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 --memory-model model Set the memory model
116 --pagelength n Set the page length for the listing
117 --smart Enable smart mode
118 --target sys Set the target system
119 --verbose Increase verbosity
120 --version Print the assembler version
121 ---------------------------------------------------------------------------
125 <sect1>Command line options in detail<p>
127 Here is a description of all the command line options:
131 <label id="option--cpu">
132 <tag><tt>--cpu type</tt></tag>
134 Set the default for the CPU type. The option takes a parameter, which
137 6502, 65SC02, 65C02, 65816, sunplus, sweet16
139 The sunplus cpu is not available in the freeware version, because the
140 instruction set is "proprietary and confidential".
143 <label id="option--feature">
144 <tag><tt>--feature name</tt></tag>
146 Enable an emulation feature. This is identical as using <tt/.FEATURE/
147 in the source with two exceptions: Feature names must be lower case, and
148 each feature must be specified by using an extra <tt/--feature/ option,
149 comma separated lists are not allowed.
151 See the discussion of the <tt><ref id=".FEATURE" name=".FEATURE"></tt>
152 command for a list of emulation features.
155 <label id="option-g">
156 <tag><tt>-g, --debug-info</tt></tag>
158 When this option (or the equivalent control command <tt/.DEBUGINFO/) is
159 used, the assembler will add a section to the object file that contains
160 all symbols (including local ones) together with the symbol values and
161 source file positions. The linker will put these additional symbols into
162 the VICE label file, so even local symbols can be seen in the VICE
166 <tag><tt>-h, --help</tt></tag>
168 Print the short option summary shown above.
171 <tag><tt>-i, --ignore-case</tt></tag>
173 This option makes the assembler case insensitive on identifiers and labels.
174 This option will override the default, but may itself be overridden by the
175 <tt><ref id=".CASE" name=".CASE"></tt> control command.
178 <tag><tt>-l, --listing</tt></tag>
180 Generate an assembler listing. The listing file will always have the
181 name of the main input file with the extension replaced by ".lst". This
182 may change in future versions.
185 <tag><tt>--list-bytes n</tt></tag>
187 Set the maximum number of bytes printed in the listing for one line of
188 input. See the <tt><ref id=".LISTBYTES" name=".LISTBYTES"></tt> directive
189 for more information. The value zero can be used to encode an unlimited
190 number of printed bytes.
193 <tag><tt>-mm model, --memory-model model</tt></tag>
195 Define the default memory model. Possible model specifiers are near, far and
199 <tag><tt>-o name</tt></tag>
201 The default output name is the name of the input file with the extension
202 replaced by ".o". If you don't like that, you may give another name with
203 the -o option. The output file will be placed in the same directory as
204 the source file, or, if -o is given, the full path in this name is used.
207 <tag><tt>--pagelength n</tt></tag>
209 sets the length of a listing page in lines. See the <tt><ref
210 id=".PAGELENGTH" name=".PAGELENGTH"></tt> directive for more information.
213 <tag><tt>-s, --smart-mode</tt></tag>
215 In smart mode (enabled by -s or the <tt><ref id=".SMART" name=".SMART"></tt>
216 pseudo instruction) the assembler will track usage of the <tt/REP/ and
217 <tt/SEP/ instructions in 65816 mode and update the operand sizes
218 accordingly. If the operand of such an instruction cannot be evaluated by
219 the assembler (for example, because the operand is an imported symbol), a
222 Beware: Since the assembler cannot trace the execution flow this may
223 lead to false results in some cases. If in doubt, use the .ixx and .axx
224 instructions to tell the assembler about the current settings. Smart
225 mode is off by default.
228 <label id="option-t">
229 <tag><tt>-t sys, --target sys</tt></tag>
231 Set the target system. This will enable translation of character strings
232 and character constants into the character set of the target platform.
233 The default for the target system is "none", which means that no translation
234 will take place. The assembler supports the same target systems as the
235 compiler, see there for a list.
238 <tag><tt>-v, --verbose</tt></tag>
240 Increase the assembler verbosity. Usually only needed for debugging
241 purposes. You may use this option more than one time for even more
245 <tag><tt>-D</tt></tag>
247 This option allows you to define symbols on the command line. Without a
248 value, the symbol is defined with the value zero. When giving a value,
249 you may use the '$' prefix for hexadecimal symbols. Please note
250 that for some operating systems, '$' has a special meaning, so
251 you may have to quote the expression.
254 <tag><tt>-I dir, --include-dir dir</tt></tag>
256 Name a directory which is searched for include files. The option may be
257 used more than once to specify more than one directory to search. The
258 current directory is always searched first before considering any
259 additional directories.
262 <tag><tt>-U, --auto-import</tt></tag>
264 Mark symbols that are not defined in the sources as imported symbols. This
265 should be used with care since it delays error messages about typos and such
266 until the linker is run. The compiler uses the equivalent of this switch
267 (<tt><ref id=".AUTOIMPORT" name=".AUTOIMPORT"></tt>) to enable auto imported
268 symbols for the runtime library. However, the compiler is supposed to
269 generate code that runs through the assembler without problems, something
270 which is not always true for assembler programmers.
273 <tag><tt>-V, --version</tt></tag>
275 Print the version number of the assembler. If you send any suggestions
276 or bugfixes, please include the version number.
279 <label id="option-W">
280 <tag><tt>-Wn</tt></tag>
282 Set the warning level for the assembler. Using -W2 the assembler will
283 even warn about such things like unused imported symbols. The default
284 warning level is 1, and it would probably be silly to set it to
291 <sect>Input format<p>
293 <sect1>Assembler syntax<p>
295 The assembler accepts the standard 6502/65816 assembler syntax. One line may
296 contain a label (which is identified by a colon), and, in addition to the
297 label, an assembler mnemonic, a macro, or a control command (see section <ref
298 id="control-commands" name="Control Commands"> for supported control
299 commands). Alternatively, the line may contain a symbol definition using
300 the '=' token. Everything after a semicolon is handled as a comment (that is,
303 Here are some examples for valid input lines:
306 Label: ; A label and a comment
307 lda #$20 ; A 6502 instruction plus comment
308 L1: ldx #$20 ; Same with label
309 L2: .byte "Hello world" ; Label plus control command
310 mymac $20 ; Macro expansion
311 MySym = 3*L1 ; Symbol definition
312 MaSym = Label ; Another symbol
315 The assembler accepts
318 <item>all valid 6502 mnemonics when in 6502 mode (the default or after the
319 <tt><ref id=".P02" name=".P02"></tt> command was given).
320 <item>all valid 6502 mnemonics plus a set of illegal instructions when in
321 <ref id="6502X-mode" name="6502X mode">.
322 <item>all valid 65SC02 mnemonics when in 65SC02 mode (after the
323 <tt><ref id=".PSC02" name=".PSC02"></tt> command was given).
324 <item>all valid 65C02 mnemonics when in 65C02 mode (after the
325 <tt><ref id=".PC02" name=".PC02"></tt> command was given).
326 <item>all valid 65618 mnemonics when in 65816 mode (after the
327 <tt><ref id=".P816" name=".P816"></tt> command was given).
328 <item>all valid SunPlus mnemonics when in SunPlus mode (after the
329 <tt><ref id=".SUNPLUS" name=".SUNPLUS"></tt> command was given).
335 In 65816 mode several aliases are accepted in addition to the official
339 BGE is an alias for BCS
340 BLT is an alias for BCC
341 CPA is an alias for CMP
342 DEA is an alias for DEC A
343 INA is an alias for INC A
344 SWA is an alias for XBA
345 TAD is an alias for TCD
346 TAS is an alias for TCS
347 TDA is an alias for TDC
348 TSA is an alias for TSC
353 <sect1>6502X mode<label id="6502X-mode"><p>
355 6502X mode is an extension to the normal 6502 mode. In this mode, several
356 mnemonics for illegal instructions of the NMOS 6502 CPUs are accepted. Since
357 these instructions are illegal, there are no official mnemonics for them. The
358 unofficial ones are taken from <htmlurl
359 url="http://oxyron.net/graham/opcodes02.html"
360 name="http://oxyron.net/graham/opcodes02.html">. Please note that only the
361 ones marked as "stable" are supported. The following table uses information
362 from the mentioned web page, for more information, see there.
365 <item><tt>ALR: A:=(A and #{imm})*2;</tt>
366 <item><tt>ANC: A:=A and #{imm};</tt> Generates opcode $0B.
367 <item><tt>ARR: A:=(A and #{imm})/2;</tt>
368 <item><tt>AXS: X:=A and X-#{imm};</tt>
369 <item><tt>DCP: {adr}:={adr}-1; A-{adr};</tt>
370 <item><tt>ISC: {adr}:={adr}+1; A:=A-{adr};</tt>
371 <item><tt>LAS: A,X,S:={adr} and S;</tt>
372 <item><tt>LAX: A,X:={adr};</tt>
373 <item><tt>RLA: {adr}:={adr}rol; A:=A and {adr};</tt>
374 <item><tt>RRA: {adr}:={adr}ror; A:=A adc {adr};</tt>
375 <item><tt>SAX: {adr}:=A and X;</tt>
376 <item><tt>SLO: {adr}:={adr}*2; A:=A or {adr};</tt>
377 <item><tt>SRE: {adr}:={adr}/2; A:=A xor {adr};</tt>
382 <sect1>sweet16 mode<label id="sweet16-mode"><p>
384 SWEET 16 is an interpreter for a pseudo 16 bit CPU written by Steve Wozniak
385 for the Apple ][ machines. It is available in the Apple ][ ROM. ca65 can
386 generate code for this pseudo CPU when switched into sweet16 mode. The
387 following is special in sweet16 mode:
391 <item>The '@' character denotes indirect addressing and is no longer available
392 for cheap local labels. If you need cheap local labels, you will have to
393 switch to another lead character using the <tt/<ref id=".LOCALCHAR"
394 name=".LOCALCHAR">/ command.
396 <item>Registers are specified using <tt/R0/ .. <tt/R15/. In sweet16 mode,
397 these identifiers are reserved words.
401 Please note that the assembler does neither supply the interpreter needed for
402 SWEET 16 code, nor the zero page locations needed for the SWEET 16 registers,
403 nor does it call the interpreter. All this must be done by your program. Apple
404 ][ programmers do probably know how to use sweet16 mode.
406 For more information about SWEET 16, see
407 <htmlurl url="http://www.6502.org/source/interpreters/sweet16.htm"
408 name="http://www.6502.org/source/interpreters/sweet16.htm">.
411 <sect1>Number format<p>
413 For literal values, the assembler accepts the widely used number formats: A
414 preceding '$' or a trailing 'h' denotes a hex value, a preceding '%'
415 denotes a binary value, and a bare number is interpreted as a decimal. There
416 are currently no octal values and no floats.
419 <sect1>Conditional assembly<p>
421 Please note that when using the conditional directives (<tt/.IF/ and friends),
422 the input must consist of valid assembler tokens, even in <tt/.IF/ branches
423 that are not assembled. The reason for this behaviour is that the assembler
424 must still be able to detect the ending tokens (like <tt/.ENDIF/), so
425 conversion of the input stream into tokens still takes place. As a consequence
426 conditional assembly directives may <bf/not/ be used to prevent normal text
427 (used as a comment or similar) from being assembled. <p>
433 <sect1>Expression evaluation<p>
435 All expressions are evaluated with (at least) 32 bit precision. An
436 expression may contain constant values and any combination of internal and
437 external symbols. Expressions that cannot be evaluated at assembly time
438 are stored inside the object file for evaluation by the linker.
439 Expressions referencing imported symbols must always be evaluated by the
443 <sect1>Size of an expression result<p>
445 Sometimes, the assembler must know about the size of the value that is the
446 result of an expression. This is usually the case, if a decision has to be
447 made, to generate a zero page or an absolute memory references. In this
448 case, the assembler has to make some assumptions about the result of an
452 <item> If the result of an expression is constant, the actual value is
453 checked to see if it's a byte sized expression or not.
454 <item> If the expression is explicitly casted to a byte sized expression by
455 one of the '>', '<' or '^' operators, it is a byte expression.
456 <item> If this is not the case, and the expression contains a symbol,
457 explicitly declared as zero page symbol (by one of the .importzp or
458 .exportzp instructions), then the whole expression is assumed to be
460 <item> If the expression contains symbols that are not defined, and these
461 symbols are local symbols, the enclosing scopes are searched for a
462 symbol with the same name. If one exists and this symbol is defined,
463 it's attributes are used to determine the result size.
464 <item> In all other cases the expression is assumed to be word sized.
467 Note: If the assembler is not able to evaluate the expression at assembly
468 time, the linker will evaluate it and check for range errors as soon as
472 <sect1>Boolean expressions<p>
474 In the context of a boolean expression, any non zero value is evaluated as
475 true, any other value to false. The result of a boolean expression is 1 if
476 it's true, and zero if it's false. There are boolean operators with extreme
477 low precedence with version 2.x (where x > 0). The <tt/.AND/ and <tt/.OR/
478 operators are shortcut operators. That is, if the result of the expression is
479 already known, after evaluating the left hand side, the right hand side is
483 <sect1>Constant expressions<p>
485 Sometimes an expression must evaluate to a constant without looking at any
486 further input. One such example is the <tt/<ref id=".IF" name=".IF">/ command
487 that decides if parts of the code are assembled or not. An expression used in
488 the <tt/.IF/ command cannot reference a symbol defined later, because the
489 decision about the <tt/.IF/ must be made at the point when it is read. If the
490 expression used in such a context contains only constant numerical values,
491 there is no problem. When unresolvable symbols are involved it may get harder
492 for the assembler to determine if the expression is actually constant, and it
493 is even possible to create expressions that aren't recognized as constant.
494 Simplifying the expressions will often help.
496 In cases where the result of the expression is not needed immediately, the
497 assembler will delay evaluation until all input is read, at which point all
498 symbols are known. So using arbitrary complex constant expressions is no
499 problem in most cases.
503 <sect1>Available operators<label id="operators"><p>
505 Available operators sorted by precedence:
509 Op|Description|Precedence@<hline>
510 |Builtin string functions|0@
511 |Builtin pseudo variables|1@
512 |Builtin pseudo functions|1@
515 ˜|Unary bitwise not|1@
516 .BITNOT|Unary bitwise not|1@
517 <|Low byte operator|1@
518 >|High byte operator|1@
519 ^|Bank byte operator|1@
522 .MOD|Modulo operation|2@
524 .BITAND|Bitwise and|2@
526 .BITXOR|Bitwise xor|2@
527 <<|Shift left operator|2@
528 .SHL|Shift left operator|2@
529 >>|Shift right operato|r@
530 .SHR|Shift right operator|2@
533 ||Binary or|3@
535 =|Compare operation (equal)|4@
536 <>|Compare operation (not equal)|4@
537 <|Compare operation (less)|4@
538 >|Compare operation (greater)|4@
539 <=|Compare operation (less or equal)|4@
540 >=|Compare operation (greater or equal)|4@
541 &&|Boolean and|5@
544 |||Boolean or|6@
549 <caption>Available operators sorted by precedence
552 To force a specific order of evaluation, braces may be used as usual.
557 <sect>Symbols and labels<p>
559 The assembler allows you to use symbols instead of naked values to make
560 the source more readable. There are a lot of different ways to define and
561 use symbols and labels, giving a lot of flexibility.
564 <sect1>Numeric constants<p>
566 Numeric constants are defined using the equal sign or the label assignment
567 operator. After doing
573 may use the symbol "two" in every place where a number is expected, and it is
574 evaluated to the value 2 in this context. The label assignment operator causes
575 the same, but causes the symbol to be marked as a label, which may cause a
576 different handling in the debugger:
582 The right side can of course be an expression:
589 <sect1>Standard labels<p>
591 A label is defined by writing the name of the label at the start of the line
592 (before any instruction mnemonic, macro or pseudo directive), followed by a
593 colon. This will declare a symbol with the given name and the value of the
594 current program counter.
597 <sect1>Local labels and symbols<p>
599 Using the <tt><ref id=".PROC" name=".PROC"></tt> directive, it is possible to
600 create regions of code where the names of labels and symbols are local to this
601 region. They are not known outside of this region and cannot be accessed from
602 there. Such regions may be nested like PROCEDUREs in Pascal.
604 See the description of the <tt><ref id=".PROC" name=".PROC"></tt>
605 directive for more information.
608 <sect1>Cheap local labels<p>
610 Cheap local labels are defined like standard labels, but the name of the
611 label must begin with a special symbol (usually '@', but this can be
612 changed by the <tt><ref id=".LOCALCHAR" name=".LOCALCHAR"></tt>
615 Cheap local labels are visible only between two non cheap labels. As soon as a
616 standard symbol is encountered (this may also be a local symbol if inside a
617 region defined with the <tt><ref id=".PROC" name=".PROC"></tt> directive), the
618 cheap local symbol goes out of scope.
620 You may use cheap local labels as an easy way to reuse common label
621 names like "Loop". Here is an example:
624 Clear: lda #$00 ; Global label
626 @Loop: sta Mem,y ; Local label
630 Sub: ... ; New global label
631 bne @Loop ; ERROR: Unknown identifier!
634 <sect1>Unnamed labels<p>
636 If you really want to write messy code, there are also unnamed labels. These
637 labels do not have a name (you guessed that already, didn't you?). A colon is
638 used to mark the absence of the name.
640 Unnamed labels may be accessed by using the colon plus several minus or plus
641 characters as a label designator. Using the '-' characters will create a back
642 reference (use the n'th label backwards), using '+' will create a forward
643 reference (use the n'th label in forward direction). An example will help to
666 As you can see from the example, unnamed labels will make even short
667 sections of code hard to understand, because you have to count labels
668 to find branch targets (this is the reason why I for my part do
669 prefer the "cheap" local labels). Nevertheless, unnamed labels are
670 convenient in some situations, so it's your decision.
673 <sect1>Using macros to define labels and constants<p>
675 While there are drawbacks with this approach, it may be handy in some
676 situations. Using <tt><ref id=".DEFINE" name=".DEFINE"></tt>, it is
677 possible to define symbols or constants that may be used elsewhere. Since
678 the macro facility works on a very low level, there is no scoping. On the
679 other side, you may also define string constants this way (this is not
680 possible with the other symbol types).
686 .DEFINE version "SOS V2.3"
688 four = two * two ; Ok
691 .PROC ; Start local scope
692 two = 3 ; Will give "2 = 3" - invalid!
697 <sect1>Symbols and <tt>.DEBUGINFO</tt><p>
699 If <tt><ref id=".DEBUGINFO" name=".DEBUGINFO"></tt> is enabled (or <ref
700 id="option-g" name="-g"> is given on the command line), global, local and
701 cheap local labels are written to the object file and will be available in the
702 symbol file via the linker. Unnamed labels are not written to the object file,
703 because they don't have a name which would allow to access them.
707 <sect>Scopes<label id="scopes"><p>
709 ca65 implements several sorts of scopes for symbols.
711 <sect1>Global scope<p>
713 All (non cheap local) symbols that are declared outside of any nested scopes
717 <sect1>Cheap locals<p>
719 A special scope is the scope for cheap local symbols. It lasts from one non
720 local symbol to the next one, without any provisions made by the programmer.
721 All other scopes differ in usage but use the same concept internally.
724 <sect1>Generic nested scopes<p>
726 A nested scoped for generic use is started with <tt/<ref id=".SCOPE"
727 name=".SCOPE">/ and closed with <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/.
728 The scope can have a name, in which case it is accessible from the outside by
729 using <ref id="scopesyntax" name="explicit scopes">. If the scope does not
730 have a name, all symbols created within the scope are local to the scope, and
731 aren't accessible from the outside.
733 A nested scope can access symbols from the local or from enclosing scopes by
734 name without using explicit scope names. In some cases there may be
735 ambiguities, for example if there is a reference to a local symbol that is not
736 yet defined, but a symbol with the same name exists in outer scopes:
748 In the example above, the <tt/lda/ instruction will load the value 3 into the
749 accumulator, because <tt/foo/ is redefined in the scope. However:
761 Here, <tt/lda/ will still load from <tt/$12,x/, but since it is unknown to the
762 assembler that <tt/foo/ is a zeropage symbol when translating the instruction,
763 absolute mode is used instead. In fact, the assembler will not use absolute
764 mode by default, but it will search through the enclosing scopes for a symbol
765 with the given name. If one is found, the address size of this symbol is used.
766 This may lead to errors:
778 In this case, when the assembler sees the symbol <tt/foo/ in the <tt/lda/
779 instruction, it will search for an already defined symbol <tt/foo/. It will
780 find <tt/foo/ in scope <tt/outer/, and a close look reveals that it is a
781 zeropage symbol. So the assembler will use zeropage addressing mode. If
782 <tt/foo/ is redefined later in scope <tt/inner/, the assembler tries to change
783 the address in the <tt/lda/ instruction already translated, but since the new
784 value needs absolute addressing mode, this fails, and an error message "Range
787 Of course the most simple solution for the problem is to move the definition
788 of <tt/foo/ in scope <tt/inner/ upwards, so it precedes its use. There may be
789 rare cases when this cannot be done. In these cases, you can use one of the
790 address size override operators:
802 This will cause the <tt/lda/ instruction to be translated using absolute
803 addressing mode, which means changing the symbol reference later does not
807 <sect1>Nested procedures<p>
809 A nested procedure is created by use of <tt/<ref id=".PROC" name=".PROC">/. It
810 differs from a <tt/<ref id=".SCOPE" name=".SCOPE">/ in that it must have a
811 name, and a it will introduce a symbol with this name in the enclosing scope.
820 is actually the same as
829 This is the reason why a procedure must have a name. If you want a scope
830 without a name, use <tt/<ref id=".SCOPE" name=".SCOPE">/.
832 <bf/Note:/ As you can see from the example above, scopes and symbols live in
833 different namespaces. There can be a symbol named <tt/foo/ and a scope named
834 <tt/foo/ without any conflicts (but see the section titled <ref
835 id="scopesearch" name=""Scope search order"">).
838 <sect1>Structs, unions and enums<p>
840 Structs, unions and enums are explained in a <ref id="structs" name="separate
841 section">, I do only cover them here, because if they are declared with a
842 name, they open a nested scope, similar to <tt/<ref id=".SCOPE"
843 name=".SCOPE">/. However, when no name is specified, the behaviour is
844 different: In this case, no new scope will be opened, symbols declared within
845 a struct, union, or enum declaration will then be added to the enclosing scope
849 <sect1>Explicit scope specification<label id="scopesyntax"><p>
851 Accessing symbols from other scopes is possible by using an explicit scope
852 specification, provided that the scope where the symbol lives in has a name.
853 The namespace token (<tt/::/) is used to access other scopes:
861 lda foo::bar ; Access foo in scope bar
864 The only way to deny access to a scope from the outside is to declare a scope
865 without a name (using the <tt/<ref id=".SCOPE" name=".SCOPE">/ command).
867 A special syntax is used to specify the global scope: If a symbol or scope is
868 preceded by the namespace token, the global scope is searched:
875 lda #::bar ; Access the global bar (which is 3)
880 <sect1>Scope search order<label id="scopesearch"><p>
882 The assembler searches for a scope in a similar way as for a symbol. First, it
883 looks in the current scope, and then it walks up the enclosing scopes until
886 However, one important thing to note when using explicit scope syntax is, that
887 a symbol may be accessed before it is defined, but a scope may <bf/not/ be
888 used without a preceding definition. This means that in the following
897 lda #foo::bar ; Will load 3, not 2!
904 the reference to the scope <tt/foo/ will use the global scope, and not the
905 local one, because the local one is not visible at the point where it is
908 Things get more complex if a complete chain of scopes is specified:
919 lda #outer::inner::bar ; 1
931 When <tt/outer::inner::bar/ is referenced in the <tt/lda/ instruction, the
932 assembler will first search in the local scope for a scope named <tt/outer/.
933 Since none is found, the enclosing scope (<tt/another/) is checked. There is
934 still no scope named <tt/outer/, so scope <tt/foo/ is checked, and finally
935 scope <tt/outer/ is found. Within this scope, <tt/inner/ is searched, and in
936 this scope, the assembler looks for a symbol named <tt/bar/.
938 Please note that once the anchor scope is found, all following scopes
939 (<tt/inner/ in this case) are expected to be found exactly in this scope. The
940 assembler will search the scope tree only for the first scope (if it is not
941 anchored in the root scope). Starting from there on, there is no flexibility,
942 so if the scope named <tt/outer/ found by the assembler does not contain a
943 scope named <tt/inner/, this would be an error, even if such a pair does exist
944 (one level up in global scope).
946 Ambiguities that may be introduced by this search algorithm may be removed by
947 anchoring the scope specification in the global scope. In the example above,
948 if you want to access the "other" symbol <tt/bar/, you would have to write:
959 lda #::outer::inner::bar ; 2
972 <sect>Address sizes and memory models<label id="address-sizes"><p>
974 <sect1>Address sizes<p>
976 ca65 assigns each segment and each symbol an address size. This is true, even
977 if the symbol is not used as an address. You may also think of a value range
978 of the symbol instead of an address size.
980 Possible address sizes are:
983 <item>Zeropage or direct (8 bits)
984 <item>Absolute (16 bits)
989 Since the assembler uses default address sizes for the segments and symbols,
990 it is usually not necessary to override the default behaviour. In cases, where
991 it is necessary, the following keywords may be used to specify address sizes:
994 <item>DIRECT, ZEROPAGE or ZP for zeropage addressing (8 bits).
995 <item>ABSOLUTE, ABS or NEAR for absolute addressing (16 bits).
996 <item>FAR for far addressing (24 bits).
997 <item>LONG or DWORD for long addressing (32 bits).
1001 <sect1>Address sizes of segments<p>
1003 The assembler assigns an address size to each segment. Since the
1004 representation of a label within this segment is "segment start + offset",
1005 labels will inherit the address size of the segment they are declared in.
1007 The address size of a segment may be changed, by using an optional address
1008 size modifier. See the <tt/<ref id=".SEGMENT" name="segment directive">/ for
1009 an explanation on how this is done.
1012 <sect1>Address sizes of symbols<p>
1017 <sect1>Memory models<p>
1019 The default address size of a segment depends on the memory model used. Since
1020 labels inherit the address size from the segment they are declared in,
1021 changing the memory model is an easy way to change the address size of many
1027 <sect>Pseudo variables<label id="pseudo-variables"><p>
1029 Pseudo variables are readable in all cases, and in some special cases also
1032 <sect1><tt>*</tt><p>
1034 Reading this pseudo variable will return the program counter at the start
1035 of the current input line.
1037 Assignment to this variable is possible when <tt/<ref id=".FEATURE"
1038 name=".FEATURE pc_assignment">/ is used. Note: You should not use
1039 assignments to <tt/*/, use <tt/<ref id=".ORG" name=".ORG">/ instead.
1042 <sect1><tt>.CPU</tt><label id=".CPU"><p>
1044 Reading this pseudo variable will give a constant integer value that
1045 tells which CPU is currently enabled. It can also tell which instruction
1046 set the CPU is able to translate. The value read from the pseudo variable
1047 should be further examined by using one of the constants defined by the
1048 "cpu" macro package (see <tt/<ref id=".MACPACK" name=".MACPACK">/).
1050 It may be used to replace the .IFPxx pseudo instructions or to construct
1051 even more complex expressions.
1057 .if (.cpu .bitand CPU_ISET_65816)
1069 <sect1><tt>.PARAMCOUNT</tt><label id=".PARAMCOUNT"><p>
1071 This builtin pseudo variable is only available in macros. It is replaced by
1072 the actual number of parameters that were given in the macro invocation.
1077 .macro foo arg1, arg2, arg3
1078 .if .paramcount <> 3
1079 .error "Too few parameters for macro foo"
1085 See section <ref id="macros" name="Macros">.
1088 <sect1><tt>.TIME</tt><label id=".TIME"><p>
1090 Reading this pseudo variable will give a constant integer value that
1091 represents the current time in POSIX standard (as seconds since the
1094 It may be used to encode the time of translation somewhere in the created
1100 .dword .time ; Place time here
1104 <sect1><tt>.VERSION</tt><label id=".VERSION"><p>
1106 Reading this pseudo variable will give the assembler version according to
1107 the following formula:
1109 VER_MAJOR*$100 + VER_MINOR*$10 + VER_PATCH
1111 It may be used to encode the assembler version or check the assembler for
1112 special features not available with older versions.
1116 Version 2.11.1 of the assembler will return $2B1 as numerical constant when
1117 reading the pseudo variable <tt/.VERSION/.
1121 <sect>Pseudo functions<label id="pseudo-functions"><p>
1123 Pseudo functions expect their arguments in parenthesis, and they have a result,
1124 either a string or an expression.
1127 <sect1><tt>.BANKBYTE</tt><label id=".BANKBYTE"><p>
1129 The function returns the bank byte (that is, bits 16-23) of its argument.
1130 It works identical to the '^' operator.
1132 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1133 <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>
1136 <sect1><tt>.BLANK</tt><label id=".BLANK"><p>
1138 Builtin function. The function evaluates its argument in braces and yields
1139 "false" if the argument is non blank (there is an argument), and "true" if
1140 there is no argument. The token list that makes up the function argument
1141 may optionally be enclosed in curly braces. This allows the inclusion of
1142 tokens that would otherwise terminate the list (the closing right
1143 parenthesis). The curly braces are not considered part of the list, a list
1144 just consisting of curly braces is considered to be empty.
1146 As an example, the <tt/.IFBLANK/ statement may be replaced by
1154 <sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
1156 Builtin string function. The function allows to concatenate a list of string
1157 constants separated by commas. The result is a string constant that is the
1158 concatenation of all arguments. This function is most useful in macros and
1159 when used together with the <tt/.STRING/ builtin function. The function may
1160 be used in any case where a string constant is expected.
1165 .include .concat ("myheader", ".", "inc")
1168 This is the same as the command
1171 .include "myheader.inc"
1175 <sect1><tt>.CONST</tt><label id=".CONST"><p>
1177 Builtin function. The function evaluates its argument in braces and
1178 yields "true" if the argument is a constant expression (that is, an
1179 expression that yields a constant value at assembly time) and "false"
1180 otherwise. As an example, the .IFCONST statement may be replaced by
1187 <sect1><tt>.HIBYTE</tt><label id=".HIBYTE"><p>
1189 The function returns the high byte (that is, bits 8-15) of its argument.
1190 It works identical to the '>' operator.
1192 See: <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>,
1193 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1196 <sect1><tt>.HIWORD</tt><label id=".HIWORD"><p>
1198 The function returns the high word (that is, bits 16-31) of its argument.
1200 See: <tt><ref id=".LOWORD" name=".LOWORD"></tt>
1203 <sect1><tt>.IDENT</tt><label id=".IDENT"><p>
1205 The function expects a string as its argument, and converts this argument
1206 into an identifier. If the string starts with the current <tt/<ref
1207 id=".LOCALCHAR" name=".LOCALCHAR">/, it will be converted into a cheap local
1208 identifier, otherwise it will be converted into a normal identifier.
1213 .macro makelabel arg1, arg2
1214 .ident (.concat (arg1, arg2)):
1217 makelabel "foo", "bar"
1219 .word foobar ; Valid label
1223 <sect1><tt>.LEFT</tt><label id=".LEFT"><p>
1225 Builtin function. Extracts the left part of a given token list.
1230 .LEFT (<int expr>, <token list>)
1233 The first integer expression gives the number of tokens to extract from
1234 the token list. The second argument is the token list itself. The token
1235 list may optionally be enclosed into curly braces. This allows the
1236 inclusion of tokens that would otherwise terminate the list (the closing
1237 right paren in the given case).
1241 To check in a macro if the given argument has a '#' as first token
1242 (immediate addressing mode), use something like this:
1247 .if (.match (.left (1, {arg}), #))
1249 ; ldax called with immediate operand
1257 See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
1258 name=".RIGHT"></tt> builtin functions.
1261 <sect1><tt>.LOBYTE</tt><label id=".LOBYTE"><p>
1263 The function returns the low byte (that is, bits 0-7) of its argument.
1264 It works identical to the '<' operator.
1266 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1267 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1270 <sect1><tt>.LOWORD</tt><label id=".LOWORD"><p>
1272 The function returns the low word (that is, bits 0-15) of its argument.
1274 See: <tt><ref id=".HIWORD" name=".HIWORD"></tt>
1277 <sect1><tt>.MATCH</tt><label id=".MATCH"><p>
1279 Builtin function. Matches two token lists against each other. This is
1280 most useful within macros, since macros are not stored as strings, but
1286 .MATCH(<token list #1>, <token list #2>)
1289 Both token list may contain arbitrary tokens with the exception of the
1290 terminator token (comma resp. right parenthesis) and
1297 The token lists may optionally be enclosed into curly braces. This allows
1298 the inclusion of tokens that would otherwise terminate the list (the closing
1299 right paren in the given case). Often a macro parameter is used for any of
1302 Please note that the function does only compare tokens, not token
1303 attributes. So any number is equal to any other number, regardless of the
1304 actual value. The same is true for strings. If you need to compare tokens
1305 <em/and/ token attributes, use the <tt><ref id=".XMATCH"
1306 name=".XMATCH"></tt> function.
1310 Assume the macro <tt/ASR/, that will shift right the accumulator by one,
1311 while honoring the sign bit. The builtin processor instructions will allow
1312 an optional "A" for accu addressing for instructions like <tt/ROL/ and
1313 <tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
1314 to check for this and print and error for invalid calls.
1319 .if (.not .blank(arg)) .and (.not .match ({arg}, a))
1320 .error "Syntax error"
1323 cmp #$80 ; Bit 7 into carry
1324 lsr a ; Shift carry into bit 7
1329 The macro will only accept no arguments, or one argument that must be the
1330 reserved keyword "A".
1332 See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
1335 <sect1><tt>.MID</tt><label id=".MID"><p>
1337 Builtin function. Takes a starting index, a count and a token list as
1338 arguments. Will return part of the token list.
1343 .MID (<int expr>, <int expr>, <token list>)
1346 The first integer expression gives the starting token in the list (the first
1347 token has index 0). The second integer expression gives the number of tokens
1348 to extract from the token list. The third argument is the token list itself.
1349 The token list may optionally be enclosed into curly braces. This allows the
1350 inclusion of tokens that would otherwise terminate the list (the closing
1351 right paren in the given case).
1355 To check in a macro if the given argument has a '<tt/#/' as first token
1356 (immediate addressing mode), use something like this:
1361 .if (.match (.mid (0, 1, {arg}), #))
1363 ; ldax called with immediate operand
1371 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
1372 name=".RIGHT"></tt> builtin functions.
1375 <sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
1377 Builtin function. The function expects an identifier as argument in braces.
1378 The argument is evaluated, and the function yields "true" if the identifier
1379 is a symbol that has already been referenced somewhere in the source file up
1380 to the current position. Otherwise the function yields false. As an example,
1381 the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
1387 See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1390 <sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
1392 Builtin function. Extracts the right part of a given token list.
1397 .RIGHT (<int expr>, <token list>)
1400 The first integer expression gives the number of tokens to extract from the
1401 token list. The second argument is the token list itself. The token list
1402 may optionally be enclosed into curly braces. This allows the inclusion of
1403 tokens that would otherwise terminate the list (the closing right paren in
1406 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
1407 name=".MID"></tt> builtin functions.
1410 <sect1><tt>.SIZEOF</tt><label id=".SIZEOF"><p>
1412 <tt/.SIZEOF/ is a pseudo function that returns the size of its argument. The
1413 argument can be a struct/union, a struct member, a procedure, or a label. In
1414 case of a procedure or label, its size is defined by the amount of data
1415 placed in the segment where the label is relative to. If a line of code
1416 switches segments (for example in a macro) data placed in other segments
1417 does not count for the size.
1419 Please note that a symbol or scope must exist, before it is used together with
1420 <tt/.SIZEOF/ (this may get relaxed later, but will always be true for scopes).
1421 A scope has preference over a symbol with the same name, so if the last part
1422 of a name represents both, a scope and a symbol, the scope is chosen over the
1425 After the following code:
1428 .struct Point ; Struct size = 4
1433 P: .tag Point ; Declare a point
1434 @P: .tag Point ; Declare another point
1446 .data ; Segment switch!!!
1452 <tag><tt/.sizeof(Point)/</tag>
1453 will have the value 4, because this is the size of struct <tt/Point/.
1455 <tag><tt/.sizeof(Point::xcoord)/</tag>
1456 will have the value 2, because this is the size of the member <tt/xcoord/
1457 in struct <tt/Point/.
1459 <tag><tt/.sizeof(P)/</tag>
1460 will have the value 4, this is the size of the data declared on the same
1461 source line as the label <tt/P/, which is in the same segment that <tt/P/
1464 <tag><tt/.sizeof(@P)/</tag>
1465 will have the value 4, see above. The example demonstrates that <tt/.SIZEOF/
1466 does also work for cheap local symbols.
1468 <tag><tt/.sizeof(Code)/</tag>
1469 will have the value 3, since this is amount of data emitted into the code
1470 segment, the segment that was active when <tt/Code/ was entered. Note that
1471 this value includes the amount of data emitted in child scopes (in this
1472 case <tt/Code::Inner/).
1474 <tag><tt/.sizeof(Code::Inner)/</tag>
1475 will have the value 1 as expected.
1477 <tag><tt/.sizeof(Data)/</tag>
1478 will have the value 0. Data is emitted within the scope <tt/Data/, but since
1479 the segment is switched after entry, this data is emitted into another
1484 <sect1><tt>.STRAT</tt><label id=".STRAT"><p>
1486 Builtin function. The function accepts a string and an index as
1487 arguments and returns the value of the character at the given position
1488 as an integer value. The index is zero based.
1494 ; Check if the argument string starts with '#'
1495 .if (.strat (Arg, 0) = '#')
1502 <sect1><tt>.SPRINTF</tt><label id=".SPRINTF"><p>
1504 Builtin function. It expects a format string as first argument. The number
1505 and type of the following arguments depend on the format string. The format
1506 string is similar to the one of the C <tt/printf/ function. Missing things
1507 are: Length modifiers, variable width.
1509 The result of the function is a string.
1516 ; Generate an identifier:
1517 .ident (.sprintf ("%s%03d", "label", num)):
1521 <sect1><tt>.STRING</tt><label id=".STRING"><p>
1523 Builtin function. The function accepts an argument in braces and converts
1524 this argument into a string constant. The argument may be an identifier, or
1525 a constant numeric value.
1527 Since you can use a string in the first place, the use of the function may
1528 not be obvious. However, it is useful in macros, or more complex setups.
1533 ; Emulate other assemblers:
1535 .segment .string(name)
1540 <sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
1542 Builtin function. The function accepts a string argument in braces and
1543 evaluates to the length of the string.
1547 The following macro encodes a string as a pascal style string with
1548 a leading length byte.
1552 .byte .strlen(Arg), Arg
1557 <sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
1559 Builtin function. The function accepts a token list in braces. The function
1560 result is the number of tokens given as argument. The token list may
1561 optionally be enclosed into curly braces which are not considered part of
1562 the list and not counted. Enclosement in curly braces allows the inclusion
1563 of tokens that would otherwise terminate the list (the closing right paren
1568 The <tt/ldax/ macro accepts the '#' token to denote immediate addressing (as
1569 with the normal 6502 instructions). To translate it into two separate 8 bit
1570 load instructions, the '#' token has to get stripped from the argument:
1574 .if (.match (.mid (0, 1, {arg}), #))
1575 ; ldax called with immediate operand
1576 lda #<(.right (.tcount ({arg})-1, {arg}))
1577 ldx #>(.right (.tcount ({arg})-1, {arg}))
1585 <sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
1587 Builtin function. Matches two token lists against each other. This is
1588 most useful within macros, since macros are not stored as strings, but
1594 .XMATCH(<token list #1>, <token list #2>)
1597 Both token list may contain arbitrary tokens with the exception of the
1598 terminator token (comma resp. right parenthesis) and
1605 The token lists may optionally be enclosed into curly braces. This allows
1606 the inclusion of tokens that would otherwise terminate the list (the closing
1607 right paren in the given case). Often a macro parameter is used for any of
1610 The function compares tokens <em/and/ token values. If you need a function
1611 that just compares the type of tokens, have a look at the <tt><ref
1612 id=".MATCH" name=".MATCH"></tt> function.
1614 See: <tt><ref id=".MATCH" name=".MATCH"></tt>
1618 <sect>Control commands<label id="control-commands"><p>
1620 Here's a list of all control commands and a description, what they do:
1623 <sect1><tt>.A16</tt><label id=".A16"><p>
1625 Valid only in 65816 mode. Switch the accumulator to 16 bit.
1627 Note: This command will not emit any code, it will tell the assembler to
1628 create 16 bit operands for immediate accumulator addressing mode.
1630 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1633 <sect1><tt>.A8</tt><label id=".A8"><p>
1635 Valid only in 65816 mode. Switch the accumulator to 8 bit.
1637 Note: This command will not emit any code, it will tell the assembler to
1638 create 8 bit operands for immediate accu addressing mode.
1640 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1643 <sect1><tt>.ADDR</tt><label id=".ADDR"><p>
1645 Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
1646 may be used for better readability if the data words are address values. In
1647 65816 mode, the address is forced to be 16 bit wide to fit into the current
1648 segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
1649 must be followed by a sequence of (not necessarily constant) expressions.
1654 .addr $0D00, $AF13, _Clear
1657 See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
1661 <sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
1663 Align data to a given boundary. The command expects a constant integer
1664 argument that must be a power of two, plus an optional second argument
1665 in byte range. If there is a second argument, it is used as fill value,
1666 otherwise the value defined in the linker configuration file is used
1667 (the default for this value is zero).
1669 Since alignment depends on the base address of the module, you must
1670 give the same (or a greater) alignment for the segment when linking.
1671 The linker will give you a warning, if you don't do that.
1680 <sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
1682 Define a string with a trailing zero.
1687 Msg: .asciiz "Hello world"
1690 This will put the string "Hello world" followed by a binary zero into
1691 the current segment. There may be more strings separated by commas, but
1692 the binary zero is only appended once (after the last one).
1695 <sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
1697 Add an assertion. The command is followed by an expression, an action
1698 specifier, and an optional message that is output in case the assertion
1699 fails. If no message was given, the string "Assertion failed" is used. The
1700 action specifier may be one of <tt/warning/ or <tt/error/. The assertion is
1701 evaluated by the assembler if possible, and also passed to the linker in the
1702 object file (if one is generated). The linker will then evaluate the
1703 expression when segment placement has been done.
1708 .assert * = $8000, error, "Code not at $8000"
1711 The example assertion will check that the current location is at $8000,
1712 when the output file is written, and abort with an error if this is not
1713 the case. More complex expressions are possible. The action specifier
1714 <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
1715 an error message. In the latter case, generation if the output file is
1716 suppressed in both the assembler and linker.
1719 <sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
1721 Is followed by a plus or a minus character. When switched on (using a
1722 +), undefined symbols are automatically marked as import instead of
1723 giving errors. When switched off (which is the default so this does not
1724 make much sense), this does not happen and an error message is
1725 displayed. The state of the autoimport flag is evaluated when the
1726 complete source was translated, before outputting actual code, so it is
1727 <em/not/ possible to switch this feature on or off for separate sections
1728 of code. The last setting is used for all symbols.
1730 You should probably not use this switch because it delays error
1731 messages about undefined symbols until the link stage. The cc65
1732 compiler (which is supposed to produce correct assembler code in all
1733 circumstances, something which is not true for most assembler
1734 programmers) will insert this command to avoid importing each and every
1735 routine from the runtime library.
1740 .autoimport + ; Switch on auto import
1744 <sect1><tt>.BSS</tt><label id=".BSS"><p>
1746 Switch to the BSS segment. The name of the BSS segment is always "BSS",
1747 so this is a shortcut for
1753 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1756 <sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
1758 Define byte sized data. Must be followed by a sequence of (byte ranged)
1759 expressions or strings.
1765 .byt "world", $0D, $00
1769 <sect1><tt>.CASE</tt><label id=".CASE"><p>
1771 Switch on or off case sensitivity on identifiers. The default is off
1772 (that is, identifiers are case sensitive), but may be changed by the
1773 -i switch on the command line.
1774 The command must be followed by a '+' or '-' character to switch the
1775 option on or off respectively.
1780 .case - ; Identifiers are not case sensitive
1784 <sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
1786 Apply a custom mapping for characters. The command is followed by two
1787 numbers in the range 1..255. The first one is the index of the source
1788 character, the second one is the mapping. The mapping applies to all
1789 character and string constants when they generate output, and overrides
1790 a mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
1791 command line switch.
1796 .charmap $41, $61 ; Map 'A' to 'a'
1800 <sect1><tt>.CODE</tt><label id=".CODE"><p>
1802 Switch to the CODE segment. The name of the CODE segment is always
1803 "CODE", so this is a shortcut for
1809 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1812 <sect1><tt>.CONDES</tt><label id=".CONDES"><p>
1814 Export a symbol and mark it in a special way. The linker is able to build
1815 tables of all such symbols. This may be used to automatically create a list
1816 of functions needed to initialize linked library modules.
1818 Note: The linker has a feature to build a table of marked routines, but it
1819 is your code that must call these routines, so just declaring a symbol with
1820 <tt/.CONDES/ does nothing by itself.
1822 All symbols are exported as an absolute (16 bit) symbol. You don't need to
1823 use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
1824 is implied by <tt/.CONDES/.
1826 <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
1827 <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
1828 specifying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
1829 The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
1830 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
1831 name=".INTERRUPTOR"></tt> commands are actually shortcuts for <tt/.CONDES/
1832 with a type of <tt/constructor/ resp. <tt/destructor/ or <tt/interruptor/.
1834 After the type, an optional priority may be specified. Higher numeric values
1835 mean higher priority. If no priority is given, the default priority of 7 is
1836 used. Be careful when assigning priorities to your own module constructors
1837 so they won't interfere with the ones in the cc65 library.
1842 .condes ModuleInit, constructor
1843 .condes ModInit, 0, 16
1846 See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
1847 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
1848 name=".INTERRUPTOR"></tt> commands and the separate section <ref id="condes"
1849 name="Module constructors/destructors"> explaining the feature in more
1853 <sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
1855 Export a symbol and mark it as a module constructor. This may be used
1856 together with the linker to build a table of constructor subroutines that
1857 are called by the startup code.
1859 Note: The linker has a feature to build a table of marked routines, but it
1860 is your code that must call these routines, so just declaring a symbol as
1861 constructor does nothing by itself.
1863 A constructor is always exported as an absolute (16 bit) symbol. You don't
1864 need to use an additional <tt/.export/ statement, this is implied by
1865 <tt/.constructor/. It may have an optional priority that is separated by a
1866 comma. Higher numeric values mean a higher priority. If no priority is
1867 given, the default priority of 7 is used. Be careful when assigning
1868 priorities to your own module constructors so they won't interfere with the
1869 ones in the cc65 library.
1874 .constructor ModuleInit
1875 .constructor ModInit, 16
1878 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
1879 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
1880 <ref id="condes" name="Module constructors/destructors"> explaining the
1881 feature in more detail.
1884 <sect1><tt>.DATA</tt><label id=".DATA"><p>
1886 Switch to the DATA segment. The name of the DATA segment is always
1887 "DATA", so this is a shortcut for
1893 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1896 <sect1><tt>.DBYT</tt><label id=".DBYT"><p>
1898 Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
1899 create word sized data in native 65XX format). Must be followed by a
1900 sequence of (word ranged) expressions.
1908 This will emit the bytes
1914 into the current segment in that order.
1917 <sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
1919 Switch on or off debug info generation. The default is off (that is,
1920 the object file will not contain debug infos), but may be changed by the
1921 -g switch on the command line.
1922 The command must be followed by a '+' or '-' character to switch the
1923 option on or off respectively.
1928 .debuginfo + ; Generate debug info
1932 <sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
1934 Start a define style macro definition. The command is followed by an
1935 identifier (the macro name) and optionally by a list of formal arguments
1937 See section <ref id="macros" name="Macros">.
1940 <sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
1942 Builtin function. The function expects an identifier as argument in braces.
1943 The argument is evaluated, and the function yields "true" if the identifier
1944 is a symbol that is already defined somewhere in the source file up to the
1945 current position. Otherwise the function yields false. As an example, the
1946 <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
1953 <sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
1955 Export a symbol and mark it as a module destructor. This may be used
1956 together with the linker to build a table of destructor subroutines that
1957 are called by the startup code.
1959 Note: The linker has a feature to build a table of marked routines, but it
1960 is your code that must call these routines, so just declaring a symbol as
1961 constructor does nothing by itself.
1963 A destructor is always exported as an absolute (16 bit) symbol. You don't
1964 need to use an additional <tt/.export/ statement, this is implied by
1965 <tt/.destructor/. It may have an optional priority that is separated by a
1966 comma. Higher numerical values mean a higher priority. If no priority is
1967 given, the default priority of 7 is used. Be careful when assigning
1968 priorities to your own module destructors so they won't interfere with the
1969 ones in the cc65 library.
1974 .destructor ModuleDone
1975 .destructor ModDone, 16
1978 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
1979 id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
1980 section <ref id="condes" name="Module constructors/destructors"> explaining
1981 the feature in more detail.
1984 <sect1><tt>.DWORD</tt><label id=".DWORD"><p>
1986 Define dword sized data (4 bytes) Must be followed by a sequence of
1992 .dword $12344512, $12FA489
1996 <sect1><tt>.ELSE</tt><label id=".ELSE"><p>
1998 Conditional assembly: Reverse the current condition.
2001 <sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
2003 Conditional assembly: Reverse current condition and test a new one.
2006 <sect1><tt>.END</tt><label id=".END"><p>
2008 Forced end of assembly. Assembly stops at this point, even if the command
2009 is read from an include file.
2012 <sect1><tt>.ENDENUM</tt><label id=".ENDENUM"><p>
2014 End a <tt><ref id=".ENUM" name=".ENUM"></tt> declaration.
2017 <sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
2019 Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
2020 <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
2023 <sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
2025 End of macro definition (see section <ref id="macros" name="Macros">).
2028 <sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
2030 End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
2033 <sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
2035 End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
2038 <sect1><tt>.ENDSCOPE</tt><label id=".ENDSCOPE"><p>
2040 End of local lexical level (see <tt/<ref id=".SCOPE" name=".SCOPE">/).
2043 <sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
2045 Ends a struct definition. See the <tt/<ref id=".STRUCT" name=".STRUCT">/
2046 command and the separate section named <ref id="structs" name=""Structs
2050 <sect1><tt>.ENUM</tt><label id=".ENUM"><p>
2052 Start an enumeration. This directive is very similar to the C <tt/enum/
2053 keyword. If a name is given, a new scope is created for the enumeration,
2054 otherwise the enumeration members are placed in the enclosing scope.
2056 In the enumeration body, symbols are declared. The first symbol has a value
2057 of zero, and each following symbol will get the value of the preceding plus
2058 one. This behaviour may be overridden by an explicit assignment. Two symbols
2059 may have the same value.
2071 Above example will create a new scope named <tt/errorcodes/ with three
2072 symbols in it that get the values 0, 1 and 2 respectively. Another way
2073 to write this would have been:
2083 Please note that explicit scoping must be used to access the identifiers:
2086 .word errorcodes::no_error
2089 A more complex example:
2098 EWOULDBLOCK = EAGAIN
2102 In this example, the enumeration does not have a name, which means that the
2103 members will be visible in the enclosing scope and can be used in this scope
2104 without explicit scoping. The first member (<tt/EUNKNOWN/) has the value -1.
2105 The value for the following members is incremented by one, so <tt/EOK/ would
2106 be zero and so on. <tt/EWOULDBLOCK/ is an alias for <tt/EGAIN/, so it has an
2107 override for the value using an already defined symbol.
2110 <sect1><tt>.ERROR</tt><label id=".ERROR"><p>
2112 Force an assembly error. The assembler will output an error message
2113 preceded by "User error" and will <em/not/ produce an object file.
2115 This command may be used to check for initial conditions that must be
2116 set before assembling a source file.
2126 .error "Must define foo or bar!"
2130 See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
2131 id=".OUT" name=".OUT"></tt> directives.
2134 <sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
2136 Abort a macro expansion immediately. This command is often useful in
2137 recursive macros. See separate section <ref id="macros" name="Macros">.
2140 <sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
2142 Make symbols accessible from other modules. Must be followed by a comma
2143 separated list of symbols to export, with each one optionally followed by
2144 an address specification. The default is to export the symbol with the
2145 address size it actually has. The assembler will issue a warning, if the
2146 symbol is exported with an address size smaller than the actual address
2156 See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
2159 <sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
2161 Make symbols accessible from other modules. Must be followed by a comma
2162 separated list of symbols to export. The exported symbols are explicitly
2163 marked as zero page symbols.
2171 See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
2174 <sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
2176 Define far (24 bit) address data. The command must be followed by a
2177 sequence of (not necessarily constant) expressions.
2182 .faraddr DrawCircle, DrawRectangle, DrawHexagon
2185 See: <tt><ref id=".ADDR" name=".ADDR"></tt>
2188 <sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
2190 This directive may be used to enable one or more compatibility features
2191 of the assembler. While the use of <tt/.FEATURE/ should be avoided when
2192 possible, it may be useful when porting sources written for other
2193 assemblers. There is no way to switch a feature off, once you have
2194 enabled it, so using
2200 will enable the feature until end of assembly is reached.
2202 The following features are available:
2206 <tag><tt>at_in_identifiers</tt></tag>
2208 Accept the at character (`@') as a valid character in identifiers. The
2209 at character is not allowed to start an identifier, even with this
2212 <tag><tt>dollar_in_identifiers</tt></tag>
2214 Accept the dollar sign (`$') as a valid character in identifiers. The
2215 at character is not allowed to start an identifier, even with this
2218 <tag><tt>dollar_is_pc</tt></tag>
2220 The dollar sign may be used as an alias for the star (`*'), which
2221 gives the value of the current PC in expressions.
2222 Note: Assignment to the pseudo variable is not allowed.
2224 <tag><tt>labels_without_colons</tt></tag>
2226 Allow labels without a trailing colon. These labels are only accepted,
2227 if they start at the beginning of a line (no leading white space).
2229 <tag><tt>leading_dot_in_identifiers</tt></tag>
2231 Accept the dot (`.') as the first character of an identifier. This may be
2232 used for example to create macro names that start with a dot emulating
2233 control directives of other assemblers. Note however, that none of the
2234 reserved keywords built into the assembler, that starts with a dot, may be
2235 overridden. When using this feature, you may also get into trouble if
2236 later versions of the assembler define new keywords starting with a dot.
2238 <tag><tt>loose_char_term</tt></tag>
2240 Accept single quotes as well as double quotes as terminators for char
2243 <tag><tt>loose_string_term</tt></tag>
2245 Accept single quotes as well as double quotes as terminators for string
2248 <tag><tt>missing_char_term</tt></tag>
2250 Accept single quoted character constants where the terminating quote is
2255 <bf/Note:/ This does not work in conjunction with <tt/.FEATURE
2256 loose_string_term/, since in this case the input would be ambiguous.
2258 <tag><tt>pc_assignment</tt></tag>
2260 Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
2261 is enabled). Such an assignment is handled identical to the <tt><ref
2262 id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
2263 removing the lines with the assignments may also be an option when porting
2264 code written for older assemblers).
2266 <tag><tt>ubiquitous_idents</tt></tag>
2268 Allow the use of instructions names as names for macros and symbols. This
2269 makes it possible to "overload" instructions by defining a macro with the
2270 same name. This does also make it possible to introduce hard to find errors
2271 in your code, so be careful!
2275 It is also possible to specify features on the command line using the
2276 <tt><ref id="option--feature" name="--feature"></tt> command line option.
2277 This is useful when translating sources written for older assemblers, when
2278 you don't want to change the source code.
2280 As an example, to translate sources written for Andre Fachats xa65
2281 assembler, the features
2284 labels_without_colons, pc_assignment, loose_char_term
2287 may be helpful. They do not make ca65 completely compatible, so you may not
2288 be able to translate the sources without changes, even when enabling these
2289 features. However, I have found several sources that translate without
2290 problems when enabling these features on the command line.
2293 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
2295 Insert an option string into the object file. There are two forms of
2296 this command, one specifies the option by a keyword, the second
2297 specifies it as a number. Since usage of the second one needs knowledge
2298 of the internal encoding, its use is not recommended and I will only
2299 describe the first form here.
2301 The command is followed by one of the keywords
2309 a comma and a string. The option is written into the object file
2310 together with the string value. This is currently unidirectional and
2311 there is no way to actually use these options once they are in the
2317 .fileopt comment, "Code stolen from my brother"
2318 .fileopt compiler, "BASIC 2.0"
2319 .fopt author, "J. R. User"
2323 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
2325 Import an absolute symbol from another module. The command is followed by a
2326 comma separated list of symbols to import. The command is similar to <tt>
2327 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
2328 written to the generated object file, even if the symbol is never referenced
2329 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
2330 references for unused symbols).
2335 .forceimport needthisone, needthistoo
2338 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2341 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
2343 Declare symbols as global. Must be followed by a comma separated list of
2344 symbols to declare. Symbols from the list, that are defined somewhere in the
2345 source, are exported, all others are imported. Additional <tt><ref
2346 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
2347 name=".EXPORT"></tt> commands for the same symbol are allowed.
2356 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
2358 Declare symbols as global. Must be followed by a comma separated list of
2359 symbols to declare. Symbols from the list, that are defined somewhere in the
2360 source, are exported, all others are imported. Additional <tt><ref
2361 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
2362 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
2363 in the list are explicitly marked as zero page symbols.
2372 <sect1><tt>.I16</tt><label id=".I16"><p>
2374 Valid only in 65816 mode. Switch the index registers to 16 bit.
2376 Note: This command will not emit any code, it will tell the assembler to
2377 create 16 bit operands for immediate operands.
2379 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
2380 name=".SMART"></tt> commands.
2383 <sect1><tt>.I8</tt><label id=".I8"><p>
2385 Valid only in 65816 mode. Switch the index registers to 8 bit.
2387 Note: This command will not emit any code, it will tell the assembler to
2388 create 8 bit operands for immediate operands.
2390 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
2391 name=".SMART"></tt> commands.
2394 <sect1><tt>.IF</tt><label id=".IF"><p>
2396 Conditional assembly: Evaluate an expression and switch assembler output
2397 on or off depending on the expression. The expression must be a constant
2398 expression, that is, all operands must be defined.
2400 A expression value of zero evaluates to FALSE, any other value evaluates
2404 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
2406 Conditional assembly: Check if there are any remaining tokens in this line,
2407 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
2408 condition is not true, further lines are not assembled until an <tt><ref
2409 id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2410 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2412 This command is often used to check if a macro parameter was given. Since an
2413 empty macro parameter will evaluate to nothing, the condition will evaluate
2414 to FALSE if an empty parameter was given.
2428 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2431 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
2433 Conditional assembly: Evaluate an expression and switch assembler output
2434 on or off depending on the constness of the expression.
2436 A const expression evaluates to to TRUE, a non const expression (one
2437 containing an imported or currently undefined symbol) evaluates to
2440 See also: <tt><ref id=".CONST" name=".CONST"></tt>
2443 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
2445 Conditional assembly: Check if a symbol is defined. Must be followed by
2446 a symbol name. The condition is true if the the given symbol is already
2447 defined, and false otherwise.
2449 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2452 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
2454 Conditional assembly: Check if there are any remaining tokens in this line,
2455 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
2456 condition is not true, further lines are not assembled until an <tt><ref
2457 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2458 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2460 This command is often used to check if a macro parameter was given.
2461 Since an empty macro parameter will evaluate to nothing, the condition
2462 will evaluate to FALSE if an empty parameter was given.
2475 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2478 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
2480 Conditional assembly: Check if a symbol is defined. Must be followed by
2481 a symbol name. The condition is true if the the given symbol is not
2482 defined, and false otherwise.
2484 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2487 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
2489 Conditional assembly: Check if a symbol is referenced. Must be followed
2490 by a symbol name. The condition is true if if the the given symbol was
2491 not referenced before, and false otherwise.
2493 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2496 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
2498 Conditional assembly: Check if the assembler is currently in 6502 mode
2499 (see <tt><ref id=".P02" name=".P02"></tt> command).
2502 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
2504 Conditional assembly: Check if the assembler is currently in 65816 mode
2505 (see <tt><ref id=".P816" name=".P816"></tt> command).
2508 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
2510 Conditional assembly: Check if the assembler is currently in 65C02 mode
2511 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
2514 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
2516 Conditional assembly: Check if the assembler is currently in 65SC02 mode
2517 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
2520 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
2522 Conditional assembly: Check if a symbol is referenced. Must be followed
2523 by a symbol name. The condition is true if if the the given symbol was
2524 referenced before, and false otherwise.
2526 This command may be used to build subroutine libraries in include files
2527 (you may use separate object modules for this purpose too).
2532 .ifref ToHex ; If someone used this subroutine
2533 ToHex: tay ; Define subroutine
2539 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2542 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
2544 Import a symbol from another module. The command is followed by a comma
2545 separated list of symbols to import, with each one optionally followed by
2546 an address specification.
2552 .import bar: zeropage
2555 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
2558 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
2560 Import a symbol from another module. The command is followed by a comma
2561 separated list of symbols to import. The symbols are explicitly imported
2562 as zero page symbols (that is, symbols with values in byte range).
2570 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2573 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
2575 Include a file as binary data. The command expects a string argument
2576 that is the name of a file to include literally in the current segment.
2577 In addition to that, a start offset and a size value may be specified,
2578 separated by commas. If no size is specified, all of the file from the
2579 start offset to end-of-file is used. If no start position is specified
2580 either, zero is assumed (which means that the whole file is inserted).
2585 ; Include whole file
2586 .incbin "sprites.dat"
2588 ; Include file starting at offset 256
2589 .incbin "music.dat", $100
2591 ; Read 100 bytes starting at offset 200
2592 .incbin "graphics.dat", 200, 100
2596 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
2598 Include another file. Include files may be nested up to a depth of 16.
2607 <sect1><tt>.INTERRUPTOR</tt><label id=".INTERRUPTOR"><p>
2609 Export a symbol and mark it as an interruptor. This may be used together
2610 with the linker to build a table of interruptor subroutines that are called
2613 Note: The linker has a feature to build a table of marked routines, but it
2614 is your code that must call these routines, so just declaring a symbol as
2615 interruptor does nothing by itself.
2617 An interruptor is always exported as an absolute (16 bit) symbol. You don't
2618 need to use an additional <tt/.export/ statement, this is implied by
2619 <tt/.interruptor/. It may have an optional priority that is separated by a
2620 comma. Higher numeric values mean a higher priority. If no priority is
2621 given, the default priority of 7 is used. Be careful when assigning
2622 priorities to your own module constructors so they won't interfere with the
2623 ones in the cc65 library.
2628 .interruptor IrqHandler
2629 .interruptor Handler, 16
2632 See the <tt><ref id=".CONDES" name=".CONDES"></tt> command and the separate
2633 section <ref id="condes" name="Module constructors/destructors"> explaining
2634 the feature in more detail.
2637 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
2639 Switch on or off line continuations using the backslash character
2640 before a newline. The option is off by default.
2641 Note: Line continuations do not work in a comment. A backslash at the
2642 end of a comment is treated as part of the comment and does not trigger
2644 The command must be followed by a '+' or '-' character to switch the
2645 option on or off respectively.
2650 .linecont + ; Allow line continuations
2653 #$20 ; This is legal now
2657 <sect1><tt>.LIST</tt><label id=".LIST"><p>
2659 Enable output to the listing. The command must be followed by a boolean
2660 switch ("on", "off", "+" or "-") and will enable or disable listing
2662 The option has no effect if the listing is not enabled by the command line
2663 switch -l. If -l is used, an internal counter is set to 1. Lines are output
2664 to the listing file, if the counter is greater than zero, and suppressed if
2665 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
2671 .list on ; Enable listing output
2675 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
2677 Set, how many bytes are shown in the listing for one source line. The
2678 default is 12, so the listing will show only the first 12 bytes for any
2679 source line that generates more than 12 bytes of code or data.
2680 The directive needs an argument, which is either "unlimited", or an
2681 integer constant in the range 4..255.
2686 .listbytes unlimited ; List all bytes
2687 .listbytes 12 ; List the first 12 bytes
2688 .incbin "data.bin" ; Include large binary file
2692 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
2694 This command may only be used inside a macro definition. It declares a
2695 list of identifiers as local to the macro expansion.
2697 A problem when using macros are labels: Since they don't change their name,
2698 you get a "duplicate symbol" error if the macro is expanded the second time.
2699 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
2700 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
2703 Some other assemblers start a new lexical block inside a macro expansion.
2704 This has some drawbacks however, since that will not allow <em/any/ symbol
2705 to be visible outside a macro, a feature that is sometimes useful. The
2706 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
2707 to address the problem.
2709 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
2713 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
2715 Defines the character that start "cheap" local labels. You may use one
2716 of '@' and '?' as start character. The default is '@'.
2718 Cheap local labels are labels that are visible only between two non
2719 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
2720 using explicit lexical nesting.
2727 Clear: lda #$00 ; Global label
2728 ?Loop: sta Mem,y ; Local label
2732 Sub: ... ; New global label
2733 bne ?Loop ; ERROR: Unknown identifier!
2737 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
2739 Insert a predefined macro package. The command is followed by an
2740 identifier specifying the macro package to insert. Available macro
2744 generic Defines generic macros like add and sub.
2745 longbranch Defines conditional long jump macros.
2746 cbm Defines the scrcode macro
2747 cpu Defines constants for the .CPU variable
2750 Including a macro package twice, or including a macro package that
2751 redefines already existing macros will lead to an error.
2756 .macpack longbranch ; Include macro package
2758 cmp #$20 ; Set condition codes
2759 jne Label ; Jump long on condition
2762 Macro packages are explained in more detail in section <ref
2763 id="macropackages" name="Macro packages">.
2766 <sect1><tt>.MAC, .MACRO</tt><label id=".MAC"><p>
2768 Start a classic macro definition. The command is followed by an identifier
2769 (the macro name) and optionally by a comma separated list of identifiers
2770 that are macro parameters.
2772 See section <ref id="macros" name="Macros">.
2775 <sect1><tt>.ORG</tt><label id=".ORG"><p>
2777 Start a section of absolute code. The command is followed by a constant
2778 expression that gives the new PC counter location for which the code is
2779 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
2782 Please note that you <em/do not need/ this command in most cases. Placing
2783 code at a specific address is the job of the linker, not the assembler, so
2784 there is usually no reason to assemble code to a specific address.
2786 You may not switch segments while inside a section of absolute code.
2791 .org $7FF ; Emit code starting at $7FF
2795 <sect1><tt>.OUT</tt><label id=".OUT"><p>
2797 Output a string to the console without producing an error. This command
2798 is similar to <tt/.ERROR/, however, it does not force an assembler error
2799 that prevents the creation of an object file.
2804 .out "This code was written by the codebuster(tm)"
2807 See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
2808 id=".ERROR" name=".ERROR"></tt> directives.
2811 <sect1><tt>.P02</tt><label id=".P02"><p>
2813 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
2814 instructions. This is the default if not overridden by the
2815 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
2817 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
2818 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
2821 <sect1><tt>.P816</tt><label id=".P816"><p>
2823 Enable the 65816 instruction set. This is a superset of the 65SC02 and
2824 6502 instruction sets.
2826 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
2827 name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
2830 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
2832 Set the page length for the listing. Must be followed by an integer
2833 constant. The value may be "unlimited", or in the range 32 to 127. The
2834 statement has no effect if no listing is generated. The default value is -1
2835 (unlimited) but may be overridden by the <tt/--pagelength/ command line
2836 option. Beware: Since ca65 is a one pass assembler, the listing is generated
2837 after assembly is complete, you cannot use multiple line lengths with one
2838 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
2843 .pagelength 66 ; Use 66 lines per listing page
2845 .pagelength unlimited ; Unlimited page length
2849 <sect1><tt>.PC02</tt><label id=".PC02"><p>
2851 Enable the 65C02 instructions set. This instruction set includes all
2852 6502 and 65SC02 instructions.
2854 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
2855 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
2858 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
2860 Pop the last pushed segment from the stack, and set it.
2862 This command will switch back to the segment that was last pushed onto the
2863 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
2864 command, and remove this entry from the stack.
2866 The assembler will print an error message if the segment stack is empty
2867 when this command is issued.
2869 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
2872 <sect1><tt>.PROC</tt><label id=".PROC"><p>
2874 Start a nested lexical level with the given name and adds a symbol with this
2875 name to the enclosing scope. All new symbols from now on are in the local
2876 lexical level and are accessible from outside only via <ref id="scopesyntax"
2877 name="explicit scope specification">. Symbols defined outside this local
2878 level may be accessed as long as their names are not used for new symbols
2879 inside the level. Symbols names in other lexical levels do not clash, so you
2880 may use the same names for identifiers. The lexical level ends when the
2881 <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
2882 may be nested up to a depth of 16 (this is an artificial limit to protect
2883 against errors in the source).
2885 Note: Macro names are always in the global level and in a separate name
2886 space. There is no special reason for this, it's just that I've never
2887 had any need for local macro definitions.
2892 .proc Clear ; Define Clear subroutine, start new level
2894 L1: sta Mem,y ; L1 is local and does not cause a
2895 ; duplicate symbol error if used in other
2898 bne L1 ; Reference local symbol
2900 .endproc ; Leave lexical level
2903 See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
2907 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
2909 Enable the 65SC02 instructions set. This instruction set includes all
2912 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
2913 name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
2916 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
2918 Push the currently active segment onto a stack. The entries on the stack
2919 include the name of the segment and the segment type. The stack has a size
2922 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
2923 to switch to another segment and to restore the old segment later, without
2924 even knowing the name and type of the current segment.
2926 The assembler will print an error message if the segment stack is already
2927 full, when this command is issued.
2929 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
2932 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
2934 Switch back to relocatable mode. See the <tt><ref id=".ORG"
2935 name=".ORG"></tt> command.
2938 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
2940 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
2941 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
2942 a constant expression that tells how many times the commands in the body
2943 should get repeated. Optionally, a comma and an identifier may be specified.
2944 If this identifier is found in the body of the repeat statement, it is
2945 replaced by the current repeat count (starting with zero for the first time
2946 the body is repeated).
2948 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
2949 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
2950 level will be used, not the one from the outer level.
2954 The following macro will emit a string that is "encrypted" in that all
2955 characters of the string are XORed by the value $55.
2959 .repeat .strlen(Arg), I
2960 .byte .strat(Arg, I) ^ $55
2965 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
2968 <sect1><tt>.RES</tt><label id=".RES"><p>
2970 Reserve storage. The command is followed by one or two constant
2971 expressions. The first one is mandatory and defines, how many bytes of
2972 storage should be defined. The second, optional expression must by a
2973 constant byte value that will be used as value of the data. If there
2974 is no fill value given, the linker will use the value defined in the
2975 linker configuration file (default: zero).
2980 ; Reserve 12 bytes of memory with value $AA
2985 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
2987 Switch to the RODATA segment. The name of the RODATA segment is always
2988 "RODATA", so this is a shortcut for
2994 The RODATA segment is a segment that is used by the compiler for
2995 readonly data like string constants.
2997 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
3000 <sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
3002 Start a nested lexical level with the given name. All new symbols from now
3003 on are in the local lexical level and are accessible from outside only via
3004 <ref id="scopesyntax" name="explicit scope specification">. Symbols defined
3005 outside this local level may be accessed as long as their names are not used
3006 for new symbols inside the level. Symbols names in other lexical levels do
3007 not clash, so you may use the same names for identifiers. The lexical level
3008 ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
3009 read. Lexical levels may be nested up to a depth of 16 (this is an
3010 artificial limit to protect against errors in the source).
3012 Note: Macro names are always in the global level and in a separate name
3013 space. There is no special reason for this, it's just that I've never
3014 had any need for local macro definitions.
3019 .scope Error ; Start new scope named Error
3021 File = 1 ; File error
3022 Parse = 2 ; Parse error
3023 .endproc ; Close lexical level
3026 lda #Error::File ; Use symbol from scope Error
3029 See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
3033 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
3035 Switch to another segment. Code and data is always emitted into a
3036 segment, that is, a named section of data. The default segment is
3037 "CODE". There may be up to 254 different segments per object file
3038 (and up to 65534 per executable). There are shortcut commands for
3039 the most common segments ("CODE", "DATA" and "BSS").
3041 The command is followed by a string containing the segment name (there are
3042 some constraints for the name - as a rule of thumb use only those segment
3043 names that would also be valid identifiers). There may also be an optional
3044 address size separated by a colon. See the section covering <tt/<ref
3045 id="address-sizes" name="address sizes">/ for more information.
3047 The default address size for a segment depends on the memory model specified
3048 on the command line. The default is "absolute", which means that you don't
3049 have to use an address size modifier in most cases.
3051 "absolute" means that the is a segment with 16 bit (absolute) addressing.
3052 That is, the segment will reside somewhere in core memory outside the zero
3053 page. "zeropage" (8 bit) means that the segment will be placed in the zero
3054 page and direct (short) addressing is possible for data in this segment.
3056 Beware: Only labels in a segment with the zeropage attribute are marked
3057 as reachable by short addressing. The `*' (PC counter) operator will
3058 work as in other segments and will create absolute variable values.
3060 Please note that a segment cannot have two different address sizes. A
3061 segment specified as zeropage cannot be declared as being absolute later.
3066 .segment "ROM2" ; Switch to ROM2 segment
3067 .segment "ZP2": zeropage ; New direct segment
3068 .segment "ZP2" ; Ok, will use last attribute
3069 .segment "ZP2": absolute ; Error, redecl mismatch
3072 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
3073 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt> and <tt><ref
3074 id=".RODATA" name=".RODATA"></tt>
3077 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
3079 Switch the CPU instruction set. The command is followed by a string that
3080 specifies the CPU. Possible values are those that can also be supplied to
3081 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
3082 namely: 6502, 6502X, 65SC02, 65C02, 65816 and sunplus. Please note that
3083 support for the sunplus CPU is not available in the freeware version,
3084 because the instruction set of the sunplus CPU is "proprietary and
3087 See: <tt><ref id=".CPU" name=".CPU"></tt>,
3088 <tt><ref id=".IFP02" name=".IFP02"></tt>,
3089 <tt><ref id=".IFP816" name=".IFP816"></tt>,
3090 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
3091 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
3092 <tt><ref id=".P02" name=".P02"></tt>,
3093 <tt><ref id=".P816" name=".P816"></tt>,
3094 <tt><ref id=".PC02" name=".PC02"></tt>,
3095 <tt><ref id=".PSC02" name=".PSC02"></tt>
3098 <sect1><tt>.SMART</tt><label id=".SMART"><p>
3100 Switch on or off smart mode. The command must be followed by a '+' or '-'
3101 character to switch the option on or off respectively. The default is off
3102 (that is, the assembler doesn't try to be smart), but this default may be
3103 changed by the -s switch on the command line.
3105 In smart mode the assembler will do the following:
3108 <item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
3109 and update the operand sizes accordingly. If the operand of such an
3110 instruction cannot be evaluated by the assembler (for example, because
3111 the operand is an imported symbol), a warning is issued. Beware: Since
3112 the assembler cannot trace the execution flow this may lead to false
3113 results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
3114 instructions to tell the assembler about the current settings.
3115 <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
3116 used within a procedure declared as <tt/far/, or if the procedure has
3117 no explicit address specification, but it is <tt/far/ because of the
3125 .smart - ; Stop being smart
3128 See: <tt><ref id=".A16" name=".A16"></tt>,
3129 <tt><ref id=".A8" name=".A8"></tt>,
3130 <tt><ref id=".I16" name=".I16"></tt>,
3131 <tt><ref id=".I8" name=".I8"></tt>
3134 <sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
3136 Starts a struct definition. Structs are covered in a separate section named
3137 <ref id="structs" name=""Structs and unions"">.
3139 See: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>
3142 <sect1><tt>.SUNPLUS</tt><label id=".SUNPLUS"><p>
3144 Enable the SunPlus instructions set. This command will not work in the
3145 freeware version of the assembler, because the instruction set is
3146 "proprietary and confidential".
3148 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3149 name=".PSC02"></tt>, <tt><ref id=".PC02" name=".PC02"></tt>, and
3150 <tt><ref id=".P816" name=".P816"></tt>
3153 <sect1><tt>.TAG</tt><label id=".TAG"><p>
3155 Allocate space for a struct or union.
3166 .tag Point ; Allocate 4 bytes
3170 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
3172 Force an assembly warning. The assembler will output a warning message
3173 preceded by "User warning". This warning will always be output, even if
3174 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
3175 command line option.
3177 This command may be used to output possible problems when assembling
3186 .warning "Forward jump in jne, cannot optimize!"
3196 See also the <tt><ref id=".ERROR" name=".ERROR"></tt> and <tt><ref id=".OUT"
3197 name=".OUT"></tt> directives.
3200 <sect1><tt>.WORD</tt><label id=".WORD"><p>
3202 Define word sized data. Must be followed by a sequence of (word ranged,
3203 but not necessarily constant) expressions.
3208 .word $0D00, $AF13, _Clear
3212 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
3214 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
3215 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
3219 .segment "ZEROPAGE", zeropage
3222 Because of the "zeropage" attribute, labels declared in this segment are
3223 addressed using direct addressing mode if possible. You <em/must/ instruct
3224 the linker to place this segment somewhere in the address range 0..$FF
3225 otherwise you will get errors.
3227 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
3231 <sect>Macros<label id="macros"><p>
3234 <sect1>Introduction<p>
3236 Macros may be thought of as "parametrized super instructions". Macros are
3237 sequences of tokens that have a name. If that name is used in the source
3238 file, the macro is "expanded", that is, it is replaced by the tokens that
3239 were specified when the macro was defined.
3242 <sect1>Macros without parameters<p>
3244 In it's simplest form, a macro does not have parameters. Here's an
3248 .macro asr ; Arithmetic shift right
3249 cmp #$80 ; Put bit 7 into carry
3250 ror ; Rotate right with carry
3254 The macro above consists of two real instructions, that are inserted into
3255 the code, whenever the macro is expanded. Macro expansion is simply done
3256 by using the name, like this:
3265 <sect1>Parametrized macros<p>
3267 When using macro parameters, macros can be even more useful:
3281 When calling the macro, you may give a parameter, and each occurrence of
3282 the name "addr" in the macro definition will be replaced by the given
3301 A macro may have more than one parameter, in this case, the parameters
3302 are separated by commas. You are free to give less parameters than the
3303 macro actually takes in the definition. You may also leave intermediate
3304 parameters empty. Empty parameters are replaced by empty space (that is,
3305 they are removed when the macro is expanded). If you have a look at our
3306 macro definition above, you will see, that replacing the "addr" parameter
3307 by nothing will lead to wrong code in most lines. To help you, writing
3308 macros with a variable parameter list, there are some control commands:
3310 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
3311 returns true, if there are any tokens on the remainder of the line. Since
3312 empty parameters are replaced by nothing, this may be used to test if a given
3313 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
3316 Look at this example:
3319 .macro ldaxy a, x, y
3332 This macro may be called as follows:
3335 ldaxy 1, 2, 3 ; Load all three registers
3337 ldaxy 1, , 3 ; Load only a and y
3339 ldaxy , , 3 ; Load y only
3342 There's another helper command for determining, which macro parameters are
3343 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt> This command is
3344 replaced by the parameter count given, <em/including/ intermediate empty macro
3348 ldaxy 1 ; .PARAMCOUNT = 1
3349 ldaxy 1,,3 ; .PARAMCOUNT = 3
3350 ldaxy 1,2 ; .PARAMCOUNT = 2
3351 ldaxy 1, ; .PARAMCOUNT = 2
3352 ldaxy 1,2,3 ; .PARAMCOUNT = 3
3355 Macro parameters may optionally be enclosed into curly braces. This allows the
3356 inclusion of tokens that would otherwise terminate the parameter (the comma in
3357 case of a macro parameter).
3360 .macro foo arg1, arg2
3364 foo ($00,x) ; Two parameters passed
3365 foo {($00,x)} ; One parameter passed
3368 In the first case, the macro is called with two parameters: '<tt/($00/'
3369 and 'x)'. The comma is not passed to the macro, since it is part of the
3370 calling sequence, not the parameters.
3372 In the second case, '($00,x)' is passed to the macro, this time
3373 including the comma.
3376 <sect1>Detecting parameter types<p>
3378 Sometimes it is nice to write a macro that acts differently depending on the
3379 type of the argument supplied. An example would be a macro that loads a 16 bit
3380 value from either an immediate operand, or from memory. The <tt/<ref
3381 id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
3382 functions will allow you to do exactly this:
3386 .if (.match (.left (1, {arg}), #))
3388 lda #<(.right (.tcount ({arg})-1, {arg}))
3389 ldx #>(.right (.tcount ({arg})-1, {arg}))
3391 ; assume absolute or zero page
3398 Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
3399 check if its argument begins with a hash mark. If so, two immediate loads are
3400 emitted, Otherwise a load from an absolute zero page memory location is
3401 assumed. Please note how the curly braces are used to enclose parameters to
3402 pseudo functions handling token lists. This is necessary, because the token
3403 lists may include commas or parens, which would be treated by the assembler
3406 The macro can be used as
3411 ldax #$1234 ; X=$12, A=$34
3413 ldax foo ; X=$56, A=$78
3417 <sect1>Recursive macros<p>
3419 Macros may be used recursively:
3422 .macro push r1, r2, r3
3431 There's also a special macro to help writing recursive macros: <tt><ref
3432 id=".EXITMACRO" name=".EXITMACRO"></tt> This command will stop macro expansion
3436 .macro push r1, r2, r3, r4, r5, r6, r7
3438 ; First parameter is empty
3444 push r2, r3, r4, r5, r6, r7
3448 When expanding this macro, the expansion will push all given parameters
3449 until an empty one is encountered. The macro may be called like this:
3452 push $20, $21, $32 ; Push 3 ZP locations
3453 push $21 ; Push one ZP location
3457 <sect1>Local symbols inside macros<p>
3459 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
3460 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
3461 Have a look at the inc16 macro above. Here is it again:
3475 If you have a closer look at the code, you will notice, that it could be
3476 written more efficiently, like this:
3487 But imagine what happens, if you use this macro twice? Since the label
3488 "Skip" has the same name both times, you get a "duplicate symbol" error.
3489 Without a way to circumvent this problem, macros are not as useful, as
3490 they could be. One solution is, to start a new lexical block inside the
3504 Now the label is local to the block and not visible outside. However,
3505 sometimes you want a label inside the macro to be visible outside. To make
3506 that possible, there's a new command that's only usable inside a macro
3507 definition: <tt><ref id=".LOCAL" name=".LOCAL"></tt>. <tt/.LOCAL/ declares one
3508 or more symbols as local to the macro expansion. The names of local variables
3509 are replaced by a unique name in each separate macro expansion. So we could
3510 also solve the problem above by using <tt/.LOCAL/:
3514 .local Skip ; Make Skip a local symbol
3521 Skip: ; Not visible outside
3526 <sect1>C style macros<p>
3528 Starting with version 2.5 of the assembler, there is a second macro type
3529 available: C style macros using the <tt/.DEFINE/ directive. These macros are
3530 similar to the classic macro type described above, but behaviour is sometimes
3535 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
3536 span more than a line. You may use line continuation (see <tt><ref
3537 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
3538 more than one line for increased readability, but the macro itself
3539 may not contain an end-of-line token.
3541 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
3542 the name space with classic macros, but they are detected and replaced
3543 at the scanner level. While classic macros may be used in every place,
3544 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
3545 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
3546 they are more versatile in some situations.
3548 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
3549 parameters. While classic macros may have empty parameters, this is
3550 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
3551 For this macro type, the number of actual parameters must match
3552 exactly the number of formal parameters.
3554 To make this possible, formal parameters are enclosed in braces when
3555 defining the macro. If there are no parameters, the empty braces may
3558 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
3559 contain end-of-line tokens, there are things that cannot be done. They
3560 may not contain several processor instructions for example. So, while
3561 some things may be done with both macro types, each type has special
3562 usages. The types complement each other.
3566 Let's look at a few examples to make the advantages and disadvantages
3569 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
3570 following <tt/.DEFINE/:
3575 foo EQU $1234 ; This is accepted now
3578 You may use the directive to define string constants used elsewhere:
3581 ; Define the version number
3582 .define VERSION "12.3a"
3588 Macros with parameters may also be useful:
3591 .define DEBUG(message) .out message
3593 DEBUG "Assembling include file #3"
3596 Note that, while formal parameters have to be placed in braces, this is
3597 not true for the actual parameters. Beware: Since the assembler cannot
3598 detect the end of one parameter, only the first token is used. If you
3599 don't like that, use classic macros instead:
3607 (This is an example where a problem can be solved with both macro types).
3610 <sect1>Characters in macros<p>
3612 When using the <ref id="option-t" name="-t"> option, characters are translated
3613 into the target character set of the specific machine. However, this happens
3614 as late as possible. This means that strings are translated if they are part
3615 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
3616 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
3617 used as part of an expression.
3619 This behaviour is very intuitive outside of macros but may be confusing when
3620 doing more complex macros. If you compare characters against numeric values,
3621 be sure to take the translation into account.
3626 <sect>Macro packages<label id="macropackages"><p>
3628 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
3629 macro packages may be included with just one command. Available macro packages
3633 <sect1><tt>.MACPACK generic</tt><p>
3635 This macro package defines macros that are useful in almost any program.
3636 Currently, two macros are defined:
3651 <sect1><tt>.MACPACK longbranch</tt><p>
3653 This macro package defines long conditional jumps. They are named like the
3654 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
3655 definition for the "<tt/jeq/" macro, the other macros are built using the same
3660 .if .def(Target) .and ((*+2)-(Target) <= 127)
3669 All macros expand to a short branch, if the label is already defined (back
3670 jump) and is reachable with a short jump. Otherwise the macro expands to a
3671 conditional branch with the branch condition inverted, followed by an absolute
3672 jump to the actual branch target.
3674 The package defines the following macros:
3677 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
3682 <sect1><tt>.MACPACK cbm</tt><p>
3684 The cbm macro package will define a macro named <tt/scrcode/. It takes a
3685 string as argument and places this string into memory translated into screen
3689 <sect1><tt>.MACPACK cpu</tt><p>
3691 This macro package does not define any macros but constants used to examine
3692 the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
3693 each supported CPU a constant similar to
3704 is defined. These constants may be used to determine the exact type of the
3705 currently enabled CPU. In addition to that, for each CPU instruction set,
3706 another constant is defined:
3717 The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
3718 be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
3719 currently enabled CPU supports a specific instruction set. For example the
3720 65C02 supports all instructions of the 65SC02 CPU, so it has the
3721 <tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
3725 .if (.cpu .bitand CPU_ISET_65SC02)
3733 it is possible to determine if the
3739 instruction is supported, which is the case for the 65SC02, 65C02 and 65816
3740 CPUs (the latter two are upwards compatible to the 65SC02).
3744 <sect>Predefined constants<label id="predefined-constants"><p>
3746 For better orthogonality, the assembler defines similar symbols as the
3747 compiler, depending on the target system selected:
3750 <item><tt/__ACE__/ - Target system is <tt/ace/
3751 <item><tt/__APPLE2__",/ - Target system is <tt/apple2/
3752 <item><tt/__APPLE2ENH__",/ - Target system is <tt/apple2enh/
3753 <item><tt/__ATARI__/ - Target system is <tt/atari/
3754 <item><tt/__ATMOS__",/ - Target system is <tt/atmos/
3755 <item><tt/__BBC__",/ - Target system is <tt/bbc/
3756 <item><tt/__C128__/ - Target system is <tt/c128/
3757 <item><tt/__C16__/ - Target system is <tt/c16/
3758 <item><tt/__C64__/ - Target system is <tt/c64/
3759 <item><tt/__CBM__/ - Target is a Commodore system
3760 <item><tt/__CBM510__/ - Target system is <tt/cbm510/
3761 <item><tt/__CBM610__/ - Target system is <tt/cbm610/
3762 <item><tt/__GEOS__",/ - Target system is <tt/geos/
3763 <item><tt/__LUNIX__",/ - Target system is <tt/lunix/
3764 <item><tt/__NES__",/ - Target system is <tt/nes/
3765 <item><tt/__PET__/ - Target system is <tt/pet/
3766 <item><tt/__PLUS4__/ - Target system is <tt/plus4/
3767 <item><tt/__SUPERVISION__",/ - Target system is <tt/supervision/
3768 <item><tt/__VIC20__/ - Target system is <tt/vic20/
3772 <sect>Structs and unions<label id="structs"><p>
3776 Structs and unions are special forms of <ref id="scopes" name="scopes">. They
3777 are to some degree comparable to their C counterparts. Both have a list of
3778 members. Each member allocates storage and may optionally have a name, which,
3779 in case of a struct, is the offset from the beginning and, in case of a union,
3783 <sect1>Declaration<p>
3785 Here is an example for a very simple struct with two members and a total size
3795 A union shares the total space between all its members, its size is the same
3796 as that of the largest member.
3798 A struct or union must not necessarily have a name. If it is anonymous, no
3799 local scope is opened, the identifiers used to name the members are placed
3800 into the current scope instead.
3802 A struct may contain unnamed members and definitions of local structs. The
3803 storage allocators may contain a multiplier, as in the example below:
3808 .word 2 ; Allocate two words
3815 <sect1>The <tt/.TAG/ keyword<p>
3817 Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to reserve space
3818 for an already defined struct or unions within another struct:
3832 Space for a struct or union may be allocated using the <ref id=".TAG"
3833 name=".TAG"> directive.
3839 Currently, members are just offsets from the start of the struct or union. To
3840 access a field of a struct, the member offset has to be added to the address
3841 of the struct itself:
3844 lda C+Circle::Radius ; Load circle radius into A
3847 This may change in a future version of the assembler.
3850 <sect1>Limitations<p>
3852 Structs and unions are currently implemented as nested symbol tables (in fact,
3853 they were a by-product of the improved scoping rules). Currently, the
3854 assembler has no idea of types. This means that the <ref id=".TAG"
3855 name=".TAG"> keyword will only allocate space. You won't be able to initialize
3856 variables declared with <ref id=".TAG" name=".TAG">, and adding an embedded
3857 structure to another structure with <ref id=".TAG" name=".TAG"> will not make
3858 this structure accessible by using the '::' operator.
3862 <sect>Module constructors/destructors<label id="condes"><p>
3864 <em>Note:</em> This section applies mostly to C programs, so the explanation
3865 below uses examples from the C libraries. However, the feature may also be
3866 useful for assembler programs.
3871 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
3872 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
3873 name=".INTERRUPTOR"></tt> keywords it it possible to export functions in a
3874 special way. The linker is able to generate tables with all functions of a
3875 specific type. Such a table will <em>only</em> include symbols from object
3876 files that are linked into a specific executable. This may be used to add
3877 initialization and cleanup code for library modules, or a table of interrupt
3880 The C heap functions are an example where module initialization code is used.
3881 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
3882 variables that contain the start and the end of the heap, pointers to the free
3883 list and so on. Since the end of the heap depends on the size and start of the
3884 stack, it must be initialized at runtime. However, initializing these
3885 variables for programs that do not use the heap are a waste of time and
3888 So the central module defines a function that contains initialization code and
3889 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
3890 this module is added to an executable by the linker, the initialization
3891 function will be placed into the table of constructors by the linker. The C
3892 startup code will call all constructors before <tt/main/ and all destructors
3893 after <tt/main/, so without any further work, the heap initialization code is
3894 called once the module is linked in.
3896 While it would be possible to add explicit calls to initialization functions
3897 in the startup code, the new approach has several advantages:
3901 If a module is not included, the initialization code is not linked in and not
3902 called. So you don't pay for things you don't need.
3905 Adding another library that needs initialization does not mean that the
3906 startup code has to be changed. Before we had module constructors and
3907 destructors, the startup code for all systems had to be adjusted to call the
3908 new initialization code.
3911 The feature saves memory: Each additional initialization function needs just
3912 two bytes in the table (a pointer to the function).
3917 <sect1>Calling order<p>
3919 The symbols are sorted in increasing priority order by the linker when using
3920 one of the builtin linker configurations, so the functions with lower
3921 priorities come first and are followed by those with higher priorities. The C
3922 library runtime subroutine that walks over the function tables calls the
3923 functions starting from the top of the table - which means that functions with
3924 a high priority are called first.
3926 So when using the C runtime, functions are called with high priority functions
3927 first, followed by low priority functions.
3932 When using these special symbols, please take care of the following:
3937 The linker will only generate function tables, it will not generate code to
3938 call these functions. If you're using the feature in some other than the
3939 existing C environments, you have to write code to call all functions in a
3940 linker generated table yourself. See the <tt/condes/ and <tt/callirq/ modules
3941 in the C runtime for an example on how to do this.
3944 The linker will only add addresses of functions that are in modules linked to
3945 the executable. This means that you have to be careful where to place the
3946 condes functions. If initialization or an irq handler is needed for a group of
3947 functions, be sure to place the function into a module that is linked in
3948 regardless of which function is called by the user.
3951 The linker will generate the tables only when requested to do so by the
3952 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
3953 be requested separately.
3956 Constructors and destructors may have priorities. These priorities determine
3957 the order of the functions in the table. If your initialization or cleanup code
3958 does depend on other initialization or cleanup code, you have to choose the
3959 priority for the functions accordingly.
3962 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt>, <tt><ref
3963 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> and <tt><ref id=".INTERRUPTOR"
3964 name=".INTERRUPTOR"></tt> statements, there is also a more generic command:
3965 <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to specify an
3966 additional type. Predefined types are 0 (constructor), 1 (destructor) and 2
3967 (interruptor). The linker generates a separate table for each type on request.
3972 <sect>Porting sources from other assemblers<p>
3974 Sometimes it is necessary to port code written for older assemblers to ca65.
3975 In some cases, this can be done without any changes to the source code by
3976 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
3977 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
3980 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
3981 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
3982 done by the linker. Most other assemblers generate absolute code, placement is
3983 done within the assembler and there is no external linker.
3985 In general it is not a good idea to write new code using the emulation
3986 features of the assembler, but there may be situations where even this rule is
3991 You need to use some of the ca65 emulation features to simulate the behaviour
3992 of such simple assemblers.
3995 <item>Prepare your sourcecode like this:
3998 ; if you want TASS style labels without colons
3999 .feature labels_without_colons
4001 ; if you want TASS style character constants
4002 ; ("a" instead of the default 'a')
4003 .feature loose_char_term
4005 .word *+2 ; the cbm load address
4010 notice that the two emulation features are mostly useful for porting
4011 sources originally written in/for TASS, they are not needed for the
4012 actual "simple assembler operation" and are not recommended if you are
4013 writing new code from scratch.
4015 <item>Replace all program counter assignments (which are not possible in ca65
4016 by default, and the respective emulation feature works different from what
4017 you'd expect) by another way to skip to memory locations, for example the
4018 <tt><ref id=".RES" name=".RES"></tt> directive.
4022 .res $2000-* ; reserve memory up to $2000
4025 Please note that other than the original TASS, ca65 can never move the program
4026 counter backwards - think of it as if you are assembling to disk with TASS.
4028 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
4029 rewritten to match ca65 syntax. Most importantly notice that due to the lack
4030 of <tt/.goto/, everything involving loops must be replaced by
4031 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
4033 <item>To assemble code to a different address than it is executed at, use the
4034 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
4035 <tt/.offs/-constructs.
4042 .reloc ; back to normal
4045 <item>Then assemble like this:
4048 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
4051 Note that you need to use the actual start address minus two, since two bytes
4052 are used for the cbm load address.
4057 <sect>Bugs/Feedback<p>
4059 If you have problems using the assembler, if you find any bugs, or if
4060 you're doing something interesting with the assembler, I would be glad to
4061 hear from you. Feel free to contact me by email
4062 (<htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">).
4068 ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
4069 Bassewitz. For usage of the binaries and/or sources the following
4070 conditions do apply:
4072 This software is provided 'as-is', without any expressed or implied
4073 warranty. In no event will the authors be held liable for any damages
4074 arising from the use of this software.
4076 Permission is granted to anyone to use this software for any purpose,
4077 including commercial applications, and to alter it and redistribute it
4078 freely, subject to the following restrictions:
4081 <item> The origin of this software must not be misrepresented; you must not
4082 claim that you wrote the original software. If you use this software
4083 in a product, an acknowledgment in the product documentation would be
4084 appreciated but is not required.
4085 <item> Altered source versions must be plainly marked as such, and must not
4086 be misrepresented as being the original software.
4087 <item> This notice may not be removed or altered from any source