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 -o name Name the output file
101 -t sys Set the target system
102 -v Increase verbosity
105 --auto-import Mark unresolved symbols as import
106 --cpu type Set cpu type
107 --debug-info Add debug info to object file
108 --feature name Set an emulation feature
109 --help Help (this text)
110 --ignore-case Ignore case of symbols
111 --include-dir dir Set an include directory search path
112 --listing Create a listing if assembly was ok
113 --pagelength n Set the page length for the listing
114 --smart Enable smart mode
115 --target sys Set the target system
116 --verbose Increase verbosity
117 --version Print the assembler version
118 ---------------------------------------------------------------------------
122 <sect1>Command line options in detail<p>
124 Here is a description of all the command line options:
128 <label id="option--cpu">
129 <tag><tt>--cpu type</tt></tag>
131 Set the default for the CPU type. The option takes a parameter, which
134 6502, 65SC02, 65C02, 65816 and sunplus
136 The last one (sunplus) is not available in the freeware version, because the
137 instruction set of the sunplus CPU is "proprietary and confidential".
140 <label id="option--feature">
141 <tag><tt>--feature name</tt></tag>
143 Enable an emulation feature. This is identical as using <tt/.FEATURE/
144 in the source with two exceptions: Feature names must be lower case, and
145 each feature must be specified by using an extra <tt/--feature/ option,
146 comma separated lists are not allowed.
148 See the discussion of the <tt><ref id=".FEATURE" name=".FEATURE"></tt>
149 command for a list of emulation features.
152 <label id="option-g">
153 <tag><tt>-g, --debug-info</tt></tag>
155 When this option (or the equivalent control command <tt/.DEBUGINFO/) is
156 used, the assembler will add a section to the object file that contains
157 all symbols (including local ones) together with the symbol values and
158 source file positions. The linker will put these additional symbols into
159 the VICE label file, so even local symbols can be seen in the VICE
163 <tag><tt>-h, --help</tt></tag>
165 Print the short option summary shown above.
168 <tag><tt>-i, --ignore-case</tt></tag>
170 This option makes the assembler case insensitive on identifiers and labels.
171 This option will override the default, but may itself be overriden by the
172 <tt><ref id=".CASE" name=".CASE"></tt> control command.
175 <tag><tt>-l, --listing</tt></tag>
177 Generate an assembler listing. The listing file will always have the
178 name of the main input file with the extension replaced by ".lst". This
179 may change in future versions.
182 <tag><tt>-o name</tt></tag>
184 The default output name is the name of the input file with the extension
185 replaced by ".o". If you don't like that, you may give another name with
186 the -o option. The output file will be placed in the same directory as
187 the source file, or, if -o is given, the full path in this name is used.
190 <tag><tt>--pagelength n</tt></tag>
192 sets the length of a listing page in lines. See the <tt><ref
193 id=".PAGELENGTH" name=".PAGELENGTH"></tt> directive for more information.
196 <tag><tt>-s, --smart-mode</tt></tag>
198 In smart mode (enabled by -s or the <tt><ref id=".SMART" name=".SMART"></tt>
199 pseudo instruction) the assembler will track usage of the <tt/REP/ and
200 <tt/SEP/ instructions in 65816 mode and update the operand sizes
201 accordingly. If the operand of such an instruction cannot be evaluated by
202 the assembler (for example, because the operand is an imported symbol), a
205 Beware: Since the assembler cannot trace the execution flow this may
206 lead to false results in some cases. If in doubt, use the .ixx and .axx
207 instructions to tell the assembler about the current settings. Smart
208 mode is off by default.
211 <label id="option-t">
212 <tag><tt>-t sys, --target sys</tt></tag>
214 Set the target system. This will enable translation of character strings
215 and character constants into the character set of the target platform.
216 The default for the target system is "none", which means that no translation
217 will take place. The assembler supports the same target systems as the
218 compiler, see there for a list.
221 <tag><tt>-v, --verbose</tt></tag>
223 Increase the assembler verbosity. Usually only needed for debugging
224 purposes. You may use this option more than one time for even more
228 <tag><tt>-D</tt></tag>
230 This option allows you to define symbols on the command line. Without a
231 value, the symbol is defined with the value zero. When giving a value,
232 you may use the '$' prefix for hexadecimal symbols. Please note
233 that for some operating systems, '$' has a special meaning, so
234 you may have to quote the expression.
237 <tag><tt>-I dir, --include-dir dir</tt></tag>
239 Name a directory which is searched for include files. The option may be
240 used more than once to specify more than one directory to search. The
241 current directory is always searched first before considering any
242 additional directores.
245 <tag><tt>-U, --auto-import</tt></tag>
247 Mark symbols that are not defined in the sources as imported symbols. This
248 should be used with care since it delays error messages about typos and such
249 until the linker is run. The compiler uses the equivalent of this switch
250 (<tt><ref id=".AUTOIMPORT" name=".AUTOIMPORT"></tt>) to enable auto imported
251 symbols for the runtime library. However, the compiler is supposed to
252 generate code that runs through the assembler without problems, something
253 which is not always true for assembler programmers.
256 <tag><tt>-V, --version</tt></tag>
258 Print the version number of the assembler. If you send any suggestions
259 or bugfixes, please include the version number.
262 <label id="option-W">
263 <tag><tt>-Wn</tt></tag>
265 Set the warning level for the assembler. Using -W2 the assembler will
266 even warn about such things like unused imported symbols. The default
267 warning level is 1, and it would probably be silly to set it to
274 <sect>Input format<p>
276 <sect1>Assembler syntax<p>
278 The assembler accepts the standard 6502/65816 assembler syntax. One line may
279 contain a label (which is identified by a colon), and, in addition to the
280 label, an assembler mnemonic, a macro, or a control command (see section <ref
281 id="control-commands" name="Control Commands"> for supported control
282 commands). Alternatively, the line may contain a symbol definition using the
283 '=' token. Everything after a semicolon is handled as a comment (that is, it
286 Here are some examples for valid input lines:
289 Label: ; A label and a comment
290 lda #$20 ; A 6502 instruction plus comment
291 L1: ldx #$20 ; Same with label
292 L2: .byte "Hello world" ; Label plus control command
293 mymac $20 ; Macro expansion
294 MySym = 3*L1 ; Symbol definition
295 MaSym = Label ; Another symbol
298 The assembler accepts
301 <item>all valid 6502 mnemonics when in 6502 mode (the default or after the
302 <tt><ref id=".P02" name=".P02"></tt> command was given).
303 <item>all valid 65SC02 mnemonics when in 65SC02 mode (after the
304 <tt><ref id=".PSC02" name=".PSC02"></tt> command was given).
305 <item>all valid 65C02 mnemonics when in 65C02 mode (after the
306 <tt><ref id=".PC02" name=".PC02"></tt> command was given).
307 <item>all valid 65618 mnemonics when in 65816 mode (after the
308 <tt><ref id=".P816" name=".P816"></tt> command was given).
309 <item>all valid SunPlus mnemonics when in SunPlus mode (after the
310 <tt><ref id=".SUNPLUS" name=".SUNPLUS"></tt> command was given).
316 In 65816 mode several aliases are accepted in addition to the official
320 BGE is an alias for BCS
321 BLT is an alias for BCC
322 CPA is an alias for CMP
323 DEA is an alias for DEC A
324 INA is an alias for INC A
325 SWA is an alias for XBA
326 TAD is an alias for TCD
327 TAS is an alias for TCS
328 TDA is an alias for TDC
329 TSA is an alias for TSC
332 Evaluation of banked expressions in 65816 mode differs slightly from the
335 Instead of accepting a 24 bit address (something that is difficult for
336 the assembler to determine and would have required one more special
337 .import command), the bank and the absolute address in that bank are
341 jsl 3.$1234 ; Call subroutine at $1234 in bank 3
344 <sect1>Number format<p>
346 For literal values, the assembler accepts the widely used number formats:
347 A preceeding '$' denotes a hex value, a preceeding '%' denotes a
348 binary value, and a bare number is interpeted as a decimal. There are
349 currently no octal values and no floats.
352 <sect1>Conditional assembly<p>
354 Please note that when using the conditional directives (<tt/.IF/ and friends),
355 the input must consist of valid assembler tokens, even in <tt/.IF/ branches
356 that are not assembled. The reason for this behaviour is that the assembler
357 must still be able to detect the ending tokens (like <tt/.ENDIF/), so
358 conversion of the input stream into tokens still takes place. As a consequence
359 conditional assembly directives may <bf/not/ be used to prevent normal text
360 (used as a comment or similar) from being assembled. <p>
366 <sect1>Expression evaluation<p>
368 All expressions are evaluated with (at least) 32 bit precision. An
369 expression may contain constant values and any combination of internal and
370 external symbols. Expressions that cannot be evaluated at assembly time
371 are stored inside the object file for evaluation by the linker.
372 Expressions referencing imported symbols must always be evaluated by the
376 <sect1>Size of an expressions result<p>
378 Sometimes, the assembler must know about the size of the value that is the
379 result of an expression. This is usually the case, if a decision has to be
380 made, to generate a zero page or an absolute memory references. In this
381 case, the assembler has to make some assumptions about the result of an
385 <item> If the result of an expression is constant, the actual value is
386 checked to see if it's a byte sized expression or not.
387 <item> If the expression is explicitly casted to a byte sized expression by
388 one of the '>'/'<' operators, it is a byte expression.
389 <item> If this is not the case, and the expression contains a symbol,
390 explicitly declared as zero page symbol (by one of the .importzp or
391 .exportzp instructions), then the whole expression is assumed to be
393 <item> If the expression contains symbols that are not defined, and these
394 symbols are local symbols, the enclosing scopes are searched for a
395 symbol with the same name. If one exists and this symbol is defined,
396 it's attributes are used to determine the result size.
397 <item> In all other cases the expression is assumed to be word sized.
400 Note: If the assembler is not able to evaluate the expression at assembly
401 time, the linker will evaluate it and check for range errors as soon as
405 <sect1>Boolean expressions<p>
407 In the context of a boolean expression, any non zero value is evaluated as
408 true, any other value to false. The result of a boolean expression is 1 if
409 it's true, and zero if it's false. There are boolean operators with extrem
410 low precedence with version 2.x (where x > 0). The <tt/.AND/ and <tt/.OR/
411 operators are shortcut operators. That is, if the result of the expression is
412 already known, after evaluating the left hand side, the right hand side is
416 <sect1>Available operators<p>
418 Available operators sorted by precedence:
421 Op Description Precedence
422 -------------------------------------------------------------------
423 .CONCAT Builtin function 0
424 .LEFT Builtin function 0
425 .MID Builtin function 0
426 .RIGHT Builtin function 0
427 .STRING Builtin function 0
429 * Builtin pseudo variable (r/o) 1
430 .BLANK Builtin function 1
431 .CONST Builtin function 1
432 .CPU Builtin pseudo variable (r/o) 1
433 .DEFINED Builtin function 1
434 .MATCH Builtin function 1
435 .TCOUNT Builtin function 1
436 .TIME Builtin function 1
437 .VERSION Builtin function 1
438 .XMATCH Builtin function 1
439 .PARAMCOUNT Builtin pseudo variable (r/o) 1
440 .REFERENCED Builtin function 1
441 :: Global namespace override 1
444 ~ Unary bitwise not 1
445 .BITNOT Unary bitwise not 1
446 < Low byte operator 1
447 > High byte operator 1
451 .MOD Modulo operation 2
453 .BITAND Bitwise and 2
455 .BITXOR Bitwise xor 2
456 << Shift left operator 2
457 .SHL Shift left operator 2
458 >> Shift right operator
459 .SHR Shift right operator 2
466 = Compare operation (equal) 4
467 <> Compare operation (not equal) 4
468 < Compare operation (less) 4
469 > Compare operation (greater) 4
470 <= Compare operation (less or equal) 4
471 >= Compare operation (greater or equal) 4
473 && Boolean and 5
485 To force a specific order of evaluation, braces may be used as usual.
487 Some of the pseudo variables mentioned above need some more explanation:
490 * This symbol is replaced by the value of the program
491 counter at start of the current instruction. Note, that
492 '*' yields a rvalue, that means, you cannot assign to it.
493 Use <tt/.ORG/ to set the program counter in sections with
500 <sect>Symbols and labels<p>
502 The assembler allows you to use symbols instead of naked values to make
503 the source more readable. There are a lot of different ways to define and
504 use symbols and labels, giving a lot of flexibility.
507 <sect1>Numeric constants<p>
509 Numeric constants are defined using the equal sign. After doing
515 may use the symbol "two" in every place where a number is expected, and it is
516 evaluated to the value 2 in this context. An example would be
523 <sect1>Standard labels<p>
525 A label is defined by writing the name of the label at the start of the line
526 (before any instruction mnemonic, macro or pseudo directive), followed by a
527 colon. This will declare a symbol with the given name and the value of the
528 current program counter.
531 <sect1>Local labels and symbols<p>
533 Using the <tt><ref id=".PROC" name=".PROC"></tt> directive, it is possible to
534 create regions of code where the names of labels and symbols are local to this
535 region. They are not known outside of this region and cannot be accessed from
536 there. Such regions may be nested like PROCEDUREs in Pascal.
538 See the description of the <tt><ref id=".PROC" name=".PROC"></tt>
539 directive for more information.
542 <sect1>Cheap local labels<p>
544 Cheap local labels are defined like standard labels, but the name of the
545 label must begin with a special symbol (usually '@', but this can be
546 changed by the <tt><ref id=".LOCALCHAR" name=".LOCALCHAR"></tt>
549 Cheap local labels are visible only between two non cheap labels. As soon as a
550 standard symbol is encountered (this may also be a local symbol if inside a
551 region defined with the <tt><ref id=".PROC" name=".PROC"></tt> directive), the
552 cheap local symbol goes out of scope.
554 You may use cheap local labels as an easy way to reuse common label
555 names like "Loop". Here is an example:
558 Clear: lda #$00 ; Global label
560 @Loop: sta Mem,y ; Local label
564 Sub: ... ; New global label
565 bne @Loop ; ERROR: Unknown identifier!
568 <sect1>Unnamed labels<p>
570 If you really want to write messy code, there are also unnamed
571 labels. These labels do not have a name (you guessed that already,
572 didn't you?). A colon is used to mark the absence of the name.
574 Unnamed labels may be accessed by using the colon plus several minus
575 or plus characters as a label designator. Using the '-' characters
576 will create a back reference (use the n'th label backwards), using
577 '+' will create a forward reference (use the n'th label in forward
578 direction). An example will help to understand this:
600 As you can see from the example, unnamed labels will make even short
601 sections of code hard to understand, because you have to count labels
602 to find branch targets (this is the reason why I for my part do
603 prefer the "cheap" local labels). Nevertheless, unnamed labels are
604 convenient in some situations, so it's your decision.
607 <sect1>Using macros to define labels and constants<p>
609 While there are drawbacks with this approach, it may be handy in some
610 situations. Using <tt><ref id=".DEFINE" name=".DEFINE"></tt>, it is
611 possible to define symbols or constants that may be used elsewhere. Since
612 the macro facility works on a very low level, there is no scoping. On the
613 other side, you may also define string constants this way (this is not
614 possible with the other symbol types).
620 .DEFINE version "SOS V2.3"
622 four = two * two ; Ok
625 .PROC ; Start local scope
626 two = 3 ; Will give "2 = 3" - invalid!
631 <sect1>Symbols and <tt>.DEBUGINFO</tt><p>
633 If <tt><ref id=".DEBUGINFO" name=".DEBUGINFO"></tt> is enabled (or <ref
634 id="option-g" name="-g"> is given on the command line), global, local and
635 cheap local labels are written to the object file and will be available in the
636 symbol file via the linker. Unnamed labels are not written to the object file,
637 because they don't have a name which would allow to access them.
641 <sect>Control commands<label id="control-commands">
644 Here's a list of all control commands and a description, what they do:
647 <sect1><tt>.A16</tt><label id=".A16"><p>
649 Valid only in 65816 mode. Switch the accumulator to 16 bit.
651 Note: This command will not emit any code, it will tell the assembler to
652 create 16 bit operands for immediate accumulator adressing mode.
654 See also: <tt><ref id=".SMART" name=".SMART"></tt>
657 <sect1><tt>.A8</tt><label id=".A8"><p>
659 Valid only in 65816 mode. Switch the accumulator to 8 bit.
661 Note: This command will not emit any code, it will tell the assembler to
662 create 8 bit operands for immediate accu adressing mode.
664 See also: <tt><ref id=".SMART" name=".SMART"></tt>
667 <sect1><tt>.ADDR</tt><label id=".ADDR"><p>
669 Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
670 may be used for better readability if the data words are address values. In
671 65816 mode, the address is forced to be 16 bit wide to fit into the current
672 segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
673 must be followed by a sequence of (not necessarily constant) expressions.
678 .addr $0D00, $AF13, _Clear
681 See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
685 <sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
687 Align data to a given boundary. The command expects a constant integer
688 argument that must be a power of two, plus an optional second argument
689 in byte range. If there is a second argument, it is used as fill value,
690 otherwise the value defined in the linker configuration file is used
691 (the default for this value is zero).
693 Since alignment depends on the base address of the module, you must
694 give the same (or a greater) alignment for the segment when linking.
695 The linker will give you a warning, if you don't do that.
704 <sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
706 Define a string with a trailing zero.
711 Msg: .asciiz "Hello world"
714 This will put the string "Hello world" followed by a binary zero into
715 the current segment. There may be more strings separated by commas, but
716 the binary zero is only appended once (after the last one).
719 <sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
721 Add an assertion. The command is followed by an expression, an action
722 specifier and a message that is output in case the assertion fails. The
723 action specifier may be one of <tt/warning/ or <tt/error/. The assertion
724 is passed to the linker and will be evaluated when segment placement has
730 .assert * = $8000, error, "Code not at $8000"
733 The example assertion will check that the current location is at $8000,
734 when the output file is written, and abort with an error if this is not
735 the case. More complex expressions are possible. The action specifier
736 <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
737 an error message. In the latter case, generation if the output file is
741 <sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
743 Is followed by a plus or a minus character. When switched on (using a
744 +), undefined symbols are automatically marked as import instead of
745 giving errors. When switched off (which is the default so this does not
746 make much sense), this does not happen and an error message is
747 displayed. The state of the autoimport flag is evaluated when the
748 complete source was translated, before outputing actual code, so it is
749 <em/not/ possible to switch this feature on or off for separate sections
750 of code. The last setting is used for all symbols.
752 You should probably not use this switch because it delays error
753 messages about undefined symbols until the link stage. The cc65
754 compiler (which is supposed to produce correct assembler code in all
755 circumstances, something which is not true for most assembler
756 programmers) will insert this command to avoid importing each and every
757 routine from the runtime library.
762 .autoimport + ; Switch on auto import
766 <sect1><tt>.BLANK</tt><label id=".BLANK"><p>
768 Builtin function. The function evaluates its argument in braces and
769 yields "false" if the argument is non blank (there is an argument), and
770 "true" if there is no argument. As an example, the <tt/.IFBLANK/ statement
778 <sect1><tt>.BSS</tt><label id=".BSS"><p>
780 Switch to the BSS segment. The name of the BSS segment is always "BSS",
781 so this is a shortcut for
787 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
790 <sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
792 Define byte sized data. Must be followed by a sequence of (byte ranged)
793 expressions or strings.
799 .byt "world", $0D, $00
803 <sect1><tt>.CASE</tt><label id=".CASE"><p>
805 Switch on or off case sensitivity on identifiers. The default is off
806 (that is, identifiers are case sensitive), but may be changed by the
807 -i switch on the command line.
808 The command must be followed by a '+' or '-' character to switch the
809 option on or off respectively.
814 .case - ; Identifiers are not case sensitive
818 <sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
820 Apply a custom mapping for characters. The command is followed by two
821 numbers in the range 1..255. The first one is the index of the source
822 character, the second one is the mapping. The mapping applies to all
823 character and string constants when they generate output, and overrides
824 a mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
830 .charmap $41, $61 ; Map 'A' to 'a'
834 <sect1><tt>.CODE</tt><label id=".CODE"><p>
836 Switch to the CODE segment. The name of the CODE segment is always
837 "CODE", so this is a shortcut for
843 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
846 <sect1><tt>.CONDES</tt><label id=".CONDES"><p>
848 Export a symbol and mark it in a special way. The linker is able to build
849 tables of all such symbols. This may be used to automatically create a list
850 of functions needed to initialize linked library modules.
852 Note: The linker has a feature to build a table of marked routines, but it
853 is your code that must call these routines, so just declaring a symbol with
854 <tt/.CONDES/ does nothing by itself.
856 All symbols are exported as an absolute (16 bit) symbol. You don't need to
857 use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
858 is implied by <tt/.CONDES/.
860 <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
861 <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
862 specifiying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
863 The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> and <tt><ref
864 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands are actually shortcuts
865 for <tt/.CONDES/ with a type of <tt/constructor/ resp. <tt/destructor/.
867 After the type, an optional priority may be specified. Higher numeric values
868 mean higher priority. If no priority is given, the default priority of 7 is
869 used. Be careful when assigning priorities to your own module constructors
870 so they won't interfere with the ones in the cc65 library.
875 .condes ModuleInit, constructor
876 .condes ModInit, 0, 16
879 See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> and <tt><ref
880 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
881 <ref id="condes" name="Module constructors/destructors"> explaining the
882 feature in more detail.
885 <sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
887 Builtin function. The function allows to concatenate a list of string
888 constants separated by commas. The result is a string constant that
889 is the concatentation of all arguments. This function is most useful
890 in macros and when used together with the <tt/.STRING/ builtin function.
891 The function may be used in any case where a string constant is
897 .include .concat ("myheader", ".", "inc")
900 This is the same as the command
903 .include "myheader.inc"
907 <sect1><tt>.CONST</tt><label id=".CONST"><p>
909 Builtin function. The function evaluates its argument in braces and
910 yields "true" if the argument is a constant expression (that is, an
911 expression that yields a constant value at assembly time) and "false"
912 otherwise. As an example, the .IFCONST statement may be replaced by
919 <sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
921 Export a symbol and mark it as a module constructor. This may be used
922 together with the linker to build a table of constructor subroutines that
923 are called by the startup code.
925 Note: The linker has a feature to build a table of marked routines, but it
926 is your code that must call these routines, so just declaring a symbol as
927 constructor does nothing by itself.
929 A constructor is always exported as an absolute (16 bit) symbol. You don't
930 need to use an additional <tt/.export/ statement, this is implied by
931 <tt/.constructor/. It may have an optional priority that is separated by a
932 comma. Higher numeric values mean a higher priority. If no priority is
933 given, the default priority of 7 is used. Be careful when assigning
934 priorities to your own module constructors so they won't interfere with the
935 ones in the cc65 library.
940 .constructor ModuleInit
941 .constructor ModInit, 16
944 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
945 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
946 <ref id="condes" name="Module constructors/destructors"> explaining the
947 feature in more detail.
950 <sect1><tt>.CPU</tt><label id=".CPU"><p>
952 Reading this pseudo variable will give a constant integer value that
953 tells which instruction set is currently enabled. Possible values are:
963 It may be used to replace the .IFPxx pseudo instructions or to construct
964 even more complex expressions.
969 .if (.cpu = 0) .or (.cpu = 1) .or (.cpu = 2)
981 <sect1><tt>.DATA</tt><label id=".DATA"><p>
983 Switch to the DATA segment. The name of the DATA segment is always
984 "DATA", so this is a shortcut for
990 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
993 <sect1><tt>.DBYT</tt><label id=".DBYT"><p>
995 Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
996 create word sized data in native 65XX format). Must be followed by a
997 sequence of (word ranged) expressions.
1005 This will emit the bytes
1011 into the current segment in that order.
1014 <sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
1016 Switch on or off debug info generation. The default is off (that is,
1017 the object file will not contain debug infos), but may be changed by the
1018 -g switch on the command line.
1019 The command must be followed by a '+' or '-' character to switch the
1020 option on or off respectively.
1025 .debuginfo + ; Generate debug info
1029 <sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
1031 Start a define style macro definition. The command is followed by an
1032 identifier (the macro name) and optionally by a list of formal arguments
1034 See section <ref id="macros" name="Macros">.
1037 <sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
1039 Builtin function. The function expects an identifier as argument in braces.
1040 The argument is evaluated, and the function yields "true" if the identifier
1041 is a symbol that is already defined somewhere in the source file up to the
1042 current position. Otherwise the function yields false. As an example, the
1043 <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
1050 <sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
1052 Export a symbol and mark it as a module destructor. This may be used
1053 together with the linker to build a table of destructor subroutines that
1054 are called by the startup code.
1056 Note: The linker has a feature to build a table of marked routines, but it
1057 is your code that must call these routines, so just declaring a symbol as
1058 constructor does nothing by itself.
1060 A destructor is always exported as an absolute (16 bit) symbol. You don't
1061 need to use an additional <tt/.export/ statement, this is implied by
1062 <tt/.destructor/. It may have an optional priority that is separated by a
1063 comma. Higher numerical values mean a higher priority. If no priority is
1064 given, the default priority of 7 is used. Be careful when assigning
1065 priorities to your own module destructors so they won't interfere with the
1066 ones in the cc65 library.
1071 .destructor ModuleDone
1072 .destructor ModDone, 16
1075 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
1076 id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
1077 section <ref id="condes" name="Module constructors/destructors"> explaining
1078 the feature in more detail.
1081 <sect1><tt>.DWORD</tt><label id=".DWORD"><p>
1083 Define dword sized data (4 bytes) Must be followed by a sequence of
1089 .dword $12344512, $12FA489
1093 <sect1><tt>.ELSE</tt><label id=".ELSE"><p>
1095 Conditional assembly: Reverse the current condition.
1098 <sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
1100 Conditional assembly: Reverse current condition and test a new one.
1103 <sect1><tt>.END</tt><label id=".END"><p>
1105 Forced end of assembly. Assembly stops at this point, even if the command
1106 is read from an include file.
1109 <sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
1111 Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
1112 <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
1115 <sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
1117 End of macro definition (see section <ref id="macros" name="Macros">).
1120 <sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
1122 End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
1125 <sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
1127 End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
1130 <sect1><tt>.ERROR</tt><label id=".ERROR"><p>
1132 Force an assembly error. The assembler will output an error message
1133 preceeded by "User error" and will <em/not/ produce an object file.
1135 This command may be used to check for initial conditions that must be
1136 set before assembling a source file.
1146 .error "Must define foo or bar!"
1150 See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
1151 id=".OUT" name=".OUT"></tt> directives.
1154 <sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
1156 Abort a macro expansion immidiately. This command is often useful in
1157 recursive macros. See separate section <ref id="macros" name="Macros">.
1160 <sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
1162 Make symbols accessible from other modules. Must be followed by a comma
1163 separated list of symbols to export.
1171 See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
1174 <sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
1176 Make symbols accessible from other modules. Must be followed by a comma
1177 separated list of symbols to export. The exported symbols are explicitly
1178 marked as zero page symols.
1186 See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
1189 <sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
1191 Define far (24 bit) address data. The command must be followed by a
1192 sequence of (not necessarily constant) expressions.
1197 .faraddr DrawCircle, DrawRectangle, DrawHexagon
1200 See: <tt><ref id=".ADDR" name=".ADDR"></tt>
1203 <sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
1205 This directive may be used to enable one or more compatibility features
1206 of the assembler. While the use of <tt/.FEATURE/ should be avoided when
1207 possible, it may be useful when porting sources written for other
1208 assemblers. There is no way to switch a feature off, once you have
1209 enabled it, so using
1215 will enable the feature until end of assembly is reached.
1217 The following features are available:
1221 <tag><tt>dollar_is_pc</tt></tag>
1223 The dollar sign may be used as an alias for the star (`*'), which
1224 gives the value of the current PC in expressions.
1225 Note: Assignment to the pseudo variable is not allowed.
1227 <tag><tt>labels_without_colons</tt></tag>
1229 Allow labels without a trailing colon. These labels are only accepted,
1230 if they start at the beginning of a line (no leading white space).
1232 <tag><tt>loose_string_term</tt></tag>
1234 Accept single quotes as well as double quotes as terminators for string
1237 <tag><tt>loose_char_term</tt></tag>
1239 Accept single quotes as well as double quotes as terminators for char
1242 <tag><tt>at_in_identifiers</tt></tag>
1244 Accept the at character (`@') as a valid character in identifiers. The
1245 at character is not allowed to start an identifier, even with this
1248 <tag><tt>dollar_in_identifiers</tt></tag>
1250 Accept the dollar sign (`$') as a valid character in identifiers. The
1251 at character is not allowed to start an identifier, even with this
1254 <tag><tt>leading_dot_in_identifiers</tt></tag>
1256 Accept the dot (`.') as the first character of an identifier. This may be
1257 used for example to create macro names that start with a dot emulating
1258 control directives of other assemblers. Note however, that none of the
1259 reserved keywords built into the assembler, that starts with a dot, may be
1260 overridden. When using this feature, you may also get into trouble if
1261 later versions of the assembler define new keywords starting with a dot.
1263 <tag><tt>pc_assignment</tt></tag>
1265 Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
1266 is enabled). Such an assignment is handled identical to the <tt><ref
1267 id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
1268 removing the lines with the assignments may also be an option when porting
1269 code written for older assemblers).
1273 It is also possible to specify features on the command line using the
1274 <tt><ref id="option--feature" name="--feature"></tt> command line option.
1275 This is useful when translating sources written for older assemblers, when
1276 you don't want to change the source code.
1278 As an example, to translate sources written for Andre Fachats xa65
1279 assembler, the features
1282 labels_without_colons, pc_assignment, loose_char_term
1285 may be helpful. They do not make ca65 completely compatible, so you may not
1286 be able to translate the sources without changes, even when enabling these
1287 features. However, I have found several sources that translate without
1288 problems when enabling these features on the command line.
1291 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
1293 Insert an option string into the object file. There are two forms of
1294 this command, one specifies the option by a keyword, the second
1295 specifies it as a number. Since usage of the second one needs knowledge
1296 of the internal encoding, its use is not recommended and I will only
1297 describe the first form here.
1299 The command is followed by one of the keywords
1307 a comma and a string. The option is written into the object file
1308 together with the string value. This is currently unidirectional and
1309 there is no way to actually use these options once they are in the
1315 .fileopt comment, "Code stolen from my brother"
1316 .fileopt compiler, "BASIC 2.0"
1317 .fopt author, "J. R. User"
1321 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
1323 Import an absolute symbol from another module. The command is followed by a
1324 comma separated list of symbols to import. The command is similar to <tt>
1325 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
1326 written to the generated object file, even if the symbol is never referenced
1327 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
1328 references for unused symbols).
1333 .forceimport needthisone, needthistoo
1336 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
1339 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
1341 Declare symbols as global. Must be followed by a comma separated list of
1342 symbols to declare. Symbols from the list, that are defined somewhere in the
1343 source, are exported, all others are imported. Additional <tt><ref
1344 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
1345 name=".EXPORT"></tt> commands for the same symbol are allowed.
1354 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
1356 Declare symbols as global. Must be followed by a comma separated list of
1357 symbols to declare. Symbols from the list, that are defined somewhere in the
1358 source, are exported, all others are imported. Additional <tt><ref
1359 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
1360 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
1361 in the list are explicitly marked as zero page symols.
1370 <sect1><tt>.I16</tt><label id=".I16"><p>
1372 Valid only in 65816 mode. Switch the index registers to 16 bit.
1374 Note: This command will not emit any code, it will tell the assembler to
1375 create 16 bit operands for immediate operands.
1377 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
1378 name=".SMART"></tt> commands.
1381 <sect1><tt>.I8</tt><label id=".I8"><p>
1383 Valid only in 65816 mode. Switch the index registers to 8 bit.
1385 Note: This command will not emit any code, it will tell the assembler to
1386 create 8 bit operands for immediate operands.
1388 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
1389 name=".SMART"></tt> commands.
1392 <sect1><tt>.IF</tt><label id=".IF"><p>
1394 Conditional assembly: Evalute an expression and switch assembler output
1395 on or off depending on the expression. The expression must be a constant
1396 expression, that is, all operands must be defined.
1398 A expression value of zero evaluates to FALSE, any other value evaluates
1402 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
1404 Conditional assembly: Check if there are any remaining tokens in this line,
1405 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
1406 condition is not true, further lines are not assembled until an <tt><ref
1407 id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
1408 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
1410 This command is often used to check if a macro parameter was given. Since an
1411 empty macro parameter will evaluate to nothing, the condition will evaluate
1412 to FALSE if an empty parameter was given.
1426 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
1429 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
1431 Conditional assembly: Evaluate an expression and switch assembler output
1432 on or off depending on the constness of the expression.
1434 A const expression evaluates to to TRUE, a non const expression (one
1435 containing an imported or currently undefined symbol) evaluates to
1438 See also: <tt><ref id=".CONST" name=".CONST"></tt>
1441 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
1443 Conditional assembly: Check if a symbol is defined. Must be followed by
1444 a symbol name. The condition is true if the the given symbol is already
1445 defined, and false otherwise.
1447 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1450 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
1452 Conditional assembly: Check if there are any remaining tokens in this line,
1453 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
1454 condition is not true, further lines are not assembled until an <tt><ref
1455 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
1456 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
1458 This command is often used to check if a macro parameter was given.
1459 Since an empty macro parameter will evaluate to nothing, the condition
1460 will evaluate to FALSE if an empty parameter was given.
1473 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
1476 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
1478 Conditional assembly: Check if a symbol is defined. Must be followed by
1479 a symbol name. The condition is true if the the given symbol is not
1480 defined, and false otherwise.
1482 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1485 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
1487 Conditional assembly: Check if a symbol is referenced. Must be followed
1488 by a symbol name. The condition is true if if the the given symbol was
1489 not referenced before, and false otherwise.
1491 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
1494 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
1496 Conditional assembly: Check if the assembler is currently in 6502 mode
1497 (see <tt><ref id=".P02" name=".P02"></tt> command).
1500 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
1502 Conditional assembly: Check if the assembler is currently in 65816 mode
1503 (see <tt><ref id=".P816" name=".P816"></tt> command).
1506 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
1508 Conditional assembly: Check if the assembler is currently in 65C02 mode
1509 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
1512 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
1514 Conditional assembly: Check if the assembler is currently in 65SC02 mode
1515 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
1518 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
1520 Conditional assembly: Check if a symbol is referenced. Must be followed
1521 by a symbol name. The condition is true if if the the given symbol was
1522 referenced before, and false otherwise.
1524 This command may be used to build subroutine libraries in include files
1525 (you may use separate object modules for this purpose too).
1530 .ifref ToHex ; If someone used this subroutine
1531 ToHex: tay ; Define subroutine
1537 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
1540 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
1542 Import a symbol from another module. The command is followed by a comma
1543 separated list of symbols to import.
1551 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
1554 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
1556 Import a symbol from another module. The command is followed by a comma
1557 separated list of symbols to import. The symbols are explicitly imported
1558 as zero page symbols (that is, symbols with values in byte range).
1566 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
1569 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
1571 Include a file as binary data. The command expects a string argument
1572 that is the name of a file to include literally in the current segment.
1573 In addition to that, a start offset and a size value may be specified,
1574 separated by commas. If no size is specified, all of the file from the
1575 start offset to end-of-file is used. If no start position is specified
1576 either, zero is assume (which means that the whole file is inserted).
1581 ; Include whole file
1582 .incbin "sprites.dat"
1584 ; Include file starting at offset 256
1585 .incbin "music.dat", $100
1587 ; Read 100 bytes starting at offset 200
1588 .incbin "graphics.dat", 200, 100
1592 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
1594 Include another file. Include files may be nested up to a depth of 16.
1603 <sect1><tt>.LEFT</tt><label id=".LEFT"><p>
1605 Builtin function. Extracts the left part of a given token list.
1610 .LEFT (<int expr>, <token list>)
1613 The first integer expression gives the number of tokens to extract from
1614 the token list. The second argument is the token list itself.
1618 To check in a macro if the given argument has a '#' as first token
1619 (immidiate addressing mode), use something like this:
1624 .if (.match (.left (1, arg), #))
1626 ; ldax called with immidiate operand
1634 See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
1635 name=".RIGHT"></tt> builtin functions.
1638 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
1640 Switch on or off line continuations using the backslash character
1641 before a newline. The option is off by default.
1642 Note: Line continuations do not work in a comment. A backslash at the
1643 end of a comment is treated as part of the comment and does not trigger
1645 The command must be followed by a '+' or '-' character to switch the
1646 option on or off respectively.
1651 .linecont + ; Allow line continuations
1654 #$20 ; This is legal now
1658 <sect1><tt>.LIST</tt><label id=".LIST"><p>
1660 Enable output to the listing. The command must be followed by a boolean
1661 switch ("on", "off", "+" or "-") and will enable or disable listing
1663 The option has no effect if the listing is not enabled by the command line
1664 switch -l. If -l is used, an internal counter is set to 1. Lines are output
1665 to the listing file, if the counter is greater than zero, and suppressed if
1666 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
1672 .list on ; Enable listing output
1676 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
1678 Set, how many bytes are shown in the listing for one source line. The
1679 default is 12, so the listing will show only the first 12 bytes for any
1680 source line that generates more than 12 bytes of code or data.
1681 The directive needs an argument, which is either "unlimited", or an
1682 integer constant in the range 4..255.
1687 .listbytes unlimited ; List all bytes
1688 .listbytes 12 ; List the first 12 bytes
1689 .incbin "data.bin" ; Include large binary file
1693 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
1695 This command may only be used inside a macro definition. It declares a
1696 list of identifiers as local to the macro expansion.
1698 A problem when using macros are labels: Since they don't change their name,
1699 you get a "duplicate symbol" error if the macro is expanded the second time.
1700 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
1701 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
1704 Some other assemblers start a new lexical block inside a macro expansion.
1705 This has some drawbacks however, since that will not allow <em/any/ symbol
1706 to be visible outside a macro, a feature that is sometimes useful. The
1707 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
1708 to address the problem.
1710 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
1714 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
1716 Defines the character that start "cheap" local labels. You may use one
1717 of '@' and '?' as start character. The default is '@'.
1719 Cheap local labels are labels that are visible only between two non
1720 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
1721 using explicit lexical nesting.
1728 Clear: lda #$00 ; Global label
1729 ?Loop: sta Mem,y ; Local label
1733 Sub: ... ; New global label
1734 bne ?Loop ; ERROR: Unknown identifier!
1738 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
1740 Insert a predefined macro package. The command is followed by an
1741 identifier specifying the macro package to insert. Available macro
1745 generic Defines generic macros like add and sub.
1746 longbranch Defines conditional long jump macros.
1749 Including a macro package twice, or including a macro package that
1750 redefines already existing macros will lead to an error.
1755 .macpack longbranch ; Include macro package
1757 cmp #$20 ; Set condition codes
1758 jne Label ; Jump long on condition
1761 Macro packages are explained in more detail in section <ref
1762 id="macropackages" name="Macro packages">.
1765 <sect1><tt>.MAC, .MACRO</tt><label id=".MAC"><p>
1767 Start a classic macro definition. The command is followed by an identifier
1768 (the macro name) and optionally by a comma separated list of identifiers
1769 that are macro parameters.
1771 See section <ref id="macros" name="Macros">.
1774 <sect1><tt>.MATCH</tt><label id=".MATCH"><p>
1776 Builtin function. Matches two token lists against each other. This is
1777 most useful within macros, since macros are not stored as strings, but
1783 .MATCH(<token list #1>, <token list #2>)
1786 Both token list may contain arbitrary tokens with the exception of the
1787 terminator token (comma resp. right parenthesis) and
1794 Often a macro parameter is used for any of the token lists.
1796 Please note that the function does only compare tokens, not token
1797 attributes. So any number is equal to any other number, regardless of the
1798 actual value. The same is true for strings. If you need to compare tokens
1799 <em/and/ token attributes, use the <tt><ref id=".XMATCH"
1800 name=".XMATCH"></tt> function.
1804 Assume the macro <tt/ASR/, that will shift right the accumulator by one,
1805 while honoring the sign bit. The builtin processor instructions will allow
1806 an optional "A" for accu addressing for instructions like <tt/ROL/ and
1807 <tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
1808 to check for this and print and error for invalid calls.
1813 .if (.not .blank(arg)) .and (.not .match (arg, a))
1814 .error "Syntax error"
1817 cmp #$80 ; Bit 7 into carry
1818 lsr a ; Shift carry into bit 7
1823 The macro will only accept no arguments, or one argument that must be the
1824 reserved keyword "A".
1826 See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
1829 <sect1><tt>.MID</tt><label id=".MID"><p>
1831 Builtin function. Takes a starting index, a count and a token list as
1832 arguments. Will return part of the token list.
1837 .MID (<int expr>, <int expr>, <token list>)
1840 The first integer expression gives the starting token in the list (the
1841 first token has index 0). The second integer expression gives the number
1842 of tokens to extract from the token list. The third argument is the
1847 To check in a macro if the given argument has a '<tt/#/' as first token
1848 (immidiate addressing mode), use something like this:
1853 .if (.match (.mid (0, 1, arg), #))
1855 ; ldax called with immidiate operand
1863 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
1864 name=".RIGHT"></tt> builtin functions.
1867 <sect1><tt>.ORG</tt><label id=".ORG"><p>
1869 Start a section of absolute code. The command is followed by a constant
1870 expression that gives the new PC counter location for which the code is
1871 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
1874 Please note that you <em/do not need/ this command in most cases. Placing
1875 code at a specific address is the job of the linker, not the assembler, so
1876 there is usually no reason to assemble code to a specific address.
1878 You may not switch segments while inside a section of absolute code.
1883 .org $7FF ; Emit code starting at $7FF
1887 <sect1><tt>.OUT</tt><label id=".OUT"><p>
1889 Output a string to the console without producing an error. This command
1890 is similiar to <tt/.ERROR/, however, it does not force an assembler error
1891 that prevents the creation of an object file.
1896 .out "This code was written by the codebuster(tm)"
1899 See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
1900 id=".ERROR" name=".ERROR"></tt> directives.
1903 <sect1><tt>.P02</tt><label id=".P02"><p>
1905 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
1906 instructions. This is the default if not overridden by the
1907 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
1909 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
1910 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
1913 <sect1><tt>.P816</tt><label id=".P816"><p>
1915 Enable the 65816 instruction set. This is a superset of the 65SC02 and
1916 6502 instruction sets.
1918 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
1919 name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
1922 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
1924 Set the page length for the listing. Must be followed by an integer
1925 constant. The value may be "unlimited", or in the range 32 to 127. The
1926 statement has no effect if no listing is generated. The default value is -1
1927 (unlimited) but may be overridden by the <tt/--pagelength/ command line
1928 option. Beware: Since ca65 is a one pass assembler, the listing is generated
1929 after assembly is complete, you cannot use multiple line lengths with one
1930 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
1935 .pagelength 66 ; Use 66 lines per listing page
1937 .pagelength unlimited ; Unlimited page length
1941 <sect1><tt>.PARAMCOUNT</tt><label id=".PARAMCOUNT"><p>
1943 This builtin pseudo variable is only available in macros. It is replaced by
1944 the actual number of parameters that were given in the macro invocation.
1949 .macro foo arg1, arg2, arg3
1950 .if .paramcount <> 3
1951 .error "Too few parameters for macro foo"
1957 See section <ref id="macros" name="Macros">.
1960 <sect1><tt>.PC02</tt><label id=".PC02"><p>
1962 Enable the 65C02 instructions set. This instruction set includes all
1963 6502 and 65SC02 instructions.
1965 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
1966 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
1969 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
1971 Pop the last pushed segment from the stack, and set it.
1973 This command will switch back to the segment that was last pushed onto the
1974 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
1975 command, and remove this entry from the stack.
1977 The assembler will print an error message if the segment stack is empty
1978 when this command is issued.
1980 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
1983 <sect1><tt>.PROC</tt><label id=".PROC"><p>
1985 Start a nested lexical level. All new symbols from now on are in the local
1986 lexical level and are not accessible from outside. Symbols defined outside
1987 this local level may be accessed as long as their names are not used for new
1988 symbols inside the level. Symbols names in other lexical levels do not
1989 clash, so you may use the same names for identifiers. The lexical level ends
1990 when the <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read.
1991 Lexical levels may be nested up to a depth of 16.
1993 The command may be followed by an identifier, in this case the
1994 identifier is declared in the outer level as a label having the value of
1995 the program counter at the start of the lexical level.
1997 Note: Macro names are always in the global level and in a separate name
1998 space. There is no special reason for this, it's just that I've never
1999 had any need for local macro definitions.
2004 .proc Clear ; Define Clear subroutine, start new level
2006 L1: sta Mem,y ; L1 is local and does not cause a
2007 ; duplicate symbol error if used in other
2010 bne L1 ; Reference local symbol
2012 .endproc ; Leave lexical level
2015 See: <tt><ref id=".ENDPROC" name=".ENDPROC"></tt>
2018 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
2020 Enable the 65SC02 instructions set. This instruction set includes all
2023 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
2024 name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
2027 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
2029 Push the currently active segment onto a stack. The entries on the stack
2030 include the name of the segment and the segment type. The stack has a size
2033 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
2034 to switch to another segment and to restore the old segment later, without
2035 even knowing the name and type of the current segment.
2037 The assembler will print an error message if the segment stack is already
2038 full, when this command is issued.
2040 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
2043 <sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
2045 Builtin function. The function expects an identifier as argument in braces.
2046 The argument is evaluated, and the function yields "true" if the identifier
2047 is a symbol that has already been referenced somewhere in the source file up
2048 to the current position. Otherwise the function yields false. As an example,
2049 the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
2055 See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2058 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
2060 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
2061 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
2062 a constant expression that tells how many times the commands in the body
2063 should get repeated. Optionally, a comma and an identifier may be specified.
2064 If this identifier is found in the body of the repeat statement, it is
2065 replaced by the current repeat count (starting with zero for the first time
2066 the body is repeated).
2068 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
2069 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
2070 level will be used, not the one from the outer level.
2074 The following macro will emit a string that is "encrypted" in that all
2075 characters of the string are XORed by the value $55.
2079 .repeat .strlen(Arg), I
2080 .byte .strat(Arg, I) .xor $55
2085 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
2088 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
2090 Switch back to relocatable mode. See the <tt><ref id=".ORG"
2091 name=".ORG"></tt> command.
2094 <sect1><tt>.RES</tt><label id=".RES"><p>
2096 Reserve storage. The command is followed by one or two constant
2097 expressions. The first one is mandatory and defines, how many bytes of
2098 storage should be defined. The second, optional expression must by a
2099 constant byte value that will be used as value of the data. If there
2100 is no fill value given, the linker will use the value defined in the
2101 linker configuration file (default: zero).
2106 ; Reserve 12 bytes of memory with value $AA
2111 <sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
2113 Builtin function. Extracts the right part of a given token list.
2118 .RIGHT (<int expr>, <token list>)
2121 The first integer expression gives the number of tokens to extract from
2122 the token list. The second argument is the token list itself.
2124 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
2125 name=".MID"></tt> builtin functions.
2128 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
2130 Switch to the RODATA segment. The name of the RODATA segment is always
2131 "RODATA", so this is a shortcut for
2137 The RODATA segment is a segment that is used by the compiler for
2138 readonly data like string constants.
2140 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2143 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
2145 Switch to another segment. Code and data is always emitted into a
2146 segment, that is, a named section of data. The default segment is
2147 "CODE". There may be up to 254 different segments per object file
2148 (and up to 65534 per executable). There are shortcut commands for
2149 the most common segments ("CODE", "DATA" and "BSS").
2151 The command is followed by a string containing the segment name (there
2152 are some constraints for the name - as a rule of thumb use only those
2153 segment names that would also be valid identifiers). There may also be
2154 an optional attribute separated by a comma. Valid attributes are
2155 "<tt/zeropage/" and "<tt/absolute/".
2157 When specifying a segment for the first time, "absolute" is the
2158 default. For all other uses, the attribute specified the first time
2161 "absolute" means that this is a segment with absolute addressing. That
2162 is, the segment will reside somewhere in core memory outside the zero
2163 page. "zeropage" means the opposite: The segment will be placed in the
2164 zero page and direct (short) addressing is possible for data in this
2167 Beware: Only labels in a segment with the zeropage attribute are marked
2168 as reachable by short addressing. The `*' (PC counter) operator will
2169 work as in other segments and will create absolute variable values.
2174 .segment "ROM2" ; Switch to ROM2 segment
2175 .segment "ZP2", zeropage ; New direct segment
2176 .segment "ZP2" ; Ok, will use last attribute
2177 .segment "ZP2", absolute ; Error, redecl mismatch
2180 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
2181 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt> and <tt><ref
2182 id=".RODATA" name=".RODATA"></tt>
2185 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
2187 Switch the CPU instruction set. The command is followed by a string that
2188 specifies the CPU. Possible values are those that can also be supplied to
2189 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
2190 namely: 6502, 65SC02, 65C02, 65816 and sunplus. Please note that support
2191 for the sunplus CPU is not available in the freeware version, because the
2192 instruction set of the sunplus CPU is "proprietary and confidential".
2194 See: <tt><ref id=".CPU" name=".CPU"></tt>,
2195 <tt><ref id=".IFP02" name=".IFP02"></tt>,
2196 <tt><ref id=".IFP816" name=".IFP816"></tt>,
2197 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
2198 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
2199 <tt><ref id=".P02" name=".P02"></tt>,
2200 <tt><ref id=".P816" name=".P816"></tt>,
2201 <tt><ref id=".PC02" name=".PC02"></tt>,
2202 <tt><ref id=".PSC02" name=".PSC02"></tt>
2205 <sect1><tt>.SMART</tt><label id=".SMART"><p>
2207 Switch on or off smart mode. The command must be followed by a '+' or
2208 '-' character to switch the option on or off respectively. The default
2209 is off (that is, the assembler doesn't try to be smart), but this
2210 default may be changed by the -s switch on the command line.
2212 In smart mode the assembler will track usage of the <tt/REP/ and <tt/SEP/
2213 instructions in 65816 mode and update the operand sizes accordingly. If
2214 the operand of such an instruction cannot be evaluated by the assembler
2215 (for example, because the operand is an imported symbol), a warning is
2216 issued. Beware: Since the assembler cannot trace the execution flow this
2217 may lead to false results in some cases. If in doubt, use the <tt/.Inn/ and
2218 <tt/.Ann/ instructions to tell the assembler about the current settings.
2224 .smart - ; Stop being smart
2228 <sect1><tt>.STRAT</tt><label id=".STRAT"><p>
2230 Builtin function. The function accepts a string and an index as
2231 arguments and returns the value of the character at the given position
2232 as an integer value. The index is zero based.
2238 ; Check if the argument string starts with '#'
2239 .if (.strat (Arg, 0) = '#')
2246 <sect1><tt>.STRING</tt><label id=".STRING"><p>
2248 Builtin function. The function accepts an argument in braces and converts
2249 this argument into a string constant. The argument may be an identifier, or
2250 a constant numeric value.
2252 Since you can use a string in the first place, the use of the function may
2253 not be obvious. However, it is useful in macros, or more complex setups.
2258 ; Emulate other assemblers:
2260 .segment .string(name)
2265 <sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
2267 Builtin function. The function accepts a string argument in braces and
2268 eveluates to the length of the string.
2272 The following macro encodes a string as a pascal style string with
2273 a leading length byte.
2277 .byte .strlen(Arg), Arg
2282 <sect1><tt>.SUNPLUS</tt><label id=".SUNPLUS"><p>
2284 Enable the SunPlus instructions set. This command will not work in the
2285 freeware version of the assembler, because the instruction set is
2286 "proprietary and confidential".
2288 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
2289 name=".PSC02"></tt>, <tt><ref id=".PC02" name=".PC02"></tt>, and
2290 <tt><ref id=".P816" name=".P816"></tt>
2293 <sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
2295 Builtin function. The function accepts a token list in braces. The
2296 function result is the number of tokens given as argument.
2300 The <tt/ldax/ macro accepts the '#' token to denote immidiate addressing (as
2301 with the normal 6502 instructions). To translate it into two separate 8 bit
2302 load instructions, the '#' token has to get stripped from the argument:
2306 .if (.match (.mid (0, 1, arg), #))
2307 ; ldax called with immidiate operand
2308 lda #<(.right (.tcount (arg)-1, arg))
2309 ldx #>(.right (.tcount (arg)-1, arg))
2317 <sect1><tt>.TIME</tt><label id=".TIME"><p>
2319 Reading this pseudo variable will give a constant integer value that
2320 represents the current time in POSIX standard (as seconds since the
2323 It may be used to encode the time of translation somewhere in the created
2329 .dword .time ; Place time here
2333 <sect1><tt>.VERSION</tt><label id=".VERSION"><p>
2335 Reading this pseudo variable will give the assembler version according to
2336 the following formula:
2338 VER_MAJOR*$100 + VER_MINOR*$10 + VER_PATCH
2340 It may be used to encode the assembler version or check the assembler for
2341 special features not available with older versions.
2345 Version 2.11.1 of the assembler will return $2B1 as numerical constant when
2346 reading the pseudo variable <tt/.VERSION/.
2349 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
2351 Force an assembly warning. The assembler will output a warning message
2352 preceeded by "User warning". This warning will always be output, even if
2353 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
2354 command line option.
2356 This command may be used to output possible problems when assembling
2365 .warning "Forward jump in jne, cannot optimize!"
2375 See also the <tt><ref id=".ERROR" name=".ERROR"></tt> and <tt><ref id=".OUT"
2376 name=".OUT"></tt> directives.
2379 <sect1><tt>.WORD</tt><label id=".WORD"><p>
2381 Define word sized data. Must be followed by a sequence of (word ranged,
2382 but not necessarily constant) expressions.
2387 .word $0D00, $AF13, _Clear
2391 <sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
2393 Builtin function. Matches two token lists against each other. This is
2394 most useful within macros, since macros are not stored as strings, but
2400 .XMATCH(<token list #1>, <token list #2>)
2403 Both token list may contain arbitrary tokens with the exception of the
2404 terminator token (comma resp. right parenthesis) and
2411 Often a macro parameter is used for any of the token lists.
2413 The function compares tokens <em/and/ token values. If you need a function
2414 that just compares the type of tokens, have a look at the <tt><ref
2415 id=".MATCH" name=".MATCH"></tt> function.
2417 See: <tt><ref id=".MATCH" name=".MATCH"></tt>
2420 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
2422 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
2423 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
2427 .segment "ZEROPAGE", zeropage
2430 Because of the "zeropage" attribute, labels declared in this segment are
2431 addressed using direct addressing mode if possible. You <em/must/ instruct
2432 the linker to place this segment somewhere in the address range 0..$FF
2433 otherwise you will get errors.
2435 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
2439 <sect>Macros<label id="macros"><p>
2442 <sect1>Introduction<p>
2444 Macros may be thought of as "parametrized super instructions". Macros are
2445 sequences of tokens that have a name. If that name is used in the source
2446 file, the macro is "expanded", that is, it is replaced by the tokens that
2447 were specified when the macro was defined.
2450 <sect1>Macros without parameters<p>
2452 In it's simplest form, a macro does not have parameters. Here's an
2456 .macro asr ; Arithmetic shift right
2457 cmp #$80 ; Put bit 7 into carry
2458 ror ; Rotate right with carry
2462 The macro above consists of two real instructions, that are inserted into
2463 the code, whenever the macro is expanded. Macro expansion is simply done
2464 by using the name, like this:
2473 <sect1>Parametrized macros<p>
2475 When using macro parameters, macros can be even more useful:
2489 When calling the macro, you may give a parameter, and each occurence of
2490 the name "addr" in the macro definition will be replaced by the given
2509 A macro may have more than one parameter, in this case, the parameters
2510 are separated by commas. You are free to give less parameters than the
2511 macro actually takes in the definition. You may also leave intermediate
2512 parameters empty. Empty parameters are replaced by empty space (that is,
2513 they are removed when the macro is exanded). If you have a look at our
2514 macro definition above, you will see, that replacing the "addr" parameter
2515 by nothing will lead to wrong code in most lines. To help you, writing
2516 macros with a variable parameter list, there are some control commands:
2518 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
2519 returns true, if there are any tokens on the remainder of the line. Since
2520 empty parameters are replaced by nothing, this may be used to test if a given
2521 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
2524 Look at this example:
2527 .macro ldaxy a, x, y
2540 This macro may be called as follows:
2543 ldaxy 1, 2, 3 ; Load all three registers
2545 ldaxy 1, , 3 ; Load only a and y
2547 ldaxy , , 3 ; Load y only
2550 There's another helper command for determining, which macro parameters are
2551 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt> This command is
2552 replaced by the parameter count given, <em/including/ intermediate empty macro
2556 ldaxy 1 ; .PARAMCOUNT = 1
2557 ldaxy 1,,3 ; .PARAMCOUNT = 3
2558 ldaxy 1,2 ; .PARAMCOUNT = 2
2559 ldaxy 1, ; .PARAMCOUNT = 2
2560 ldaxy 1,2,3 ; .PARAMCOUNT = 3
2564 <sect1>Recursive macros<p>
2566 Macros may be used recursively:
2569 .macro push r1, r2, r3
2578 There's also a special macro to help writing recursive macros: <tt><ref
2579 id=".EXITMACRO" name=".EXITMACRO"></tt> This command will stop macro expansion
2583 .macro push r1, r2, r3, r4, r5, r6, r7
2585 ; First parameter is empty
2591 push r2, r3, r4, r5, r6, r7
2595 When expanding this macro, the expansion will push all given parameters
2596 until an empty one is encountered. The macro may be called like this:
2599 push $20, $21, $32 ; Push 3 ZP locations
2600 push $21 ; Push one ZP location
2604 <sect1>Local symbols inside macros<p>
2606 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
2607 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
2608 Have a look at the inc16 macro above. Here is it again:
2622 If you have a closer look at the code, you will notice, that it could be
2623 written more efficiently, like this:
2634 But imagine what happens, if you use this macro twice? Since the label
2635 "Skip" has the same name both times, you get a "duplicate symbol" error.
2636 Without a way to circumvent this problem, macros are not as useful, as
2637 they could be. One solution is, to start a new lexical block inside the
2651 Now the label is local to the block and not visible outside. However,
2652 sometimes you want a label inside the macro to be visible outside. To make
2653 that possible, there's a new command that's only usable inside a macro
2654 definition: <tt><ref id=".LOCAL" name=".LOCAL"></tt>. <tt/.LOCAL/ declares one
2655 or more symbols as local to the macro expansion. The names of local variables
2656 are replaced by a unique name in each separate macro expansion. So we could
2657 also solve the problem above by using <tt/.LOCAL/:
2661 .local Skip ; Make Skip a local symbol
2668 Skip: ; Not visible outside
2673 <sect1>C style macros<p>
2675 Starting with version 2.5 of the assembler, there is a second macro type
2676 available: C style macros using the <tt/.DEFINE/ directive. These macros are
2677 similar to the classic macro type described above, but behaviour is sometimes
2682 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
2683 span more than a line. You may use line continuation (see <tt><ref
2684 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
2685 more than one line for increased readability, but the macro itself
2686 may not contain an end-of-line token.
2688 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
2689 the name space with classic macros, but they are detected and replaced
2690 at the scanner level. While classic macros may be used in every place,
2691 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
2692 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
2693 they are more versatile in some situations.
2695 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
2696 parameters. While classic macros may have empty parameters, this is
2697 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
2698 For this macro type, the number of actual parameters must match
2699 exactly the number of formal parameters.
2701 To make this possible, formal parameters are enclosed in braces when
2702 defining the macro. If there are no parameters, the empty braces may
2705 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
2706 contain end-of-line tokens, there are things that cannot be done. They
2707 may not contain several processor instructions for example. So, while
2708 some things may be done with both macro types, each type has special
2709 usages. The types complement each other.
2713 Let's look at a few examples to make the advantages and disadvantages
2716 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
2717 following <tt/.DEFINE/:
2722 foo EQU $1234 ; This is accepted now
2725 You may use the directive to define string constants used elsewhere:
2728 ; Define the version number
2729 .define VERSION "12.3a"
2735 Macros with parameters may also be useful:
2738 .define DEBUG(message) .out message
2740 DEBUG "Assembling include file #3"
2743 Note that, while formal parameters have to be placed in braces, this is
2744 not true for the actual parameters. Beware: Since the assembler cannot
2745 detect the end of one parameter, only the first token is used. If you
2746 don't like that, use classic macros instead:
2754 (This is an example where a problem can be solved with both macro types).
2757 <sect1>Characters in macros<p>
2759 When using the <ref id="option-t" name="-t"> option, characters are translated
2760 into the target character set of the specific machine. However, this happens
2761 as late as possible. This means that strings are translated if they are part
2762 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
2763 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
2764 used as part of an expression.
2766 This behaviour is very intuitive outside of macros but may be confusing when
2767 doing more complex macros. If you compare characters against numeric values,
2768 be sure to take the translation into account.
2773 <sect>Macro packages<label id="macropackages"><p>
2775 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
2776 macro packages may be included with just one command. Available macro packages
2780 <sect1><tt>.MACPACK generic</tt><p>
2782 This macro package defines macros that are useful in almost any program.
2783 Currently, two macros are defined:
2798 <sect1><tt>.MACPACK longbranch</tt><p>
2800 This macro package defines long conditional jumps. They are named like the
2801 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
2802 definition for the "<tt/jeq/" macro, the other macros are built using the same
2807 .if .def(Target) .and ((*+2)-(Target) <= 127)
2816 All macros expand to a short branch, if the label is already defined (back
2817 jump) and is reachable with a short jump. Otherwise the macro expands to a
2818 conditional branch with the branch condition inverted, followed by an absolute
2819 jump to the actual branch target.
2821 The package defines the following macros:
2824 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
2829 <sect>Module constructors/destructors<label id="condes"><p>
2831 <em>Note:</em> This section applies mostly to C programs, so the explanation
2832 below uses examples from the C libraries. However, the feature may also be
2833 useful for assembler programs.
2836 <sect1>Module overview<p>
2838 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> and <tt><ref
2839 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> keywords it it possible to export
2840 functions in a special way. The linker is able to generate tables with all
2841 functions of a specific type. Such a table will <em>only</em> include symbols
2842 from object files that are linked into a specific executable. This may be used
2843 to add initialization and cleanup code for library modules.
2845 The C heap functions are an example where module initialization code is used.
2846 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
2847 variables that contain the start and the end of the heap, pointers to the free
2848 list and so on. Since the end of the heap depends on the size and start of the
2849 stack, it must be initialized at runtime. However, initializing these
2850 variables for programs that do not use the heap are a waste of time and
2853 So the central module defines a function that contains initialization code and
2854 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
2855 this module is added to an executable by the linker, the initialization
2856 function will be placed into the table of constructors by the linker. The C
2857 startup code will call all constructors before <tt/main/ and all destructors
2858 after <tt/main/, so without any further work, the heap initialization code is
2859 called once the module is linked in.
2861 While it would be possible to add explicit calls to initialization functions
2862 in the startup code, the new approach has several advantages:
2866 If a module is not included, the initialization code is not linked in and not
2867 called. So you don't pay for things you don't need.
2870 Adding another library that needs initialization does not mean that the
2871 startup code has to be changed. Before we had module constructors and
2872 destructors, the startup code for all systems had to be adjusted to call the
2873 new initialization code.
2876 The feature saves memory: Each additional initialization function needs just
2877 two bytes in the table (a pointer to the function).
2882 <sect1>Calling order<p>
2884 Both, constructors and destructors are sorted in increasing priority order by
2885 the linker when using one of the builtin linker configurations, so the
2886 functions with lower priorities come first and are followed by those with
2887 higher priorities. The C library runtime subroutine that walks over the
2888 constructor and destructor tables calls the functions starting from the top of
2889 the table - which means that functions with a high priority are called first.
2891 So when using the C runtime, both constructors and destructors are called with
2892 high priority functions first, followed by low priority functions.
2897 When creating and using module constructors and destructors, please take care
2903 The linker will only generate function tables, it will not generate code to
2904 call these functions. If you're using the feature in some other than the
2905 existing C environments, you have to write code to call all functions in a
2906 linker generated table yourself. See the <tt>condes</tt> module in the C
2907 runtime for an example on how to do this.
2910 The linker will only add addresses of functions that are in modules linked to
2911 the executable. This means that you have to be careful where to place the
2912 condes functions. If initialization is needed for a group of functions, be
2913 sure to place the initialization function into a module that is linked in
2914 regardless of which function is called by the user.
2917 The linker will generate the tables only when requested to do so by the
2918 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
2919 be requested separately.
2922 Constructors and destructors may have priorities. These priorities determine
2923 the order of the functions in the table. If your intialization or cleanup code
2924 does depend on other initialization or cleanup code, you have to choose the
2925 priority for the functions accordingly.
2928 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> and <tt><ref
2929 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> statements, there is also a more
2930 generic command: <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to
2931 specify an additional type. Predefined types are 0 (constructor) and 1
2932 (destructor). The linker generates a separate table for each type on request.
2937 <sect>Porting sources from other assemblers<p>
2939 Sometimes it is necessary to port code written for older assemblers to ca65.
2940 In some cases, this can be done without any changes to the source code by
2941 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
2942 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
2945 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
2946 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
2947 done by the linker. Most other assemblers generate absolute code, placement is
2948 done within the assembler and there is no external linker.
2950 In general it is not a good idea to write new code using the emulation
2951 features of the assembler, but there may be situations where even this rule is
2956 You need to use some of the ca65 emulation features to simulate the behaviour
2957 of such simple assemblers.
2960 <item>Prepare your sourcecode like this:
2963 ; if you want TASS style labels without colons
2964 .feature labels_without_colons
2966 ; if you want TASS style character constants
2967 ; ("a" instead of the default 'a')
2968 .feature loose_char_term
2970 .word *+2 ; the cbm load address
2975 notice that the two emulation features are mostly useful for porting
2976 sources originally written in/for TASS, they are not needed for the
2977 actual "simple assembler operation" and are not recommended if you are
2978 writing new code from scratch.
2980 <item>Replace all program counter assignments (which are not possible in ca65
2981 by default, and the respective emulation feature works different from what
2982 you'd expect) by another way to skip to another memory location, for example
2983 the <tt><ref id=".RES" name=".RES"></tt>directive.
2987 .res $2000-* ; reserve memory up to $2000
2990 notice that other than the original TASS, ca65 can never move the
2991 programmcounter backwards - think of it as if you are assembling to disc with
2994 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.gogo/ etc.) must be
2995 rewritten to match ca65 syntax. Most importantly notice that due to the lack
2996 of <tt/.goto/, everything involving loops must be replaced by
2997 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
2999 <item>To assemble code to a different address than it is executed at, use the
3000 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
3001 <tt/.offs/-constructs.
3008 .reloc ; back to normal
3011 <item>Then assemble like this:
3014 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
3017 notice that you need to use the actual start address minus two, since two
3018 bytes are used for the cbm load address.
3023 <sect>Bugs/Feedback<p>
3025 If you have problems using the assembler, if you find any bugs, or if
3026 you're doing something interesting with the assembler, I would be glad to
3027 hear from you. Feel free to contact me by email
3028 (<htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">).
3034 ca65 (and all cc65 binutils) are (C) Copyright 1998-2001 Ullrich von
3035 Bassewitz. For usage of the binaries and/or sources the following
3036 conditions do apply:
3038 This software is provided 'as-is', without any expressed or implied
3039 warranty. In no event will the authors be held liable for any damages
3040 arising from the use of this software.
3042 Permission is granted to anyone to use this software for any purpose,
3043 including commercial applications, and to alter it and redistribute it
3044 freely, subject to the following restrictions:
3047 <item> The origin of this software must not be misrepresented; you must not
3048 claim that you wrote the original software. If you use this software
3049 in a product, an acknowledgment in the product documentation would be
3050 appreciated but is not required.
3051 <item> Altered source versions must be plainly marked as such, and must not
3052 be misrepresented as being the original software.
3053 <item> This notice may not be removed or altered from any source