1 <!doctype linuxdoc system>
4 <title>ca65 Users Guide
5 <author>Ullrich von Bassewitz, <htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">
6 <date>19.07.2000, 29.11.2000, 02.10.2001
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
95 -g Add debug info to object file
97 -i Ignore case of symbols
98 -l Create a listing if assembly was ok
99 -mm model Set the memory model
100 -o name Name the output file
102 -t sys Set the target system
103 -v Increase verbosity
106 --auto-import Mark unresolved symbols as import
107 --cpu type Set cpu type
108 --debug-info Add debug info to object file
109 --feature name Set an emulation feature
110 --help Help (this text)
111 --ignore-case Ignore case of symbols
112 --include-dir dir Set an include directory search path
113 --listing Create a listing if assembly was ok
114 --list-bytes n Maximum number of bytes per listing line
115 --macpack-dir dir Set a macro package directory
116 --memory-model model Set the memory model
117 --pagelength n Set the page length for the listing
118 --smart Enable smart mode
119 --target sys Set the target system
120 --verbose Increase verbosity
121 --version Print the assembler version
122 ---------------------------------------------------------------------------
126 <sect1>Command line options in detail<p>
128 Here is a description of all the command line options:
132 <label id="option--cpu">
133 <tag><tt>--cpu type</tt></tag>
135 Set the default for the CPU type. The option takes a parameter, which
138 6502, 65SC02, 65C02, 65816, sunplus, sweet16, HuC6280
140 The sunplus cpu is not available in the freeware version, because the
141 instruction set is "proprietary and confidential".
144 <label id="option--feature">
145 <tag><tt>--feature name</tt></tag>
147 Enable an emulation feature. This is identical as using <tt/.FEATURE/
148 in the source with two exceptions: Feature names must be lower case, and
149 each feature must be specified by using an extra <tt/--feature/ option,
150 comma separated lists are not allowed.
152 See the discussion of the <tt><ref id=".FEATURE" name=".FEATURE"></tt>
153 command for a list of emulation features.
156 <label id="option-g">
157 <tag><tt>-g, --debug-info</tt></tag>
159 When this option (or the equivalent control command <tt/.DEBUGINFO/) is
160 used, the assembler will add a section to the object file that contains
161 all symbols (including local ones) together with the symbol values and
162 source file positions. The linker will put these additional symbols into
163 the VICE label file, so even local symbols can be seen in the VICE
167 <tag><tt>-h, --help</tt></tag>
169 Print the short option summary shown above.
172 <tag><tt>-i, --ignore-case</tt></tag>
174 This option makes the assembler case insensitive on identifiers and labels.
175 This option will override the default, but may itself be overridden by the
176 <tt><ref id=".CASE" name=".CASE"></tt> control command.
179 <tag><tt>-l, --listing</tt></tag>
181 Generate an assembler listing. The listing file will always have the
182 name of the main input file with the extension replaced by ".lst". This
183 may change in future versions.
186 <tag><tt>--list-bytes n</tt></tag>
188 Set the maximum number of bytes printed in the listing for one line of
189 input. See the <tt><ref id=".LISTBYTES" name=".LISTBYTES"></tt> directive
190 for more information. The value zero can be used to encode an unlimited
191 number of printed bytes.
194 <tag><tt>--macpack-dir dir</tt></tag>
196 This options allows to specify a directory containing macro files that are
197 used instead of the builtin images when a <tt><ref id=".MACPACK"
198 name=".MACPACK"></tt> directive is encountered. If <tt>--macpack-dir</tt>
199 was specified, a <tt>.mac</tt> extension is added to the package name and
200 the resulting file is loaded from the given directory. This is most useful
201 when debugging the builtin macro packages.
204 <tag><tt>-mm model, --memory-model model</tt></tag>
206 Define the default memory model. Possible model specifiers are near, far and
210 <tag><tt>-o name</tt></tag>
212 The default output name is the name of the input file with the extension
213 replaced by ".o". If you don't like that, you may give another name with
214 the -o option. The output file will be placed in the same directory as
215 the source file, or, if -o is given, the full path in this name is used.
218 <tag><tt>--pagelength n</tt></tag>
220 sets the length of a listing page in lines. See the <tt><ref
221 id=".PAGELENGTH" name=".PAGELENGTH"></tt> directive for more information.
224 <tag><tt>-s, --smart-mode</tt></tag>
226 In smart mode (enabled by -s or the <tt><ref id=".SMART" name=".SMART"></tt>
227 pseudo instruction) the assembler will track usage of the <tt/REP/ and
228 <tt/SEP/ instructions in 65816 mode and update the operand sizes
229 accordingly. If the operand of such an instruction cannot be evaluated by
230 the assembler (for example, because the operand is an imported symbol), a
233 Beware: Since the assembler cannot trace the execution flow this may
234 lead to false results in some cases. If in doubt, use the .ixx and .axx
235 instructions to tell the assembler about the current settings. Smart
236 mode is off by default.
239 <label id="option-t">
240 <tag><tt>-t sys, --target sys</tt></tag>
242 Set the target system. This will enable translation of character strings
243 and character constants into the character set of the target platform.
244 The default for the target system is "none", which means that no translation
245 will take place. The assembler supports the same target systems as the
246 compiler, see there for a list.
249 <tag><tt>-v, --verbose</tt></tag>
251 Increase the assembler verbosity. Usually only needed for debugging
252 purposes. You may use this option more than one time for even more
256 <tag><tt>-D</tt></tag>
258 This option allows you to define symbols on the command line. Without a
259 value, the symbol is defined with the value zero. When giving a value,
260 you may use the '$' prefix for hexadecimal symbols. Please note
261 that for some operating systems, '$' has a special meaning, so
262 you may have to quote the expression.
265 <tag><tt>-I dir, --include-dir dir</tt></tag>
267 Name a directory which is searched for include files. The option may be
268 used more than once to specify more than one directory to search. The
269 current directory is always searched first before considering any
270 additional directories.
273 <tag><tt>-U, --auto-import</tt></tag>
275 Mark symbols that are not defined in the sources as imported symbols. This
276 should be used with care since it delays error messages about typos and such
277 until the linker is run. The compiler uses the equivalent of this switch
278 (<tt><ref id=".AUTOIMPORT" name=".AUTOIMPORT"></tt>) to enable auto imported
279 symbols for the runtime library. However, the compiler is supposed to
280 generate code that runs through the assembler without problems, something
281 which is not always true for assembler programmers.
284 <tag><tt>-V, --version</tt></tag>
286 Print the version number of the assembler. If you send any suggestions
287 or bugfixes, please include the version number.
290 <label id="option-W">
291 <tag><tt>-Wn</tt></tag>
293 Set the warning level for the assembler. Using -W2 the assembler will
294 even warn about such things like unused imported symbols. The default
295 warning level is 1, and it would probably be silly to set it to
302 <sect>Input format<p>
304 <sect1>Assembler syntax<p>
306 The assembler accepts the standard 6502/65816 assembler syntax. One line may
307 contain a label (which is identified by a colon), and, in addition to the
308 label, an assembler mnemonic, a macro, or a control command (see section <ref
309 id="control-commands" name="Control Commands"> for supported control
310 commands). Alternatively, the line may contain a symbol definition using
311 the '=' token. Everything after a semicolon is handled as a comment (that is,
314 Here are some examples for valid input lines:
317 Label: ; A label and a comment
318 lda #$20 ; A 6502 instruction plus comment
319 L1: ldx #$20 ; Same with label
320 L2: .byte "Hello world" ; Label plus control command
321 mymac $20 ; Macro expansion
322 MySym = 3*L1 ; Symbol definition
323 MaSym = Label ; Another symbol
326 The assembler accepts
329 <item>all valid 6502 mnemonics when in 6502 mode (the default or after the
330 <tt><ref id=".P02" name=".P02"></tt> command was given).
331 <item>all valid 6502 mnemonics plus a set of illegal instructions when in
332 <ref id="6502X-mode" name="6502X mode">.
333 <item>all valid 65SC02 mnemonics when in 65SC02 mode (after the
334 <tt><ref id=".PSC02" name=".PSC02"></tt> command was given).
335 <item>all valid 65C02 mnemonics when in 65C02 mode (after the
336 <tt><ref id=".PC02" name=".PC02"></tt> command was given).
337 <item>all valid 65618 mnemonics when in 65816 mode (after the
338 <tt><ref id=".P816" name=".P816"></tt> command was given).
339 <item>all valid SunPlus mnemonics when in SunPlus mode (after the
340 <tt><ref id=".SUNPLUS" name=".SUNPLUS"></tt> command was given).
346 In 65816 mode several aliases are accepted in addition to the official
350 BGE is an alias for BCS
351 BLT is an alias for BCC
352 CPA is an alias for CMP
353 DEA is an alias for DEC A
354 INA is an alias for INC A
355 SWA is an alias for XBA
356 TAD is an alias for TCD
357 TAS is an alias for TCS
358 TDA is an alias for TDC
359 TSA is an alias for TSC
364 <sect1>6502X mode<label id="6502X-mode"><p>
366 6502X mode is an extension to the normal 6502 mode. In this mode, several
367 mnemonics for illegal instructions of the NMOS 6502 CPUs are accepted. Since
368 these instructions are illegal, there are no official mnemonics for them. The
369 unofficial ones are taken from <htmlurl
370 url="http://oxyron.net/graham/opcodes02.html"
371 name="http://oxyron.net/graham/opcodes02.html">. Please note that only the
372 ones marked as "stable" are supported. The following table uses information
373 from the mentioned web page, for more information, see there.
376 <item><tt>ALR: A:=(A and #{imm})*2;</tt>
377 <item><tt>ANC: A:=A and #{imm};</tt> Generates opcode $0B.
378 <item><tt>ARR: A:=(A and #{imm})/2;</tt>
379 <item><tt>AXS: X:=A and X-#{imm};</tt>
380 <item><tt>DCP: {adr}:={adr}-1; A-{adr};</tt>
381 <item><tt>ISC: {adr}:={adr}+1; A:=A-{adr};</tt>
382 <item><tt>LAS: A,X,S:={adr} and S;</tt>
383 <item><tt>LAX: A,X:={adr};</tt>
384 <item><tt>RLA: {adr}:={adr}rol; A:=A and {adr};</tt>
385 <item><tt>RRA: {adr}:={adr}ror; A:=A adc {adr};</tt>
386 <item><tt>SAX: {adr}:=A and X;</tt>
387 <item><tt>SLO: {adr}:={adr}*2; A:=A or {adr};</tt>
388 <item><tt>SRE: {adr}:={adr}/2; A:=A xor {adr};</tt>
393 <sect1>sweet16 mode<label id="sweet16-mode"><p>
395 SWEET 16 is an interpreter for a pseudo 16 bit CPU written by Steve Wozniak
396 for the Apple ][ machines. It is available in the Apple ][ ROM. ca65 can
397 generate code for this pseudo CPU when switched into sweet16 mode. The
398 following is special in sweet16 mode:
402 <item>The '@' character denotes indirect addressing and is no longer available
403 for cheap local labels. If you need cheap local labels, you will have to
404 switch to another lead character using the <tt/<ref id=".LOCALCHAR"
405 name=".LOCALCHAR">/ command.
407 <item>Registers are specified using <tt/R0/ .. <tt/R15/. In sweet16 mode,
408 these identifiers are reserved words.
412 Please note that the assembler does neither supply the interpreter needed for
413 SWEET 16 code, nor the zero page locations needed for the SWEET 16 registers,
414 nor does it call the interpreter. All this must be done by your program. Apple
415 ][ programmers do probably know how to use sweet16 mode.
417 For more information about SWEET 16, see
418 <htmlurl url="http://www.6502.org/source/interpreters/sweet16.htm"
419 name="http://www.6502.org/source/interpreters/sweet16.htm">.
422 <sect1>Number format<p>
424 For literal values, the assembler accepts the widely used number formats: A
425 preceding '$' or a trailing 'h' denotes a hex value, a preceding '%'
426 denotes a binary value, and a bare number is interpreted as a decimal. There
427 are currently no octal values and no floats.
430 <sect1>Conditional assembly<p>
432 Please note that when using the conditional directives (<tt/.IF/ and friends),
433 the input must consist of valid assembler tokens, even in <tt/.IF/ branches
434 that are not assembled. The reason for this behaviour is that the assembler
435 must still be able to detect the ending tokens (like <tt/.ENDIF/), so
436 conversion of the input stream into tokens still takes place. As a consequence
437 conditional assembly directives may <bf/not/ be used to prevent normal text
438 (used as a comment or similar) from being assembled. <p>
444 <sect1>Expression evaluation<p>
446 All expressions are evaluated with (at least) 32 bit precision. An
447 expression may contain constant values and any combination of internal and
448 external symbols. Expressions that cannot be evaluated at assembly time
449 are stored inside the object file for evaluation by the linker.
450 Expressions referencing imported symbols must always be evaluated by the
454 <sect1>Size of an expression result<p>
456 Sometimes, the assembler must know about the size of the value that is the
457 result of an expression. This is usually the case, if a decision has to be
458 made, to generate a zero page or an absolute memory references. In this
459 case, the assembler has to make some assumptions about the result of an
463 <item> If the result of an expression is constant, the actual value is
464 checked to see if it's a byte sized expression or not.
465 <item> If the expression is explicitly casted to a byte sized expression by
466 one of the '>', '<' or '^' operators, it is a byte expression.
467 <item> If this is not the case, and the expression contains a symbol,
468 explicitly declared as zero page symbol (by one of the .importzp or
469 .exportzp instructions), then the whole expression is assumed to be
471 <item> If the expression contains symbols that are not defined, and these
472 symbols are local symbols, the enclosing scopes are searched for a
473 symbol with the same name. If one exists and this symbol is defined,
474 it's attributes are used to determine the result size.
475 <item> In all other cases the expression is assumed to be word sized.
478 Note: If the assembler is not able to evaluate the expression at assembly
479 time, the linker will evaluate it and check for range errors as soon as
483 <sect1>Boolean expressions<p>
485 In the context of a boolean expression, any non zero value is evaluated as
486 true, any other value to false. The result of a boolean expression is 1 if
487 it's true, and zero if it's false. There are boolean operators with extreme
488 low precedence with version 2.x (where x > 0). The <tt/.AND/ and <tt/.OR/
489 operators are shortcut operators. That is, if the result of the expression is
490 already known, after evaluating the left hand side, the right hand side is
494 <sect1>Constant expressions<p>
496 Sometimes an expression must evaluate to a constant without looking at any
497 further input. One such example is the <tt/<ref id=".IF" name=".IF">/ command
498 that decides if parts of the code are assembled or not. An expression used in
499 the <tt/.IF/ command cannot reference a symbol defined later, because the
500 decision about the <tt/.IF/ must be made at the point when it is read. If the
501 expression used in such a context contains only constant numerical values,
502 there is no problem. When unresolvable symbols are involved it may get harder
503 for the assembler to determine if the expression is actually constant, and it
504 is even possible to create expressions that aren't recognized as constant.
505 Simplifying the expressions will often help.
507 In cases where the result of the expression is not needed immediately, the
508 assembler will delay evaluation until all input is read, at which point all
509 symbols are known. So using arbitrary complex constant expressions is no
510 problem in most cases.
514 <sect1>Available operators<label id="operators"><p>
516 Available operators sorted by precedence:
520 Op|Description|Precedence@<hline>
521 |Builtin string functions|0@
522 |Builtin pseudo variables|1@
523 |Builtin pseudo functions|1@
526 ˜|Unary bitwise not|1@
527 .BITNOT|Unary bitwise not|1@
528 <|Low byte operator|1@
529 >|High byte operator|1@
530 ^|Bank byte operator|1@
533 .MOD|Modulo operation|2@
535 .BITAND|Bitwise and|2@
537 .BITXOR|Bitwise xor|2@
538 <<|Shift left operator|2@
539 .SHL|Shift left operator|2@
540 >>|Shift right operato|r@
541 .SHR|Shift right operator|2@
544 ||Binary or|3@
546 =|Compare operation (equal)|4@
547 <>|Compare operation (not equal)|4@
548 <|Compare operation (less)|4@
549 >|Compare operation (greater)|4@
550 <=|Compare operation (less or equal)|4@
551 >=|Compare operation (greater or equal)|4@
552 &&|Boolean and|5@
555 |||Boolean or|6@
560 <caption>Available operators sorted by precedence
563 To force a specific order of evaluation, braces may be used as usual.
568 <sect>Symbols and labels<p>
570 The assembler allows you to use symbols instead of naked values to make
571 the source more readable. There are a lot of different ways to define and
572 use symbols and labels, giving a lot of flexibility.
575 <sect1>Numeric constants<p>
577 Numeric constants are defined using the equal sign or the label assignment
578 operator. After doing
584 may use the symbol "two" in every place where a number is expected, and it is
585 evaluated to the value 2 in this context. The label assignment operator causes
586 the same, but causes the symbol to be marked as a label, which may cause a
587 different handling in the debugger:
593 The right side can of course be an expression:
600 <sect1>Standard labels<p>
602 A label is defined by writing the name of the label at the start of the line
603 (before any instruction mnemonic, macro or pseudo directive), followed by a
604 colon. This will declare a symbol with the given name and the value of the
605 current program counter.
608 <sect1>Local labels and symbols<p>
610 Using the <tt><ref id=".PROC" name=".PROC"></tt> directive, it is possible to
611 create regions of code where the names of labels and symbols are local to this
612 region. They are not known outside of this region and cannot be accessed from
613 there. Such regions may be nested like PROCEDUREs in Pascal.
615 See the description of the <tt><ref id=".PROC" name=".PROC"></tt>
616 directive for more information.
619 <sect1>Cheap local labels<p>
621 Cheap local labels are defined like standard labels, but the name of the
622 label must begin with a special symbol (usually '@', but this can be
623 changed by the <tt><ref id=".LOCALCHAR" name=".LOCALCHAR"></tt>
626 Cheap local labels are visible only between two non cheap labels. As soon as a
627 standard symbol is encountered (this may also be a local symbol if inside a
628 region defined with the <tt><ref id=".PROC" name=".PROC"></tt> directive), the
629 cheap local symbol goes out of scope.
631 You may use cheap local labels as an easy way to reuse common label
632 names like "Loop". Here is an example:
635 Clear: lda #$00 ; Global label
637 @Loop: sta Mem,y ; Local label
641 Sub: ... ; New global label
642 bne @Loop ; ERROR: Unknown identifier!
645 <sect1>Unnamed labels<p>
647 If you really want to write messy code, there are also unnamed labels. These
648 labels do not have a name (you guessed that already, didn't you?). A colon is
649 used to mark the absence of the name.
651 Unnamed labels may be accessed by using the colon plus several minus or plus
652 characters as a label designator. Using the '-' characters will create a back
653 reference (use the n'th label backwards), using '+' will create a forward
654 reference (use the n'th label in forward direction). An example will help to
677 As you can see from the example, unnamed labels will make even short
678 sections of code hard to understand, because you have to count labels
679 to find branch targets (this is the reason why I for my part do
680 prefer the "cheap" local labels). Nevertheless, unnamed labels are
681 convenient in some situations, so it's your decision.
684 <sect1>Using macros to define labels and constants<p>
686 While there are drawbacks with this approach, it may be handy in some
687 situations. Using <tt><ref id=".DEFINE" name=".DEFINE"></tt>, it is
688 possible to define symbols or constants that may be used elsewhere. Since
689 the macro facility works on a very low level, there is no scoping. On the
690 other side, you may also define string constants this way (this is not
691 possible with the other symbol types).
697 .DEFINE version "SOS V2.3"
699 four = two * two ; Ok
702 .PROC ; Start local scope
703 two = 3 ; Will give "2 = 3" - invalid!
708 <sect1>Symbols and <tt>.DEBUGINFO</tt><p>
710 If <tt><ref id=".DEBUGINFO" name=".DEBUGINFO"></tt> is enabled (or <ref
711 id="option-g" name="-g"> is given on the command line), global, local and
712 cheap local labels are written to the object file and will be available in the
713 symbol file via the linker. Unnamed labels are not written to the object file,
714 because they don't have a name which would allow to access them.
718 <sect>Scopes<label id="scopes"><p>
720 ca65 implements several sorts of scopes for symbols.
722 <sect1>Global scope<p>
724 All (non cheap local) symbols that are declared outside of any nested scopes
728 <sect1>Cheap locals<p>
730 A special scope is the scope for cheap local symbols. It lasts from one non
731 local symbol to the next one, without any provisions made by the programmer.
732 All other scopes differ in usage but use the same concept internally.
735 <sect1>Generic nested scopes<p>
737 A nested scoped for generic use is started with <tt/<ref id=".SCOPE"
738 name=".SCOPE">/ and closed with <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/.
739 The scope can have a name, in which case it is accessible from the outside by
740 using <ref id="scopesyntax" name="explicit scopes">. If the scope does not
741 have a name, all symbols created within the scope are local to the scope, and
742 aren't accessible from the outside.
744 A nested scope can access symbols from the local or from enclosing scopes by
745 name without using explicit scope names. In some cases there may be
746 ambiguities, for example if there is a reference to a local symbol that is not
747 yet defined, but a symbol with the same name exists in outer scopes:
759 In the example above, the <tt/lda/ instruction will load the value 3 into the
760 accumulator, because <tt/foo/ is redefined in the scope. However:
772 Here, <tt/lda/ will still load from <tt/$12,x/, but since it is unknown to the
773 assembler that <tt/foo/ is a zeropage symbol when translating the instruction,
774 absolute mode is used instead. In fact, the assembler will not use absolute
775 mode by default, but it will search through the enclosing scopes for a symbol
776 with the given name. If one is found, the address size of this symbol is used.
777 This may lead to errors:
789 In this case, when the assembler sees the symbol <tt/foo/ in the <tt/lda/
790 instruction, it will search for an already defined symbol <tt/foo/. It will
791 find <tt/foo/ in scope <tt/outer/, and a close look reveals that it is a
792 zeropage symbol. So the assembler will use zeropage addressing mode. If
793 <tt/foo/ is redefined later in scope <tt/inner/, the assembler tries to change
794 the address in the <tt/lda/ instruction already translated, but since the new
795 value needs absolute addressing mode, this fails, and an error message "Range
798 Of course the most simple solution for the problem is to move the definition
799 of <tt/foo/ in scope <tt/inner/ upwards, so it precedes its use. There may be
800 rare cases when this cannot be done. In these cases, you can use one of the
801 address size override operators:
813 This will cause the <tt/lda/ instruction to be translated using absolute
814 addressing mode, which means changing the symbol reference later does not
818 <sect1>Nested procedures<p>
820 A nested procedure is created by use of <tt/<ref id=".PROC" name=".PROC">/. It
821 differs from a <tt/<ref id=".SCOPE" name=".SCOPE">/ in that it must have a
822 name, and a it will introduce a symbol with this name in the enclosing scope.
831 is actually the same as
840 This is the reason why a procedure must have a name. If you want a scope
841 without a name, use <tt/<ref id=".SCOPE" name=".SCOPE">/.
843 <bf/Note:/ As you can see from the example above, scopes and symbols live in
844 different namespaces. There can be a symbol named <tt/foo/ and a scope named
845 <tt/foo/ without any conflicts (but see the section titled <ref
846 id="scopesearch" name=""Scope search order"">).
849 <sect1>Structs, unions and enums<p>
851 Structs, unions and enums are explained in a <ref id="structs" name="separate
852 section">, I do only cover them here, because if they are declared with a
853 name, they open a nested scope, similar to <tt/<ref id=".SCOPE"
854 name=".SCOPE">/. However, when no name is specified, the behaviour is
855 different: In this case, no new scope will be opened, symbols declared within
856 a struct, union, or enum declaration will then be added to the enclosing scope
860 <sect1>Explicit scope specification<label id="scopesyntax"><p>
862 Accessing symbols from other scopes is possible by using an explicit scope
863 specification, provided that the scope where the symbol lives in has a name.
864 The namespace token (<tt/::/) is used to access other scopes:
872 lda foo::bar ; Access foo in scope bar
875 The only way to deny access to a scope from the outside is to declare a scope
876 without a name (using the <tt/<ref id=".SCOPE" name=".SCOPE">/ command).
878 A special syntax is used to specify the global scope: If a symbol or scope is
879 preceded by the namespace token, the global scope is searched:
886 lda #::bar ; Access the global bar (which is 3)
891 <sect1>Scope search order<label id="scopesearch"><p>
893 The assembler searches for a scope in a similar way as for a symbol. First, it
894 looks in the current scope, and then it walks up the enclosing scopes until
897 However, one important thing to note when using explicit scope syntax is, that
898 a symbol may be accessed before it is defined, but a scope may <bf/not/ be
899 used without a preceding definition. This means that in the following
908 lda #foo::bar ; Will load 3, not 2!
915 the reference to the scope <tt/foo/ will use the global scope, and not the
916 local one, because the local one is not visible at the point where it is
919 Things get more complex if a complete chain of scopes is specified:
930 lda #outer::inner::bar ; 1
942 When <tt/outer::inner::bar/ is referenced in the <tt/lda/ instruction, the
943 assembler will first search in the local scope for a scope named <tt/outer/.
944 Since none is found, the enclosing scope (<tt/another/) is checked. There is
945 still no scope named <tt/outer/, so scope <tt/foo/ is checked, and finally
946 scope <tt/outer/ is found. Within this scope, <tt/inner/ is searched, and in
947 this scope, the assembler looks for a symbol named <tt/bar/.
949 Please note that once the anchor scope is found, all following scopes
950 (<tt/inner/ in this case) are expected to be found exactly in this scope. The
951 assembler will search the scope tree only for the first scope (if it is not
952 anchored in the root scope). Starting from there on, there is no flexibility,
953 so if the scope named <tt/outer/ found by the assembler does not contain a
954 scope named <tt/inner/, this would be an error, even if such a pair does exist
955 (one level up in global scope).
957 Ambiguities that may be introduced by this search algorithm may be removed by
958 anchoring the scope specification in the global scope. In the example above,
959 if you want to access the "other" symbol <tt/bar/, you would have to write:
970 lda #::outer::inner::bar ; 2
983 <sect>Address sizes and memory models<label id="address-sizes"><p>
985 <sect1>Address sizes<p>
987 ca65 assigns each segment and each symbol an address size. This is true, even
988 if the symbol is not used as an address. You may also think of a value range
989 of the symbol instead of an address size.
991 Possible address sizes are:
994 <item>Zeropage or direct (8 bits)
995 <item>Absolute (16 bits)
1000 Since the assembler uses default address sizes for the segments and symbols,
1001 it is usually not necessary to override the default behaviour. In cases, where
1002 it is necessary, the following keywords may be used to specify address sizes:
1005 <item>DIRECT, ZEROPAGE or ZP for zeropage addressing (8 bits).
1006 <item>ABSOLUTE, ABS or NEAR for absolute addressing (16 bits).
1007 <item>FAR for far addressing (24 bits).
1008 <item>LONG or DWORD for long addressing (32 bits).
1012 <sect1>Address sizes of segments<p>
1014 The assembler assigns an address size to each segment. Since the
1015 representation of a label within this segment is "segment start + offset",
1016 labels will inherit the address size of the segment they are declared in.
1018 The address size of a segment may be changed, by using an optional address
1019 size modifier. See the <tt/<ref id=".SEGMENT" name="segment directive">/ for
1020 an explanation on how this is done.
1023 <sect1>Address sizes of symbols<p>
1028 <sect1>Memory models<p>
1030 The default address size of a segment depends on the memory model used. Since
1031 labels inherit the address size from the segment they are declared in,
1032 changing the memory model is an easy way to change the address size of many
1038 <sect>Pseudo variables<label id="pseudo-variables"><p>
1040 Pseudo variables are readable in all cases, and in some special cases also
1043 <sect1><tt>*</tt><p>
1045 Reading this pseudo variable will return the program counter at the start
1046 of the current input line.
1048 Assignment to this variable is possible when <tt/<ref id=".FEATURE"
1049 name=".FEATURE pc_assignment">/ is used. Note: You should not use
1050 assignments to <tt/*/, use <tt/<ref id=".ORG" name=".ORG">/ instead.
1053 <sect1><tt>.CPU</tt><label id=".CPU"><p>
1055 Reading this pseudo variable will give a constant integer value that
1056 tells which CPU is currently enabled. It can also tell which instruction
1057 set the CPU is able to translate. The value read from the pseudo variable
1058 should be further examined by using one of the constants defined by the
1059 "cpu" macro package (see <tt/<ref id=".MACPACK" name=".MACPACK">/).
1061 It may be used to replace the .IFPxx pseudo instructions or to construct
1062 even more complex expressions.
1068 .if (.cpu .bitand CPU_ISET_65816)
1080 <sect1><tt>.PARAMCOUNT</tt><label id=".PARAMCOUNT"><p>
1082 This builtin pseudo variable is only available in macros. It is replaced by
1083 the actual number of parameters that were given in the macro invocation.
1088 .macro foo arg1, arg2, arg3
1089 .if .paramcount <> 3
1090 .error "Too few parameters for macro foo"
1096 See section <ref id="macros" name="Macros">.
1099 <sect1><tt>.TIME</tt><label id=".TIME"><p>
1101 Reading this pseudo variable will give a constant integer value that
1102 represents the current time in POSIX standard (as seconds since the
1105 It may be used to encode the time of translation somewhere in the created
1111 .dword .time ; Place time here
1115 <sect1><tt>.VERSION</tt><label id=".VERSION"><p>
1117 Reading this pseudo variable will give the assembler version according to
1118 the following formula:
1120 VER_MAJOR*$100 + VER_MINOR*$10 + VER_PATCH
1122 It may be used to encode the assembler version or check the assembler for
1123 special features not available with older versions.
1127 Version 2.11.1 of the assembler will return $2B1 as numerical constant when
1128 reading the pseudo variable <tt/.VERSION/.
1132 <sect>Pseudo functions<label id="pseudo-functions"><p>
1134 Pseudo functions expect their arguments in parenthesis, and they have a result,
1135 either a string or an expression.
1138 <sect1><tt>.BANKBYTE</tt><label id=".BANKBYTE"><p>
1140 The function returns the bank byte (that is, bits 16-23) of its argument.
1141 It works identical to the '^' operator.
1143 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1144 <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>
1147 <sect1><tt>.BLANK</tt><label id=".BLANK"><p>
1149 Builtin function. The function evaluates its argument in braces and yields
1150 "false" if the argument is non blank (there is an argument), and "true" if
1151 there is no argument. The token list that makes up the function argument
1152 may optionally be enclosed in curly braces. This allows the inclusion of
1153 tokens that would otherwise terminate the list (the closing right
1154 parenthesis). The curly braces are not considered part of the list, a list
1155 just consisting of curly braces is considered to be empty.
1157 As an example, the <tt/.IFBLANK/ statement may be replaced by
1165 <sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
1167 Builtin string function. The function allows to concatenate a list of string
1168 constants separated by commas. The result is a string constant that is the
1169 concatenation of all arguments. This function is most useful in macros and
1170 when used together with the <tt/.STRING/ builtin function. The function may
1171 be used in any case where a string constant is expected.
1176 .include .concat ("myheader", ".", "inc")
1179 This is the same as the command
1182 .include "myheader.inc"
1186 <sect1><tt>.CONST</tt><label id=".CONST"><p>
1188 Builtin function. The function evaluates its argument in braces and
1189 yields "true" if the argument is a constant expression (that is, an
1190 expression that yields a constant value at assembly time) and "false"
1191 otherwise. As an example, the .IFCONST statement may be replaced by
1198 <sect1><tt>.HIBYTE</tt><label id=".HIBYTE"><p>
1200 The function returns the high byte (that is, bits 8-15) of its argument.
1201 It works identical to the '>' operator.
1203 See: <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>,
1204 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1207 <sect1><tt>.HIWORD</tt><label id=".HIWORD"><p>
1209 The function returns the high word (that is, bits 16-31) of its argument.
1211 See: <tt><ref id=".LOWORD" name=".LOWORD"></tt>
1214 <sect1><tt>.IDENT</tt><label id=".IDENT"><p>
1216 The function expects a string as its argument, and converts this argument
1217 into an identifier. If the string starts with the current <tt/<ref
1218 id=".LOCALCHAR" name=".LOCALCHAR">/, it will be converted into a cheap local
1219 identifier, otherwise it will be converted into a normal identifier.
1224 .macro makelabel arg1, arg2
1225 .ident (.concat (arg1, arg2)):
1228 makelabel "foo", "bar"
1230 .word foobar ; Valid label
1234 <sect1><tt>.LEFT</tt><label id=".LEFT"><p>
1236 Builtin function. Extracts the left part of a given token list.
1241 .LEFT (<int expr>, <token list>)
1244 The first integer expression gives the number of tokens to extract from
1245 the token list. The second argument is the token list itself. The token
1246 list may optionally be enclosed into curly braces. This allows the
1247 inclusion of tokens that would otherwise terminate the list (the closing
1248 right paren in the given case).
1252 To check in a macro if the given argument has a '#' as first token
1253 (immediate addressing mode), use something like this:
1258 .if (.match (.left (1, {arg}), #))
1260 ; ldax called with immediate operand
1268 See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
1269 name=".RIGHT"></tt> builtin functions.
1272 <sect1><tt>.LOBYTE</tt><label id=".LOBYTE"><p>
1274 The function returns the low byte (that is, bits 0-7) of its argument.
1275 It works identical to the '<' operator.
1277 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1278 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1281 <sect1><tt>.LOWORD</tt><label id=".LOWORD"><p>
1283 The function returns the low word (that is, bits 0-15) of its argument.
1285 See: <tt><ref id=".HIWORD" name=".HIWORD"></tt>
1288 <sect1><tt>.MATCH</tt><label id=".MATCH"><p>
1290 Builtin function. Matches two token lists against each other. This is
1291 most useful within macros, since macros are not stored as strings, but
1297 .MATCH(<token list #1>, <token list #2>)
1300 Both token list may contain arbitrary tokens with the exception of the
1301 terminator token (comma resp. right parenthesis) and
1308 The token lists may optionally be enclosed into curly braces. This allows
1309 the inclusion of tokens that would otherwise terminate the list (the closing
1310 right paren in the given case). Often a macro parameter is used for any of
1313 Please note that the function does only compare tokens, not token
1314 attributes. So any number is equal to any other number, regardless of the
1315 actual value. The same is true for strings. If you need to compare tokens
1316 <em/and/ token attributes, use the <tt><ref id=".XMATCH"
1317 name=".XMATCH"></tt> function.
1321 Assume the macro <tt/ASR/, that will shift right the accumulator by one,
1322 while honoring the sign bit. The builtin processor instructions will allow
1323 an optional "A" for accu addressing for instructions like <tt/ROL/ and
1324 <tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
1325 to check for this and print and error for invalid calls.
1330 .if (.not .blank(arg)) .and (.not .match ({arg}, a))
1331 .error "Syntax error"
1334 cmp #$80 ; Bit 7 into carry
1335 lsr a ; Shift carry into bit 7
1340 The macro will only accept no arguments, or one argument that must be the
1341 reserved keyword "A".
1343 See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
1346 <sect1><tt>.MID</tt><label id=".MID"><p>
1348 Builtin function. Takes a starting index, a count and a token list as
1349 arguments. Will return part of the token list.
1354 .MID (<int expr>, <int expr>, <token list>)
1357 The first integer expression gives the starting token in the list (the first
1358 token has index 0). The second integer expression gives the number of tokens
1359 to extract from the token list. The third argument is the token list itself.
1360 The token list may optionally be enclosed into curly braces. This allows the
1361 inclusion of tokens that would otherwise terminate the list (the closing
1362 right paren in the given case).
1366 To check in a macro if the given argument has a '<tt/#/' as first token
1367 (immediate addressing mode), use something like this:
1372 .if (.match (.mid (0, 1, {arg}), #))
1374 ; ldax called with immediate operand
1382 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
1383 name=".RIGHT"></tt> builtin functions.
1386 <sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
1388 Builtin function. The function expects an identifier as argument in braces.
1389 The argument is evaluated, and the function yields "true" if the identifier
1390 is a symbol that has already been referenced somewhere in the source file up
1391 to the current position. Otherwise the function yields false. As an example,
1392 the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
1398 See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1401 <sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
1403 Builtin function. Extracts the right part of a given token list.
1408 .RIGHT (<int expr>, <token list>)
1411 The first integer expression gives the number of tokens to extract from the
1412 token list. The second argument is the token list itself. The token list
1413 may optionally be enclosed into curly braces. This allows the inclusion of
1414 tokens that would otherwise terminate the list (the closing right paren in
1417 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
1418 name=".MID"></tt> builtin functions.
1421 <sect1><tt>.SIZEOF</tt><label id=".SIZEOF"><p>
1423 <tt/.SIZEOF/ is a pseudo function that returns the size of its argument. The
1424 argument can be a struct/union, a struct member, a procedure, or a label. In
1425 case of a procedure or label, its size is defined by the amount of data
1426 placed in the segment where the label is relative to. If a line of code
1427 switches segments (for example in a macro) data placed in other segments
1428 does not count for the size.
1430 Please note that a symbol or scope must exist, before it is used together with
1431 <tt/.SIZEOF/ (this may get relaxed later, but will always be true for scopes).
1432 A scope has preference over a symbol with the same name, so if the last part
1433 of a name represents both, a scope and a symbol, the scope is chosen over the
1436 After the following code:
1439 .struct Point ; Struct size = 4
1444 P: .tag Point ; Declare a point
1445 @P: .tag Point ; Declare another point
1457 .data ; Segment switch!!!
1463 <tag><tt/.sizeof(Point)/</tag>
1464 will have the value 4, because this is the size of struct <tt/Point/.
1466 <tag><tt/.sizeof(Point::xcoord)/</tag>
1467 will have the value 2, because this is the size of the member <tt/xcoord/
1468 in struct <tt/Point/.
1470 <tag><tt/.sizeof(P)/</tag>
1471 will have the value 4, this is the size of the data declared on the same
1472 source line as the label <tt/P/, which is in the same segment that <tt/P/
1475 <tag><tt/.sizeof(@P)/</tag>
1476 will have the value 4, see above. The example demonstrates that <tt/.SIZEOF/
1477 does also work for cheap local symbols.
1479 <tag><tt/.sizeof(Code)/</tag>
1480 will have the value 3, since this is amount of data emitted into the code
1481 segment, the segment that was active when <tt/Code/ was entered. Note that
1482 this value includes the amount of data emitted in child scopes (in this
1483 case <tt/Code::Inner/).
1485 <tag><tt/.sizeof(Code::Inner)/</tag>
1486 will have the value 1 as expected.
1488 <tag><tt/.sizeof(Data)/</tag>
1489 will have the value 0. Data is emitted within the scope <tt/Data/, but since
1490 the segment is switched after entry, this data is emitted into another
1495 <sect1><tt>.STRAT</tt><label id=".STRAT"><p>
1497 Builtin function. The function accepts a string and an index as
1498 arguments and returns the value of the character at the given position
1499 as an integer value. The index is zero based.
1505 ; Check if the argument string starts with '#'
1506 .if (.strat (Arg, 0) = '#')
1513 <sect1><tt>.SPRINTF</tt><label id=".SPRINTF"><p>
1515 Builtin function. It expects a format string as first argument. The number
1516 and type of the following arguments depend on the format string. The format
1517 string is similar to the one of the C <tt/printf/ function. Missing things
1518 are: Length modifiers, variable width.
1520 The result of the function is a string.
1527 ; Generate an identifier:
1528 .ident (.sprintf ("%s%03d", "label", num)):
1532 <sect1><tt>.STRING</tt><label id=".STRING"><p>
1534 Builtin function. The function accepts an argument in braces and converts
1535 this argument into a string constant. The argument may be an identifier, or
1536 a constant numeric value.
1538 Since you can use a string in the first place, the use of the function may
1539 not be obvious. However, it is useful in macros, or more complex setups.
1544 ; Emulate other assemblers:
1546 .segment .string(name)
1551 <sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
1553 Builtin function. The function accepts a string argument in braces and
1554 evaluates to the length of the string.
1558 The following macro encodes a string as a pascal style string with
1559 a leading length byte.
1563 .byte .strlen(Arg), Arg
1568 <sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
1570 Builtin function. The function accepts a token list in braces. The function
1571 result is the number of tokens given as argument. The token list may
1572 optionally be enclosed into curly braces which are not considered part of
1573 the list and not counted. Enclosement in curly braces allows the inclusion
1574 of tokens that would otherwise terminate the list (the closing right paren
1579 The <tt/ldax/ macro accepts the '#' token to denote immediate addressing (as
1580 with the normal 6502 instructions). To translate it into two separate 8 bit
1581 load instructions, the '#' token has to get stripped from the argument:
1585 .if (.match (.mid (0, 1, {arg}), #))
1586 ; ldax called with immediate operand
1587 lda #<(.right (.tcount ({arg})-1, {arg}))
1588 ldx #>(.right (.tcount ({arg})-1, {arg}))
1596 <sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
1598 Builtin function. Matches two token lists against each other. This is
1599 most useful within macros, since macros are not stored as strings, but
1605 .XMATCH(<token list #1>, <token list #2>)
1608 Both token list may contain arbitrary tokens with the exception of the
1609 terminator token (comma resp. right parenthesis) and
1616 The token lists may optionally be enclosed into curly braces. This allows
1617 the inclusion of tokens that would otherwise terminate the list (the closing
1618 right paren in the given case). Often a macro parameter is used for any of
1621 The function compares tokens <em/and/ token values. If you need a function
1622 that just compares the type of tokens, have a look at the <tt><ref
1623 id=".MATCH" name=".MATCH"></tt> function.
1625 See: <tt><ref id=".MATCH" name=".MATCH"></tt>
1629 <sect>Control commands<label id="control-commands"><p>
1631 Here's a list of all control commands and a description, what they do:
1634 <sect1><tt>.A16</tt><label id=".A16"><p>
1636 Valid only in 65816 mode. Switch the accumulator to 16 bit.
1638 Note: This command will not emit any code, it will tell the assembler to
1639 create 16 bit operands for immediate accumulator addressing mode.
1641 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1644 <sect1><tt>.A8</tt><label id=".A8"><p>
1646 Valid only in 65816 mode. Switch the accumulator to 8 bit.
1648 Note: This command will not emit any code, it will tell the assembler to
1649 create 8 bit operands for immediate accu addressing mode.
1651 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1654 <sect1><tt>.ADDR</tt><label id=".ADDR"><p>
1656 Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
1657 may be used for better readability if the data words are address values. In
1658 65816 mode, the address is forced to be 16 bit wide to fit into the current
1659 segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
1660 must be followed by a sequence of (not necessarily constant) expressions.
1665 .addr $0D00, $AF13, _Clear
1668 See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
1672 <sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
1674 Align data to a given boundary. The command expects a constant integer
1675 argument that must be a power of two, plus an optional second argument
1676 in byte range. If there is a second argument, it is used as fill value,
1677 otherwise the value defined in the linker configuration file is used
1678 (the default for this value is zero).
1680 Since alignment depends on the base address of the module, you must
1681 give the same (or a greater) alignment for the segment when linking.
1682 The linker will give you a warning, if you don't do that.
1691 <sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
1693 Define a string with a trailing zero.
1698 Msg: .asciiz "Hello world"
1701 This will put the string "Hello world" followed by a binary zero into
1702 the current segment. There may be more strings separated by commas, but
1703 the binary zero is only appended once (after the last one).
1706 <sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
1708 Add an assertion. The command is followed by an expression, an action
1709 specifier, and an optional message that is output in case the assertion
1710 fails. If no message was given, the string "Assertion failed" is used. The
1711 action specifier may be one of <tt/warning/ or <tt/error/. The assertion is
1712 evaluated by the assembler if possible, and also passed to the linker in the
1713 object file (if one is generated). The linker will then evaluate the
1714 expression when segment placement has been done.
1719 .assert * = $8000, error, "Code not at $8000"
1722 The example assertion will check that the current location is at $8000,
1723 when the output file is written, and abort with an error if this is not
1724 the case. More complex expressions are possible. The action specifier
1725 <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
1726 an error message. In the latter case, generation if the output file is
1727 suppressed in both the assembler and linker.
1730 <sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
1732 Is followed by a plus or a minus character. When switched on (using a
1733 +), undefined symbols are automatically marked as import instead of
1734 giving errors. When switched off (which is the default so this does not
1735 make much sense), this does not happen and an error message is
1736 displayed. The state of the autoimport flag is evaluated when the
1737 complete source was translated, before outputting actual code, so it is
1738 <em/not/ possible to switch this feature on or off for separate sections
1739 of code. The last setting is used for all symbols.
1741 You should probably not use this switch because it delays error
1742 messages about undefined symbols until the link stage. The cc65
1743 compiler (which is supposed to produce correct assembler code in all
1744 circumstances, something which is not true for most assembler
1745 programmers) will insert this command to avoid importing each and every
1746 routine from the runtime library.
1751 .autoimport + ; Switch on auto import
1755 <sect1><tt>.BSS</tt><label id=".BSS"><p>
1757 Switch to the BSS segment. The name of the BSS segment is always "BSS",
1758 so this is a shortcut for
1764 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1767 <sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
1769 Define byte sized data. Must be followed by a sequence of (byte ranged)
1770 expressions or strings.
1776 .byt "world", $0D, $00
1780 <sect1><tt>.CASE</tt><label id=".CASE"><p>
1782 Switch on or off case sensitivity on identifiers. The default is off
1783 (that is, identifiers are case sensitive), but may be changed by the
1784 -i switch on the command line.
1785 The command must be followed by a '+' or '-' character to switch the
1786 option on or off respectively.
1791 .case - ; Identifiers are not case sensitive
1795 <sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
1797 Apply a custom mapping for characters. The command is followed by two
1798 numbers in the range 1..255. The first one is the index of the source
1799 character, the second one is the mapping. The mapping applies to all
1800 character and string constants when they generate output, and overrides
1801 a mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
1802 command line switch.
1807 .charmap $41, $61 ; Map 'A' to 'a'
1811 <sect1><tt>.CODE</tt><label id=".CODE"><p>
1813 Switch to the CODE segment. The name of the CODE segment is always
1814 "CODE", so this is a shortcut for
1820 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1823 <sect1><tt>.CONDES</tt><label id=".CONDES"><p>
1825 Export a symbol and mark it in a special way. The linker is able to build
1826 tables of all such symbols. This may be used to automatically create a list
1827 of functions needed to initialize linked library modules.
1829 Note: The linker has a feature to build a table of marked routines, but it
1830 is your code that must call these routines, so just declaring a symbol with
1831 <tt/.CONDES/ does nothing by itself.
1833 All symbols are exported as an absolute (16 bit) symbol. You don't need to
1834 use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
1835 is implied by <tt/.CONDES/.
1837 <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
1838 <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
1839 specifying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
1840 The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
1841 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
1842 name=".INTERRUPTOR"></tt> commands are actually shortcuts for <tt/.CONDES/
1843 with a type of <tt/constructor/ resp. <tt/destructor/ or <tt/interruptor/.
1845 After the type, an optional priority may be specified. Higher numeric values
1846 mean higher priority. If no priority is given, the default priority of 7 is
1847 used. Be careful when assigning priorities to your own module constructors
1848 so they won't interfere with the ones in the cc65 library.
1853 .condes ModuleInit, constructor
1854 .condes ModInit, 0, 16
1857 See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
1858 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
1859 name=".INTERRUPTOR"></tt> commands and the separate section <ref id="condes"
1860 name="Module constructors/destructors"> explaining the feature in more
1864 <sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
1866 Export a symbol and mark it as a module constructor. This may be used
1867 together with the linker to build a table of constructor subroutines that
1868 are called by the startup code.
1870 Note: The linker has a feature to build a table of marked routines, but it
1871 is your code that must call these routines, so just declaring a symbol as
1872 constructor does nothing by itself.
1874 A constructor is always exported as an absolute (16 bit) symbol. You don't
1875 need to use an additional <tt/.export/ statement, this is implied by
1876 <tt/.constructor/. It may have an optional priority that is separated by a
1877 comma. Higher numeric values mean a higher priority. If no priority is
1878 given, the default priority of 7 is used. Be careful when assigning
1879 priorities to your own module constructors so they won't interfere with the
1880 ones in the cc65 library.
1885 .constructor ModuleInit
1886 .constructor ModInit, 16
1889 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
1890 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
1891 <ref id="condes" name="Module constructors/destructors"> explaining the
1892 feature in more detail.
1895 <sect1><tt>.DATA</tt><label id=".DATA"><p>
1897 Switch to the DATA segment. The name of the DATA segment is always
1898 "DATA", so this is a shortcut for
1904 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1907 <sect1><tt>.DBYT</tt><label id=".DBYT"><p>
1909 Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
1910 create word sized data in native 65XX format). Must be followed by a
1911 sequence of (word ranged) expressions.
1919 This will emit the bytes
1925 into the current segment in that order.
1928 <sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
1930 Switch on or off debug info generation. The default is off (that is,
1931 the object file will not contain debug infos), but may be changed by the
1932 -g switch on the command line.
1933 The command must be followed by a '+' or '-' character to switch the
1934 option on or off respectively.
1939 .debuginfo + ; Generate debug info
1943 <sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
1945 Start a define style macro definition. The command is followed by an
1946 identifier (the macro name) and optionally by a list of formal arguments
1948 See section <ref id="macros" name="Macros">.
1951 <sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
1953 Builtin function. The function expects an identifier as argument in braces.
1954 The argument is evaluated, and the function yields "true" if the identifier
1955 is a symbol that is already defined somewhere in the source file up to the
1956 current position. Otherwise the function yields false. As an example, the
1957 <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
1964 <sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
1966 Export a symbol and mark it as a module destructor. This may be used
1967 together with the linker to build a table of destructor subroutines that
1968 are called by the startup code.
1970 Note: The linker has a feature to build a table of marked routines, but it
1971 is your code that must call these routines, so just declaring a symbol as
1972 constructor does nothing by itself.
1974 A destructor is always exported as an absolute (16 bit) symbol. You don't
1975 need to use an additional <tt/.export/ statement, this is implied by
1976 <tt/.destructor/. It may have an optional priority that is separated by a
1977 comma. Higher numerical values mean a higher priority. If no priority is
1978 given, the default priority of 7 is used. Be careful when assigning
1979 priorities to your own module destructors so they won't interfere with the
1980 ones in the cc65 library.
1985 .destructor ModuleDone
1986 .destructor ModDone, 16
1989 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
1990 id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
1991 section <ref id="condes" name="Module constructors/destructors"> explaining
1992 the feature in more detail.
1995 <sect1><tt>.DWORD</tt><label id=".DWORD"><p>
1997 Define dword sized data (4 bytes) Must be followed by a sequence of
2003 .dword $12344512, $12FA489
2007 <sect1><tt>.ELSE</tt><label id=".ELSE"><p>
2009 Conditional assembly: Reverse the current condition.
2012 <sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
2014 Conditional assembly: Reverse current condition and test a new one.
2017 <sect1><tt>.END</tt><label id=".END"><p>
2019 Forced end of assembly. Assembly stops at this point, even if the command
2020 is read from an include file.
2023 <sect1><tt>.ENDENUM</tt><label id=".ENDENUM"><p>
2025 End a <tt><ref id=".ENUM" name=".ENUM"></tt> declaration.
2028 <sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
2030 Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
2031 <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
2034 <sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
2036 End of macro definition (see section <ref id="macros" name="Macros">).
2039 <sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
2041 End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
2044 <sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
2046 End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
2049 <sect1><tt>.ENDSCOPE</tt><label id=".ENDSCOPE"><p>
2051 End of local lexical level (see <tt/<ref id=".SCOPE" name=".SCOPE">/).
2054 <sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
2056 Ends a struct definition. See the <tt/<ref id=".STRUCT" name=".STRUCT">/
2057 command and the separate section named <ref id="structs" name=""Structs
2061 <sect1><tt>.ENUM</tt><label id=".ENUM"><p>
2063 Start an enumeration. This directive is very similar to the C <tt/enum/
2064 keyword. If a name is given, a new scope is created for the enumeration,
2065 otherwise the enumeration members are placed in the enclosing scope.
2067 In the enumeration body, symbols are declared. The first symbol has a value
2068 of zero, and each following symbol will get the value of the preceding plus
2069 one. This behaviour may be overridden by an explicit assignment. Two symbols
2070 may have the same value.
2082 Above example will create a new scope named <tt/errorcodes/ with three
2083 symbols in it that get the values 0, 1 and 2 respectively. Another way
2084 to write this would have been:
2094 Please note that explicit scoping must be used to access the identifiers:
2097 .word errorcodes::no_error
2100 A more complex example:
2109 EWOULDBLOCK = EAGAIN
2113 In this example, the enumeration does not have a name, which means that the
2114 members will be visible in the enclosing scope and can be used in this scope
2115 without explicit scoping. The first member (<tt/EUNKNOWN/) has the value -1.
2116 The value for the following members is incremented by one, so <tt/EOK/ would
2117 be zero and so on. <tt/EWOULDBLOCK/ is an alias for <tt/EGAIN/, so it has an
2118 override for the value using an already defined symbol.
2121 <sect1><tt>.ERROR</tt><label id=".ERROR"><p>
2123 Force an assembly error. The assembler will output an error message
2124 preceded by "User error" and will <em/not/ produce an object file.
2126 This command may be used to check for initial conditions that must be
2127 set before assembling a source file.
2137 .error "Must define foo or bar!"
2141 See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
2142 id=".OUT" name=".OUT"></tt> directives.
2145 <sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
2147 Abort a macro expansion immediately. This command is often useful in
2148 recursive macros. See separate section <ref id="macros" name="Macros">.
2151 <sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
2153 Make symbols accessible from other modules. Must be followed by a comma
2154 separated list of symbols to export, with each one optionally followed by
2155 an address specification. The default is to export the symbol with the
2156 address size it actually has. The assembler will issue a warning, if the
2157 symbol is exported with an address size smaller than the actual address
2167 See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
2170 <sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
2172 Make symbols accessible from other modules. Must be followed by a comma
2173 separated list of symbols to export. The exported symbols are explicitly
2174 marked as zero page symbols.
2182 See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
2185 <sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
2187 Define far (24 bit) address data. The command must be followed by a
2188 sequence of (not necessarily constant) expressions.
2193 .faraddr DrawCircle, DrawRectangle, DrawHexagon
2196 See: <tt><ref id=".ADDR" name=".ADDR"></tt>
2199 <sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
2201 This directive may be used to enable one or more compatibility features
2202 of the assembler. While the use of <tt/.FEATURE/ should be avoided when
2203 possible, it may be useful when porting sources written for other
2204 assemblers. There is no way to switch a feature off, once you have
2205 enabled it, so using
2211 will enable the feature until end of assembly is reached.
2213 The following features are available:
2217 <tag><tt>at_in_identifiers</tt></tag>
2219 Accept the at character (`@') as a valid character in identifiers. The
2220 at character is not allowed to start an identifier, even with this
2223 <tag><tt>dollar_in_identifiers</tt></tag>
2225 Accept the dollar sign (`$') as a valid character in identifiers. The
2226 at character is not allowed to start an identifier, even with this
2229 <tag><tt>dollar_is_pc</tt></tag>
2231 The dollar sign may be used as an alias for the star (`*'), which
2232 gives the value of the current PC in expressions.
2233 Note: Assignment to the pseudo variable is not allowed.
2235 <tag><tt>labels_without_colons</tt></tag>
2237 Allow labels without a trailing colon. These labels are only accepted,
2238 if they start at the beginning of a line (no leading white space).
2240 <tag><tt>leading_dot_in_identifiers</tt></tag>
2242 Accept the dot (`.') as the first character of an identifier. This may be
2243 used for example to create macro names that start with a dot emulating
2244 control directives of other assemblers. Note however, that none of the
2245 reserved keywords built into the assembler, that starts with a dot, may be
2246 overridden. When using this feature, you may also get into trouble if
2247 later versions of the assembler define new keywords starting with a dot.
2249 <tag><tt>loose_char_term</tt></tag>
2251 Accept single quotes as well as double quotes as terminators for char
2254 <tag><tt>loose_string_term</tt></tag>
2256 Accept single quotes as well as double quotes as terminators for string
2259 <tag><tt>missing_char_term</tt></tag>
2261 Accept single quoted character constants where the terminating quote is
2266 <bf/Note:/ This does not work in conjunction with <tt/.FEATURE
2267 loose_string_term/, since in this case the input would be ambiguous.
2269 <tag><tt>pc_assignment</tt></tag>
2271 Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
2272 is enabled). Such an assignment is handled identical to the <tt><ref
2273 id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
2274 removing the lines with the assignments may also be an option when porting
2275 code written for older assemblers).
2277 <tag><tt>ubiquitous_idents</tt></tag>
2279 Allow the use of instructions names as names for macros and symbols. This
2280 makes it possible to "overload" instructions by defining a macro with the
2281 same name. This does also make it possible to introduce hard to find errors
2282 in your code, so be careful!
2286 It is also possible to specify features on the command line using the
2287 <tt><ref id="option--feature" name="--feature"></tt> command line option.
2288 This is useful when translating sources written for older assemblers, when
2289 you don't want to change the source code.
2291 As an example, to translate sources written for Andre Fachats xa65
2292 assembler, the features
2295 labels_without_colons, pc_assignment, loose_char_term
2298 may be helpful. They do not make ca65 completely compatible, so you may not
2299 be able to translate the sources without changes, even when enabling these
2300 features. However, I have found several sources that translate without
2301 problems when enabling these features on the command line.
2304 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
2306 Insert an option string into the object file. There are two forms of
2307 this command, one specifies the option by a keyword, the second
2308 specifies it as a number. Since usage of the second one needs knowledge
2309 of the internal encoding, its use is not recommended and I will only
2310 describe the first form here.
2312 The command is followed by one of the keywords
2320 a comma and a string. The option is written into the object file
2321 together with the string value. This is currently unidirectional and
2322 there is no way to actually use these options once they are in the
2328 .fileopt comment, "Code stolen from my brother"
2329 .fileopt compiler, "BASIC 2.0"
2330 .fopt author, "J. R. User"
2334 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
2336 Import an absolute symbol from another module. The command is followed by a
2337 comma separated list of symbols to import. The command is similar to <tt>
2338 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
2339 written to the generated object file, even if the symbol is never referenced
2340 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
2341 references for unused symbols).
2346 .forceimport needthisone, needthistoo
2349 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2352 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
2354 Declare symbols as global. Must be followed by a comma separated list of
2355 symbols to declare. Symbols from the list, that are defined somewhere in the
2356 source, are exported, all others are imported. Additional <tt><ref
2357 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
2358 name=".EXPORT"></tt> commands for the same symbol are allowed.
2367 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
2369 Declare symbols as global. Must be followed by a comma separated list of
2370 symbols to declare. Symbols from the list, that are defined somewhere in the
2371 source, are exported, all others are imported. Additional <tt><ref
2372 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
2373 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
2374 in the list are explicitly marked as zero page symbols.
2383 <sect1><tt>.I16</tt><label id=".I16"><p>
2385 Valid only in 65816 mode. Switch the index registers to 16 bit.
2387 Note: This command will not emit any code, it will tell the assembler to
2388 create 16 bit operands for immediate operands.
2390 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
2391 name=".SMART"></tt> commands.
2394 <sect1><tt>.I8</tt><label id=".I8"><p>
2396 Valid only in 65816 mode. Switch the index registers to 8 bit.
2398 Note: This command will not emit any code, it will tell the assembler to
2399 create 8 bit operands for immediate operands.
2401 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
2402 name=".SMART"></tt> commands.
2405 <sect1><tt>.IF</tt><label id=".IF"><p>
2407 Conditional assembly: Evaluate an expression and switch assembler output
2408 on or off depending on the expression. The expression must be a constant
2409 expression, that is, all operands must be defined.
2411 A expression value of zero evaluates to FALSE, any other value evaluates
2415 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
2417 Conditional assembly: Check if there are any remaining tokens in this line,
2418 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
2419 condition is not true, further lines are not assembled until an <tt><ref
2420 id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2421 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2423 This command is often used to check if a macro parameter was given. Since an
2424 empty macro parameter will evaluate to nothing, the condition will evaluate
2425 to FALSE if an empty parameter was given.
2439 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2442 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
2444 Conditional assembly: Evaluate an expression and switch assembler output
2445 on or off depending on the constness of the expression.
2447 A const expression evaluates to to TRUE, a non const expression (one
2448 containing an imported or currently undefined symbol) evaluates to
2451 See also: <tt><ref id=".CONST" name=".CONST"></tt>
2454 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
2456 Conditional assembly: Check if a symbol is defined. Must be followed by
2457 a symbol name. The condition is true if the the given symbol is already
2458 defined, and false otherwise.
2460 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2463 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
2465 Conditional assembly: Check if there are any remaining tokens in this line,
2466 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
2467 condition is not true, further lines are not assembled until an <tt><ref
2468 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2469 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2471 This command is often used to check if a macro parameter was given.
2472 Since an empty macro parameter will evaluate to nothing, the condition
2473 will evaluate to FALSE if an empty parameter was given.
2486 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2489 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
2491 Conditional assembly: Check if a symbol is defined. Must be followed by
2492 a symbol name. The condition is true if the the given symbol is not
2493 defined, and false otherwise.
2495 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2498 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
2500 Conditional assembly: Check if a symbol is referenced. Must be followed
2501 by a symbol name. The condition is true if if the the given symbol was
2502 not referenced before, and false otherwise.
2504 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2507 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
2509 Conditional assembly: Check if the assembler is currently in 6502 mode
2510 (see <tt><ref id=".P02" name=".P02"></tt> command).
2513 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
2515 Conditional assembly: Check if the assembler is currently in 65816 mode
2516 (see <tt><ref id=".P816" name=".P816"></tt> command).
2519 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
2521 Conditional assembly: Check if the assembler is currently in 65C02 mode
2522 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
2525 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
2527 Conditional assembly: Check if the assembler is currently in 65SC02 mode
2528 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
2531 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
2533 Conditional assembly: Check if a symbol is referenced. Must be followed
2534 by a symbol name. The condition is true if if the the given symbol was
2535 referenced before, and false otherwise.
2537 This command may be used to build subroutine libraries in include files
2538 (you may use separate object modules for this purpose too).
2543 .ifref ToHex ; If someone used this subroutine
2544 ToHex: tay ; Define subroutine
2550 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2553 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
2555 Import a symbol from another module. The command is followed by a comma
2556 separated list of symbols to import, with each one optionally followed by
2557 an address specification.
2563 .import bar: zeropage
2566 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
2569 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
2571 Import a symbol from another module. The command is followed by a comma
2572 separated list of symbols to import. The symbols are explicitly imported
2573 as zero page symbols (that is, symbols with values in byte range).
2581 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2584 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
2586 Include a file as binary data. The command expects a string argument
2587 that is the name of a file to include literally in the current segment.
2588 In addition to that, a start offset and a size value may be specified,
2589 separated by commas. If no size is specified, all of the file from the
2590 start offset to end-of-file is used. If no start position is specified
2591 either, zero is assumed (which means that the whole file is inserted).
2596 ; Include whole file
2597 .incbin "sprites.dat"
2599 ; Include file starting at offset 256
2600 .incbin "music.dat", $100
2602 ; Read 100 bytes starting at offset 200
2603 .incbin "graphics.dat", 200, 100
2607 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
2609 Include another file. Include files may be nested up to a depth of 16.
2618 <sect1><tt>.INTERRUPTOR</tt><label id=".INTERRUPTOR"><p>
2620 Export a symbol and mark it as an interruptor. This may be used together
2621 with the linker to build a table of interruptor subroutines that are called
2624 Note: The linker has a feature to build a table of marked routines, but it
2625 is your code that must call these routines, so just declaring a symbol as
2626 interruptor does nothing by itself.
2628 An interruptor is always exported as an absolute (16 bit) symbol. You don't
2629 need to use an additional <tt/.export/ statement, this is implied by
2630 <tt/.interruptor/. It may have an optional priority that is separated by a
2631 comma. Higher numeric values mean a higher priority. If no priority is
2632 given, the default priority of 7 is used. Be careful when assigning
2633 priorities to your own module constructors so they won't interfere with the
2634 ones in the cc65 library.
2639 .interruptor IrqHandler
2640 .interruptor Handler, 16
2643 See the <tt><ref id=".CONDES" name=".CONDES"></tt> command and the separate
2644 section <ref id="condes" name="Module constructors/destructors"> explaining
2645 the feature in more detail.
2648 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
2650 Switch on or off line continuations using the backslash character
2651 before a newline. The option is off by default.
2652 Note: Line continuations do not work in a comment. A backslash at the
2653 end of a comment is treated as part of the comment and does not trigger
2655 The command must be followed by a '+' or '-' character to switch the
2656 option on or off respectively.
2661 .linecont + ; Allow line continuations
2664 #$20 ; This is legal now
2668 <sect1><tt>.LIST</tt><label id=".LIST"><p>
2670 Enable output to the listing. The command must be followed by a boolean
2671 switch ("on", "off", "+" or "-") and will enable or disable listing
2673 The option has no effect if the listing is not enabled by the command line
2674 switch -l. If -l is used, an internal counter is set to 1. Lines are output
2675 to the listing file, if the counter is greater than zero, and suppressed if
2676 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
2682 .list on ; Enable listing output
2686 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
2688 Set, how many bytes are shown in the listing for one source line. The
2689 default is 12, so the listing will show only the first 12 bytes for any
2690 source line that generates more than 12 bytes of code or data.
2691 The directive needs an argument, which is either "unlimited", or an
2692 integer constant in the range 4..255.
2697 .listbytes unlimited ; List all bytes
2698 .listbytes 12 ; List the first 12 bytes
2699 .incbin "data.bin" ; Include large binary file
2703 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
2705 This command may only be used inside a macro definition. It declares a
2706 list of identifiers as local to the macro expansion.
2708 A problem when using macros are labels: Since they don't change their name,
2709 you get a "duplicate symbol" error if the macro is expanded the second time.
2710 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
2711 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
2714 Some other assemblers start a new lexical block inside a macro expansion.
2715 This has some drawbacks however, since that will not allow <em/any/ symbol
2716 to be visible outside a macro, a feature that is sometimes useful. The
2717 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
2718 to address the problem.
2720 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
2724 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
2726 Defines the character that start "cheap" local labels. You may use one
2727 of '@' and '?' as start character. The default is '@'.
2729 Cheap local labels are labels that are visible only between two non
2730 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
2731 using explicit lexical nesting.
2738 Clear: lda #$00 ; Global label
2739 ?Loop: sta Mem,y ; Local label
2743 Sub: ... ; New global label
2744 bne ?Loop ; ERROR: Unknown identifier!
2748 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
2750 Insert a predefined macro package. The command is followed by an
2751 identifier specifying the macro package to insert. Available macro
2755 atari Defines the scrcode macro.
2756 cbm Defines the scrcode macro.
2757 cpu Defines constants for the .CPU variable.
2758 generic Defines generic macros like add and sub.
2759 longbranch Defines conditional long jump macros.
2762 Including a macro package twice, or including a macro package that
2763 redefines already existing macros will lead to an error.
2768 .macpack longbranch ; Include macro package
2770 cmp #$20 ; Set condition codes
2771 jne Label ; Jump long on condition
2774 Macro packages are explained in more detail in section <ref
2775 id="macropackages" name="Macro packages">.
2778 <sect1><tt>.MAC, .MACRO</tt><label id=".MAC"><p>
2780 Start a classic macro definition. The command is followed by an identifier
2781 (the macro name) and optionally by a comma separated list of identifiers
2782 that are macro parameters.
2784 See section <ref id="macros" name="Macros">.
2787 <sect1><tt>.ORG</tt><label id=".ORG"><p>
2789 Start a section of absolute code. The command is followed by a constant
2790 expression that gives the new PC counter location for which the code is
2791 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
2794 Please note that you <em/do not need/ this command in most cases. Placing
2795 code at a specific address is the job of the linker, not the assembler, so
2796 there is usually no reason to assemble code to a specific address.
2798 You may not switch segments while inside a section of absolute code.
2803 .org $7FF ; Emit code starting at $7FF
2807 <sect1><tt>.OUT</tt><label id=".OUT"><p>
2809 Output a string to the console without producing an error. This command
2810 is similar to <tt/.ERROR/, however, it does not force an assembler error
2811 that prevents the creation of an object file.
2816 .out "This code was written by the codebuster(tm)"
2819 See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
2820 id=".ERROR" name=".ERROR"></tt> directives.
2823 <sect1><tt>.P02</tt><label id=".P02"><p>
2825 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
2826 instructions. This is the default if not overridden by the
2827 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
2829 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
2830 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
2833 <sect1><tt>.P816</tt><label id=".P816"><p>
2835 Enable the 65816 instruction set. This is a superset of the 65SC02 and
2836 6502 instruction sets.
2838 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
2839 name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
2842 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
2844 Set the page length for the listing. Must be followed by an integer
2845 constant. The value may be "unlimited", or in the range 32 to 127. The
2846 statement has no effect if no listing is generated. The default value is -1
2847 (unlimited) but may be overridden by the <tt/--pagelength/ command line
2848 option. Beware: Since ca65 is a one pass assembler, the listing is generated
2849 after assembly is complete, you cannot use multiple line lengths with one
2850 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
2855 .pagelength 66 ; Use 66 lines per listing page
2857 .pagelength unlimited ; Unlimited page length
2861 <sect1><tt>.PC02</tt><label id=".PC02"><p>
2863 Enable the 65C02 instructions set. This instruction set includes all
2864 6502 and 65SC02 instructions.
2866 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
2867 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
2870 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
2872 Pop the last pushed segment from the stack, and set it.
2874 This command will switch back to the segment that was last pushed onto the
2875 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
2876 command, and remove this entry from the stack.
2878 The assembler will print an error message if the segment stack is empty
2879 when this command is issued.
2881 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
2884 <sect1><tt>.PROC</tt><label id=".PROC"><p>
2886 Start a nested lexical level with the given name and adds a symbol with this
2887 name to the enclosing scope. All new symbols from now on are in the local
2888 lexical level and are accessible from outside only via <ref id="scopesyntax"
2889 name="explicit scope specification">. Symbols defined outside this local
2890 level may be accessed as long as their names are not used for new symbols
2891 inside the level. Symbols names in other lexical levels do not clash, so you
2892 may use the same names for identifiers. The lexical level ends when the
2893 <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
2894 may be nested up to a depth of 16 (this is an artificial limit to protect
2895 against errors in the source).
2897 Note: Macro names are always in the global level and in a separate name
2898 space. There is no special reason for this, it's just that I've never
2899 had any need for local macro definitions.
2904 .proc Clear ; Define Clear subroutine, start new level
2906 L1: sta Mem,y ; L1 is local and does not cause a
2907 ; duplicate symbol error if used in other
2910 bne L1 ; Reference local symbol
2912 .endproc ; Leave lexical level
2915 See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
2919 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
2921 Enable the 65SC02 instructions set. This instruction set includes all
2924 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
2925 name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
2928 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
2930 Push the currently active segment onto a stack. The entries on the stack
2931 include the name of the segment and the segment type. The stack has a size
2934 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
2935 to switch to another segment and to restore the old segment later, without
2936 even knowing the name and type of the current segment.
2938 The assembler will print an error message if the segment stack is already
2939 full, when this command is issued.
2941 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
2944 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
2946 Switch back to relocatable mode. See the <tt><ref id=".ORG"
2947 name=".ORG"></tt> command.
2950 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
2952 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
2953 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
2954 a constant expression that tells how many times the commands in the body
2955 should get repeated. Optionally, a comma and an identifier may be specified.
2956 If this identifier is found in the body of the repeat statement, it is
2957 replaced by the current repeat count (starting with zero for the first time
2958 the body is repeated).
2960 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
2961 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
2962 level will be used, not the one from the outer level.
2966 The following macro will emit a string that is "encrypted" in that all
2967 characters of the string are XORed by the value $55.
2971 .repeat .strlen(Arg), I
2972 .byte .strat(Arg, I) ^ $55
2977 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
2980 <sect1><tt>.RES</tt><label id=".RES"><p>
2982 Reserve storage. The command is followed by one or two constant
2983 expressions. The first one is mandatory and defines, how many bytes of
2984 storage should be defined. The second, optional expression must by a
2985 constant byte value that will be used as value of the data. If there
2986 is no fill value given, the linker will use the value defined in the
2987 linker configuration file (default: zero).
2992 ; Reserve 12 bytes of memory with value $AA
2997 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
2999 Switch to the RODATA segment. The name of the RODATA segment is always
3000 "RODATA", so this is a shortcut for
3006 The RODATA segment is a segment that is used by the compiler for
3007 readonly data like string constants.
3009 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
3012 <sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
3014 Start a nested lexical level with the given name. All new symbols from now
3015 on are in the local lexical level and are accessible from outside only via
3016 <ref id="scopesyntax" name="explicit scope specification">. Symbols defined
3017 outside this local level may be accessed as long as their names are not used
3018 for new symbols inside the level. Symbols names in other lexical levels do
3019 not clash, so you may use the same names for identifiers. The lexical level
3020 ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
3021 read. Lexical levels may be nested up to a depth of 16 (this is an
3022 artificial limit to protect against errors in the source).
3024 Note: Macro names are always in the global level and in a separate name
3025 space. There is no special reason for this, it's just that I've never
3026 had any need for local macro definitions.
3031 .scope Error ; Start new scope named Error
3033 File = 1 ; File error
3034 Parse = 2 ; Parse error
3035 .endproc ; Close lexical level
3038 lda #Error::File ; Use symbol from scope Error
3041 See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
3045 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
3047 Switch to another segment. Code and data is always emitted into a
3048 segment, that is, a named section of data. The default segment is
3049 "CODE". There may be up to 254 different segments per object file
3050 (and up to 65534 per executable). There are shortcut commands for
3051 the most common segments ("CODE", "DATA" and "BSS").
3053 The command is followed by a string containing the segment name (there are
3054 some constraints for the name - as a rule of thumb use only those segment
3055 names that would also be valid identifiers). There may also be an optional
3056 address size separated by a colon. See the section covering <tt/<ref
3057 id="address-sizes" name="address sizes">/ for more information.
3059 The default address size for a segment depends on the memory model specified
3060 on the command line. The default is "absolute", which means that you don't
3061 have to use an address size modifier in most cases.
3063 "absolute" means that the is a segment with 16 bit (absolute) addressing.
3064 That is, the segment will reside somewhere in core memory outside the zero
3065 page. "zeropage" (8 bit) means that the segment will be placed in the zero
3066 page and direct (short) addressing is possible for data in this segment.
3068 Beware: Only labels in a segment with the zeropage attribute are marked
3069 as reachable by short addressing. The `*' (PC counter) operator will
3070 work as in other segments and will create absolute variable values.
3072 Please note that a segment cannot have two different address sizes. A
3073 segment specified as zeropage cannot be declared as being absolute later.
3078 .segment "ROM2" ; Switch to ROM2 segment
3079 .segment "ZP2": zeropage ; New direct segment
3080 .segment "ZP2" ; Ok, will use last attribute
3081 .segment "ZP2": absolute ; Error, redecl mismatch
3084 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
3085 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt> and <tt><ref
3086 id=".RODATA" name=".RODATA"></tt>
3089 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
3091 Switch the CPU instruction set. The command is followed by a string that
3092 specifies the CPU. Possible values are those that can also be supplied to
3093 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
3094 namely: 6502, 6502X, 65SC02, 65C02, 65816, sunplus and HuC6280. Please
3095 note that support for the sunplus CPU is not available in the freeware
3096 version, because the instruction set of the sunplus CPU is "proprietary
3099 See: <tt><ref id=".CPU" name=".CPU"></tt>,
3100 <tt><ref id=".IFP02" name=".IFP02"></tt>,
3101 <tt><ref id=".IFP816" name=".IFP816"></tt>,
3102 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
3103 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
3104 <tt><ref id=".P02" name=".P02"></tt>,
3105 <tt><ref id=".P816" name=".P816"></tt>,
3106 <tt><ref id=".PC02" name=".PC02"></tt>,
3107 <tt><ref id=".PSC02" name=".PSC02"></tt>
3110 <sect1><tt>.SMART</tt><label id=".SMART"><p>
3112 Switch on or off smart mode. The command must be followed by a '+' or '-'
3113 character to switch the option on or off respectively. The default is off
3114 (that is, the assembler doesn't try to be smart), but this default may be
3115 changed by the -s switch on the command line.
3117 In smart mode the assembler will do the following:
3120 <item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
3121 and update the operand sizes accordingly. If the operand of such an
3122 instruction cannot be evaluated by the assembler (for example, because
3123 the operand is an imported symbol), a warning is issued. Beware: Since
3124 the assembler cannot trace the execution flow this may lead to false
3125 results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
3126 instructions to tell the assembler about the current settings.
3127 <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
3128 used within a procedure declared as <tt/far/, or if the procedure has
3129 no explicit address specification, but it is <tt/far/ because of the
3137 .smart - ; Stop being smart
3140 See: <tt><ref id=".A16" name=".A16"></tt>,
3141 <tt><ref id=".A8" name=".A8"></tt>,
3142 <tt><ref id=".I16" name=".I16"></tt>,
3143 <tt><ref id=".I8" name=".I8"></tt>
3146 <sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
3148 Starts a struct definition. Structs are covered in a separate section named
3149 <ref id="structs" name=""Structs and unions"">.
3151 See: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>
3154 <sect1><tt>.SUNPLUS</tt><label id=".SUNPLUS"><p>
3156 Enable the SunPlus instructions set. This command will not work in the
3157 freeware version of the assembler, because the instruction set is
3158 "proprietary and confidential".
3160 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3161 name=".PSC02"></tt>, <tt><ref id=".PC02" name=".PC02"></tt>, and
3162 <tt><ref id=".P816" name=".P816"></tt>
3165 <sect1><tt>.TAG</tt><label id=".TAG"><p>
3167 Allocate space for a struct or union.
3178 .tag Point ; Allocate 4 bytes
3182 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
3184 Force an assembly warning. The assembler will output a warning message
3185 preceded by "User warning". This warning will always be output, even if
3186 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
3187 command line option.
3189 This command may be used to output possible problems when assembling
3198 .warning "Forward jump in jne, cannot optimize!"
3208 See also the <tt><ref id=".ERROR" name=".ERROR"></tt> and <tt><ref id=".OUT"
3209 name=".OUT"></tt> directives.
3212 <sect1><tt>.WORD</tt><label id=".WORD"><p>
3214 Define word sized data. Must be followed by a sequence of (word ranged,
3215 but not necessarily constant) expressions.
3220 .word $0D00, $AF13, _Clear
3224 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
3226 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
3227 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
3231 .segment "ZEROPAGE", zeropage
3234 Because of the "zeropage" attribute, labels declared in this segment are
3235 addressed using direct addressing mode if possible. You <em/must/ instruct
3236 the linker to place this segment somewhere in the address range 0..$FF
3237 otherwise you will get errors.
3239 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
3243 <sect>Macros<label id="macros"><p>
3246 <sect1>Introduction<p>
3248 Macros may be thought of as "parametrized super instructions". Macros are
3249 sequences of tokens that have a name. If that name is used in the source
3250 file, the macro is "expanded", that is, it is replaced by the tokens that
3251 were specified when the macro was defined.
3254 <sect1>Macros without parameters<p>
3256 In it's simplest form, a macro does not have parameters. Here's an
3260 .macro asr ; Arithmetic shift right
3261 cmp #$80 ; Put bit 7 into carry
3262 ror ; Rotate right with carry
3266 The macro above consists of two real instructions, that are inserted into
3267 the code, whenever the macro is expanded. Macro expansion is simply done
3268 by using the name, like this:
3277 <sect1>Parametrized macros<p>
3279 When using macro parameters, macros can be even more useful:
3293 When calling the macro, you may give a parameter, and each occurrence of
3294 the name "addr" in the macro definition will be replaced by the given
3313 A macro may have more than one parameter, in this case, the parameters
3314 are separated by commas. You are free to give less parameters than the
3315 macro actually takes in the definition. You may also leave intermediate
3316 parameters empty. Empty parameters are replaced by empty space (that is,
3317 they are removed when the macro is expanded). If you have a look at our
3318 macro definition above, you will see, that replacing the "addr" parameter
3319 by nothing will lead to wrong code in most lines. To help you, writing
3320 macros with a variable parameter list, there are some control commands:
3322 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
3323 returns true, if there are any tokens on the remainder of the line. Since
3324 empty parameters are replaced by nothing, this may be used to test if a given
3325 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
3328 Look at this example:
3331 .macro ldaxy a, x, y
3344 This macro may be called as follows:
3347 ldaxy 1, 2, 3 ; Load all three registers
3349 ldaxy 1, , 3 ; Load only a and y
3351 ldaxy , , 3 ; Load y only
3354 There's another helper command for determining, which macro parameters are
3355 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt> This command is
3356 replaced by the parameter count given, <em/including/ intermediate empty macro
3360 ldaxy 1 ; .PARAMCOUNT = 1
3361 ldaxy 1,,3 ; .PARAMCOUNT = 3
3362 ldaxy 1,2 ; .PARAMCOUNT = 2
3363 ldaxy 1, ; .PARAMCOUNT = 2
3364 ldaxy 1,2,3 ; .PARAMCOUNT = 3
3367 Macro parameters may optionally be enclosed into curly braces. This allows the
3368 inclusion of tokens that would otherwise terminate the parameter (the comma in
3369 case of a macro parameter).
3372 .macro foo arg1, arg2
3376 foo ($00,x) ; Two parameters passed
3377 foo {($00,x)} ; One parameter passed
3380 In the first case, the macro is called with two parameters: '<tt/($00/'
3381 and 'x)'. The comma is not passed to the macro, since it is part of the
3382 calling sequence, not the parameters.
3384 In the second case, '($00,x)' is passed to the macro, this time
3385 including the comma.
3388 <sect1>Detecting parameter types<p>
3390 Sometimes it is nice to write a macro that acts differently depending on the
3391 type of the argument supplied. An example would be a macro that loads a 16 bit
3392 value from either an immediate operand, or from memory. The <tt/<ref
3393 id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
3394 functions will allow you to do exactly this:
3398 .if (.match (.left (1, {arg}), #))
3400 lda #<(.right (.tcount ({arg})-1, {arg}))
3401 ldx #>(.right (.tcount ({arg})-1, {arg}))
3403 ; assume absolute or zero page
3410 Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
3411 check if its argument begins with a hash mark. If so, two immediate loads are
3412 emitted, Otherwise a load from an absolute zero page memory location is
3413 assumed. Please note how the curly braces are used to enclose parameters to
3414 pseudo functions handling token lists. This is necessary, because the token
3415 lists may include commas or parens, which would be treated by the assembler
3418 The macro can be used as
3423 ldax #$1234 ; X=$12, A=$34
3425 ldax foo ; X=$56, A=$78
3429 <sect1>Recursive macros<p>
3431 Macros may be used recursively:
3434 .macro push r1, r2, r3
3443 There's also a special macro to help writing recursive macros: <tt><ref
3444 id=".EXITMACRO" name=".EXITMACRO"></tt> This command will stop macro expansion
3448 .macro push r1, r2, r3, r4, r5, r6, r7
3450 ; First parameter is empty
3456 push r2, r3, r4, r5, r6, r7
3460 When expanding this macro, the expansion will push all given parameters
3461 until an empty one is encountered. The macro may be called like this:
3464 push $20, $21, $32 ; Push 3 ZP locations
3465 push $21 ; Push one ZP location
3469 <sect1>Local symbols inside macros<p>
3471 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
3472 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
3473 Have a look at the inc16 macro above. Here is it again:
3487 If you have a closer look at the code, you will notice, that it could be
3488 written more efficiently, like this:
3499 But imagine what happens, if you use this macro twice? Since the label
3500 "Skip" has the same name both times, you get a "duplicate symbol" error.
3501 Without a way to circumvent this problem, macros are not as useful, as
3502 they could be. One solution is, to start a new lexical block inside the
3516 Now the label is local to the block and not visible outside. However,
3517 sometimes you want a label inside the macro to be visible outside. To make
3518 that possible, there's a new command that's only usable inside a macro
3519 definition: <tt><ref id=".LOCAL" name=".LOCAL"></tt>. <tt/.LOCAL/ declares one
3520 or more symbols as local to the macro expansion. The names of local variables
3521 are replaced by a unique name in each separate macro expansion. So we could
3522 also solve the problem above by using <tt/.LOCAL/:
3526 .local Skip ; Make Skip a local symbol
3533 Skip: ; Not visible outside
3538 <sect1>C style macros<p>
3540 Starting with version 2.5 of the assembler, there is a second macro type
3541 available: C style macros using the <tt/.DEFINE/ directive. These macros are
3542 similar to the classic macro type described above, but behaviour is sometimes
3547 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
3548 span more than a line. You may use line continuation (see <tt><ref
3549 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
3550 more than one line for increased readability, but the macro itself
3551 may not contain an end-of-line token.
3553 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
3554 the name space with classic macros, but they are detected and replaced
3555 at the scanner level. While classic macros may be used in every place,
3556 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
3557 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
3558 they are more versatile in some situations.
3560 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
3561 parameters. While classic macros may have empty parameters, this is
3562 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
3563 For this macro type, the number of actual parameters must match
3564 exactly the number of formal parameters.
3566 To make this possible, formal parameters are enclosed in braces when
3567 defining the macro. If there are no parameters, the empty braces may
3570 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
3571 contain end-of-line tokens, there are things that cannot be done. They
3572 may not contain several processor instructions for example. So, while
3573 some things may be done with both macro types, each type has special
3574 usages. The types complement each other.
3578 Let's look at a few examples to make the advantages and disadvantages
3581 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
3582 following <tt/.DEFINE/:
3587 foo EQU $1234 ; This is accepted now
3590 You may use the directive to define string constants used elsewhere:
3593 ; Define the version number
3594 .define VERSION "12.3a"
3600 Macros with parameters may also be useful:
3603 .define DEBUG(message) .out message
3605 DEBUG "Assembling include file #3"
3608 Note that, while formal parameters have to be placed in braces, this is
3609 not true for the actual parameters. Beware: Since the assembler cannot
3610 detect the end of one parameter, only the first token is used. If you
3611 don't like that, use classic macros instead:
3619 (This is an example where a problem can be solved with both macro types).
3622 <sect1>Characters in macros<p>
3624 When using the <ref id="option-t" name="-t"> option, characters are translated
3625 into the target character set of the specific machine. However, this happens
3626 as late as possible. This means that strings are translated if they are part
3627 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
3628 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
3629 used as part of an expression.
3631 This behaviour is very intuitive outside of macros but may be confusing when
3632 doing more complex macros. If you compare characters against numeric values,
3633 be sure to take the translation into account.
3638 <sect>Macro packages<label id="macropackages"><p>
3640 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
3641 macro packages may be included with just one command. Available macro packages
3645 <sect1><tt>.MACPACK generic</tt><p>
3647 This macro package defines macros that are useful in almost any program.
3648 Currently, two macros are defined:
3663 <sect1><tt>.MACPACK longbranch</tt><p>
3665 This macro package defines long conditional jumps. They are named like the
3666 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
3667 definition for the "<tt/jeq/" macro, the other macros are built using the same
3672 .if .def(Target) .and ((*+2)-(Target) <= 127)
3681 All macros expand to a short branch, if the label is already defined (back
3682 jump) and is reachable with a short jump. Otherwise the macro expands to a
3683 conditional branch with the branch condition inverted, followed by an absolute
3684 jump to the actual branch target.
3686 The package defines the following macros:
3689 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
3694 <sect1><tt>.MACPACK cbm</tt><p>
3696 The cbm macro package will define a macro named <tt/scrcode/. It takes a
3697 string as argument and places this string into memory translated into screen
3701 <sect1><tt>.MACPACK cpu</tt><p>
3703 This macro package does not define any macros but constants used to examine
3704 the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
3705 each supported CPU a constant similar to
3717 is defined. These constants may be used to determine the exact type of the
3718 currently enabled CPU. In addition to that, for each CPU instruction set,
3719 another constant is defined:
3731 The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
3732 be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
3733 currently enabled CPU supports a specific instruction set. For example the
3734 65C02 supports all instructions of the 65SC02 CPU, so it has the
3735 <tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
3739 .if (.cpu .bitand CPU_ISET_65SC02)
3747 it is possible to determine if the
3753 instruction is supported, which is the case for the 65SC02, 65C02 and 65816
3754 CPUs (the latter two are upwards compatible to the 65SC02).
3758 <sect>Predefined constants<label id="predefined-constants"><p>
3760 For better orthogonality, the assembler defines similar symbols as the
3761 compiler, depending on the target system selected:
3764 <item><tt/__ACE__/ - Target system is <tt/ace/
3765 <item><tt/__APPLE2__",/ - Target system is <tt/apple2/
3766 <item><tt/__APPLE2ENH__",/ - Target system is <tt/apple2enh/
3767 <item><tt/__ATARI__/ - Target system is <tt/atari/
3768 <item><tt/__ATMOS__",/ - Target system is <tt/atmos/
3769 <item><tt/__BBC__",/ - Target system is <tt/bbc/
3770 <item><tt/__C128__/ - Target system is <tt/c128/
3771 <item><tt/__C16__/ - Target system is <tt/c16/
3772 <item><tt/__C64__/ - Target system is <tt/c64/
3773 <item><tt/__CBM__/ - Target is a Commodore system
3774 <item><tt/__CBM510__/ - Target system is <tt/cbm510/
3775 <item><tt/__CBM610__/ - Target system is <tt/cbm610/
3776 <item><tt/__GEOS__",/ - Target system is <tt/geos/
3777 <item><tt/__LUNIX__",/ - Target system is <tt/lunix/
3778 <item><tt/__NES__",/ - Target system is <tt/nes/
3779 <item><tt/__PET__/ - Target system is <tt/pet/
3780 <item><tt/__PLUS4__/ - Target system is <tt/plus4/
3781 <item><tt/__SUPERVISION__",/ - Target system is <tt/supervision/
3782 <item><tt/__VIC20__/ - Target system is <tt/vic20/
3786 <sect>Structs and unions<label id="structs"><p>
3790 Structs and unions are special forms of <ref id="scopes" name="scopes">. They
3791 are to some degree comparable to their C counterparts. Both have a list of
3792 members. Each member allocates storage and may optionally have a name, which,
3793 in case of a struct, is the offset from the beginning and, in case of a union,
3797 <sect1>Declaration<p>
3799 Here is an example for a very simple struct with two members and a total size
3809 A union shares the total space between all its members, its size is the same
3810 as that of the largest member.
3812 A struct or union must not necessarily have a name. If it is anonymous, no
3813 local scope is opened, the identifiers used to name the members are placed
3814 into the current scope instead.
3816 A struct may contain unnamed members and definitions of local structs. The
3817 storage allocators may contain a multiplier, as in the example below:
3822 .word 2 ; Allocate two words
3829 <sect1>The <tt/.TAG/ keyword<p>
3831 Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to reserve space
3832 for an already defined struct or unions within another struct:
3846 Space for a struct or union may be allocated using the <ref id=".TAG"
3847 name=".TAG"> directive.
3853 Currently, members are just offsets from the start of the struct or union. To
3854 access a field of a struct, the member offset has to be added to the address
3855 of the struct itself:
3858 lda C+Circle::Radius ; Load circle radius into A
3861 This may change in a future version of the assembler.
3864 <sect1>Limitations<p>
3866 Structs and unions are currently implemented as nested symbol tables (in fact,
3867 they were a by-product of the improved scoping rules). Currently, the
3868 assembler has no idea of types. This means that the <ref id=".TAG"
3869 name=".TAG"> keyword will only allocate space. You won't be able to initialize
3870 variables declared with <ref id=".TAG" name=".TAG">, and adding an embedded
3871 structure to another structure with <ref id=".TAG" name=".TAG"> will not make
3872 this structure accessible by using the '::' operator.
3876 <sect>Module constructors/destructors<label id="condes"><p>
3878 <em>Note:</em> This section applies mostly to C programs, so the explanation
3879 below uses examples from the C libraries. However, the feature may also be
3880 useful for assembler programs.
3885 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
3886 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
3887 name=".INTERRUPTOR"></tt> keywords it it possible to export functions in a
3888 special way. The linker is able to generate tables with all functions of a
3889 specific type. Such a table will <em>only</em> include symbols from object
3890 files that are linked into a specific executable. This may be used to add
3891 initialization and cleanup code for library modules, or a table of interrupt
3894 The C heap functions are an example where module initialization code is used.
3895 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
3896 variables that contain the start and the end of the heap, pointers to the free
3897 list and so on. Since the end of the heap depends on the size and start of the
3898 stack, it must be initialized at runtime. However, initializing these
3899 variables for programs that do not use the heap are a waste of time and
3902 So the central module defines a function that contains initialization code and
3903 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
3904 this module is added to an executable by the linker, the initialization
3905 function will be placed into the table of constructors by the linker. The C
3906 startup code will call all constructors before <tt/main/ and all destructors
3907 after <tt/main/, so without any further work, the heap initialization code is
3908 called once the module is linked in.
3910 While it would be possible to add explicit calls to initialization functions
3911 in the startup code, the new approach has several advantages:
3915 If a module is not included, the initialization code is not linked in and not
3916 called. So you don't pay for things you don't need.
3919 Adding another library that needs initialization does not mean that the
3920 startup code has to be changed. Before we had module constructors and
3921 destructors, the startup code for all systems had to be adjusted to call the
3922 new initialization code.
3925 The feature saves memory: Each additional initialization function needs just
3926 two bytes in the table (a pointer to the function).
3931 <sect1>Calling order<p>
3933 The symbols are sorted in increasing priority order by the linker when using
3934 one of the builtin linker configurations, so the functions with lower
3935 priorities come first and are followed by those with higher priorities. The C
3936 library runtime subroutine that walks over the function tables calls the
3937 functions starting from the top of the table - which means that functions with
3938 a high priority are called first.
3940 So when using the C runtime, functions are called with high priority functions
3941 first, followed by low priority functions.
3946 When using these special symbols, please take care of the following:
3951 The linker will only generate function tables, it will not generate code to
3952 call these functions. If you're using the feature in some other than the
3953 existing C environments, you have to write code to call all functions in a
3954 linker generated table yourself. See the <tt/condes/ and <tt/callirq/ modules
3955 in the C runtime for an example on how to do this.
3958 The linker will only add addresses of functions that are in modules linked to
3959 the executable. This means that you have to be careful where to place the
3960 condes functions. If initialization or an irq handler is needed for a group of
3961 functions, be sure to place the function into a module that is linked in
3962 regardless of which function is called by the user.
3965 The linker will generate the tables only when requested to do so by the
3966 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
3967 be requested separately.
3970 Constructors and destructors may have priorities. These priorities determine
3971 the order of the functions in the table. If your initialization or cleanup code
3972 does depend on other initialization or cleanup code, you have to choose the
3973 priority for the functions accordingly.
3976 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
3977 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
3978 name=".INTERRUPTOR"></tt> statements, there is also a more generic command:
3979 <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to specify an
3980 additional type. Predefined types are 0 (constructor), 1 (destructor) and 2
3981 (interruptor). The linker generates a separate table for each type on request.
3986 <sect>Porting sources from other assemblers<p>
3988 Sometimes it is necessary to port code written for older assemblers to ca65.
3989 In some cases, this can be done without any changes to the source code by
3990 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
3991 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
3994 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
3995 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
3996 done by the linker. Most other assemblers generate absolute code, placement is
3997 done within the assembler and there is no external linker.
3999 In general it is not a good idea to write new code using the emulation
4000 features of the assembler, but there may be situations where even this rule is
4005 You need to use some of the ca65 emulation features to simulate the behaviour
4006 of such simple assemblers.
4009 <item>Prepare your sourcecode like this:
4012 ; if you want TASS style labels without colons
4013 .feature labels_without_colons
4015 ; if you want TASS style character constants
4016 ; ("a" instead of the default 'a')
4017 .feature loose_char_term
4019 .word *+2 ; the cbm load address
4024 notice that the two emulation features are mostly useful for porting
4025 sources originally written in/for TASS, they are not needed for the
4026 actual "simple assembler operation" and are not recommended if you are
4027 writing new code from scratch.
4029 <item>Replace all program counter assignments (which are not possible in ca65
4030 by default, and the respective emulation feature works different from what
4031 you'd expect) by another way to skip to memory locations, for example the
4032 <tt><ref id=".RES" name=".RES"></tt> directive.
4036 .res $2000-* ; reserve memory up to $2000
4039 Please note that other than the original TASS, ca65 can never move the program
4040 counter backwards - think of it as if you are assembling to disk with TASS.
4042 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
4043 rewritten to match ca65 syntax. Most importantly notice that due to the lack
4044 of <tt/.goto/, everything involving loops must be replaced by
4045 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
4047 <item>To assemble code to a different address than it is executed at, use the
4048 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
4049 <tt/.offs/-constructs.
4056 .reloc ; back to normal
4059 <item>Then assemble like this:
4062 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
4065 Note that you need to use the actual start address minus two, since two bytes
4066 are used for the cbm load address.
4071 <sect>Bugs/Feedback<p>
4073 If you have problems using the assembler, if you find any bugs, or if
4074 you're doing something interesting with the assembler, I would be glad to
4075 hear from you. Feel free to contact me by email
4076 (<htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">).
4082 ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
4083 Bassewitz. For usage of the binaries and/or sources the following
4084 conditions do apply:
4086 This software is provided 'as-is', without any expressed or implied
4087 warranty. In no event will the authors be held liable for any damages
4088 arising from the use of this software.
4090 Permission is granted to anyone to use this software for any purpose,
4091 including commercial applications, and to alter it and redistribute it
4092 freely, subject to the following restrictions:
4095 <item> The origin of this software must not be misrepresented; you must not
4096 claim that you wrote the original software. If you use this software
4097 in a product, an acknowledgment in the product documentation would be
4098 appreciated but is not required.
4099 <item> Altered source versions must be plainly marked as such, and must not
4100 be misrepresented as being the original software.
4101 <item> This notice may not be removed or altered from any source