><ref id=".RELOC" name=".RELOC"></tt>.
2731 <tag><tt>pc_assignment</tt><label id="pc_assignment"></tag>
2733 Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
2734 is enabled). Such an assignment is handled identical to the <tt><ref
2735 id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
2736 removing the lines with the assignments may also be an option when porting
2737 code written for older assemblers).
2739 <tag><tt>ubiquitous_idents</tt><label id="ubiquitous_idents"></tag>
2741 Allow the use of instructions names as names for macros and symbols. This
2742 makes it possible to "overload" instructions by defining a macro with the
2743 same name. This does also make it possible to introduce hard to find errors
2744 in your code, so be careful!
2746 <tag><tt>underline_in_numbers</tt><label id="underline_in_numbers"></tag>
2748 Allow underlines within numeric constants. These may be used for grouping
2749 the digits of numbers for easier reading.
2752 .feature underline_in_numbers
2753 .word %1100001110100101
2754 .word %1100_0011_1010_0101 ; Identical but easier to read
2759 It is also possible to specify features on the command line using the
2760 <tt><ref id="option--feature" name="--feature"></tt> command line option.
2761 This is useful when translating sources written for older assemblers, when
2762 you don't want to change the source code.
2764 As an example, to translate sources written for Andre Fachats xa65
2765 assembler, the features
2768 labels_without_colons, pc_assignment, loose_char_term
2771 may be helpful. They do not make ca65 completely compatible, so you may not
2772 be able to translate the sources without changes, even when enabling these
2773 features. However, I have found several sources that translate without
2774 problems when enabling these features on the command line.
2777 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
2779 Insert an option string into the object file. There are two forms of
2780 this command, one specifies the option by a keyword, the second
2781 specifies it as a number. Since usage of the second one needs knowledge
2782 of the internal encoding, its use is not recommended and I will only
2783 describe the first form here.
2785 The command is followed by one of the keywords
2793 a comma and a string. The option is written into the object file
2794 together with the string value. This is currently unidirectional and
2795 there is no way to actually use these options once they are in the
2801 .fileopt comment, "Code stolen from my brother"
2802 .fileopt compiler, "BASIC 2.0"
2803 .fopt author, "J. R. User"
2807 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
2809 Import an absolute symbol from another module. The command is followed by a
2810 comma separated list of symbols to import. The command is similar to <tt>
2811 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
2812 written to the generated object file, even if the symbol is never referenced
2813 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
2814 references for unused symbols).
2819 .forceimport needthisone, needthistoo
2822 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2825 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
2827 Declare symbols as global. Must be followed by a comma separated list of
2828 symbols to declare. Symbols from the list, that are defined somewhere in the
2829 source, are exported, all others are imported. Additional <tt><ref
2830 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
2831 name=".EXPORT"></tt> commands for the same symbol are allowed.
2840 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
2842 Declare symbols as global. Must be followed by a comma separated list of
2843 symbols to declare. Symbols from the list, that are defined somewhere in the
2844 source, are exported, all others are imported. Additional <tt><ref
2845 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
2846 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
2847 in the list are explicitly marked as zero page symbols.
2855 <sect1><tt>.HIBYTES</tt><label id=".HIBYTES"><p>
2857 Define byte sized data by extracting only the high byte (that is, bits 8-15) from
2858 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
2859 the operator '>' prepended to each expression in its list.
2864 .lobytes $1234, $2345, $3456, $4567
2865 .hibytes $fedc, $edcb, $dcba, $cba9
2868 which is equivalent to
2871 .byte $34, $45, $56, $67
2872 .byte $fe, $ed, $dc, $cb
2878 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
2880 TableLookupLo: .lobytes MyTable
2881 TableLookupHi: .hibytes MyTable
2884 which is equivalent to
2887 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
2888 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
2891 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
2892 <tt><ref id=".LOBYTES" name=".LOBYTES"></tt>,
2893 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
2896 <sect1><tt>.I16</tt><label id=".I16"><p>
2898 Valid only in 65816 mode. Switch the index registers to 16 bit.
2900 Note: This command will not emit any code, it will tell the assembler to
2901 create 16 bit operands for immediate operands.
2903 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
2904 name=".SMART"></tt> commands.
2907 <sect1><tt>.I8</tt><label id=".I8"><p>
2909 Valid only in 65816 mode. Switch the index registers to 8 bit.
2911 Note: This command will not emit any code, it will tell the assembler to
2912 create 8 bit operands for immediate operands.
2914 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
2915 name=".SMART"></tt> commands.
2918 <sect1><tt>.IF</tt><label id=".IF"><p>
2920 Conditional assembly: Evaluate an expression and switch assembler output
2921 on or off depending on the expression. The expression must be a constant
2922 expression, that is, all operands must be defined.
2924 A expression value of zero evaluates to FALSE, any other value evaluates
2928 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
2930 Conditional assembly: Check if there are any remaining tokens in this line,
2931 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
2932 condition is not true, further lines are not assembled until an <tt><ref
2933 id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2934 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2936 This command is often used to check if a macro parameter was given. Since an
2937 empty macro parameter will evaluate to nothing, the condition will evaluate
2938 to TRUE if an empty parameter was given.
2952 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2955 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
2957 Conditional assembly: Evaluate an expression and switch assembler output
2958 on or off depending on the constness of the expression.
2960 A const expression evaluates to to TRUE, a non const expression (one
2961 containing an imported or currently undefined symbol) evaluates to
2964 See also: <tt><ref id=".CONST" name=".CONST"></tt>
2967 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
2969 Conditional assembly: Check if a symbol is defined. Must be followed by
2970 a symbol name. The condition is true if the the given symbol is already
2971 defined, and false otherwise.
2973 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2976 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
2978 Conditional assembly: Check if there are any remaining tokens in this line,
2979 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
2980 condition is not true, further lines are not assembled until an <tt><ref
2981 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2982 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2984 This command is often used to check if a macro parameter was given.
2985 Since an empty macro parameter will evaluate to nothing, the condition
2986 will evaluate to FALSE if an empty parameter was given.
2999 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
3002 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
3004 Conditional assembly: Check if a symbol is defined. Must be followed by
3005 a symbol name. The condition is true if the the given symbol is not
3006 defined, and false otherwise.
3008 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
3011 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
3013 Conditional assembly: Check if a symbol is referenced. Must be followed
3014 by a symbol name. The condition is true if if the the given symbol was
3015 not referenced before, and false otherwise.
3017 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
3020 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
3022 Conditional assembly: Check if the assembler is currently in 6502 mode
3023 (see <tt><ref id=".P02" name=".P02"></tt> command).
3026 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
3028 Conditional assembly: Check if the assembler is currently in 65816 mode
3029 (see <tt><ref id=".P816" name=".P816"></tt> command).
3032 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
3034 Conditional assembly: Check if the assembler is currently in 65C02 mode
3035 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
3038 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
3040 Conditional assembly: Check if the assembler is currently in 65SC02 mode
3041 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
3044 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
3046 Conditional assembly: Check if a symbol is referenced. Must be followed
3047 by a symbol name. The condition is true if if the the given symbol was
3048 referenced before, and false otherwise.
3050 This command may be used to build subroutine libraries in include files
3051 (you may use separate object modules for this purpose too).
3056 .ifref ToHex ; If someone used this subroutine
3057 ToHex: tay ; Define subroutine
3063 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
3066 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
3068 Import a symbol from another module. The command is followed by a comma
3069 separated list of symbols to import, with each one optionally followed by
3070 an address specification.
3076 .import bar: zeropage
3079 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
3082 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
3084 Import a symbol from another module. The command is followed by a comma
3085 separated list of symbols to import. The symbols are explicitly imported
3086 as zero page symbols (that is, symbols with values in byte range).
3094 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
3097 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
3099 Include a file as binary data. The command expects a string argument
3100 that is the name of a file to include literally in the current segment.
3101 In addition to that, a start offset and a size value may be specified,
3102 separated by commas. If no size is specified, all of the file from the
3103 start offset to end-of-file is used. If no start position is specified
3104 either, zero is assumed (which means that the whole file is inserted).
3109 ; Include whole file
3110 .incbin "sprites.dat"
3112 ; Include file starting at offset 256
3113 .incbin "music.dat", $100
3115 ; Read 100 bytes starting at offset 200
3116 .incbin "graphics.dat", 200, 100
3120 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
3122 Include another file. Include files may be nested up to a depth of 16.
3131 <sect1><tt>.INTERRUPTOR</tt><label id=".INTERRUPTOR"><p>
3133 Export a symbol and mark it as an interruptor. This may be used together
3134 with the linker to build a table of interruptor subroutines that are called
3137 Note: The linker has a feature to build a table of marked routines, but it
3138 is your code that must call these routines, so just declaring a symbol as
3139 interruptor does nothing by itself.
3141 An interruptor is always exported as an absolute (16 bit) symbol. You don't
3142 need to use an additional <tt/.export/ statement, this is implied by
3143 <tt/.interruptor/. It may have an optional priority that is separated by a
3144 comma. Higher numeric values mean a higher priority. If no priority is
3145 given, the default priority of 7 is used. Be careful when assigning
3146 priorities to your own module constructors so they won't interfere with the
3147 ones in the cc65 library.
3152 .interruptor IrqHandler
3153 .interruptor Handler, 16
3156 See the <tt><ref id=".CONDES" name=".CONDES"></tt> command and the separate
3157 section <ref id="condes" name="Module constructors/destructors"> explaining
3158 the feature in more detail.
3161 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
3163 Switch on or off line continuations using the backslash character
3164 before a newline. The option is off by default.
3165 Note: Line continuations do not work in a comment. A backslash at the
3166 end of a comment is treated as part of the comment and does not trigger
3168 The command must be followed by a '+' or '-' character to switch the
3169 option on or off respectively.
3174 .linecont + ; Allow line continuations
3177 #$20 ; This is legal now
3181 <sect1><tt>.LIST</tt><label id=".LIST"><p>
3183 Enable output to the listing. The command must be followed by a boolean
3184 switch ("on", "off", "+" or "-") and will enable or disable listing
3186 The option has no effect if the listing is not enabled by the command line
3187 switch -l. If -l is used, an internal counter is set to 1. Lines are output
3188 to the listing file, if the counter is greater than zero, and suppressed if
3189 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
3195 .list on ; Enable listing output
3199 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
3201 Set, how many bytes are shown in the listing for one source line. The
3202 default is 12, so the listing will show only the first 12 bytes for any
3203 source line that generates more than 12 bytes of code or data.
3204 The directive needs an argument, which is either "unlimited", or an
3205 integer constant in the range 4..255.
3210 .listbytes unlimited ; List all bytes
3211 .listbytes 12 ; List the first 12 bytes
3212 .incbin "data.bin" ; Include large binary file
3216 <sect1><tt>.LOBYTES</tt><label id=".LOBYTES"><p>
3218 Define byte sized data by extracting only the low byte (that is, bits 0-7) from
3219 each expression. This is equivalent to <tt><ref id=".BYTE" name=".BYTE"></tt> with
3220 the operator '<' prepended to each expression in its list.
3225 .lobytes $1234, $2345, $3456, $4567
3226 .hibytes $fedc, $edcb, $dcba, $cba9
3229 which is equivalent to
3232 .byte $34, $45, $56, $67
3233 .byte $fe, $ed, $dc, $cb
3239 .define MyTable TableItem0, TableItem1, TableItem2, TableItem3
3241 TableLookupLo: .lobytes MyTable
3242 TableLookupHi: .hibytes MyTable
3245 which is equivalent to
3248 TableLookupLo: .byte <TableItem0, <TableItem1, <TableItem2, <TableItem3
3249 TableLookupHi: .byte >TableItem0, >TableItem1, >TableItem2, >TableItem3
3252 See also: <tt><ref id=".BYTE" name=".BYTE"></tt>,
3253 <tt><ref id=".HIBYTES" name=".HIBYTES"></tt>,
3254 <tt><ref id=".BANKBYTES" name=".BANKBYTES"></tt>
3257 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
3259 This command may only be used inside a macro definition. It declares a
3260 list of identifiers as local to the macro expansion.
3262 A problem when using macros are labels: Since they don't change their name,
3263 you get a "duplicate symbol" error if the macro is expanded the second time.
3264 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
3265 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
3268 Some other assemblers start a new lexical block inside a macro expansion.
3269 This has some drawbacks however, since that will not allow <em/any/ symbol
3270 to be visible outside a macro, a feature that is sometimes useful. The
3271 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
3272 to address the problem.
3274 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
3278 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
3280 Defines the character that start "cheap" local labels. You may use one
3281 of '@' and '?' as start character. The default is '@'.
3283 Cheap local labels are labels that are visible only between two non
3284 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
3285 using explicit lexical nesting.
3292 Clear: lda #$00 ; Global label
3293 ?Loop: sta Mem,y ; Local label
3297 Sub: ... ; New global label
3298 bne ?Loop ; ERROR: Unknown identifier!
3302 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
3304 Insert a predefined macro package. The command is followed by an
3305 identifier specifying the macro package to insert. Available macro
3309 atari Defines the scrcode macro.
3310 cbm Defines the scrcode macro.
3311 cpu Defines constants for the .CPU variable.
3312 generic Defines generic macros like add and sub.
3313 longbranch Defines conditional long jump macros.
3316 Including a macro package twice, or including a macro package that
3317 redefines already existing macros will lead to an error.
3322 .macpack longbranch ; Include macro package
3324 cmp #$20 ; Set condition codes
3325 jne Label ; Jump long on condition
3328 Macro packages are explained in more detail in section <ref
3329 id="macropackages" name="Macro packages">.
3332 <sect1><tt>.MAC, .MACRO</tt><label id=".MACRO"><p>
3334 Start a classic macro definition. The command is followed by an identifier
3335 (the macro name) and optionally by a comma separated list of identifiers
3336 that are macro parameters. A macro definition is terminated by <tt><ref
3337 id=".ENDMACRO" name=".ENDMACRO"></tt>.
3342 .macro ldax arg ; Define macro ldax
3347 See: <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>,
3348 <tt><ref id=".ENDMACRO" name=".ENDMACRO"></tt>,
3349 <tt><ref id=".EXITMACRO" name=".EXITMACRO"></tt>
3351 See also section <ref id="macros" name="Macros">.
3354 <sect1><tt>.ORG</tt><label id=".ORG"><p>
3356 Start a section of absolute code. The command is followed by a constant
3357 expression that gives the new PC counter location for which the code is
3358 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
3361 By default, absolute/relocatable mode is global (valid even when switching
3362 segments). Using <tt>.FEATURE <ref id="org_per_seg" name="org_per_seg"></tt>
3363 it can be made segment local.
3365 Please note that you <em/do not need/ <tt/.ORG/ in most cases. Placing
3366 code at a specific address is the job of the linker, not the assembler, so
3367 there is usually no reason to assemble code to a specific address.
3372 .org $7FF ; Emit code starting at $7FF
3376 <sect1><tt>.OUT</tt><label id=".OUT"><p>
3378 Output a string to the console without producing an error. This command
3379 is similar to <tt/.ERROR/, however, it does not force an assembler error
3380 that prevents the creation of an object file.
3385 .out "This code was written by the codebuster(tm)"
3388 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3389 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3390 <tt><ref id=".WARNING" name=".WARNING"></tt>
3393 <sect1><tt>.P02</tt><label id=".P02"><p>
3395 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
3396 instructions. This is the default if not overridden by the
3397 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
3399 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
3400 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3403 <sect1><tt>.P816</tt><label id=".P816"><p>
3405 Enable the 65816 instruction set. This is a superset of the 65SC02 and
3406 6502 instruction sets.
3408 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3409 name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
3412 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
3414 Set the page length for the listing. Must be followed by an integer
3415 constant. The value may be "unlimited", or in the range 32 to 127. The
3416 statement has no effect if no listing is generated. The default value is -1
3417 (unlimited) but may be overridden by the <tt/--pagelength/ command line
3418 option. Beware: Since ca65 is a one pass assembler, the listing is generated
3419 after assembly is complete, you cannot use multiple line lengths with one
3420 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
3425 .pagelength 66 ; Use 66 lines per listing page
3427 .pagelength unlimited ; Unlimited page length
3431 <sect1><tt>.PC02</tt><label id=".PC02"><p>
3433 Enable the 65C02 instructions set. This instruction set includes all
3434 6502 and 65SC02 instructions.
3436 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3437 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3440 <sect1><tt>.POPCPU</tt><label id=".POPCPU"><p>
3442 Pop the last CPU setting from the stack, and activate it.
3444 This command will switch back to the CPU that was last pushed onto the CPU
3445 stack using the <tt><ref id=".PUSHCPU" name=".PUSHCPU"></tt> command, and
3446 remove this entry from the stack.
3448 The assembler will print an error message if the CPU stack is empty when
3449 this command is issued.
3451 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".PUSHCPU"
3452 name=".PUSHCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3455 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
3457 Pop the last pushed segment from the stack, and set it.
3459 This command will switch back to the segment that was last pushed onto the
3460 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3461 command, and remove this entry from the stack.
3463 The assembler will print an error message if the segment stack is empty
3464 when this command is issued.
3466 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
3469 <sect1><tt>.PROC</tt><label id=".PROC"><p>
3471 Start a nested lexical level with the given name and adds a symbol with this
3472 name to the enclosing scope. All new symbols from now on are in the local
3473 lexical level and are accessible from outside only via <ref id="scopesyntax"
3474 name="explicit scope specification">. Symbols defined outside this local
3475 level may be accessed as long as their names are not used for new symbols
3476 inside the level. Symbols names in other lexical levels do not clash, so you
3477 may use the same names for identifiers. The lexical level ends when the
3478 <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
3479 may be nested up to a depth of 16 (this is an artificial limit to protect
3480 against errors in the source).
3482 Note: Macro names are always in the global level and in a separate name
3483 space. There is no special reason for this, it's just that I've never
3484 had any need for local macro definitions.
3489 .proc Clear ; Define Clear subroutine, start new level
3491 L1: sta Mem,y ; L1 is local and does not cause a
3492 ; duplicate symbol error if used in other
3495 bne L1 ; Reference local symbol
3497 .endproc ; Leave lexical level
3500 See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
3504 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
3506 Enable the 65SC02 instructions set. This instruction set includes all
3509 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
3510 name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
3513 <sect1><tt>.PUSHCPU</tt><label id=".PUSHCPU"><p>
3515 Push the currently active CPU onto a stack. The stack has a size of 8
3518 <tt/.PUSHCPU/ allows together with <tt><ref id=".POPCPU"
3519 name=".POPCPU"></tt> to switch to another CPU and to restore the old CPU
3520 later, without knowledge of the current CPU setting.
3522 The assembler will print an error message if the CPU stack is already full,
3523 when this command is issued.
3525 See: <tt><ref id=".CPU" name=".CPU"></tt>, <tt><ref id=".POPCPU"
3526 name=".POPCPU"></tt>, <tt><ref id=".SETCPU" name=".SETCPU"></tt>
3529 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
3531 Push the currently active segment onto a stack. The entries on the stack
3532 include the name of the segment and the segment type. The stack has a size
3535 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3536 to switch to another segment and to restore the old segment later, without
3537 even knowing the name and type of the current segment.
3539 The assembler will print an error message if the segment stack is already
3540 full, when this command is issued.
3542 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
3545 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
3547 Switch back to relocatable mode. See the <tt><ref id=".ORG"
3548 name=".ORG"></tt> command.
3551 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
3553 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
3554 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
3555 a constant expression that tells how many times the commands in the body
3556 should get repeated. Optionally, a comma and an identifier may be specified.
3557 If this identifier is found in the body of the repeat statement, it is
3558 replaced by the current repeat count (starting with zero for the first time
3559 the body is repeated).
3561 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
3562 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
3563 level will be used, not the one from the outer level.
3567 The following macro will emit a string that is "encrypted" in that all
3568 characters of the string are XORed by the value $55.
3572 .repeat .strlen(Arg), I
3573 .byte .strat(Arg, I) ^ $55
3578 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
3581 <sect1><tt>.RES</tt><label id=".RES"><p>
3583 Reserve storage. The command is followed by one or two constant
3584 expressions. The first one is mandatory and defines, how many bytes of
3585 storage should be defined. The second, optional expression must by a
3586 constant byte value that will be used as value of the data. If there
3587 is no fill value given, the linker will use the value defined in the
3588 linker configuration file (default: zero).
3593 ; Reserve 12 bytes of memory with value $AA
3598 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
3600 Switch to the RODATA segment. The name of the RODATA segment is always
3601 "RODATA", so this is a shortcut for
3607 The RODATA segment is a segment that is used by the compiler for
3608 readonly data like string constants.
3610 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
3613 <sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
3615 Start a nested lexical level with the given name. All new symbols from now
3616 on are in the local lexical level and are accessible from outside only via
3617 <ref id="scopesyntax" name="explicit scope specification">. Symbols defined
3618 outside this local level may be accessed as long as their names are not used
3619 for new symbols inside the level. Symbols names in other lexical levels do
3620 not clash, so you may use the same names for identifiers. The lexical level
3621 ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
3622 read. Lexical levels may be nested up to a depth of 16 (this is an
3623 artificial limit to protect against errors in the source).
3625 Note: Macro names are always in the global level and in a separate name
3626 space. There is no special reason for this, it's just that I've never
3627 had any need for local macro definitions.
3632 .scope Error ; Start new scope named Error
3634 File = 1 ; File error
3635 Parse = 2 ; Parse error
3636 .endscope ; Close lexical level
3639 lda #Error::File ; Use symbol from scope Error
3642 See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
3646 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
3648 Switch to another segment. Code and data is always emitted into a
3649 segment, that is, a named section of data. The default segment is
3650 "CODE". There may be up to 254 different segments per object file
3651 (and up to 65534 per executable). There are shortcut commands for
3652 the most common segments ("CODE", "DATA" and "BSS").
3654 The command is followed by a string containing the segment name (there are
3655 some constraints for the name - as a rule of thumb use only those segment
3656 names that would also be valid identifiers). There may also be an optional
3657 address size separated by a colon. See the section covering <tt/<ref
3658 id="address-sizes" name="address sizes">/ for more information.
3660 The default address size for a segment depends on the memory model specified
3661 on the command line. The default is "absolute", which means that you don't
3662 have to use an address size modifier in most cases.
3664 "absolute" means that the is a segment with 16 bit (absolute) addressing.
3665 That is, the segment will reside somewhere in core memory outside the zero
3666 page. "zeropage" (8 bit) means that the segment will be placed in the zero
3667 page and direct (short) addressing is possible for data in this segment.
3669 Beware: Only labels in a segment with the zeropage attribute are marked
3670 as reachable by short addressing. The `*' (PC counter) operator will
3671 work as in other segments and will create absolute variable values.
3673 Please note that a segment cannot have two different address sizes. A
3674 segment specified as zeropage cannot be declared as being absolute later.
3679 .segment "ROM2" ; Switch to ROM2 segment
3680 .segment "ZP2": zeropage ; New direct segment
3681 .segment "ZP2" ; Ok, will use last attribute
3682 .segment "ZP2": absolute ; Error, redecl mismatch
3685 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
3686 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt> and <tt><ref
3687 id=".RODATA" name=".RODATA"></tt>
3690 <sect1><tt>.SET</tt><label id=".SET"><p>
3692 <tt/.SET/ is used to assign a value to a variable. See <ref id="variables"
3693 name="Numeric variables"> for a full description.
3696 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
3698 Switch the CPU instruction set. The command is followed by a string that
3699 specifies the CPU. Possible values are those that can also be supplied to
3700 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
3701 namely: 6502, 6502X, 65SC02, 65C02, 65816 and HuC6280.
3703 See: <tt><ref id=".CPU" name=".CPU"></tt>,
3704 <tt><ref id=".IFP02" name=".IFP02"></tt>,
3705 <tt><ref id=".IFP816" name=".IFP816"></tt>,
3706 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
3707 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
3708 <tt><ref id=".P02" name=".P02"></tt>,
3709 <tt><ref id=".P816" name=".P816"></tt>,
3710 <tt><ref id=".PC02" name=".PC02"></tt>,
3711 <tt><ref id=".PSC02" name=".PSC02"></tt>
3714 <sect1><tt>.SMART</tt><label id=".SMART"><p>
3716 Switch on or off smart mode. The command must be followed by a '+' or '-'
3717 character to switch the option on or off respectively. The default is off
3718 (that is, the assembler doesn't try to be smart), but this default may be
3719 changed by the -s switch on the command line.
3721 In smart mode the assembler will do the following:
3724 <item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
3725 and update the operand sizes accordingly. If the operand of such an
3726 instruction cannot be evaluated by the assembler (for example, because
3727 the operand is an imported symbol), a warning is issued. Beware: Since
3728 the assembler cannot trace the execution flow this may lead to false
3729 results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
3730 instructions to tell the assembler about the current settings.
3731 <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
3732 used within a procedure declared as <tt/far/, or if the procedure has
3733 no explicit address specification, but it is <tt/far/ because of the
3741 .smart - ; Stop being smart
3744 See: <tt><ref id=".A16" name=".A16"></tt>,
3745 <tt><ref id=".A8" name=".A8"></tt>,
3746 <tt><ref id=".I16" name=".I16"></tt>,
3747 <tt><ref id=".I8" name=".I8"></tt>
3750 <sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
3752 Starts a struct definition. Structs are covered in a separate section named
3753 <ref id="structs" name=""Structs and unions"">.
3755 See also: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>,
3756 <tt><ref id=".ENDUNION" name=".ENDUNION"></tt>,
3757 <tt><ref id=".UNION" name=".UNION"></tt>
3760 <sect1><tt>.TAG</tt><label id=".TAG"><p>
3762 Allocate space for a struct or union.
3773 .tag Point ; Allocate 4 bytes
3777 <sect1><tt>.UNDEF, .UNDEFINE</tt><label id=".UNDEFINE"><p>
3779 Delete a define style macro definition. The command is followed by an
3780 identifier which specifies the name of the macro to delete. Macro
3781 replacement is switched of when reading the token following the command
3782 (otherwise the macro name would be replaced by its replacement list).
3784 See also the <tt><ref id=".DEFINE" name=".DEFINE"></tt> command and
3785 section <ref id="macros" name="Macros">.
3788 <sect1><tt>.UNION</tt><label id=".UNION"><p>
3790 Starts a union definition. Unions are covered in a separate section named
3791 <ref id="structs" name=""Structs and unions"">.
3793 See also: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>,
3794 <tt><ref id=".ENDUNION" name=".ENDUNION"></tt>,
3795 <tt><ref id=".STRUCT" name=".STRUCT"></tt>
3798 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
3800 Force an assembly warning. The assembler will output a warning message
3801 preceded by "User warning". This warning will always be output, even if
3802 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
3803 command line option.
3805 This command may be used to output possible problems when assembling
3814 .warning "Forward jump in jne, cannot optimize!"
3824 See also: <tt><ref id=".ERROR" name=".ERROR"></tt>,
3825 <tt><ref id=".FATAL" name=".FATAL"></tt>,
3826 <tt><ref id=".OUT" name=".OUT"></tt>
3829 <sect1><tt>.WORD</tt><label id=".WORD"><p>
3831 Define word sized data. Must be followed by a sequence of (word ranged,
3832 but not necessarily constant) expressions.
3837 .word $0D00, $AF13, _Clear
3841 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
3843 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
3844 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
3848 .segment "ZEROPAGE", zeropage
3851 Because of the "zeropage" attribute, labels declared in this segment are
3852 addressed using direct addressing mode if possible. You <em/must/ instruct
3853 the linker to place this segment somewhere in the address range 0..$FF
3854 otherwise you will get errors.
3856 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
3860 <sect>Macros<label id="macros"><p>
3863 <sect1>Introduction<p>
3865 Macros may be thought of as "parametrized super instructions". Macros are
3866 sequences of tokens that have a name. If that name is used in the source
3867 file, the macro is "expanded", that is, it is replaced by the tokens that
3868 were specified when the macro was defined.
3871 <sect1>Macros without parameters<p>
3873 In its simplest form, a macro does not have parameters. Here's an
3877 .macro asr ; Arithmetic shift right
3878 cmp #$80 ; Put bit 7 into carry
3879 ror ; Rotate right with carry
3883 The macro above consists of two real instructions, that are inserted into
3884 the code, whenever the macro is expanded. Macro expansion is simply done
3885 by using the name, like this:
3894 <sect1>Parametrized macros<p>
3896 When using macro parameters, macros can be even more useful:
3910 When calling the macro, you may give a parameter, and each occurrence of
3911 the name "addr" in the macro definition will be replaced by the given
3930 A macro may have more than one parameter, in this case, the parameters
3931 are separated by commas. You are free to give less parameters than the
3932 macro actually takes in the definition. You may also leave intermediate
3933 parameters empty. Empty parameters are replaced by empty space (that is,
3934 they are removed when the macro is expanded). If you have a look at our
3935 macro definition above, you will see, that replacing the "addr" parameter
3936 by nothing will lead to wrong code in most lines. To help you, writing
3937 macros with a variable parameter list, there are some control commands:
3939 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
3940 returns true, if there are any tokens on the remainder of the line. Since
3941 empty parameters are replaced by nothing, this may be used to test if a given
3942 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
3945 Look at this example:
3948 .macro ldaxy a, x, y
3961 This macro may be called as follows:
3964 ldaxy 1, 2, 3 ; Load all three registers
3966 ldaxy 1, , 3 ; Load only a and y
3968 ldaxy , , 3 ; Load y only
3971 There's another helper command for determining, which macro parameters are
3972 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt> This command is
3973 replaced by the parameter count given, <em/including/ intermediate empty macro
3977 ldaxy 1 ; .PARAMCOUNT = 1
3978 ldaxy 1,,3 ; .PARAMCOUNT = 3
3979 ldaxy 1,2 ; .PARAMCOUNT = 2
3980 ldaxy 1, ; .PARAMCOUNT = 2
3981 ldaxy 1,2,3 ; .PARAMCOUNT = 3
3984 Macro parameters may optionally be enclosed into curly braces. This allows the
3985 inclusion of tokens that would otherwise terminate the parameter (the comma in
3986 case of a macro parameter).
3989 .macro foo arg1, arg2
3993 foo ($00,x) ; Two parameters passed
3994 foo {($00,x)} ; One parameter passed
3997 In the first case, the macro is called with two parameters: '<tt/($00/'
3998 and 'x)'. The comma is not passed to the macro, since it is part of the
3999 calling sequence, not the parameters.
4001 In the second case, '($00,x)' is passed to the macro, this time
4002 including the comma.
4005 <sect1>Detecting parameter types<p>
4007 Sometimes it is nice to write a macro that acts differently depending on the
4008 type of the argument supplied. An example would be a macro that loads a 16 bit
4009 value from either an immediate operand, or from memory. The <tt/<ref
4010 id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
4011 functions will allow you to do exactly this:
4015 .if (.match (.left (1, {arg}), #))
4017 lda #<(.right (.tcount ({arg})-1, {arg}))
4018 ldx #>(.right (.tcount ({arg})-1, {arg}))
4020 ; assume absolute or zero page
4027 Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
4028 check if its argument begins with a hash mark. If so, two immediate loads are
4029 emitted, Otherwise a load from an absolute zero page memory location is
4030 assumed. Please note how the curly braces are used to enclose parameters to
4031 pseudo functions handling token lists. This is necessary, because the token
4032 lists may include commas or parens, which would be treated by the assembler
4035 The macro can be used as
4040 ldax #$1234 ; X=$12, A=$34
4042 ldax foo ; X=$56, A=$78
4046 <sect1>Recursive macros<p>
4048 Macros may be used recursively:
4051 .macro push r1, r2, r3
4060 There's also a special macro to help writing recursive macros: <tt><ref
4061 id=".EXITMACRO" name=".EXITMACRO"></tt> This command will stop macro expansion
4065 .macro push r1, r2, r3, r4, r5, r6, r7
4067 ; First parameter is empty
4073 push r2, r3, r4, r5, r6, r7
4077 When expanding this macro, the expansion will push all given parameters
4078 until an empty one is encountered. The macro may be called like this:
4081 push $20, $21, $32 ; Push 3 ZP locations
4082 push $21 ; Push one ZP location
4086 <sect1>Local symbols inside macros<p>
4088 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
4089 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
4090 Have a look at the inc16 macro above. Here is it again:
4104 If you have a closer look at the code, you will notice, that it could be
4105 written more efficiently, like this:
4116 But imagine what happens, if you use this macro twice? Since the label "Skip"
4117 has the same name both times, you get a "duplicate symbol" error. Without a
4118 way to circumvent this problem, macros are not as useful, as they could be.
4119 One possible solution is the command <tt><ref id=".LOCAL" name=".LOCAL"></tt>.
4120 It declares one or more symbols as local to the macro expansion. The names of
4121 local variables are replaced by a unique name in each separate macro
4122 expansion. So we can solve the problem above by using <tt/.LOCAL/:
4126 .local Skip ; Make Skip a local symbol
4130 Skip: ; Not visible outside
4134 Another solution is of course to start a new lexical block inside the macro
4135 that hides any labels:
4149 <sect1>C style macros<p>
4151 Starting with version 2.5 of the assembler, there is a second macro type
4152 available: C style macros using the <tt/.DEFINE/ directive. These macros are
4153 similar to the classic macro type described above, but behaviour is sometimes
4158 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
4159 span more than a line. You may use line continuation (see <tt><ref
4160 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
4161 more than one line for increased readability, but the macro itself
4162 may not contain an end-of-line token.
4164 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
4165 the name space with classic macros, but they are detected and replaced
4166 at the scanner level. While classic macros may be used in every place,
4167 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
4168 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
4169 they are more versatile in some situations.
4171 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
4172 parameters. While classic macros may have empty parameters, this is
4173 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
4174 For this macro type, the number of actual parameters must match
4175 exactly the number of formal parameters.
4177 To make this possible, formal parameters are enclosed in braces when
4178 defining the macro. If there are no parameters, the empty braces may
4181 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
4182 contain end-of-line tokens, there are things that cannot be done. They
4183 may not contain several processor instructions for example. So, while
4184 some things may be done with both macro types, each type has special
4185 usages. The types complement each other.
4189 Let's look at a few examples to make the advantages and disadvantages
4192 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
4193 following <tt/.DEFINE/:
4198 foo EQU $1234 ; This is accepted now
4201 You may use the directive to define string constants used elsewhere:
4204 ; Define the version number
4205 .define VERSION "12.3a"
4211 Macros with parameters may also be useful:
4214 .define DEBUG(message) .out message
4216 DEBUG "Assembling include file #3"
4219 Note that, while formal parameters have to be placed in braces, this is
4220 not true for the actual parameters. Beware: Since the assembler cannot
4221 detect the end of one parameter, only the first token is used. If you
4222 don't like that, use classic macros instead:
4225 .macro DEBUG message
4230 (This is an example where a problem can be solved with both macro types).
4233 <sect1>Characters in macros<p>
4235 When using the <ref id="option-t" name="-t"> option, characters are translated
4236 into the target character set of the specific machine. However, this happens
4237 as late as possible. This means that strings are translated if they are part
4238 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
4239 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
4240 used as part of an expression.
4242 This behaviour is very intuitive outside of macros but may be confusing when
4243 doing more complex macros. If you compare characters against numeric values,
4244 be sure to take the translation into account.
4247 <sect1>Deleting macros<p>
4249 Macros can be deleted. This will not work if the macro that should be deleted
4250 is currently expanded as in the following non working example:
4254 .delmacro notworking
4257 notworking ; Will not work
4260 The commands to delete classic and define style macros differ. Classic macros
4261 can be deleted by use of <tt><ref id=".DELMACRO" name=".DELMACRO"></tt>, while
4262 for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros, <tt><ref
4263 id=".UNDEFINE" name=".UNDEFINE"></tt> must be used. Example:
4271 .byte value ; Emit one byte with value 1
4272 mac ; Emit another byte with value 2
4277 .byte value ; Error: Unknown identifier
4278 mac ; Error: Missing ":"
4281 A separate command for <tt>.DEFINE</tt> style macros was necessary, because
4282 the name of such a macro is replaced by its replacement list on a very low
4283 level. To get the actual name, macro replacement has to be switched off when
4284 reading the argument to <tt>.UNDEFINE</tt>. This does also mean that the
4285 argument to <tt>.UNDEFINE</tt> is not allowed to come from another
4286 <tt>.DEFINE</tt>. All this is not necessary for classic macros, so having two
4287 different commands increases flexibility.
4290 <sect>Macro packages<label id="macropackages"><p>
4292 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
4293 macro packages may be included with just one command. Available macro packages
4297 <sect1><tt>.MACPACK generic</tt><p>
4299 This macro package defines macros that are useful in almost any program.
4300 Currently defined macros are:
4344 <sect1><tt>.MACPACK longbranch</tt><p>
4346 This macro package defines long conditional jumps. They are named like the
4347 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
4348 definition for the "<tt/jeq/" macro, the other macros are built using the same
4353 .if .def(Target) .and ((*+2)-(Target) <= 127)
4362 All macros expand to a short branch, if the label is already defined (back
4363 jump) and is reachable with a short jump. Otherwise the macro expands to a
4364 conditional branch with the branch condition inverted, followed by an absolute
4365 jump to the actual branch target.
4367 The package defines the following macros:
4370 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
4375 <sect1><tt>.MACPACK atari</tt><p>
4377 This macro package defines a macro named <tt/scrcode/. It takes a string
4378 as argument and places this string into memory translated into screen codes.
4381 <sect1><tt>.MACPACK cbm</tt><p>
4383 This macro package defines a macro named <tt/scrcode/. It takes a string
4384 as argument and places this string into memory translated into screen codes.
4387 <sect1><tt>.MACPACK cpu</tt><p>
4389 This macro package does not define any macros but constants used to examine
4390 the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
4391 each supported CPU a constant similar to
4402 is defined. These constants may be used to determine the exact type of the
4403 currently enabled CPU. In addition to that, for each CPU instruction set,
4404 another constant is defined:
4415 The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
4416 be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
4417 currently enabled CPU supports a specific instruction set. For example the
4418 65C02 supports all instructions of the 65SC02 CPU, so it has the
4419 <tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
4423 .if (.cpu .bitand CPU_ISET_65SC02)
4431 it is possible to determine if the
4437 instruction is supported, which is the case for the 65SC02, 65C02 and 65816
4438 CPUs (the latter two are upwards compatible to the 65SC02).
4441 <sect1><tt>.MACPACK module</tt><p>
4443 This macro package defines a macro named <tt/module_header/. It takes an
4444 identifier as argument and is used to define the header of a module both
4445 in the dynamic and static variant.
4449 <sect>Predefined constants<label id="predefined-constants"><p>
4451 For better orthogonality, the assembler defines similar symbols as the
4452 compiler, depending on the target system selected:
4455 <item><tt/__APPLE2__/ - Target system is <tt/apple2/ or <tt/apple2enh/
4456 <item><tt/__APPLE2ENH__/ - Target system is <tt/apple2enh/
4457 <item><tt/__ATARI5200__/ - Target system is <tt/atari5200/
4458 <item><tt/__ATARI__/ - Target system is <tt/atari/ or <tt/atarixl/
4459 <item><tt/__ATARIXL__/ - Target system is <tt/atarixl/
4460 <item><tt/__ATMOS__/ - Target system is <tt/atmos/
4461 <item><tt/__BBC__/ - Target system is <tt/bbc/
4462 <item><tt/__C128__/ - Target system is <tt/c128/
4463 <item><tt/__C16__/ - Target system is <tt/c16/ or <tt/plus4/
4464 <item><tt/__C64__/ - Target system is <tt/c64/
4465 <item><tt/__CBM__/ - Target is a Commodore system
4466 <item><tt/__CBM510__/ - Target system is <tt/cbm510/
4467 <item><tt/__CBM610__/ - Target system is <tt/cbm610/
4468 <item><tt/__GEOS__/ - Target is a GEOS system
4469 <item><tt/__GEOS_APPLE__/ - Target system is <tt/geos-apple/
4470 <item><tt/__GEOS_CBM__/ - Target system is <tt/geos-cbm/
4471 <item><tt/__LUNIX__/ - Target system is <tt/lunix/
4472 <item><tt/__LYNX__/ - Target system is <tt/lynx/
4473 <item><tt/__NES__/ - Target system is <tt/nes/
4474 <item><tt/__OSIC1P__/ - Target system is <tt/osic1p/
4475 <item><tt/__PET__/ - Target system is <tt/pet/
4476 <item><tt/__PLUS4__/ - Target system is <tt/plus4/
4477 <item><tt/__SIM6502__/ - Target system is <tt/sim6502/
4478 <item><tt/__SIM65C02__/ - Target system is <tt/sim65c02/
4479 <item><tt/__SUPERVISION__/ - Target system is <tt/supervision/
4480 <item><tt/__VIC20__/ - Target system is <tt/vic20/
4484 <sect>Structs and unions<label id="structs"><p>
4486 <sect1>Structs and unions Overview<p>
4488 Structs and unions are special forms of <ref id="scopes" name="scopes">. They
4489 are to some degree comparable to their C counterparts. Both have a list of
4490 members. Each member allocates storage and may optionally have a name, which,
4491 in case of a struct, is the offset from the beginning and, in case of a union,
4495 <sect1>Declaration<p>
4497 Here is an example for a very simple struct with two members and a total size
4507 A union shares the total space between all its members, its size is the same
4508 as that of the largest member. The offset of all members relative to the union
4518 A struct or union must not necessarily have a name. If it is anonymous, no
4519 local scope is opened, the identifiers used to name the members are placed
4520 into the current scope instead.
4522 A struct may contain unnamed members and definitions of local structs. The
4523 storage allocators may contain a multiplier, as in the example below:
4528 .word 2 ; Allocate two words
4535 <sect1>The <tt/.TAG/ keyword<p>
4537 Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to reserve space
4538 for an already defined struct or unions within another struct:
4552 Space for a struct or union may be allocated using the <ref id=".TAG"
4553 name=".TAG"> directive.
4559 Currently, members are just offsets from the start of the struct or union. To
4560 access a field of a struct, the member offset has to be added to the address
4561 of the struct itself:
4564 lda C+Circle::Radius ; Load circle radius into A
4567 This may change in a future version of the assembler.
4570 <sect1>Limitations<p>
4572 Structs and unions are currently implemented as nested symbol tables (in fact,
4573 they were a by-product of the improved scoping rules). Currently, the
4574 assembler has no idea of types. This means that the <ref id=".TAG"
4575 name=".TAG"> keyword will only allocate space. You won't be able to initialize
4576 variables declared with <ref id=".TAG" name=".TAG">, and adding an embedded
4577 structure to another structure with <ref id=".TAG" name=".TAG"> will not make
4578 this structure accessible by using the '::' operator.
4582 <sect>Module constructors/destructors<label id="condes"><p>
4584 <em>Note:</em> This section applies mostly to C programs, so the explanation
4585 below uses examples from the C libraries. However, the feature may also be
4586 useful for assembler programs.
4589 <sect1>Module constructors/destructors Overview<p>
4591 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4592 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4593 name=".INTERRUPTOR"></tt> keywords it is possible to export functions in a
4594 special way. The linker is able to generate tables with all functions of a
4595 specific type. Such a table will <em>only</em> include symbols from object
4596 files that are linked into a specific executable. This may be used to add
4597 initialization and cleanup code for library modules, or a table of interrupt
4600 The C heap functions are an example where module initialization code is used.
4601 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
4602 variables that contain the start and the end of the heap, pointers to the free
4603 list and so on. Since the end of the heap depends on the size and start of the
4604 stack, it must be initialized at runtime. However, initializing these
4605 variables for programs that do not use the heap are a waste of time and
4608 So the central module defines a function that contains initialization code and
4609 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
4610 this module is added to an executable by the linker, the initialization
4611 function will be placed into the table of constructors by the linker. The C
4612 startup code will call all constructors before <tt/main/ and all destructors
4613 after <tt/main/, so without any further work, the heap initialization code is
4614 called once the module is linked in.
4616 While it would be possible to add explicit calls to initialization functions
4617 in the startup code, the new approach has several advantages:
4621 If a module is not included, the initialization code is not linked in and not
4622 called. So you don't pay for things you don't need.
4625 Adding another library that needs initialization does not mean that the
4626 startup code has to be changed. Before we had module constructors and
4627 destructors, the startup code for all systems had to be adjusted to call the
4628 new initialization code.
4631 The feature saves memory: Each additional initialization function needs just
4632 two bytes in the table (a pointer to the function).
4637 <sect1>Calling order<p>
4639 The symbols are sorted in increasing priority order by the linker when using
4640 one of the builtin linker configurations, so the functions with lower
4641 priorities come first and are followed by those with higher priorities. The C
4642 library runtime subroutine that walks over the function tables calls the
4643 functions starting from the top of the table - which means that functions with
4644 a high priority are called first.
4646 So when using the C runtime, functions are called with high priority functions
4647 first, followed by low priority functions.
4652 When using these special symbols, please take care of the following:
4657 The linker will only generate function tables, it will not generate code to
4658 call these functions. If you're using the feature in some other than the
4659 existing C environments, you have to write code to call all functions in a
4660 linker generated table yourself. See the <tt/condes/ and <tt/callirq/ modules
4661 in the C runtime for an example on how to do this.
4664 The linker will only add addresses of functions that are in modules linked to
4665 the executable. This means that you have to be careful where to place the
4666 condes functions. If initialization or an irq handler is needed for a group of
4667 functions, be sure to place the function into a module that is linked in
4668 regardless of which function is called by the user.
4671 The linker will generate the tables only when requested to do so by the
4672 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
4673 be requested separately.
4676 Constructors and destructors may have priorities. These priorities determine
4677 the order of the functions in the table. If your initialization or cleanup code
4678 does depend on other initialization or cleanup code, you have to choose the
4679 priority for the functions accordingly.
4682 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
4683 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
4684 name=".INTERRUPTOR"></tt> statements, there is also a more generic command:
4685 <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to specify an
4686 additional type. Predefined types are 0 (constructor), 1 (destructor) and 2
4687 (interruptor). The linker generates a separate table for each type on request.
4692 <sect>Porting sources from other assemblers<p>
4694 Sometimes it is necessary to port code written for older assemblers to ca65.
4695 In some cases, this can be done without any changes to the source code by
4696 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
4697 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
4700 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
4701 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
4702 done by the linker. Most other assemblers generate absolute code, placement is
4703 done within the assembler and there is no external linker.
4705 In general it is not a good idea to write new code using the emulation
4706 features of the assembler, but there may be situations where even this rule is
4711 You need to use some of the ca65 emulation features to simulate the behaviour
4712 of such simple assemblers.
4715 <item>Prepare your sourcecode like this:
4718 ; if you want TASS style labels without colons
4719 .feature labels_without_colons
4721 ; if you want TASS style character constants
4722 ; ("a" instead of the default 'a')
4723 .feature loose_char_term
4725 .word *+2 ; the cbm load address
4730 notice that the two emulation features are mostly useful for porting
4731 sources originally written in/for TASS, they are not needed for the
4732 actual "simple assembler operation" and are not recommended if you are
4733 writing new code from scratch.
4735 <item>Replace all program counter assignments (which are not possible in ca65
4736 by default, and the respective emulation feature works different from what
4737 you'd expect) by another way to skip to memory locations, for example the
4738 <tt><ref id=".RES" name=".RES"></tt> directive.
4742 .res $2000-* ; reserve memory up to $2000
4745 Please note that other than the original TASS, ca65 can never move the program
4746 counter backwards - think of it as if you are assembling to disk with TASS.
4748 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
4749 rewritten to match ca65 syntax. Most importantly notice that due to the lack
4750 of <tt/.goto/, everything involving loops must be replaced by
4751 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
4753 <item>To assemble code to a different address than it is executed at, use the
4754 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
4755 <tt/.offs/-constructs.
4762 .reloc ; back to normal
4765 <item>Then assemble like this:
4768 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
4771 Note that you need to use the actual start address minus two, since two bytes
4772 are used for the cbm load address.
4779 ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
4780 Bassewitz. For usage of the binaries and/or sources the following
4781 conditions do apply:
4783 This software is provided 'as-is', without any expressed or implied
4784 warranty. In no event will the authors be held liable for any damages
4785 arising from the use of this software.
4787 Permission is granted to anyone to use this software for any purpose,
4788 including commercial applications, and to alter it and redistribute it
4789 freely, subject to the following restrictions:
4792 <item> The origin of this software must not be misrepresented; you must not
4793 claim that you wrote the original software. If you use this software
4794 in a product, an acknowledgment in the product documentation would be
4795 appreciated but is not required.
4796 <item> Altered source versions must be plainly marked as such, and must not
4797 be misrepresented as being the original software.
4798 <item> This notice may not be removed or altered from any source