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<label id="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 or the label assignment
510 operator. After doing
516 may use the symbol "two" in every place where a number is expected, and it is
517 evaluated to the value 2 in this context. The label assignment operator causes
518 the same, but causes the symbol to be marked as a label, which may cause a
519 different handling in the debugger:
525 The right side can of course be an expression:
532 <sect1>Standard labels<p>
534 A label is defined by writing the name of the label at the start of the line
535 (before any instruction mnemonic, macro or pseudo directive), followed by a
536 colon. This will declare a symbol with the given name and the value of the
537 current program counter.
540 <sect1>Local labels and symbols<p>
542 Using the <tt><ref id=".PROC" name=".PROC"></tt> directive, it is possible to
543 create regions of code where the names of labels and symbols are local to this
544 region. They are not known outside of this region and cannot be accessed from
545 there. Such regions may be nested like PROCEDUREs in Pascal.
547 See the description of the <tt><ref id=".PROC" name=".PROC"></tt>
548 directive for more information.
551 <sect1>Cheap local labels<p>
553 Cheap local labels are defined like standard labels, but the name of the
554 label must begin with a special symbol (usually '@', but this can be
555 changed by the <tt><ref id=".LOCALCHAR" name=".LOCALCHAR"></tt>
558 Cheap local labels are visible only between two non cheap labels. As soon as a
559 standard symbol is encountered (this may also be a local symbol if inside a
560 region defined with the <tt><ref id=".PROC" name=".PROC"></tt> directive), the
561 cheap local symbol goes out of scope.
563 You may use cheap local labels as an easy way to reuse common label
564 names like "Loop". Here is an example:
567 Clear: lda #$00 ; Global label
569 @Loop: sta Mem,y ; Local label
573 Sub: ... ; New global label
574 bne @Loop ; ERROR: Unknown identifier!
577 <sect1>Unnamed labels<p>
579 If you really want to write messy code, there are also unnamed
580 labels. These labels do not have a name (you guessed that already,
581 didn't you?). A colon is used to mark the absence of the name.
583 Unnamed labels may be accessed by using the colon plus several minus
584 or plus characters as a label designator. Using the '-' characters
585 will create a back reference (use the n'th label backwards), using
586 '+' will create a forward reference (use the n'th label in forward
587 direction). An example will help to understand this:
609 As you can see from the example, unnamed labels will make even short
610 sections of code hard to understand, because you have to count labels
611 to find branch targets (this is the reason why I for my part do
612 prefer the "cheap" local labels). Nevertheless, unnamed labels are
613 convenient in some situations, so it's your decision.
616 <sect1>Using macros to define labels and constants<p>
618 While there are drawbacks with this approach, it may be handy in some
619 situations. Using <tt><ref id=".DEFINE" name=".DEFINE"></tt>, it is
620 possible to define symbols or constants that may be used elsewhere. Since
621 the macro facility works on a very low level, there is no scoping. On the
622 other side, you may also define string constants this way (this is not
623 possible with the other symbol types).
629 .DEFINE version "SOS V2.3"
631 four = two * two ; Ok
634 .PROC ; Start local scope
635 two = 3 ; Will give "2 = 3" - invalid!
640 <sect1>Symbols and <tt>.DEBUGINFO</tt><p>
642 If <tt><ref id=".DEBUGINFO" name=".DEBUGINFO"></tt> is enabled (or <ref
643 id="option-g" name="-g"> is given on the command line), global, local and
644 cheap local labels are written to the object file and will be available in the
645 symbol file via the linker. Unnamed labels are not written to the object file,
646 because they don't have a name which would allow to access them.
650 <sect>Control commands<label id="control-commands">
653 Here's a list of all control commands and a description, what they do:
656 <sect1><tt>.A16</tt><label id=".A16"><p>
658 Valid only in 65816 mode. Switch the accumulator to 16 bit.
660 Note: This command will not emit any code, it will tell the assembler to
661 create 16 bit operands for immediate accumulator adressing mode.
663 See also: <tt><ref id=".SMART" name=".SMART"></tt>
666 <sect1><tt>.A8</tt><label id=".A8"><p>
668 Valid only in 65816 mode. Switch the accumulator to 8 bit.
670 Note: This command will not emit any code, it will tell the assembler to
671 create 8 bit operands for immediate accu adressing mode.
673 See also: <tt><ref id=".SMART" name=".SMART"></tt>
676 <sect1><tt>.ADDR</tt><label id=".ADDR"><p>
678 Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
679 may be used for better readability if the data words are address values. In
680 65816 mode, the address is forced to be 16 bit wide to fit into the current
681 segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
682 must be followed by a sequence of (not necessarily constant) expressions.
687 .addr $0D00, $AF13, _Clear
690 See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
694 <sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
696 Align data to a given boundary. The command expects a constant integer
697 argument that must be a power of two, plus an optional second argument
698 in byte range. If there is a second argument, it is used as fill value,
699 otherwise the value defined in the linker configuration file is used
700 (the default for this value is zero).
702 Since alignment depends on the base address of the module, you must
703 give the same (or a greater) alignment for the segment when linking.
704 The linker will give you a warning, if you don't do that.
713 <sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
715 Define a string with a trailing zero.
720 Msg: .asciiz "Hello world"
723 This will put the string "Hello world" followed by a binary zero into
724 the current segment. There may be more strings separated by commas, but
725 the binary zero is only appended once (after the last one).
728 <sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
730 Add an assertion. The command is followed by an expression, an action
731 specifier and a message that is output in case the assertion fails. The
732 action specifier may be one of <tt/warning/ or <tt/error/. The assertion
733 is passed to the linker and will be evaluated when segment placement has
739 .assert * = $8000, error, "Code not at $8000"
742 The example assertion will check that the current location is at $8000,
743 when the output file is written, and abort with an error if this is not
744 the case. More complex expressions are possible. The action specifier
745 <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
746 an error message. In the latter case, generation if the output file is
750 <sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
752 Is followed by a plus or a minus character. When switched on (using a
753 +), undefined symbols are automatically marked as import instead of
754 giving errors. When switched off (which is the default so this does not
755 make much sense), this does not happen and an error message is
756 displayed. The state of the autoimport flag is evaluated when the
757 complete source was translated, before outputing actual code, so it is
758 <em/not/ possible to switch this feature on or off for separate sections
759 of code. The last setting is used for all symbols.
761 You should probably not use this switch because it delays error
762 messages about undefined symbols until the link stage. The cc65
763 compiler (which is supposed to produce correct assembler code in all
764 circumstances, something which is not true for most assembler
765 programmers) will insert this command to avoid importing each and every
766 routine from the runtime library.
771 .autoimport + ; Switch on auto import
775 <sect1><tt>.BLANK</tt><label id=".BLANK"><p>
777 Builtin function. The function evaluates its argument in braces and
778 yields "false" if the argument is non blank (there is an argument), and
779 "true" if there is no argument. As an example, the <tt/.IFBLANK/ statement
787 <sect1><tt>.BSS</tt><label id=".BSS"><p>
789 Switch to the BSS segment. The name of the BSS segment is always "BSS",
790 so this is a shortcut for
796 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
799 <sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
801 Define byte sized data. Must be followed by a sequence of (byte ranged)
802 expressions or strings.
808 .byt "world", $0D, $00
812 <sect1><tt>.CASE</tt><label id=".CASE"><p>
814 Switch on or off case sensitivity on identifiers. The default is off
815 (that is, identifiers are case sensitive), but may be changed by the
816 -i switch on the command line.
817 The command must be followed by a '+' or '-' character to switch the
818 option on or off respectively.
823 .case - ; Identifiers are not case sensitive
827 <sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
829 Apply a custom mapping for characters. The command is followed by two
830 numbers in the range 1..255. The first one is the index of the source
831 character, the second one is the mapping. The mapping applies to all
832 character and string constants when they generate output, and overrides
833 a mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
839 .charmap $41, $61 ; Map 'A' to 'a'
843 <sect1><tt>.CODE</tt><label id=".CODE"><p>
845 Switch to the CODE segment. The name of the CODE segment is always
846 "CODE", so this is a shortcut for
852 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
855 <sect1><tt>.CONDES</tt><label id=".CONDES"><p>
857 Export a symbol and mark it in a special way. The linker is able to build
858 tables of all such symbols. This may be used to automatically create a list
859 of functions needed to initialize linked library modules.
861 Note: The linker has a feature to build a table of marked routines, but it
862 is your code that must call these routines, so just declaring a symbol with
863 <tt/.CONDES/ does nothing by itself.
865 All symbols are exported as an absolute (16 bit) symbol. You don't need to
866 use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
867 is implied by <tt/.CONDES/.
869 <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
870 <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
871 specifiying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
872 The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> and <tt><ref
873 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands are actually shortcuts
874 for <tt/.CONDES/ with a type of <tt/constructor/ resp. <tt/destructor/.
876 After the type, an optional priority may be specified. Higher numeric values
877 mean higher priority. If no priority is given, the default priority of 7 is
878 used. Be careful when assigning priorities to your own module constructors
879 so they won't interfere with the ones in the cc65 library.
884 .condes ModuleInit, constructor
885 .condes ModInit, 0, 16
888 See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> and <tt><ref
889 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
890 <ref id="condes" name="Module constructors/destructors"> explaining the
891 feature in more detail.
894 <sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
896 Builtin function. The function allows to concatenate a list of string
897 constants separated by commas. The result is a string constant that
898 is the concatentation of all arguments. This function is most useful
899 in macros and when used together with the <tt/.STRING/ builtin function.
900 The function may be used in any case where a string constant is
906 .include .concat ("myheader", ".", "inc")
909 This is the same as the command
912 .include "myheader.inc"
916 <sect1><tt>.CONST</tt><label id=".CONST"><p>
918 Builtin function. The function evaluates its argument in braces and
919 yields "true" if the argument is a constant expression (that is, an
920 expression that yields a constant value at assembly time) and "false"
921 otherwise. As an example, the .IFCONST statement may be replaced by
928 <sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
930 Export a symbol and mark it as a module constructor. This may be used
931 together with the linker to build a table of constructor subroutines that
932 are called by the startup code.
934 Note: The linker has a feature to build a table of marked routines, but it
935 is your code that must call these routines, so just declaring a symbol as
936 constructor does nothing by itself.
938 A constructor is always exported as an absolute (16 bit) symbol. You don't
939 need to use an additional <tt/.export/ statement, this is implied by
940 <tt/.constructor/. It may have an optional priority that is separated by a
941 comma. Higher numeric values mean a higher priority. If no priority is
942 given, the default priority of 7 is used. Be careful when assigning
943 priorities to your own module constructors so they won't interfere with the
944 ones in the cc65 library.
949 .constructor ModuleInit
950 .constructor ModInit, 16
953 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
954 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
955 <ref id="condes" name="Module constructors/destructors"> explaining the
956 feature in more detail.
959 <sect1><tt>.CPU</tt><label id=".CPU"><p>
961 Reading this pseudo variable will give a constant integer value that
962 tells which CPU is currently enabled. It can also tell which instruction
963 set the CPU is able to translate. The value read from the pseudo variable
964 should be further examined by using one of the constants defined by the
965 "cpu" macro package (see <tt/<ref id=".MACPACK" name=".MACPACK">/).
967 It may be used to replace the .IFPxx pseudo instructions or to construct
968 even more complex expressions.
974 .if (.cpu .bitand CPU_ISET_65816)
986 <sect1><tt>.DATA</tt><label id=".DATA"><p>
988 Switch to the DATA segment. The name of the DATA segment is always
989 "DATA", so this is a shortcut for
995 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
998 <sect1><tt>.DBYT</tt><label id=".DBYT"><p>
1000 Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
1001 create word sized data in native 65XX format). Must be followed by a
1002 sequence of (word ranged) expressions.
1010 This will emit the bytes
1016 into the current segment in that order.
1019 <sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
1021 Switch on or off debug info generation. The default is off (that is,
1022 the object file will not contain debug infos), but may be changed by the
1023 -g switch on the command line.
1024 The command must be followed by a '+' or '-' character to switch the
1025 option on or off respectively.
1030 .debuginfo + ; Generate debug info
1034 <sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
1036 Start a define style macro definition. The command is followed by an
1037 identifier (the macro name) and optionally by a list of formal arguments
1039 See section <ref id="macros" name="Macros">.
1042 <sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
1044 Builtin function. The function expects an identifier as argument in braces.
1045 The argument is evaluated, and the function yields "true" if the identifier
1046 is a symbol that is already defined somewhere in the source file up to the
1047 current position. Otherwise the function yields false. As an example, the
1048 <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
1055 <sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
1057 Export a symbol and mark it as a module destructor. This may be used
1058 together with the linker to build a table of destructor subroutines that
1059 are called by the startup code.
1061 Note: The linker has a feature to build a table of marked routines, but it
1062 is your code that must call these routines, so just declaring a symbol as
1063 constructor does nothing by itself.
1065 A destructor is always exported as an absolute (16 bit) symbol. You don't
1066 need to use an additional <tt/.export/ statement, this is implied by
1067 <tt/.destructor/. It may have an optional priority that is separated by a
1068 comma. Higher numerical values mean a higher priority. If no priority is
1069 given, the default priority of 7 is used. Be careful when assigning
1070 priorities to your own module destructors so they won't interfere with the
1071 ones in the cc65 library.
1076 .destructor ModuleDone
1077 .destructor ModDone, 16
1080 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
1081 id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
1082 section <ref id="condes" name="Module constructors/destructors"> explaining
1083 the feature in more detail.
1086 <sect1><tt>.DWORD</tt><label id=".DWORD"><p>
1088 Define dword sized data (4 bytes) Must be followed by a sequence of
1094 .dword $12344512, $12FA489
1098 <sect1><tt>.ELSE</tt><label id=".ELSE"><p>
1100 Conditional assembly: Reverse the current condition.
1103 <sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
1105 Conditional assembly: Reverse current condition and test a new one.
1108 <sect1><tt>.END</tt><label id=".END"><p>
1110 Forced end of assembly. Assembly stops at this point, even if the command
1111 is read from an include file.
1114 <sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
1116 Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
1117 <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
1120 <sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
1122 End of macro definition (see section <ref id="macros" name="Macros">).
1125 <sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
1127 End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
1130 <sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
1132 End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
1135 <sect1><tt>.ERROR</tt><label id=".ERROR"><p>
1137 Force an assembly error. The assembler will output an error message
1138 preceeded by "User error" and will <em/not/ produce an object file.
1140 This command may be used to check for initial conditions that must be
1141 set before assembling a source file.
1151 .error "Must define foo or bar!"
1155 See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
1156 id=".OUT" name=".OUT"></tt> directives.
1159 <sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
1161 Abort a macro expansion immidiately. This command is often useful in
1162 recursive macros. See separate section <ref id="macros" name="Macros">.
1165 <sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
1167 Make symbols accessible from other modules. Must be followed by a comma
1168 separated list of symbols to export.
1176 See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
1179 <sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
1181 Make symbols accessible from other modules. Must be followed by a comma
1182 separated list of symbols to export. The exported symbols are explicitly
1183 marked as zero page symols.
1191 See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
1194 <sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
1196 Define far (24 bit) address data. The command must be followed by a
1197 sequence of (not necessarily constant) expressions.
1202 .faraddr DrawCircle, DrawRectangle, DrawHexagon
1205 See: <tt><ref id=".ADDR" name=".ADDR"></tt>
1208 <sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
1210 This directive may be used to enable one or more compatibility features
1211 of the assembler. While the use of <tt/.FEATURE/ should be avoided when
1212 possible, it may be useful when porting sources written for other
1213 assemblers. There is no way to switch a feature off, once you have
1214 enabled it, so using
1220 will enable the feature until end of assembly is reached.
1222 The following features are available:
1226 <tag><tt>dollar_is_pc</tt></tag>
1228 The dollar sign may be used as an alias for the star (`*'), which
1229 gives the value of the current PC in expressions.
1230 Note: Assignment to the pseudo variable is not allowed.
1232 <tag><tt>labels_without_colons</tt></tag>
1234 Allow labels without a trailing colon. These labels are only accepted,
1235 if they start at the beginning of a line (no leading white space).
1237 <tag><tt>loose_string_term</tt></tag>
1239 Accept single quotes as well as double quotes as terminators for string
1242 <tag><tt>loose_char_term</tt></tag>
1244 Accept single quotes as well as double quotes as terminators for char
1247 <tag><tt>at_in_identifiers</tt></tag>
1249 Accept the at character (`@') as a valid character in identifiers. The
1250 at character is not allowed to start an identifier, even with this
1253 <tag><tt>dollar_in_identifiers</tt></tag>
1255 Accept the dollar sign (`$') as a valid character in identifiers. The
1256 at character is not allowed to start an identifier, even with this
1259 <tag><tt>leading_dot_in_identifiers</tt></tag>
1261 Accept the dot (`.') as the first character of an identifier. This may be
1262 used for example to create macro names that start with a dot emulating
1263 control directives of other assemblers. Note however, that none of the
1264 reserved keywords built into the assembler, that starts with a dot, may be
1265 overridden. When using this feature, you may also get into trouble if
1266 later versions of the assembler define new keywords starting with a dot.
1268 <tag><tt>pc_assignment</tt></tag>
1270 Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
1271 is enabled). Such an assignment is handled identical to the <tt><ref
1272 id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
1273 removing the lines with the assignments may also be an option when porting
1274 code written for older assemblers).
1278 It is also possible to specify features on the command line using the
1279 <tt><ref id="option--feature" name="--feature"></tt> command line option.
1280 This is useful when translating sources written for older assemblers, when
1281 you don't want to change the source code.
1283 As an example, to translate sources written for Andre Fachats xa65
1284 assembler, the features
1287 labels_without_colons, pc_assignment, loose_char_term
1290 may be helpful. They do not make ca65 completely compatible, so you may not
1291 be able to translate the sources without changes, even when enabling these
1292 features. However, I have found several sources that translate without
1293 problems when enabling these features on the command line.
1296 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
1298 Insert an option string into the object file. There are two forms of
1299 this command, one specifies the option by a keyword, the second
1300 specifies it as a number. Since usage of the second one needs knowledge
1301 of the internal encoding, its use is not recommended and I will only
1302 describe the first form here.
1304 The command is followed by one of the keywords
1312 a comma and a string. The option is written into the object file
1313 together with the string value. This is currently unidirectional and
1314 there is no way to actually use these options once they are in the
1320 .fileopt comment, "Code stolen from my brother"
1321 .fileopt compiler, "BASIC 2.0"
1322 .fopt author, "J. R. User"
1326 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
1328 Import an absolute symbol from another module. The command is followed by a
1329 comma separated list of symbols to import. The command is similar to <tt>
1330 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
1331 written to the generated object file, even if the symbol is never referenced
1332 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
1333 references for unused symbols).
1338 .forceimport needthisone, needthistoo
1341 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
1344 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
1346 Declare symbols as global. Must be followed by a comma separated list of
1347 symbols to declare. Symbols from the list, that are defined somewhere in the
1348 source, are exported, all others are imported. Additional <tt><ref
1349 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
1350 name=".EXPORT"></tt> commands for the same symbol are allowed.
1359 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
1361 Declare symbols as global. Must be followed by a comma separated list of
1362 symbols to declare. Symbols from the list, that are defined somewhere in the
1363 source, are exported, all others are imported. Additional <tt><ref
1364 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
1365 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
1366 in the list are explicitly marked as zero page symols.
1375 <sect1><tt>.I16</tt><label id=".I16"><p>
1377 Valid only in 65816 mode. Switch the index registers to 16 bit.
1379 Note: This command will not emit any code, it will tell the assembler to
1380 create 16 bit operands for immediate operands.
1382 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
1383 name=".SMART"></tt> commands.
1386 <sect1><tt>.I8</tt><label id=".I8"><p>
1388 Valid only in 65816 mode. Switch the index registers to 8 bit.
1390 Note: This command will not emit any code, it will tell the assembler to
1391 create 8 bit operands for immediate operands.
1393 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
1394 name=".SMART"></tt> commands.
1397 <sect1><tt>.IF</tt><label id=".IF"><p>
1399 Conditional assembly: Evalute an expression and switch assembler output
1400 on or off depending on the expression. The expression must be a constant
1401 expression, that is, all operands must be defined.
1403 A expression value of zero evaluates to FALSE, any other value evaluates
1407 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
1409 Conditional assembly: Check if there are any remaining tokens in this line,
1410 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
1411 condition is not true, further lines are not assembled until an <tt><ref
1412 id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
1413 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
1415 This command is often used to check if a macro parameter was given. Since an
1416 empty macro parameter will evaluate to nothing, the condition will evaluate
1417 to FALSE if an empty parameter was given.
1431 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
1434 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
1436 Conditional assembly: Evaluate an expression and switch assembler output
1437 on or off depending on the constness of the expression.
1439 A const expression evaluates to to TRUE, a non const expression (one
1440 containing an imported or currently undefined symbol) evaluates to
1443 See also: <tt><ref id=".CONST" name=".CONST"></tt>
1446 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
1448 Conditional assembly: Check if a symbol is defined. Must be followed by
1449 a symbol name. The condition is true if the the given symbol is already
1450 defined, and false otherwise.
1452 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1455 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
1457 Conditional assembly: Check if there are any remaining tokens in this line,
1458 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
1459 condition is not true, further lines are not assembled until an <tt><ref
1460 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
1461 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
1463 This command is often used to check if a macro parameter was given.
1464 Since an empty macro parameter will evaluate to nothing, the condition
1465 will evaluate to FALSE if an empty parameter was given.
1478 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
1481 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
1483 Conditional assembly: Check if a symbol is defined. Must be followed by
1484 a symbol name. The condition is true if the the given symbol is not
1485 defined, and false otherwise.
1487 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1490 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
1492 Conditional assembly: Check if a symbol is referenced. Must be followed
1493 by a symbol name. The condition is true if if the the given symbol was
1494 not referenced before, and false otherwise.
1496 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
1499 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
1501 Conditional assembly: Check if the assembler is currently in 6502 mode
1502 (see <tt><ref id=".P02" name=".P02"></tt> command).
1505 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
1507 Conditional assembly: Check if the assembler is currently in 65816 mode
1508 (see <tt><ref id=".P816" name=".P816"></tt> command).
1511 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
1513 Conditional assembly: Check if the assembler is currently in 65C02 mode
1514 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
1517 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
1519 Conditional assembly: Check if the assembler is currently in 65SC02 mode
1520 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
1523 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
1525 Conditional assembly: Check if a symbol is referenced. Must be followed
1526 by a symbol name. The condition is true if if the the given symbol was
1527 referenced before, and false otherwise.
1529 This command may be used to build subroutine libraries in include files
1530 (you may use separate object modules for this purpose too).
1535 .ifref ToHex ; If someone used this subroutine
1536 ToHex: tay ; Define subroutine
1542 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
1545 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
1547 Import a symbol from another module. The command is followed by a comma
1548 separated list of symbols to import.
1556 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
1559 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
1561 Import a symbol from another module. The command is followed by a comma
1562 separated list of symbols to import. The symbols are explicitly imported
1563 as zero page symbols (that is, symbols with values in byte range).
1571 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
1574 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
1576 Include a file as binary data. The command expects a string argument
1577 that is the name of a file to include literally in the current segment.
1578 In addition to that, a start offset and a size value may be specified,
1579 separated by commas. If no size is specified, all of the file from the
1580 start offset to end-of-file is used. If no start position is specified
1581 either, zero is assume (which means that the whole file is inserted).
1586 ; Include whole file
1587 .incbin "sprites.dat"
1589 ; Include file starting at offset 256
1590 .incbin "music.dat", $100
1592 ; Read 100 bytes starting at offset 200
1593 .incbin "graphics.dat", 200, 100
1597 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
1599 Include another file. Include files may be nested up to a depth of 16.
1608 <sect1><tt>.LEFT</tt><label id=".LEFT"><p>
1610 Builtin function. Extracts the left part of a given token list.
1615 .LEFT (<int expr>, <token list>)
1618 The first integer expression gives the number of tokens to extract from
1619 the token list. The second argument is the token list itself.
1623 To check in a macro if the given argument has a '#' as first token
1624 (immidiate addressing mode), use something like this:
1629 .if (.match (.left (1, arg), #))
1631 ; ldax called with immidiate operand
1639 See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
1640 name=".RIGHT"></tt> builtin functions.
1643 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
1645 Switch on or off line continuations using the backslash character
1646 before a newline. The option is off by default.
1647 Note: Line continuations do not work in a comment. A backslash at the
1648 end of a comment is treated as part of the comment and does not trigger
1650 The command must be followed by a '+' or '-' character to switch the
1651 option on or off respectively.
1656 .linecont + ; Allow line continuations
1659 #$20 ; This is legal now
1663 <sect1><tt>.LIST</tt><label id=".LIST"><p>
1665 Enable output to the listing. The command must be followed by a boolean
1666 switch ("on", "off", "+" or "-") and will enable or disable listing
1668 The option has no effect if the listing is not enabled by the command line
1669 switch -l. If -l is used, an internal counter is set to 1. Lines are output
1670 to the listing file, if the counter is greater than zero, and suppressed if
1671 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
1677 .list on ; Enable listing output
1681 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
1683 Set, how many bytes are shown in the listing for one source line. The
1684 default is 12, so the listing will show only the first 12 bytes for any
1685 source line that generates more than 12 bytes of code or data.
1686 The directive needs an argument, which is either "unlimited", or an
1687 integer constant in the range 4..255.
1692 .listbytes unlimited ; List all bytes
1693 .listbytes 12 ; List the first 12 bytes
1694 .incbin "data.bin" ; Include large binary file
1698 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
1700 This command may only be used inside a macro definition. It declares a
1701 list of identifiers as local to the macro expansion.
1703 A problem when using macros are labels: Since they don't change their name,
1704 you get a "duplicate symbol" error if the macro is expanded the second time.
1705 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
1706 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
1709 Some other assemblers start a new lexical block inside a macro expansion.
1710 This has some drawbacks however, since that will not allow <em/any/ symbol
1711 to be visible outside a macro, a feature that is sometimes useful. The
1712 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
1713 to address the problem.
1715 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
1719 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
1721 Defines the character that start "cheap" local labels. You may use one
1722 of '@' and '?' as start character. The default is '@'.
1724 Cheap local labels are labels that are visible only between two non
1725 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
1726 using explicit lexical nesting.
1733 Clear: lda #$00 ; Global label
1734 ?Loop: sta Mem,y ; Local label
1738 Sub: ... ; New global label
1739 bne ?Loop ; ERROR: Unknown identifier!
1743 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
1745 Insert a predefined macro package. The command is followed by an
1746 identifier specifying the macro package to insert. Available macro
1750 generic Defines generic macros like add and sub.
1751 longbranch Defines conditional long jump macros.
1752 cbm Defines the scrcode macro
1753 cpu Defines constants for the .CPU variable
1756 Including a macro package twice, or including a macro package that
1757 redefines already existing macros will lead to an error.
1762 .macpack longbranch ; Include macro package
1764 cmp #$20 ; Set condition codes
1765 jne Label ; Jump long on condition
1768 Macro packages are explained in more detail in section <ref
1769 id="macropackages" name="Macro packages">.
1772 <sect1><tt>.MAC, .MACRO</tt><label id=".MAC"><p>
1774 Start a classic macro definition. The command is followed by an identifier
1775 (the macro name) and optionally by a comma separated list of identifiers
1776 that are macro parameters.
1778 See section <ref id="macros" name="Macros">.
1781 <sect1><tt>.MATCH</tt><label id=".MATCH"><p>
1783 Builtin function. Matches two token lists against each other. This is
1784 most useful within macros, since macros are not stored as strings, but
1790 .MATCH(<token list #1>, <token list #2>)
1793 Both token list may contain arbitrary tokens with the exception of the
1794 terminator token (comma resp. right parenthesis) and
1801 Often a macro parameter is used for any of the token lists.
1803 Please note that the function does only compare tokens, not token
1804 attributes. So any number is equal to any other number, regardless of the
1805 actual value. The same is true for strings. If you need to compare tokens
1806 <em/and/ token attributes, use the <tt><ref id=".XMATCH"
1807 name=".XMATCH"></tt> function.
1811 Assume the macro <tt/ASR/, that will shift right the accumulator by one,
1812 while honoring the sign bit. The builtin processor instructions will allow
1813 an optional "A" for accu addressing for instructions like <tt/ROL/ and
1814 <tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
1815 to check for this and print and error for invalid calls.
1820 .if (.not .blank(arg)) .and (.not .match (arg, a))
1821 .error "Syntax error"
1824 cmp #$80 ; Bit 7 into carry
1825 lsr a ; Shift carry into bit 7
1830 The macro will only accept no arguments, or one argument that must be the
1831 reserved keyword "A".
1833 See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
1836 <sect1><tt>.MID</tt><label id=".MID"><p>
1838 Builtin function. Takes a starting index, a count and a token list as
1839 arguments. Will return part of the token list.
1844 .MID (<int expr>, <int expr>, <token list>)
1847 The first integer expression gives the starting token in the list (the
1848 first token has index 0). The second integer expression gives the number
1849 of tokens to extract from the token list. The third argument is the
1854 To check in a macro if the given argument has a '<tt/#/' as first token
1855 (immidiate addressing mode), use something like this:
1860 .if (.match (.mid (0, 1, arg), #))
1862 ; ldax called with immidiate operand
1870 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
1871 name=".RIGHT"></tt> builtin functions.
1874 <sect1><tt>.ORG</tt><label id=".ORG"><p>
1876 Start a section of absolute code. The command is followed by a constant
1877 expression that gives the new PC counter location for which the code is
1878 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
1881 Please note that you <em/do not need/ this command in most cases. Placing
1882 code at a specific address is the job of the linker, not the assembler, so
1883 there is usually no reason to assemble code to a specific address.
1885 You may not switch segments while inside a section of absolute code.
1890 .org $7FF ; Emit code starting at $7FF
1894 <sect1><tt>.OUT</tt><label id=".OUT"><p>
1896 Output a string to the console without producing an error. This command
1897 is similiar to <tt/.ERROR/, however, it does not force an assembler error
1898 that prevents the creation of an object file.
1903 .out "This code was written by the codebuster(tm)"
1906 See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
1907 id=".ERROR" name=".ERROR"></tt> directives.
1910 <sect1><tt>.P02</tt><label id=".P02"><p>
1912 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
1913 instructions. This is the default if not overridden by the
1914 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
1916 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
1917 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
1920 <sect1><tt>.P816</tt><label id=".P816"><p>
1922 Enable the 65816 instruction set. This is a superset of the 65SC02 and
1923 6502 instruction sets.
1925 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
1926 name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
1929 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
1931 Set the page length for the listing. Must be followed by an integer
1932 constant. The value may be "unlimited", or in the range 32 to 127. The
1933 statement has no effect if no listing is generated. The default value is -1
1934 (unlimited) but may be overridden by the <tt/--pagelength/ command line
1935 option. Beware: Since ca65 is a one pass assembler, the listing is generated
1936 after assembly is complete, you cannot use multiple line lengths with one
1937 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
1942 .pagelength 66 ; Use 66 lines per listing page
1944 .pagelength unlimited ; Unlimited page length
1948 <sect1><tt>.PARAMCOUNT</tt><label id=".PARAMCOUNT"><p>
1950 This builtin pseudo variable is only available in macros. It is replaced by
1951 the actual number of parameters that were given in the macro invocation.
1956 .macro foo arg1, arg2, arg3
1957 .if .paramcount <> 3
1958 .error "Too few parameters for macro foo"
1964 See section <ref id="macros" name="Macros">.
1967 <sect1><tt>.PC02</tt><label id=".PC02"><p>
1969 Enable the 65C02 instructions set. This instruction set includes all
1970 6502 and 65SC02 instructions.
1972 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
1973 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
1976 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
1978 Pop the last pushed segment from the stack, and set it.
1980 This command will switch back to the segment that was last pushed onto the
1981 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
1982 command, and remove this entry from the stack.
1984 The assembler will print an error message if the segment stack is empty
1985 when this command is issued.
1987 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
1990 <sect1><tt>.PROC</tt><label id=".PROC"><p>
1992 Start a nested lexical level. All new symbols from now on are in the local
1993 lexical level and are not accessible from outside. Symbols defined outside
1994 this local level may be accessed as long as their names are not used for new
1995 symbols inside the level. Symbols names in other lexical levels do not
1996 clash, so you may use the same names for identifiers. The lexical level ends
1997 when the <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read.
1998 Lexical levels may be nested up to a depth of 16.
2000 The command may be followed by an identifier, in this case the
2001 identifier is declared in the outer level as a label having the value of
2002 the program counter at the start of the lexical level.
2004 Note: Macro names are always in the global level and in a separate name
2005 space. There is no special reason for this, it's just that I've never
2006 had any need for local macro definitions.
2011 .proc Clear ; Define Clear subroutine, start new level
2013 L1: sta Mem,y ; L1 is local and does not cause a
2014 ; duplicate symbol error if used in other
2017 bne L1 ; Reference local symbol
2019 .endproc ; Leave lexical level
2022 See: <tt><ref id=".ENDPROC" name=".ENDPROC"></tt>
2025 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
2027 Enable the 65SC02 instructions set. This instruction set includes all
2030 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
2031 name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
2034 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
2036 Push the currently active segment onto a stack. The entries on the stack
2037 include the name of the segment and the segment type. The stack has a size
2040 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
2041 to switch to another segment and to restore the old segment later, without
2042 even knowing the name and type of the current segment.
2044 The assembler will print an error message if the segment stack is already
2045 full, when this command is issued.
2047 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
2050 <sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
2052 Builtin function. The function expects an identifier as argument in braces.
2053 The argument is evaluated, and the function yields "true" if the identifier
2054 is a symbol that has already been referenced somewhere in the source file up
2055 to the current position. Otherwise the function yields false. As an example,
2056 the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
2062 See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2065 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
2067 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
2068 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
2069 a constant expression that tells how many times the commands in the body
2070 should get repeated. Optionally, a comma and an identifier may be specified.
2071 If this identifier is found in the body of the repeat statement, it is
2072 replaced by the current repeat count (starting with zero for the first time
2073 the body is repeated).
2075 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
2076 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
2077 level will be used, not the one from the outer level.
2081 The following macro will emit a string that is "encrypted" in that all
2082 characters of the string are XORed by the value $55.
2086 .repeat .strlen(Arg), I
2087 .byte .strat(Arg, I) .xor $55
2092 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
2095 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
2097 Switch back to relocatable mode. See the <tt><ref id=".ORG"
2098 name=".ORG"></tt> command.
2101 <sect1><tt>.RES</tt><label id=".RES"><p>
2103 Reserve storage. The command is followed by one or two constant
2104 expressions. The first one is mandatory and defines, how many bytes of
2105 storage should be defined. The second, optional expression must by a
2106 constant byte value that will be used as value of the data. If there
2107 is no fill value given, the linker will use the value defined in the
2108 linker configuration file (default: zero).
2113 ; Reserve 12 bytes of memory with value $AA
2118 <sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
2120 Builtin function. Extracts the right part of a given token list.
2125 .RIGHT (<int expr>, <token list>)
2128 The first integer expression gives the number of tokens to extract from
2129 the token list. The second argument is the token list itself.
2131 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
2132 name=".MID"></tt> builtin functions.
2135 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
2137 Switch to the RODATA segment. The name of the RODATA segment is always
2138 "RODATA", so this is a shortcut for
2144 The RODATA segment is a segment that is used by the compiler for
2145 readonly data like string constants.
2147 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2150 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
2152 Switch to another segment. Code and data is always emitted into a
2153 segment, that is, a named section of data. The default segment is
2154 "CODE". There may be up to 254 different segments per object file
2155 (and up to 65534 per executable). There are shortcut commands for
2156 the most common segments ("CODE", "DATA" and "BSS").
2158 The command is followed by a string containing the segment name (there
2159 are some constraints for the name - as a rule of thumb use only those
2160 segment names that would also be valid identifiers). There may also be
2161 an optional attribute separated by a comma. Valid attributes are
2162 "<tt/zeropage/" and "<tt/absolute/".
2164 When specifying a segment for the first time, "absolute" is the
2165 default. For all other uses, the attribute specified the first time
2168 "absolute" means that this is a segment with absolute addressing. That
2169 is, the segment will reside somewhere in core memory outside the zero
2170 page. "zeropage" means the opposite: The segment will be placed in the
2171 zero page and direct (short) addressing is possible for data in this
2174 Beware: Only labels in a segment with the zeropage attribute are marked
2175 as reachable by short addressing. The `*' (PC counter) operator will
2176 work as in other segments and will create absolute variable values.
2181 .segment "ROM2" ; Switch to ROM2 segment
2182 .segment "ZP2", zeropage ; New direct segment
2183 .segment "ZP2" ; Ok, will use last attribute
2184 .segment "ZP2", absolute ; Error, redecl mismatch
2187 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
2188 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt> and <tt><ref
2189 id=".RODATA" name=".RODATA"></tt>
2192 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
2194 Switch the CPU instruction set. The command is followed by a string that
2195 specifies the CPU. Possible values are those that can also be supplied to
2196 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
2197 namely: 6502, 65SC02, 65C02, 65816 and sunplus. Please note that support
2198 for the sunplus CPU is not available in the freeware version, because the
2199 instruction set of the sunplus CPU is "proprietary and confidential".
2201 See: <tt><ref id=".CPU" name=".CPU"></tt>,
2202 <tt><ref id=".IFP02" name=".IFP02"></tt>,
2203 <tt><ref id=".IFP816" name=".IFP816"></tt>,
2204 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
2205 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
2206 <tt><ref id=".P02" name=".P02"></tt>,
2207 <tt><ref id=".P816" name=".P816"></tt>,
2208 <tt><ref id=".PC02" name=".PC02"></tt>,
2209 <tt><ref id=".PSC02" name=".PSC02"></tt>
2212 <sect1><tt>.SMART</tt><label id=".SMART"><p>
2214 Switch on or off smart mode. The command must be followed by a '+' or
2215 '-' character to switch the option on or off respectively. The default
2216 is off (that is, the assembler doesn't try to be smart), but this
2217 default may be changed by the -s switch on the command line.
2219 In smart mode the assembler will track usage of the <tt/REP/ and <tt/SEP/
2220 instructions in 65816 mode and update the operand sizes accordingly. If
2221 the operand of such an instruction cannot be evaluated by the assembler
2222 (for example, because the operand is an imported symbol), a warning is
2223 issued. Beware: Since the assembler cannot trace the execution flow this
2224 may lead to false results in some cases. If in doubt, use the <tt/.Inn/ and
2225 <tt/.Ann/ instructions to tell the assembler about the current settings.
2231 .smart - ; Stop being smart
2235 <sect1><tt>.STRAT</tt><label id=".STRAT"><p>
2237 Builtin function. The function accepts a string and an index as
2238 arguments and returns the value of the character at the given position
2239 as an integer value. The index is zero based.
2245 ; Check if the argument string starts with '#'
2246 .if (.strat (Arg, 0) = '#')
2253 <sect1><tt>.STRING</tt><label id=".STRING"><p>
2255 Builtin function. The function accepts an argument in braces and converts
2256 this argument into a string constant. The argument may be an identifier, or
2257 a constant numeric value.
2259 Since you can use a string in the first place, the use of the function may
2260 not be obvious. However, it is useful in macros, or more complex setups.
2265 ; Emulate other assemblers:
2267 .segment .string(name)
2272 <sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
2274 Builtin function. The function accepts a string argument in braces and
2275 eveluates to the length of the string.
2279 The following macro encodes a string as a pascal style string with
2280 a leading length byte.
2284 .byte .strlen(Arg), Arg
2289 <sect1><tt>.SUNPLUS</tt><label id=".SUNPLUS"><p>
2291 Enable the SunPlus instructions set. This command will not work in the
2292 freeware version of the assembler, because the instruction set is
2293 "proprietary and confidential".
2295 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
2296 name=".PSC02"></tt>, <tt><ref id=".PC02" name=".PC02"></tt>, and
2297 <tt><ref id=".P816" name=".P816"></tt>
2300 <sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
2302 Builtin function. The function accepts a token list in braces. The
2303 function result is the number of tokens given as argument.
2307 The <tt/ldax/ macro accepts the '#' token to denote immidiate addressing (as
2308 with the normal 6502 instructions). To translate it into two separate 8 bit
2309 load instructions, the '#' token has to get stripped from the argument:
2313 .if (.match (.mid (0, 1, arg), #))
2314 ; ldax called with immidiate operand
2315 lda #<(.right (.tcount (arg)-1, arg))
2316 ldx #>(.right (.tcount (arg)-1, arg))
2324 <sect1><tt>.TIME</tt><label id=".TIME"><p>
2326 Reading this pseudo variable will give a constant integer value that
2327 represents the current time in POSIX standard (as seconds since the
2330 It may be used to encode the time of translation somewhere in the created
2336 .dword .time ; Place time here
2340 <sect1><tt>.VERSION</tt><label id=".VERSION"><p>
2342 Reading this pseudo variable will give the assembler version according to
2343 the following formula:
2345 VER_MAJOR*$100 + VER_MINOR*$10 + VER_PATCH
2347 It may be used to encode the assembler version or check the assembler for
2348 special features not available with older versions.
2352 Version 2.11.1 of the assembler will return $2B1 as numerical constant when
2353 reading the pseudo variable <tt/.VERSION/.
2356 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
2358 Force an assembly warning. The assembler will output a warning message
2359 preceeded by "User warning". This warning will always be output, even if
2360 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
2361 command line option.
2363 This command may be used to output possible problems when assembling
2372 .warning "Forward jump in jne, cannot optimize!"
2382 See also the <tt><ref id=".ERROR" name=".ERROR"></tt> and <tt><ref id=".OUT"
2383 name=".OUT"></tt> directives.
2386 <sect1><tt>.WORD</tt><label id=".WORD"><p>
2388 Define word sized data. Must be followed by a sequence of (word ranged,
2389 but not necessarily constant) expressions.
2394 .word $0D00, $AF13, _Clear
2398 <sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
2400 Builtin function. Matches two token lists against each other. This is
2401 most useful within macros, since macros are not stored as strings, but
2407 .XMATCH(<token list #1>, <token list #2>)
2410 Both token list may contain arbitrary tokens with the exception of the
2411 terminator token (comma resp. right parenthesis) and
2418 Often a macro parameter is used for any of the token lists.
2420 The function compares tokens <em/and/ token values. If you need a function
2421 that just compares the type of tokens, have a look at the <tt><ref
2422 id=".MATCH" name=".MATCH"></tt> function.
2424 See: <tt><ref id=".MATCH" name=".MATCH"></tt>
2427 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
2429 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
2430 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
2434 .segment "ZEROPAGE", zeropage
2437 Because of the "zeropage" attribute, labels declared in this segment are
2438 addressed using direct addressing mode if possible. You <em/must/ instruct
2439 the linker to place this segment somewhere in the address range 0..$FF
2440 otherwise you will get errors.
2442 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
2446 <sect>Macros<label id="macros"><p>
2449 <sect1>Introduction<p>
2451 Macros may be thought of as "parametrized super instructions". Macros are
2452 sequences of tokens that have a name. If that name is used in the source
2453 file, the macro is "expanded", that is, it is replaced by the tokens that
2454 were specified when the macro was defined.
2457 <sect1>Macros without parameters<p>
2459 In it's simplest form, a macro does not have parameters. Here's an
2463 .macro asr ; Arithmetic shift right
2464 cmp #$80 ; Put bit 7 into carry
2465 ror ; Rotate right with carry
2469 The macro above consists of two real instructions, that are inserted into
2470 the code, whenever the macro is expanded. Macro expansion is simply done
2471 by using the name, like this:
2480 <sect1>Parametrized macros<p>
2482 When using macro parameters, macros can be even more useful:
2496 When calling the macro, you may give a parameter, and each occurence of
2497 the name "addr" in the macro definition will be replaced by the given
2516 A macro may have more than one parameter, in this case, the parameters
2517 are separated by commas. You are free to give less parameters than the
2518 macro actually takes in the definition. You may also leave intermediate
2519 parameters empty. Empty parameters are replaced by empty space (that is,
2520 they are removed when the macro is exanded). If you have a look at our
2521 macro definition above, you will see, that replacing the "addr" parameter
2522 by nothing will lead to wrong code in most lines. To help you, writing
2523 macros with a variable parameter list, there are some control commands:
2525 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
2526 returns true, if there are any tokens on the remainder of the line. Since
2527 empty parameters are replaced by nothing, this may be used to test if a given
2528 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
2531 Look at this example:
2534 .macro ldaxy a, x, y
2547 This macro may be called as follows:
2550 ldaxy 1, 2, 3 ; Load all three registers
2552 ldaxy 1, , 3 ; Load only a and y
2554 ldaxy , , 3 ; Load y only
2557 There's another helper command for determining, which macro parameters are
2558 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt> This command is
2559 replaced by the parameter count given, <em/including/ intermediate empty macro
2563 ldaxy 1 ; .PARAMCOUNT = 1
2564 ldaxy 1,,3 ; .PARAMCOUNT = 3
2565 ldaxy 1,2 ; .PARAMCOUNT = 2
2566 ldaxy 1, ; .PARAMCOUNT = 2
2567 ldaxy 1,2,3 ; .PARAMCOUNT = 3
2571 <sect1>Recursive macros<p>
2573 Macros may be used recursively:
2576 .macro push r1, r2, r3
2585 There's also a special macro to help writing recursive macros: <tt><ref
2586 id=".EXITMACRO" name=".EXITMACRO"></tt> This command will stop macro expansion
2590 .macro push r1, r2, r3, r4, r5, r6, r7
2592 ; First parameter is empty
2598 push r2, r3, r4, r5, r6, r7
2602 When expanding this macro, the expansion will push all given parameters
2603 until an empty one is encountered. The macro may be called like this:
2606 push $20, $21, $32 ; Push 3 ZP locations
2607 push $21 ; Push one ZP location
2611 <sect1>Local symbols inside macros<p>
2613 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
2614 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
2615 Have a look at the inc16 macro above. Here is it again:
2629 If you have a closer look at the code, you will notice, that it could be
2630 written more efficiently, like this:
2641 But imagine what happens, if you use this macro twice? Since the label
2642 "Skip" has the same name both times, you get a "duplicate symbol" error.
2643 Without a way to circumvent this problem, macros are not as useful, as
2644 they could be. One solution is, to start a new lexical block inside the
2658 Now the label is local to the block and not visible outside. However,
2659 sometimes you want a label inside the macro to be visible outside. To make
2660 that possible, there's a new command that's only usable inside a macro
2661 definition: <tt><ref id=".LOCAL" name=".LOCAL"></tt>. <tt/.LOCAL/ declares one
2662 or more symbols as local to the macro expansion. The names of local variables
2663 are replaced by a unique name in each separate macro expansion. So we could
2664 also solve the problem above by using <tt/.LOCAL/:
2668 .local Skip ; Make Skip a local symbol
2675 Skip: ; Not visible outside
2680 <sect1>C style macros<p>
2682 Starting with version 2.5 of the assembler, there is a second macro type
2683 available: C style macros using the <tt/.DEFINE/ directive. These macros are
2684 similar to the classic macro type described above, but behaviour is sometimes
2689 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
2690 span more than a line. You may use line continuation (see <tt><ref
2691 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
2692 more than one line for increased readability, but the macro itself
2693 may not contain an end-of-line token.
2695 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
2696 the name space with classic macros, but they are detected and replaced
2697 at the scanner level. While classic macros may be used in every place,
2698 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
2699 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
2700 they are more versatile in some situations.
2702 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
2703 parameters. While classic macros may have empty parameters, this is
2704 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
2705 For this macro type, the number of actual parameters must match
2706 exactly the number of formal parameters.
2708 To make this possible, formal parameters are enclosed in braces when
2709 defining the macro. If there are no parameters, the empty braces may
2712 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
2713 contain end-of-line tokens, there are things that cannot be done. They
2714 may not contain several processor instructions for example. So, while
2715 some things may be done with both macro types, each type has special
2716 usages. The types complement each other.
2720 Let's look at a few examples to make the advantages and disadvantages
2723 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
2724 following <tt/.DEFINE/:
2729 foo EQU $1234 ; This is accepted now
2732 You may use the directive to define string constants used elsewhere:
2735 ; Define the version number
2736 .define VERSION "12.3a"
2742 Macros with parameters may also be useful:
2745 .define DEBUG(message) .out message
2747 DEBUG "Assembling include file #3"
2750 Note that, while formal parameters have to be placed in braces, this is
2751 not true for the actual parameters. Beware: Since the assembler cannot
2752 detect the end of one parameter, only the first token is used. If you
2753 don't like that, use classic macros instead:
2761 (This is an example where a problem can be solved with both macro types).
2764 <sect1>Characters in macros<p>
2766 When using the <ref id="option-t" name="-t"> option, characters are translated
2767 into the target character set of the specific machine. However, this happens
2768 as late as possible. This means that strings are translated if they are part
2769 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
2770 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
2771 used as part of an expression.
2773 This behaviour is very intuitive outside of macros but may be confusing when
2774 doing more complex macros. If you compare characters against numeric values,
2775 be sure to take the translation into account.
2780 <sect>Macro packages<label id="macropackages"><p>
2782 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
2783 macro packages may be included with just one command. Available macro packages
2787 <sect1><tt>.MACPACK generic</tt><p>
2789 This macro package defines macros that are useful in almost any program.
2790 Currently, two macros are defined:
2805 <sect1><tt>.MACPACK longbranch</tt><p>
2807 This macro package defines long conditional jumps. They are named like the
2808 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
2809 definition for the "<tt/jeq/" macro, the other macros are built using the same
2814 .if .def(Target) .and ((*+2)-(Target) <= 127)
2823 All macros expand to a short branch, if the label is already defined (back
2824 jump) and is reachable with a short jump. Otherwise the macro expands to a
2825 conditional branch with the branch condition inverted, followed by an absolute
2826 jump to the actual branch target.
2828 The package defines the following macros:
2831 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
2836 <sect1><tt>.MACPACK cbm</tt><p>
2838 The cbm macro package will define a macro named <tt/scrcode/. It takes a
2839 string as argument and places this string into memory translated into screen
2843 <sect1><tt>.MACPACK cpu</tt><p>
2845 This macro package does not define any macros but constants used to examine
2846 the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
2847 each supported CPU a constant similar to
2857 is defined. These constants may be used to determine the exact type of the
2858 currently enabled CPU. In addition to that, for each CPU instruction set,
2859 another constant is defined:
2869 The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
2870 be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
2871 currently enabled CPU supports a specific instruction set. For example the
2872 65C02 supports all instructions of the 65SC02 CPU, so it has the
2873 <tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
2877 .if (.cpu .bitand CPU_ISET_65SC02)
2885 it is possible to determine if the
2891 instruction is supported, which is the case for the 65SC02, 65C02 and 65816
2892 CPUs (the latter two are upwards compatible to the 65SC02).
2896 <sect>Module constructors/destructors<label id="condes"><p>
2898 <em>Note:</em> This section applies mostly to C programs, so the explanation
2899 below uses examples from the C libraries. However, the feature may also be
2900 useful for assembler programs.
2903 <sect1>Module overview<p>
2905 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> and <tt><ref
2906 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> keywords it it possible to export
2907 functions in a special way. The linker is able to generate tables with all
2908 functions of a specific type. Such a table will <em>only</em> include symbols
2909 from object files that are linked into a specific executable. This may be used
2910 to add initialization and cleanup code for library modules.
2912 The C heap functions are an example where module initialization code is used.
2913 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
2914 variables that contain the start and the end of the heap, pointers to the free
2915 list and so on. Since the end of the heap depends on the size and start of the
2916 stack, it must be initialized at runtime. However, initializing these
2917 variables for programs that do not use the heap are a waste of time and
2920 So the central module defines a function that contains initialization code and
2921 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
2922 this module is added to an executable by the linker, the initialization
2923 function will be placed into the table of constructors by the linker. The C
2924 startup code will call all constructors before <tt/main/ and all destructors
2925 after <tt/main/, so without any further work, the heap initialization code is
2926 called once the module is linked in.
2928 While it would be possible to add explicit calls to initialization functions
2929 in the startup code, the new approach has several advantages:
2933 If a module is not included, the initialization code is not linked in and not
2934 called. So you don't pay for things you don't need.
2937 Adding another library that needs initialization does not mean that the
2938 startup code has to be changed. Before we had module constructors and
2939 destructors, the startup code for all systems had to be adjusted to call the
2940 new initialization code.
2943 The feature saves memory: Each additional initialization function needs just
2944 two bytes in the table (a pointer to the function).
2949 <sect1>Calling order<p>
2951 Both, constructors and destructors are sorted in increasing priority order by
2952 the linker when using one of the builtin linker configurations, so the
2953 functions with lower priorities come first and are followed by those with
2954 higher priorities. The C library runtime subroutine that walks over the
2955 constructor and destructor tables calls the functions starting from the top of
2956 the table - which means that functions with a high priority are called first.
2958 So when using the C runtime, both constructors and destructors are called with
2959 high priority functions first, followed by low priority functions.
2964 When creating and using module constructors and destructors, please take care
2970 The linker will only generate function tables, it will not generate code to
2971 call these functions. If you're using the feature in some other than the
2972 existing C environments, you have to write code to call all functions in a
2973 linker generated table yourself. See the <tt>condes</tt> module in the C
2974 runtime for an example on how to do this.
2977 The linker will only add addresses of functions that are in modules linked to
2978 the executable. This means that you have to be careful where to place the
2979 condes functions. If initialization is needed for a group of functions, be
2980 sure to place the initialization function into a module that is linked in
2981 regardless of which function is called by the user.
2984 The linker will generate the tables only when requested to do so by the
2985 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
2986 be requested separately.
2989 Constructors and destructors may have priorities. These priorities determine
2990 the order of the functions in the table. If your intialization or cleanup code
2991 does depend on other initialization or cleanup code, you have to choose the
2992 priority for the functions accordingly.
2995 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> and <tt><ref
2996 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> statements, there is also a more
2997 generic command: <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to
2998 specify an additional type. Predefined types are 0 (constructor) and 1
2999 (destructor). The linker generates a separate table for each type on request.
3004 <sect>Porting sources from other assemblers<p>
3006 Sometimes it is necessary to port code written for older assemblers to ca65.
3007 In some cases, this can be done without any changes to the source code by
3008 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
3009 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
3012 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
3013 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
3014 done by the linker. Most other assemblers generate absolute code, placement is
3015 done within the assembler and there is no external linker.
3017 In general it is not a good idea to write new code using the emulation
3018 features of the assembler, but there may be situations where even this rule is
3023 You need to use some of the ca65 emulation features to simulate the behaviour
3024 of such simple assemblers.
3027 <item>Prepare your sourcecode like this:
3030 ; if you want TASS style labels without colons
3031 .feature labels_without_colons
3033 ; if you want TASS style character constants
3034 ; ("a" instead of the default 'a')
3035 .feature loose_char_term
3037 .word *+2 ; the cbm load address
3042 notice that the two emulation features are mostly useful for porting
3043 sources originally written in/for TASS, they are not needed for the
3044 actual "simple assembler operation" and are not recommended if you are
3045 writing new code from scratch.
3047 <item>Replace all program counter assignments (which are not possible in ca65
3048 by default, and the respective emulation feature works different from what
3049 you'd expect) by another way to skip to another memory location, for example
3050 the <tt><ref id=".RES" name=".RES"></tt>directive.
3054 .res $2000-* ; reserve memory up to $2000
3057 notice that other than the original TASS, ca65 can never move the
3058 programmcounter backwards - think of it as if you are assembling to disc with
3061 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.gogo/ etc.) must be
3062 rewritten to match ca65 syntax. Most importantly notice that due to the lack
3063 of <tt/.goto/, everything involving loops must be replaced by
3064 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
3066 <item>To assemble code to a different address than it is executed at, use the
3067 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
3068 <tt/.offs/-constructs.
3075 .reloc ; back to normal
3078 <item>Then assemble like this:
3081 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
3084 notice that you need to use the actual start address minus two, since two
3085 bytes are used for the cbm load address.
3090 <sect>Bugs/Feedback<p>
3092 If you have problems using the assembler, if you find any bugs, or if
3093 you're doing something interesting with the assembler, I would be glad to
3094 hear from you. Feel free to contact me by email
3095 (<htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">).
3101 ca65 (and all cc65 binutils) are (C) Copyright 1998-2001 Ullrich von
3102 Bassewitz. For usage of the binaries and/or sources the following
3103 conditions do apply:
3105 This software is provided 'as-is', without any expressed or implied
3106 warranty. In no event will the authors be held liable for any damages
3107 arising from the use of this software.
3109 Permission is granted to anyone to use this software for any purpose,
3110 including commercial applications, and to alter it and redistribute it
3111 freely, subject to the following restrictions:
3114 <item> The origin of this software must not be misrepresented; you must not
3115 claim that you wrote the original software. If you use this software
3116 in a product, an acknowledgment in the product documentation would be
3117 appreciated but is not required.
3118 <item> Altered source versions must be plainly marked as such, and must not
3119 be misrepresented as being the original software.
3120 <item> This notice may not be removed or altered from any source