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 expression 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 '>', '<' or '^' 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>Constant expressions<p>
418 Sometimes an expression must evaluate to a constant without looking at any
419 further input. One such example is the <tt/<ref id=".IF" name=".IF">/ command
420 that decides if parts of the code are assembled or not. An expression used in
421 the <tt/.IF/ command cannot reference a symbol defined later, because the
422 decision about the <tt/.IF/ must be made at the point when it is read. If the
423 expression used in such a context contains only constant numerical values,
424 there is no problem. When unresolvable symbols are involved it may get harder
425 for the assembler to determine if the expression is actually constant, and it
426 is even possible to create expressions that aren't recognized as constant.
427 Simplifying the expressions will often help.
429 In cases where the result of the expression is not needed immediately, the
430 assembler will delay evaluation until all input is read, at which point all
431 symbols are known. So using arbitrary complex constant expressions is no
432 problem in most cases.
436 <sect1>Available operators<label id="operators"><p>
438 Available operators sorted by precedence:
441 Op Description Precedence
442 -------------------------------------------------------------------
443 .CONCAT Builtin function 0
444 .LEFT Builtin function 0
445 .MID Builtin function 0
446 .RIGHT Builtin function 0
447 .STRING Builtin function 0
449 * Builtin pseudo variable (r/o) 1
450 .BLANK Builtin function 1
451 .CONST Builtin function 1
452 .CPU Builtin pseudo variable (r/o) 1
453 .DEFINED Builtin function 1
454 .MATCH Builtin function 1
455 .TCOUNT Builtin function 1
456 .TIME Builtin function 1
457 .VERSION Builtin function 1
458 .XMATCH Builtin function 1
459 .PARAMCOUNT Builtin pseudo variable (r/o) 1
460 .REFERENCED Builtin function 1
463 ~ Unary bitwise not 1
464 .BITNOT Unary bitwise not 1
465 < Low byte operator 1
466 > High byte operator 1
467 ^ Bank byte operator 1
471 .MOD Modulo operation 2
473 .BITAND Bitwise and 2
475 .BITXOR Bitwise xor 2
476 << Shift left operator 2
477 .SHL Shift left operator 2
478 >> Shift right operator
479 .SHR Shift right operator 2
486 = Compare operation (equal) 4
487 <> Compare operation (not equal) 4
488 < Compare operation (less) 4
489 > Compare operation (greater) 4
490 <= Compare operation (less or equal) 4
491 >= Compare operation (greater or equal) 4
493 && Boolean and 5
505 To force a specific order of evaluation, braces may be used as usual.
507 Some of the pseudo variables mentioned above need some more explanation:
510 * This symbol is replaced by the value of the program
511 counter at start of the current instruction. Note, that
512 '*' yields a rvalue, that means, you cannot assign to it.
513 Use .ORG to set the program counter in sections with
520 <sect>Symbols and labels<p>
522 The assembler allows you to use symbols instead of naked values to make
523 the source more readable. There are a lot of different ways to define and
524 use symbols and labels, giving a lot of flexibility.
527 <sect1>Numeric constants<p>
529 Numeric constants are defined using the equal sign or the label assignment
530 operator. After doing
536 may use the symbol "two" in every place where a number is expected, and it is
537 evaluated to the value 2 in this context. The label assignment operator causes
538 the same, but causes the symbol to be marked as a label, which may cause a
539 different handling in the debugger:
545 The right side can of course be an expression:
552 <sect1>Standard labels<p>
554 A label is defined by writing the name of the label at the start of the line
555 (before any instruction mnemonic, macro or pseudo directive), followed by a
556 colon. This will declare a symbol with the given name and the value of the
557 current program counter.
560 <sect1>Local labels and symbols<p>
562 Using the <tt><ref id=".PROC" name=".PROC"></tt> directive, it is possible to
563 create regions of code where the names of labels and symbols are local to this
564 region. They are not known outside of this region and cannot be accessed from
565 there. Such regions may be nested like PROCEDUREs in Pascal.
567 See the description of the <tt><ref id=".PROC" name=".PROC"></tt>
568 directive for more information.
571 <sect1>Cheap local labels<p>
573 Cheap local labels are defined like standard labels, but the name of the
574 label must begin with a special symbol (usually '@', but this can be
575 changed by the <tt><ref id=".LOCALCHAR" name=".LOCALCHAR"></tt>
578 Cheap local labels are visible only between two non cheap labels. As soon as a
579 standard symbol is encountered (this may also be a local symbol if inside a
580 region defined with the <tt><ref id=".PROC" name=".PROC"></tt> directive), the
581 cheap local symbol goes out of scope.
583 You may use cheap local labels as an easy way to reuse common label
584 names like "Loop". Here is an example:
587 Clear: lda #$00 ; Global label
589 @Loop: sta Mem,y ; Local label
593 Sub: ... ; New global label
594 bne @Loop ; ERROR: Unknown identifier!
597 <sect1>Unnamed labels<p>
599 If you really want to write messy code, there are also unnamed
600 labels. These labels do not have a name (you guessed that already,
601 didn't you?). A colon is used to mark the absence of the name.
603 Unnamed labels may be accessed by using the colon plus several minus
604 or plus characters as a label designator. Using the '-' characters
605 will create a back reference (use the n'th label backwards), using
606 '+' will create a forward reference (use the n'th label in forward
607 direction). An example will help to understand this:
629 As you can see from the example, unnamed labels will make even short
630 sections of code hard to understand, because you have to count labels
631 to find branch targets (this is the reason why I for my part do
632 prefer the "cheap" local labels). Nevertheless, unnamed labels are
633 convenient in some situations, so it's your decision.
636 <sect1>Using macros to define labels and constants<p>
638 While there are drawbacks with this approach, it may be handy in some
639 situations. Using <tt><ref id=".DEFINE" name=".DEFINE"></tt>, it is
640 possible to define symbols or constants that may be used elsewhere. Since
641 the macro facility works on a very low level, there is no scoping. On the
642 other side, you may also define string constants this way (this is not
643 possible with the other symbol types).
649 .DEFINE version "SOS V2.3"
651 four = two * two ; Ok
654 .PROC ; Start local scope
655 two = 3 ; Will give "2 = 3" - invalid!
660 <sect1>Symbols and <tt>.DEBUGINFO</tt><p>
662 If <tt><ref id=".DEBUGINFO" name=".DEBUGINFO"></tt> is enabled (or <ref
663 id="option-g" name="-g"> is given on the command line), global, local and
664 cheap local labels are written to the object file and will be available in the
665 symbol file via the linker. Unnamed labels are not written to the object file,
666 because they don't have a name which would allow to access them.
670 <sect>Scopes<label id="scopes"><p>
672 ca65 implements several sorts of scopes for symbols.
674 <sect1>Global scope<p>
676 All (non cheap local) symbols that are declared outside of any nested scopes
680 <sect1>A special scope: cheap locals<p>
682 A special scope is the scope for cheap local symbols. It lasts from one non
683 local symbol to the next one, without any provisions made by the programmer.
684 All other scopes differ in usage but use the same concept internally.
687 <sect1>Generic nested scopes<p>
689 A nested scoped for generic use is started with <tt/<ref id=".SCOPE"
690 name=".SCOPE">/ and closed with <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/.
691 The scope can have a name, in which case it is accessible from the outside by
692 using <ref id="scopesyntax" name="explicit scopes">. If the scope does not
693 have a name, all symbols created within the scope are local to the scope, and
694 aren't accessible from the outside.
696 A nested scope can access symbols from the local or from enclosing scopes by
697 name without using explicit scope names. In some cases there may be
698 ambiguities, for example if there is a reference to a local symbol that is not
699 yet defined, but a symbol with the same name exists in outer scopes:
711 In the example above, the <tt/lda/ instruction will load the value 3 into the
712 accumulator, because <tt/foo/ is redefined in the scope. However:
724 Here, <tt/lda/ will still load from <tt/$12,x/, but since it is unknown to the
725 assembler that <tt/foo/ is a zeropage symbol when translating the instruction,
726 absolute mode is used instead. In fact, the assembler will not use absolute
727 mode by default, but it will search through the enclosing scopes for a symbol
728 with the given name. If one is found, the address size of this symbol is used.
729 This may lead to errors:
741 In this case, when the assembler sees the symbol <tt/foo/ in the <tt/lda/
742 instruction, it will search for an already defined symbol <tt/foo/. It will
743 find <tt/foo/ in scope <tt/outer/, and a close look reveals that it is a
744 zeropage symbol. So the assembler will use zeropage addressing mode. If
745 <tt/foo/ is redefined later in scope <tt/inner/, the assembler tries to change
746 the address in the <tt/lda/ instruction already translated, but since the new
747 value needs absolute addressing mode, this fails, and an error message "Range
750 Of course the most simple solution for the problem is to move the definition
751 of <tt/foo/ in scope <tt/inner/ upwards, so it preceeds its use. There may be
752 rare cases when this cannot be done. In these cases, you can use one of the
753 address size override operators:
765 This will cause the <tt/lda/ instruction to be translated using absolute
766 addressing mode, which means changing the symbol reference later does not
770 <sect1>Nested procedures<p>
772 A nested procedure is created by use of <tt/<ref id=".PROC" name=".PROC">/. It
773 differs from a <tt/<ref id=".SCOPE" name=".SCOPE">/ in that it must have a
774 name, and a it will introduce a symbol with this name in the enclosing scope.
783 is actually the same as
792 This is the reason why a procedure must have a name. If you want a scope
793 without a name, use <tt/<ref id=".SCOPE" name=".SCOPE">/.
795 <bf/Note:/ As you can see from the example above, scopes and symbols live in
796 different namespaces. There can be a symbol named <tt/foo/ and a scope named
797 <tt/foo/ without any conflicts (but see the section titled <ref
798 id="scopesearch" name=""Scope search order"">).
801 <sect1>Structs, unions and enums<p>
803 Structs, unions and enums are explained in a <ref id="structs" name="separate
804 section">, I do only cover them here, because if they are declared with a
805 name, they open a nested scope, similar to <tt/<ref id=".SCOPE"
806 name=".SCOPE">/. However, when no name is specified, the behaviour is
807 different: In this case, no new scope will be opened, symbols declared within
808 a struct, union, or enum declaration will then be added to the enclosing scope
812 <sect1>Explicit scope specification<label id="scopesyntax"><p>
814 Accessing symbols from other scopes is possible by using an explicit scope
815 specification, provided that the scope where the symbol lives in has a name.
816 The namespace token (<tt/::/) is used to access other scopes:
824 lda foo::bar ; Access foo in scope bar
827 The only way to deny access to a scope from the outside is to declare a scope
828 without a name (using the <tt/<ref id=".SCOPE" name=".SCOPE">/ command).
830 A special syntax is used to specify the global scope: If a symbol or scope is
831 preceeded by the namespace token, the global scope is searched:
838 lda #::bar ; Access the global bar (which is 3)
843 <sect1>Scope search order<label id="scopesearch"><p>
845 The assembler searches for a scope in a similar way as for a symbol. First, it
846 looks in the current scope, and then it walks up the enclosing scopes until
849 However, one important thing to note when using explicit scope syntax is, that
850 a symbol may be accessed before it is defined, but a scope may <bf/not/ be
851 used without a preceeding definition. This means that in the following
860 lda #foo::bar ; Will load 3, not 2!
867 the reference to the scope <tt/foo/ will use the global scope, and not the
868 local one, because the local one is not visible at the point where it is
871 Things get more complex if a complete chain of scopes is specified:
882 lda #outer::inner::bar ; 1
894 When <tt/outer::inner::bar/ is referenced in the <tt/lda/ instruction, the
895 assembler will first search in the local scope for a scope named <tt/outer/.
896 Since none is found, the enclosing scope (<tt/another/) is checked. There is
897 still no scope named <tt/outer/, so scope <tt/foo/ is checked, and finally
898 scope <tt/outer/ is found. Within this scope, <tt/inner/ is searched, and in
899 this scope, the assembler looks for a symbol named <tt/bar/.
901 Please note that once the anchor scope is found, all following scopes
902 (<tt/inner/ in this case) are expected to be found exactly in this scope. The
903 assembler will search the scope tree only for the first scope (if it is not
904 anchored in the root scope). Starting from there on, there is no flexibility,
905 so if the scope named <tt/outer/ found by the assembler does not contain a
906 scope named <tt/inner/, this would be an error, even if such a pair does exist
907 (one level up in global scope).
909 Ambiguities that may be introduced by this search algorithm may be removed by
910 anchoring the scope specification in the global scope. In the example above,
911 if you want to access the "other" symbol <tt/bar/, you would have to write:
922 lda #::outer::inner::bar ; 2
935 <sect>Address sizes<label id="address-sizes"><p>
942 <sect>Control commands<label id="control-commands">
945 Here's a list of all control commands and a description, what they do:
948 <sect1><tt>.A16</tt><label id=".A16"><p>
950 Valid only in 65816 mode. Switch the accumulator to 16 bit.
952 Note: This command will not emit any code, it will tell the assembler to
953 create 16 bit operands for immediate accumulator adressing mode.
955 See also: <tt><ref id=".SMART" name=".SMART"></tt>
958 <sect1><tt>.A8</tt><label id=".A8"><p>
960 Valid only in 65816 mode. Switch the accumulator to 8 bit.
962 Note: This command will not emit any code, it will tell the assembler to
963 create 8 bit operands for immediate accu adressing mode.
965 See also: <tt><ref id=".SMART" name=".SMART"></tt>
968 <sect1><tt>.ADDR</tt><label id=".ADDR"><p>
970 Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
971 may be used for better readability if the data words are address values. In
972 65816 mode, the address is forced to be 16 bit wide to fit into the current
973 segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
974 must be followed by a sequence of (not necessarily constant) expressions.
979 .addr $0D00, $AF13, _Clear
982 See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
986 <sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
988 Align data to a given boundary. The command expects a constant integer
989 argument that must be a power of two, plus an optional second argument
990 in byte range. If there is a second argument, it is used as fill value,
991 otherwise the value defined in the linker configuration file is used
992 (the default for this value is zero).
994 Since alignment depends on the base address of the module, you must
995 give the same (or a greater) alignment for the segment when linking.
996 The linker will give you a warning, if you don't do that.
1005 <sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
1007 Define a string with a trailing zero.
1012 Msg: .asciiz "Hello world"
1015 This will put the string "Hello world" followed by a binary zero into
1016 the current segment. There may be more strings separated by commas, but
1017 the binary zero is only appended once (after the last one).
1020 <sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
1022 Add an assertion. The command is followed by an expression, an action
1023 specifier and a message that is output in case the assertion fails. The
1024 action specifier may be one of <tt/warning/ or <tt/error/. The assertion
1025 is passed to the linker and will be evaluated when segment placement has
1031 .assert * = $8000, error, "Code not at $8000"
1034 The example assertion will check that the current location is at $8000,
1035 when the output file is written, and abort with an error if this is not
1036 the case. More complex expressions are possible. The action specifier
1037 <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
1038 an error message. In the latter case, generation if the output file is
1042 <sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
1044 Is followed by a plus or a minus character. When switched on (using a
1045 +), undefined symbols are automatically marked as import instead of
1046 giving errors. When switched off (which is the default so this does not
1047 make much sense), this does not happen and an error message is
1048 displayed. The state of the autoimport flag is evaluated when the
1049 complete source was translated, before outputing actual code, so it is
1050 <em/not/ possible to switch this feature on or off for separate sections
1051 of code. The last setting is used for all symbols.
1053 You should probably not use this switch because it delays error
1054 messages about undefined symbols until the link stage. The cc65
1055 compiler (which is supposed to produce correct assembler code in all
1056 circumstances, something which is not true for most assembler
1057 programmers) will insert this command to avoid importing each and every
1058 routine from the runtime library.
1063 .autoimport + ; Switch on auto import
1067 <sect1><tt>.BLANK</tt><label id=".BLANK"><p>
1069 Builtin function. The function evaluates its argument in braces and
1070 yields "false" if the argument is non blank (there is an argument), and
1071 "true" if there is no argument. As an example, the <tt/.IFBLANK/ statement
1079 <sect1><tt>.BSS</tt><label id=".BSS"><p>
1081 Switch to the BSS segment. The name of the BSS segment is always "BSS",
1082 so this is a shortcut for
1088 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1091 <sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
1093 Define byte sized data. Must be followed by a sequence of (byte ranged)
1094 expressions or strings.
1100 .byt "world", $0D, $00
1104 <sect1><tt>.CASE</tt><label id=".CASE"><p>
1106 Switch on or off case sensitivity on identifiers. The default is off
1107 (that is, identifiers are case sensitive), but may be changed by the
1108 -i switch on the command line.
1109 The command must be followed by a '+' or '-' character to switch the
1110 option on or off respectively.
1115 .case - ; Identifiers are not case sensitive
1119 <sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
1121 Apply a custom mapping for characters. The command is followed by two
1122 numbers in the range 1..255. The first one is the index of the source
1123 character, the second one is the mapping. The mapping applies to all
1124 character and string constants when they generate output, and overrides
1125 a mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
1126 command line switch.
1131 .charmap $41, $61 ; Map 'A' to 'a'
1135 <sect1><tt>.CODE</tt><label id=".CODE"><p>
1137 Switch to the CODE segment. The name of the CODE segment is always
1138 "CODE", so this is a shortcut for
1144 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1147 <sect1><tt>.CONDES</tt><label id=".CONDES"><p>
1149 Export a symbol and mark it in a special way. The linker is able to build
1150 tables of all such symbols. This may be used to automatically create a list
1151 of functions needed to initialize linked library modules.
1153 Note: The linker has a feature to build a table of marked routines, but it
1154 is your code that must call these routines, so just declaring a symbol with
1155 <tt/.CONDES/ does nothing by itself.
1157 All symbols are exported as an absolute (16 bit) symbol. You don't need to
1158 use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
1159 is implied by <tt/.CONDES/.
1161 <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
1162 <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
1163 specifiying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
1164 The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> and <tt><ref
1165 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands are actually shortcuts
1166 for <tt/.CONDES/ with a type of <tt/constructor/ resp. <tt/destructor/.
1168 After the type, an optional priority may be specified. Higher numeric values
1169 mean higher priority. If no priority is given, the default priority of 7 is
1170 used. Be careful when assigning priorities to your own module constructors
1171 so they won't interfere with the ones in the cc65 library.
1176 .condes ModuleInit, constructor
1177 .condes ModInit, 0, 16
1180 See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> and <tt><ref
1181 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
1182 <ref id="condes" name="Module constructors/destructors"> explaining the
1183 feature in more detail.
1186 <sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
1188 Builtin function. The function allows to concatenate a list of string
1189 constants separated by commas. The result is a string constant that
1190 is the concatentation of all arguments. This function is most useful
1191 in macros and when used together with the <tt/.STRING/ builtin function.
1192 The function may be used in any case where a string constant is
1198 .include .concat ("myheader", ".", "inc")
1201 This is the same as the command
1204 .include "myheader.inc"
1208 <sect1><tt>.CONST</tt><label id=".CONST"><p>
1210 Builtin function. The function evaluates its argument in braces and
1211 yields "true" if the argument is a constant expression (that is, an
1212 expression that yields a constant value at assembly time) and "false"
1213 otherwise. As an example, the .IFCONST statement may be replaced by
1220 <sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
1222 Export a symbol and mark it as a module constructor. This may be used
1223 together with the linker to build a table of constructor subroutines that
1224 are called by the startup code.
1226 Note: The linker has a feature to build a table of marked routines, but it
1227 is your code that must call these routines, so just declaring a symbol as
1228 constructor does nothing by itself.
1230 A constructor is always exported as an absolute (16 bit) symbol. You don't
1231 need to use an additional <tt/.export/ statement, this is implied by
1232 <tt/.constructor/. It may have an optional priority that is separated by a
1233 comma. Higher numeric values mean a higher priority. If no priority is
1234 given, the default priority of 7 is used. Be careful when assigning
1235 priorities to your own module constructors so they won't interfere with the
1236 ones in the cc65 library.
1241 .constructor ModuleInit
1242 .constructor ModInit, 16
1245 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
1246 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
1247 <ref id="condes" name="Module constructors/destructors"> explaining the
1248 feature in more detail.
1251 <sect1><tt>.CPU</tt><label id=".CPU"><p>
1253 Reading this pseudo variable will give a constant integer value that
1254 tells which CPU is currently enabled. It can also tell which instruction
1255 set the CPU is able to translate. The value read from the pseudo variable
1256 should be further examined by using one of the constants defined by the
1257 "cpu" macro package (see <tt/<ref id=".MACPACK" name=".MACPACK">/).
1259 It may be used to replace the .IFPxx pseudo instructions or to construct
1260 even more complex expressions.
1266 .if (.cpu .bitand CPU_ISET_65816)
1278 <sect1><tt>.DATA</tt><label id=".DATA"><p>
1280 Switch to the DATA segment. The name of the DATA segment is always
1281 "DATA", so this is a shortcut for
1287 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1290 <sect1><tt>.DBYT</tt><label id=".DBYT"><p>
1292 Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
1293 create word sized data in native 65XX format). Must be followed by a
1294 sequence of (word ranged) expressions.
1302 This will emit the bytes
1308 into the current segment in that order.
1311 <sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
1313 Switch on or off debug info generation. The default is off (that is,
1314 the object file will not contain debug infos), but may be changed by the
1315 -g switch on the command line.
1316 The command must be followed by a '+' or '-' character to switch the
1317 option on or off respectively.
1322 .debuginfo + ; Generate debug info
1326 <sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
1328 Start a define style macro definition. The command is followed by an
1329 identifier (the macro name) and optionally by a list of formal arguments
1331 See section <ref id="macros" name="Macros">.
1334 <sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
1336 Builtin function. The function expects an identifier as argument in braces.
1337 The argument is evaluated, and the function yields "true" if the identifier
1338 is a symbol that is already defined somewhere in the source file up to the
1339 current position. Otherwise the function yields false. As an example, the
1340 <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
1347 <sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
1349 Export a symbol and mark it as a module destructor. This may be used
1350 together with the linker to build a table of destructor subroutines that
1351 are called by the startup code.
1353 Note: The linker has a feature to build a table of marked routines, but it
1354 is your code that must call these routines, so just declaring a symbol as
1355 constructor does nothing by itself.
1357 A destructor is always exported as an absolute (16 bit) symbol. You don't
1358 need to use an additional <tt/.export/ statement, this is implied by
1359 <tt/.destructor/. It may have an optional priority that is separated by a
1360 comma. Higher numerical values mean a higher priority. If no priority is
1361 given, the default priority of 7 is used. Be careful when assigning
1362 priorities to your own module destructors so they won't interfere with the
1363 ones in the cc65 library.
1368 .destructor ModuleDone
1369 .destructor ModDone, 16
1372 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
1373 id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
1374 section <ref id="condes" name="Module constructors/destructors"> explaining
1375 the feature in more detail.
1378 <sect1><tt>.DWORD</tt><label id=".DWORD"><p>
1380 Define dword sized data (4 bytes) Must be followed by a sequence of
1386 .dword $12344512, $12FA489
1390 <sect1><tt>.ELSE</tt><label id=".ELSE"><p>
1392 Conditional assembly: Reverse the current condition.
1395 <sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
1397 Conditional assembly: Reverse current condition and test a new one.
1400 <sect1><tt>.END</tt><label id=".END"><p>
1402 Forced end of assembly. Assembly stops at this point, even if the command
1403 is read from an include file.
1406 <sect1><tt>.ENDENUM</tt><label id=".ENDENUM"><p>
1408 End a <tt><ref id=".ENUM" name=".ENUM"></tt> declaration.
1411 <sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
1413 Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
1414 <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
1417 <sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
1419 End of macro definition (see section <ref id="macros" name="Macros">).
1422 <sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
1424 End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
1427 <sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
1429 End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
1432 <sect1><tt>.ENDSCOPE</tt><label id=".ENDSCOPE"><p>
1434 End of local lexical level (see <tt/<ref id=".SCOPE" name=".SCOPE">/).
1437 <sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
1439 Ends a struct definition. See the section named <ref id="structs"
1440 name="Structs and unions">.
1443 <sect1><tt>.ENUM</tt><label id=".ENUM"><p>
1445 Start an enumeration. This directive is very similar to the C <tt/enum/
1446 keyword. If a name is given, a new scope is created for the enumeration,
1447 otherwise the enumeration members are placed in the enclosing scope.
1449 In the enumeration body, symbols are declared. The first symbol has a value
1450 of zero, and each following symbol will get the value of the preceeding plus
1451 one. This behaviour may be overriden by an explicit assignment. Two symbols
1452 may have the same value.
1464 Above example will create a new scope named <tt/errorcodes/ with three
1465 symbols in it that get the values 0, 1 and 2 respectively. Another way
1466 to write this would have been:
1476 Please note that explicit scoping must be used to access the identifiers:
1479 .word errorcodes::no_error
1482 A more complex example:
1491 EWOULDBLOCK = EAGAIN
1495 In this example, the enumeration does not have a name, which means that the
1496 members will be visible in the enclosing scope and can be used in this scope
1497 without explicit scoping. The first member (<tt/EUNKNOWN/) has the value -1.
1498 The value for the following members is incremented by one, so <tt/EOK/ would
1499 be zero and so on. <tt/EWOULDBLOCK/ is an alias for <tt/EGAIN/, so it has an
1500 override for the value using an already defined symbol.
1503 <sect1><tt>.ERROR</tt><label id=".ERROR"><p>
1505 Force an assembly error. The assembler will output an error message
1506 preceeded by "User error" and will <em/not/ produce an object file.
1508 This command may be used to check for initial conditions that must be
1509 set before assembling a source file.
1519 .error "Must define foo or bar!"
1523 See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
1524 id=".OUT" name=".OUT"></tt> directives.
1527 <sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
1529 Abort a macro expansion immidiately. This command is often useful in
1530 recursive macros. See separate section <ref id="macros" name="Macros">.
1533 <sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
1535 Make symbols accessible from other modules. Must be followed by a comma
1536 separated list of symbols to export.
1544 See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
1547 <sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
1549 Make symbols accessible from other modules. Must be followed by a comma
1550 separated list of symbols to export. The exported symbols are explicitly
1551 marked as zero page symols.
1559 See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
1562 <sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
1564 Define far (24 bit) address data. The command must be followed by a
1565 sequence of (not necessarily constant) expressions.
1570 .faraddr DrawCircle, DrawRectangle, DrawHexagon
1573 See: <tt><ref id=".ADDR" name=".ADDR"></tt>
1576 <sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
1578 This directive may be used to enable one or more compatibility features
1579 of the assembler. While the use of <tt/.FEATURE/ should be avoided when
1580 possible, it may be useful when porting sources written for other
1581 assemblers. There is no way to switch a feature off, once you have
1582 enabled it, so using
1588 will enable the feature until end of assembly is reached.
1590 The following features are available:
1594 <tag><tt>dollar_is_pc</tt></tag>
1596 The dollar sign may be used as an alias for the star (`*'), which
1597 gives the value of the current PC in expressions.
1598 Note: Assignment to the pseudo variable is not allowed.
1600 <tag><tt>labels_without_colons</tt></tag>
1602 Allow labels without a trailing colon. These labels are only accepted,
1603 if they start at the beginning of a line (no leading white space).
1605 <tag><tt>loose_string_term</tt></tag>
1607 Accept single quotes as well as double quotes as terminators for string
1610 <tag><tt>loose_char_term</tt></tag>
1612 Accept single quotes as well as double quotes as terminators for char
1615 <tag><tt>at_in_identifiers</tt></tag>
1617 Accept the at character (`@') as a valid character in identifiers. The
1618 at character is not allowed to start an identifier, even with this
1621 <tag><tt>dollar_in_identifiers</tt></tag>
1623 Accept the dollar sign (`$') as a valid character in identifiers. The
1624 at character is not allowed to start an identifier, even with this
1627 <tag><tt>leading_dot_in_identifiers</tt></tag>
1629 Accept the dot (`.') as the first character of an identifier. This may be
1630 used for example to create macro names that start with a dot emulating
1631 control directives of other assemblers. Note however, that none of the
1632 reserved keywords built into the assembler, that starts with a dot, may be
1633 overridden. When using this feature, you may also get into trouble if
1634 later versions of the assembler define new keywords starting with a dot.
1636 <tag><tt>pc_assignment</tt></tag>
1638 Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
1639 is enabled). Such an assignment is handled identical to the <tt><ref
1640 id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
1641 removing the lines with the assignments may also be an option when porting
1642 code written for older assemblers).
1646 It is also possible to specify features on the command line using the
1647 <tt><ref id="option--feature" name="--feature"></tt> command line option.
1648 This is useful when translating sources written for older assemblers, when
1649 you don't want to change the source code.
1651 As an example, to translate sources written for Andre Fachats xa65
1652 assembler, the features
1655 labels_without_colons, pc_assignment, loose_char_term
1658 may be helpful. They do not make ca65 completely compatible, so you may not
1659 be able to translate the sources without changes, even when enabling these
1660 features. However, I have found several sources that translate without
1661 problems when enabling these features on the command line.
1664 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
1666 Insert an option string into the object file. There are two forms of
1667 this command, one specifies the option by a keyword, the second
1668 specifies it as a number. Since usage of the second one needs knowledge
1669 of the internal encoding, its use is not recommended and I will only
1670 describe the first form here.
1672 The command is followed by one of the keywords
1680 a comma and a string. The option is written into the object file
1681 together with the string value. This is currently unidirectional and
1682 there is no way to actually use these options once they are in the
1688 .fileopt comment, "Code stolen from my brother"
1689 .fileopt compiler, "BASIC 2.0"
1690 .fopt author, "J. R. User"
1694 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
1696 Import an absolute symbol from another module. The command is followed by a
1697 comma separated list of symbols to import. The command is similar to <tt>
1698 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
1699 written to the generated object file, even if the symbol is never referenced
1700 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
1701 references for unused symbols).
1706 .forceimport needthisone, needthistoo
1709 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
1712 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
1714 Declare symbols as global. Must be followed by a comma separated list of
1715 symbols to declare. Symbols from the list, that are defined somewhere in the
1716 source, are exported, all others are imported. Additional <tt><ref
1717 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
1718 name=".EXPORT"></tt> commands for the same symbol are allowed.
1727 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
1729 Declare symbols as global. Must be followed by a comma separated list of
1730 symbols to declare. Symbols from the list, that are defined somewhere in the
1731 source, are exported, all others are imported. Additional <tt><ref
1732 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
1733 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
1734 in the list are explicitly marked as zero page symols.
1743 <sect1><tt>.I16</tt><label id=".I16"><p>
1745 Valid only in 65816 mode. Switch the index registers to 16 bit.
1747 Note: This command will not emit any code, it will tell the assembler to
1748 create 16 bit operands for immediate operands.
1750 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
1751 name=".SMART"></tt> commands.
1754 <sect1><tt>.I8</tt><label id=".I8"><p>
1756 Valid only in 65816 mode. Switch the index registers to 8 bit.
1758 Note: This command will not emit any code, it will tell the assembler to
1759 create 8 bit operands for immediate operands.
1761 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
1762 name=".SMART"></tt> commands.
1765 <sect1><tt>.IF</tt><label id=".IF"><p>
1767 Conditional assembly: Evalute an expression and switch assembler output
1768 on or off depending on the expression. The expression must be a constant
1769 expression, that is, all operands must be defined.
1771 A expression value of zero evaluates to FALSE, any other value evaluates
1775 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
1777 Conditional assembly: Check if there are any remaining tokens in this line,
1778 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
1779 condition is not true, further lines are not assembled until an <tt><ref
1780 id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
1781 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
1783 This command is often used to check if a macro parameter was given. Since an
1784 empty macro parameter will evaluate to nothing, the condition will evaluate
1785 to FALSE if an empty parameter was given.
1799 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
1802 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
1804 Conditional assembly: Evaluate an expression and switch assembler output
1805 on or off depending on the constness of the expression.
1807 A const expression evaluates to to TRUE, a non const expression (one
1808 containing an imported or currently undefined symbol) evaluates to
1811 See also: <tt><ref id=".CONST" name=".CONST"></tt>
1814 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
1816 Conditional assembly: Check if a symbol is defined. Must be followed by
1817 a symbol name. The condition is true if the the given symbol is already
1818 defined, and false otherwise.
1820 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1823 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
1825 Conditional assembly: Check if there are any remaining tokens in this line,
1826 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
1827 condition is not true, further lines are not assembled until an <tt><ref
1828 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
1829 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
1831 This command is often used to check if a macro parameter was given.
1832 Since an empty macro parameter will evaluate to nothing, the condition
1833 will evaluate to FALSE if an empty parameter was given.
1846 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
1849 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
1851 Conditional assembly: Check if a symbol is defined. Must be followed by
1852 a symbol name. The condition is true if the the given symbol is not
1853 defined, and false otherwise.
1855 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1858 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
1860 Conditional assembly: Check if a symbol is referenced. Must be followed
1861 by a symbol name. The condition is true if if the the given symbol was
1862 not referenced before, and false otherwise.
1864 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
1867 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
1869 Conditional assembly: Check if the assembler is currently in 6502 mode
1870 (see <tt><ref id=".P02" name=".P02"></tt> command).
1873 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
1875 Conditional assembly: Check if the assembler is currently in 65816 mode
1876 (see <tt><ref id=".P816" name=".P816"></tt> command).
1879 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
1881 Conditional assembly: Check if the assembler is currently in 65C02 mode
1882 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
1885 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
1887 Conditional assembly: Check if the assembler is currently in 65SC02 mode
1888 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
1891 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
1893 Conditional assembly: Check if a symbol is referenced. Must be followed
1894 by a symbol name. The condition is true if if the the given symbol was
1895 referenced before, and false otherwise.
1897 This command may be used to build subroutine libraries in include files
1898 (you may use separate object modules for this purpose too).
1903 .ifref ToHex ; If someone used this subroutine
1904 ToHex: tay ; Define subroutine
1910 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
1913 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
1915 Import a symbol from another module. The command is followed by a comma
1916 separated list of symbols to import.
1924 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
1927 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
1929 Import a symbol from another module. The command is followed by a comma
1930 separated list of symbols to import. The symbols are explicitly imported
1931 as zero page symbols (that is, symbols with values in byte range).
1939 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
1942 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
1944 Include a file as binary data. The command expects a string argument
1945 that is the name of a file to include literally in the current segment.
1946 In addition to that, a start offset and a size value may be specified,
1947 separated by commas. If no size is specified, all of the file from the
1948 start offset to end-of-file is used. If no start position is specified
1949 either, zero is assume (which means that the whole file is inserted).
1954 ; Include whole file
1955 .incbin "sprites.dat"
1957 ; Include file starting at offset 256
1958 .incbin "music.dat", $100
1960 ; Read 100 bytes starting at offset 200
1961 .incbin "graphics.dat", 200, 100
1965 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
1967 Include another file. Include files may be nested up to a depth of 16.
1976 <sect1><tt>.LEFT</tt><label id=".LEFT"><p>
1978 Builtin function. Extracts the left part of a given token list.
1983 .LEFT (<int expr>, <token list>)
1986 The first integer expression gives the number of tokens to extract from
1987 the token list. The second argument is the token list itself.
1991 To check in a macro if the given argument has a '#' as first token
1992 (immidiate addressing mode), use something like this:
1997 .if (.match (.left (1, arg), #))
1999 ; ldax called with immidiate operand
2007 See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
2008 name=".RIGHT"></tt> builtin functions.
2011 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
2013 Switch on or off line continuations using the backslash character
2014 before a newline. The option is off by default.
2015 Note: Line continuations do not work in a comment. A backslash at the
2016 end of a comment is treated as part of the comment and does not trigger
2018 The command must be followed by a '+' or '-' character to switch the
2019 option on or off respectively.
2024 .linecont + ; Allow line continuations
2027 #$20 ; This is legal now
2031 <sect1><tt>.LIST</tt><label id=".LIST"><p>
2033 Enable output to the listing. The command must be followed by a boolean
2034 switch ("on", "off", "+" or "-") and will enable or disable listing
2036 The option has no effect if the listing is not enabled by the command line
2037 switch -l. If -l is used, an internal counter is set to 1. Lines are output
2038 to the listing file, if the counter is greater than zero, and suppressed if
2039 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
2045 .list on ; Enable listing output
2049 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
2051 Set, how many bytes are shown in the listing for one source line. The
2052 default is 12, so the listing will show only the first 12 bytes for any
2053 source line that generates more than 12 bytes of code or data.
2054 The directive needs an argument, which is either "unlimited", or an
2055 integer constant in the range 4..255.
2060 .listbytes unlimited ; List all bytes
2061 .listbytes 12 ; List the first 12 bytes
2062 .incbin "data.bin" ; Include large binary file
2066 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
2068 This command may only be used inside a macro definition. It declares a
2069 list of identifiers as local to the macro expansion.
2071 A problem when using macros are labels: Since they don't change their name,
2072 you get a "duplicate symbol" error if the macro is expanded the second time.
2073 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
2074 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
2077 Some other assemblers start a new lexical block inside a macro expansion.
2078 This has some drawbacks however, since that will not allow <em/any/ symbol
2079 to be visible outside a macro, a feature that is sometimes useful. The
2080 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
2081 to address the problem.
2083 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
2087 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
2089 Defines the character that start "cheap" local labels. You may use one
2090 of '@' and '?' as start character. The default is '@'.
2092 Cheap local labels are labels that are visible only between two non
2093 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
2094 using explicit lexical nesting.
2101 Clear: lda #$00 ; Global label
2102 ?Loop: sta Mem,y ; Local label
2106 Sub: ... ; New global label
2107 bne ?Loop ; ERROR: Unknown identifier!
2111 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
2113 Insert a predefined macro package. The command is followed by an
2114 identifier specifying the macro package to insert. Available macro
2118 generic Defines generic macros like add and sub.
2119 longbranch Defines conditional long jump macros.
2120 cbm Defines the scrcode macro
2121 cpu Defines constants for the .CPU variable
2124 Including a macro package twice, or including a macro package that
2125 redefines already existing macros will lead to an error.
2130 .macpack longbranch ; Include macro package
2132 cmp #$20 ; Set condition codes
2133 jne Label ; Jump long on condition
2136 Macro packages are explained in more detail in section <ref
2137 id="macropackages" name="Macro packages">.
2140 <sect1><tt>.MAC, .MACRO</tt><label id=".MAC"><p>
2142 Start a classic macro definition. The command is followed by an identifier
2143 (the macro name) and optionally by a comma separated list of identifiers
2144 that are macro parameters.
2146 See section <ref id="macros" name="Macros">.
2149 <sect1><tt>.MATCH</tt><label id=".MATCH"><p>
2151 Builtin function. Matches two token lists against each other. This is
2152 most useful within macros, since macros are not stored as strings, but
2158 .MATCH(<token list #1>, <token list #2>)
2161 Both token list may contain arbitrary tokens with the exception of the
2162 terminator token (comma resp. right parenthesis) and
2169 Often a macro parameter is used for any of the token lists.
2171 Please note that the function does only compare tokens, not token
2172 attributes. So any number is equal to any other number, regardless of the
2173 actual value. The same is true for strings. If you need to compare tokens
2174 <em/and/ token attributes, use the <tt><ref id=".XMATCH"
2175 name=".XMATCH"></tt> function.
2179 Assume the macro <tt/ASR/, that will shift right the accumulator by one,
2180 while honoring the sign bit. The builtin processor instructions will allow
2181 an optional "A" for accu addressing for instructions like <tt/ROL/ and
2182 <tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
2183 to check for this and print and error for invalid calls.
2188 .if (.not .blank(arg)) .and (.not .match (arg, a))
2189 .error "Syntax error"
2192 cmp #$80 ; Bit 7 into carry
2193 lsr a ; Shift carry into bit 7
2198 The macro will only accept no arguments, or one argument that must be the
2199 reserved keyword "A".
2201 See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
2204 <sect1><tt>.MID</tt><label id=".MID"><p>
2206 Builtin function. Takes a starting index, a count and a token list as
2207 arguments. Will return part of the token list.
2212 .MID (<int expr>, <int expr>, <token list>)
2215 The first integer expression gives the starting token in the list (the
2216 first token has index 0). The second integer expression gives the number
2217 of tokens to extract from the token list. The third argument is the
2222 To check in a macro if the given argument has a '<tt/#/' as first token
2223 (immidiate addressing mode), use something like this:
2228 .if (.match (.mid (0, 1, arg), #))
2230 ; ldax called with immidiate operand
2238 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
2239 name=".RIGHT"></tt> builtin functions.
2242 <sect1><tt>.ORG</tt><label id=".ORG"><p>
2244 Start a section of absolute code. The command is followed by a constant
2245 expression that gives the new PC counter location for which the code is
2246 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
2249 Please note that you <em/do not need/ this command in most cases. Placing
2250 code at a specific address is the job of the linker, not the assembler, so
2251 there is usually no reason to assemble code to a specific address.
2253 You may not switch segments while inside a section of absolute code.
2258 .org $7FF ; Emit code starting at $7FF
2262 <sect1><tt>.OUT</tt><label id=".OUT"><p>
2264 Output a string to the console without producing an error. This command
2265 is similiar to <tt/.ERROR/, however, it does not force an assembler error
2266 that prevents the creation of an object file.
2271 .out "This code was written by the codebuster(tm)"
2274 See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
2275 id=".ERROR" name=".ERROR"></tt> directives.
2278 <sect1><tt>.P02</tt><label id=".P02"><p>
2280 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
2281 instructions. This is the default if not overridden by the
2282 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
2284 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
2285 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
2288 <sect1><tt>.P816</tt><label id=".P816"><p>
2290 Enable the 65816 instruction set. This is a superset of the 65SC02 and
2291 6502 instruction sets.
2293 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
2294 name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
2297 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
2299 Set the page length for the listing. Must be followed by an integer
2300 constant. The value may be "unlimited", or in the range 32 to 127. The
2301 statement has no effect if no listing is generated. The default value is -1
2302 (unlimited) but may be overridden by the <tt/--pagelength/ command line
2303 option. Beware: Since ca65 is a one pass assembler, the listing is generated
2304 after assembly is complete, you cannot use multiple line lengths with one
2305 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
2310 .pagelength 66 ; Use 66 lines per listing page
2312 .pagelength unlimited ; Unlimited page length
2316 <sect1><tt>.PARAMCOUNT</tt><label id=".PARAMCOUNT"><p>
2318 This builtin pseudo variable is only available in macros. It is replaced by
2319 the actual number of parameters that were given in the macro invocation.
2324 .macro foo arg1, arg2, arg3
2325 .if .paramcount <> 3
2326 .error "Too few parameters for macro foo"
2332 See section <ref id="macros" name="Macros">.
2335 <sect1><tt>.PC02</tt><label id=".PC02"><p>
2337 Enable the 65C02 instructions set. This instruction set includes all
2338 6502 and 65SC02 instructions.
2340 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
2341 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
2344 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
2346 Pop the last pushed segment from the stack, and set it.
2348 This command will switch back to the segment that was last pushed onto the
2349 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
2350 command, and remove this entry from the stack.
2352 The assembler will print an error message if the segment stack is empty
2353 when this command is issued.
2355 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
2358 <sect1><tt>.PROC</tt><label id=".PROC"><p>
2360 Start a nested lexical level with the given name and adds a symbol with this
2361 name to the enclosing scope. All new symbols from now on are in the local
2362 lexical level and are accessible from outside only via <ref id="scopesyntax"
2363 name="explicit scope specification">. Symbols defined outside this local
2364 level may be accessed as long as their names are not used for new symbols
2365 inside the level. Symbols names in other lexical levels do not clash, so you
2366 may use the same names for identifiers. The lexical level ends when the
2367 <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
2368 may be nested up to a depth of 16 (this is an artificial limit to protect
2369 against errors in the source).
2371 Note: Macro names are always in the global level and in a separate name
2372 space. There is no special reason for this, it's just that I've never
2373 had any need for local macro definitions.
2378 .proc Clear ; Define Clear subroutine, start new level
2380 L1: sta Mem,y ; L1 is local and does not cause a
2381 ; duplicate symbol error if used in other
2384 bne L1 ; Reference local symbol
2386 .endproc ; Leave lexical level
2389 See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
2393 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
2395 Enable the 65SC02 instructions set. This instruction set includes all
2398 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
2399 name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
2402 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
2404 Push the currently active segment onto a stack. The entries on the stack
2405 include the name of the segment and the segment type. The stack has a size
2408 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
2409 to switch to another segment and to restore the old segment later, without
2410 even knowing the name and type of the current segment.
2412 The assembler will print an error message if the segment stack is already
2413 full, when this command is issued.
2415 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
2418 <sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
2420 Builtin function. The function expects an identifier as argument in braces.
2421 The argument is evaluated, and the function yields "true" if the identifier
2422 is a symbol that has already been referenced somewhere in the source file up
2423 to the current position. Otherwise the function yields false. As an example,
2424 the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
2430 See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2433 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
2435 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
2436 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
2437 a constant expression that tells how many times the commands in the body
2438 should get repeated. Optionally, a comma and an identifier may be specified.
2439 If this identifier is found in the body of the repeat statement, it is
2440 replaced by the current repeat count (starting with zero for the first time
2441 the body is repeated).
2443 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
2444 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
2445 level will be used, not the one from the outer level.
2449 The following macro will emit a string that is "encrypted" in that all
2450 characters of the string are XORed by the value $55.
2454 .repeat .strlen(Arg), I
2455 .byte .strat(Arg, I) .xor $55
2460 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
2463 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
2465 Switch back to relocatable mode. See the <tt><ref id=".ORG"
2466 name=".ORG"></tt> command.
2469 <sect1><tt>.RES</tt><label id=".RES"><p>
2471 Reserve storage. The command is followed by one or two constant
2472 expressions. The first one is mandatory and defines, how many bytes of
2473 storage should be defined. The second, optional expression must by a
2474 constant byte value that will be used as value of the data. If there
2475 is no fill value given, the linker will use the value defined in the
2476 linker configuration file (default: zero).
2481 ; Reserve 12 bytes of memory with value $AA
2486 <sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
2488 Builtin function. Extracts the right part of a given token list.
2493 .RIGHT (<int expr>, <token list>)
2496 The first integer expression gives the number of tokens to extract from
2497 the token list. The second argument is the token list itself.
2499 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
2500 name=".MID"></tt> builtin functions.
2503 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
2505 Switch to the RODATA segment. The name of the RODATA segment is always
2506 "RODATA", so this is a shortcut for
2512 The RODATA segment is a segment that is used by the compiler for
2513 readonly data like string constants.
2515 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2518 <sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
2520 Start a nested lexical level with the given name. All new symbols from now
2521 on are in the local lexical level and are accessible from outside only via
2522 <ref id="scopesyntax" name="explicit scope specification">. Symbols defined
2523 outside this local level may be accessed as long as their names are not used
2524 for new symbols inside the level. Symbols names in other lexical levels do
2525 not clash, so you may use the same names for identifiers. The lexical level
2526 ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
2527 read. Lexical levels may be nested up to a depth of 16 (this is an
2528 artificial limit to protect against errors in the source).
2530 Note: Macro names are always in the global level and in a separate name
2531 space. There is no special reason for this, it's just that I've never
2532 had any need for local macro definitions.
2537 .scope Error ; Start new scope named Error
2539 File = 1 ; File error
2540 Parse = 2 ; Parse error
2541 .endproc ; Close lexical level
2544 lda #Error::File ; Use symbol from scope Error
2547 See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
2551 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
2553 Switch to another segment. Code and data is always emitted into a
2554 segment, that is, a named section of data. The default segment is
2555 "CODE". There may be up to 254 different segments per object file
2556 (and up to 65534 per executable). There are shortcut commands for
2557 the most common segments ("CODE", "DATA" and "BSS").
2559 The command is followed by a string containing the segment name (there
2560 are some constraints for the name - as a rule of thumb use only those
2561 segment names that would also be valid identifiers). There may also be
2562 an optional attribute separated by a comma. Valid attributes are
2563 "<tt/zeropage/" and "<tt/absolute/".
2565 When specifying a segment for the first time, "absolute" is the
2566 default. For all other uses, the attribute specified the first time
2569 "absolute" means that this is a segment with absolute addressing. That
2570 is, the segment will reside somewhere in core memory outside the zero
2571 page. "zeropage" means the opposite: The segment will be placed in the
2572 zero page and direct (short) addressing is possible for data in this
2575 Beware: Only labels in a segment with the zeropage attribute are marked
2576 as reachable by short addressing. The `*' (PC counter) operator will
2577 work as in other segments and will create absolute variable values.
2582 .segment "ROM2" ; Switch to ROM2 segment
2583 .segment "ZP2", zeropage ; New direct segment
2584 .segment "ZP2" ; Ok, will use last attribute
2585 .segment "ZP2", absolute ; Error, redecl mismatch
2588 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
2589 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt> and <tt><ref
2590 id=".RODATA" name=".RODATA"></tt>
2593 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
2595 Switch the CPU instruction set. The command is followed by a string that
2596 specifies the CPU. Possible values are those that can also be supplied to
2597 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
2598 namely: 6502, 65SC02, 65C02, 65816 and sunplus. Please note that support
2599 for the sunplus CPU is not available in the freeware version, because the
2600 instruction set of the sunplus CPU is "proprietary and confidential".
2602 See: <tt><ref id=".CPU" name=".CPU"></tt>,
2603 <tt><ref id=".IFP02" name=".IFP02"></tt>,
2604 <tt><ref id=".IFP816" name=".IFP816"></tt>,
2605 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
2606 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
2607 <tt><ref id=".P02" name=".P02"></tt>,
2608 <tt><ref id=".P816" name=".P816"></tt>,
2609 <tt><ref id=".PC02" name=".PC02"></tt>,
2610 <tt><ref id=".PSC02" name=".PSC02"></tt>
2613 <sect1><tt>.SIZEOF</tt><label id=".SIZEOF"><p>
2615 <tt/.SIZEOF/ is a pseudo function that returns the size of its argument. The
2616 argument can be a struct/union, a struct member, a procedure, or a label. In
2617 case of a procedure or label, its size is defined by the amount of data
2618 placed in the segment where the label is relative to. If a line of code
2619 switches segments (for example in a macro) data placed in other segments
2620 does not count for the size.
2622 Please note that a symbol or scope must exist, before it is used together with
2623 <tt/.SIZEOF/ (this may get relaxed later, but will always be true for scopes).
2624 A scope has preference over a symbol with the same name, so if the last part
2625 of a name represents both, a scope and a symbol, the scope is choosen over the
2628 After the following code:
2631 .struct Point ; Struct size = 4
2636 P: .tag Point ; Declare a point
2637 @P: .tag Point ; Declare another point
2649 .data ; Segment switch!!!
2655 <tag><tt/.sizeof(Point)/</tag>
2656 will have the value 4, because this is the size of struct <tt/Point/.
2658 <tag><tt/.sizeof(Point::xcoord)/</tag>
2659 will have the value 2, because this is the size of the member <tt/xcoord/
2660 in struct <tt/Point/.
2662 <tag><tt/.sizeof(P)/</tag>
2663 will have the value 4, this is the size of the data declared on the same
2664 source line as the label <tt/P/, which is in the same segment that <tt/P/
2667 <tag><tt/.sizeof(@P)/</tag>
2668 will have the value 4, see above. The example demonstrates that <tt/.SIZEOF/
2669 does also work for cheap local symbols.
2671 <tag><tt/.sizeof(Code)/</tag>
2672 will have the value 3, since this is amount of data emitted into the code
2673 segment, the segment that was active when <tt/Code/ was entered. Note that
2674 this value includes the amount of data emitted in child scopes (in this
2675 case <tt/Code::Inner/).
2677 <tag><tt/.sizeof(Code::Inner)/</tag>
2678 will have the value 1 as expected.
2680 <tag><tt/.sizeof(Data)/</tag>
2681 will have the value 0. Data is emitted within the scope <tt/Data/, but since
2682 the segment is switched after entry, this data is emitted into another
2687 <sect1><tt>.SMART</tt><label id=".SMART"><p>
2689 Switch on or off smart mode. The command must be followed by a '+' or
2690 '-' character to switch the option on or off respectively. The default
2691 is off (that is, the assembler doesn't try to be smart), but this
2692 default may be changed by the -s switch on the command line.
2694 In smart mode the assembler will do the following:
2697 <item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
2698 and update the operand sizes accordingly. If the operand of such an
2699 instruction cannot be evaluated by the assembler (for example, because
2700 the operand is an imported symbol), a warning is issued. Beware: Since
2701 the assembler cannot trace the execution flow this may lead to false
2702 results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
2703 instructions to tell the assembler about the current settings.
2704 <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
2705 used within a procedure declared as <tt/far/, or if the procedure has
2706 no explicit address specification, but it is <tt/far/ because of the
2714 .smart - ; Stop being smart
2717 See: <tt><ref id=".A16" name=".A16"></tt>,
2718 <tt><ref id=".A8" name=".A8"></tt>,
2719 <tt><ref id=".I16" name=".I16"></tt>,
2720 <tt><ref id=".I8" name=".I8"></tt>
2723 <sect1><tt>.STRAT</tt><label id=".STRAT"><p>
2725 Builtin function. The function accepts a string and an index as
2726 arguments and returns the value of the character at the given position
2727 as an integer value. The index is zero based.
2733 ; Check if the argument string starts with '#'
2734 .if (.strat (Arg, 0) = '#')
2741 <sect1><tt>.STRING</tt><label id=".STRING"><p>
2743 Builtin function. The function accepts an argument in braces and converts
2744 this argument into a string constant. The argument may be an identifier, or
2745 a constant numeric value.
2747 Since you can use a string in the first place, the use of the function may
2748 not be obvious. However, it is useful in macros, or more complex setups.
2753 ; Emulate other assemblers:
2755 .segment .string(name)
2760 <sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
2762 Builtin function. The function accepts a string argument in braces and
2763 eveluates to the length of the string.
2767 The following macro encodes a string as a pascal style string with
2768 a leading length byte.
2772 .byte .strlen(Arg), Arg
2777 <sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
2779 Starts a struct definition. See the section named <ref id="structs"
2780 name="Structs and unions">.
2783 <sect1><tt>.SUNPLUS</tt><label id=".SUNPLUS"><p>
2785 Enable the SunPlus instructions set. This command will not work in the
2786 freeware version of the assembler, because the instruction set is
2787 "proprietary and confidential".
2789 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
2790 name=".PSC02"></tt>, <tt><ref id=".PC02" name=".PC02"></tt>, and
2791 <tt><ref id=".P816" name=".P816"></tt>
2794 <sect1><tt>.TAG</tt><label id=".TAG"><p>
2796 Allocate space for a struct or union.
2807 .tag Point ; Allocate 4 bytes
2811 <sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
2813 Builtin function. The function accepts a token list in braces. The
2814 function result is the number of tokens given as argument.
2818 The <tt/ldax/ macro accepts the '#' token to denote immidiate addressing (as
2819 with the normal 6502 instructions). To translate it into two separate 8 bit
2820 load instructions, the '#' token has to get stripped from the argument:
2824 .if (.match (.mid (0, 1, arg), #))
2825 ; ldax called with immidiate operand
2826 lda #<(.right (.tcount (arg)-1, arg))
2827 ldx #>(.right (.tcount (arg)-1, arg))
2835 <sect1><tt>.TIME</tt><label id=".TIME"><p>
2837 Reading this pseudo variable will give a constant integer value that
2838 represents the current time in POSIX standard (as seconds since the
2841 It may be used to encode the time of translation somewhere in the created
2847 .dword .time ; Place time here
2851 <sect1><tt>.VERSION</tt><label id=".VERSION"><p>
2853 Reading this pseudo variable will give the assembler version according to
2854 the following formula:
2856 VER_MAJOR*$100 + VER_MINOR*$10 + VER_PATCH
2858 It may be used to encode the assembler version or check the assembler for
2859 special features not available with older versions.
2863 Version 2.11.1 of the assembler will return $2B1 as numerical constant when
2864 reading the pseudo variable <tt/.VERSION/.
2867 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
2869 Force an assembly warning. The assembler will output a warning message
2870 preceeded by "User warning". This warning will always be output, even if
2871 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
2872 command line option.
2874 This command may be used to output possible problems when assembling
2883 .warning "Forward jump in jne, cannot optimize!"
2893 See also the <tt><ref id=".ERROR" name=".ERROR"></tt> and <tt><ref id=".OUT"
2894 name=".OUT"></tt> directives.
2897 <sect1><tt>.WORD</tt><label id=".WORD"><p>
2899 Define word sized data. Must be followed by a sequence of (word ranged,
2900 but not necessarily constant) expressions.
2905 .word $0D00, $AF13, _Clear
2909 <sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
2911 Builtin function. Matches two token lists against each other. This is
2912 most useful within macros, since macros are not stored as strings, but
2918 .XMATCH(<token list #1>, <token list #2>)
2921 Both token list may contain arbitrary tokens with the exception of the
2922 terminator token (comma resp. right parenthesis) and
2929 Often a macro parameter is used for any of the token lists.
2931 The function compares tokens <em/and/ token values. If you need a function
2932 that just compares the type of tokens, have a look at the <tt><ref
2933 id=".MATCH" name=".MATCH"></tt> function.
2935 See: <tt><ref id=".MATCH" name=".MATCH"></tt>
2938 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
2940 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
2941 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
2945 .segment "ZEROPAGE", zeropage
2948 Because of the "zeropage" attribute, labels declared in this segment are
2949 addressed using direct addressing mode if possible. You <em/must/ instruct
2950 the linker to place this segment somewhere in the address range 0..$FF
2951 otherwise you will get errors.
2953 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
2957 <sect>Macros<label id="macros"><p>
2960 <sect1>Introduction<p>
2962 Macros may be thought of as "parametrized super instructions". Macros are
2963 sequences of tokens that have a name. If that name is used in the source
2964 file, the macro is "expanded", that is, it is replaced by the tokens that
2965 were specified when the macro was defined.
2968 <sect1>Macros without parameters<p>
2970 In it's simplest form, a macro does not have parameters. Here's an
2974 .macro asr ; Arithmetic shift right
2975 cmp #$80 ; Put bit 7 into carry
2976 ror ; Rotate right with carry
2980 The macro above consists of two real instructions, that are inserted into
2981 the code, whenever the macro is expanded. Macro expansion is simply done
2982 by using the name, like this:
2991 <sect1>Parametrized macros<p>
2993 When using macro parameters, macros can be even more useful:
3007 When calling the macro, you may give a parameter, and each occurence of
3008 the name "addr" in the macro definition will be replaced by the given
3027 A macro may have more than one parameter, in this case, the parameters
3028 are separated by commas. You are free to give less parameters than the
3029 macro actually takes in the definition. You may also leave intermediate
3030 parameters empty. Empty parameters are replaced by empty space (that is,
3031 they are removed when the macro is exanded). If you have a look at our
3032 macro definition above, you will see, that replacing the "addr" parameter
3033 by nothing will lead to wrong code in most lines. To help you, writing
3034 macros with a variable parameter list, there are some control commands:
3036 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
3037 returns true, if there are any tokens on the remainder of the line. Since
3038 empty parameters are replaced by nothing, this may be used to test if a given
3039 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
3042 Look at this example:
3045 .macro ldaxy a, x, y
3058 This macro may be called as follows:
3061 ldaxy 1, 2, 3 ; Load all three registers
3063 ldaxy 1, , 3 ; Load only a and y
3065 ldaxy , , 3 ; Load y only
3068 There's another helper command for determining, which macro parameters are
3069 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt> This command is
3070 replaced by the parameter count given, <em/including/ intermediate empty macro
3074 ldaxy 1 ; .PARAMCOUNT = 1
3075 ldaxy 1,,3 ; .PARAMCOUNT = 3
3076 ldaxy 1,2 ; .PARAMCOUNT = 2
3077 ldaxy 1, ; .PARAMCOUNT = 2
3078 ldaxy 1,2,3 ; .PARAMCOUNT = 3
3082 <sect1>Detecting parameter types<p>
3084 Sometimes it is nice to write a macro that acts differently depending on the
3085 type of the argument supplied. An example would be a macro that loads a 16 bit
3086 value from either an immediate operand, or from memory. The <tt/<ref
3087 id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
3088 functions will allow you to do exactly this:
3092 .if (.match (.left (1, arg), #))
3094 lda #<(.right (.tcount (arg)-1, arg))
3095 ldx #>(.right (.tcount (arg)-1, arg))
3097 ; assume absolute or zero page
3104 Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
3105 check if its argument begins with a hash mark. If so, two immediate loads are
3106 emitted, Otherwise a load from an absolute zero page memory location is
3107 assumed. So this macro can be used as
3112 ldax #$1234 ; X=$12, A=$34
3114 ldax foo ; X=$56, A=$78
3118 <sect1>Recursive macros<p>
3120 Macros may be used recursively:
3123 .macro push r1, r2, r3
3132 There's also a special macro to help writing recursive macros: <tt><ref
3133 id=".EXITMACRO" name=".EXITMACRO"></tt> This command will stop macro expansion
3137 .macro push r1, r2, r3, r4, r5, r6, r7
3139 ; First parameter is empty
3145 push r2, r3, r4, r5, r6, r7
3149 When expanding this macro, the expansion will push all given parameters
3150 until an empty one is encountered. The macro may be called like this:
3153 push $20, $21, $32 ; Push 3 ZP locations
3154 push $21 ; Push one ZP location
3158 <sect1>Local symbols inside macros<p>
3160 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
3161 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
3162 Have a look at the inc16 macro above. Here is it again:
3176 If you have a closer look at the code, you will notice, that it could be
3177 written more efficiently, like this:
3188 But imagine what happens, if you use this macro twice? Since the label
3189 "Skip" has the same name both times, you get a "duplicate symbol" error.
3190 Without a way to circumvent this problem, macros are not as useful, as
3191 they could be. One solution is, to start a new lexical block inside the
3205 Now the label is local to the block and not visible outside. However,
3206 sometimes you want a label inside the macro to be visible outside. To make
3207 that possible, there's a new command that's only usable inside a macro
3208 definition: <tt><ref id=".LOCAL" name=".LOCAL"></tt>. <tt/.LOCAL/ declares one
3209 or more symbols as local to the macro expansion. The names of local variables
3210 are replaced by a unique name in each separate macro expansion. So we could
3211 also solve the problem above by using <tt/.LOCAL/:
3215 .local Skip ; Make Skip a local symbol
3222 Skip: ; Not visible outside
3227 <sect1>C style macros<p>
3229 Starting with version 2.5 of the assembler, there is a second macro type
3230 available: C style macros using the <tt/.DEFINE/ directive. These macros are
3231 similar to the classic macro type described above, but behaviour is sometimes
3236 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
3237 span more than a line. You may use line continuation (see <tt><ref
3238 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
3239 more than one line for increased readability, but the macro itself
3240 may not contain an end-of-line token.
3242 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
3243 the name space with classic macros, but they are detected and replaced
3244 at the scanner level. While classic macros may be used in every place,
3245 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
3246 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
3247 they are more versatile in some situations.
3249 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
3250 parameters. While classic macros may have empty parameters, this is
3251 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
3252 For this macro type, the number of actual parameters must match
3253 exactly the number of formal parameters.
3255 To make this possible, formal parameters are enclosed in braces when
3256 defining the macro. If there are no parameters, the empty braces may
3259 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
3260 contain end-of-line tokens, there are things that cannot be done. They
3261 may not contain several processor instructions for example. So, while
3262 some things may be done with both macro types, each type has special
3263 usages. The types complement each other.
3267 Let's look at a few examples to make the advantages and disadvantages
3270 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
3271 following <tt/.DEFINE/:
3276 foo EQU $1234 ; This is accepted now
3279 You may use the directive to define string constants used elsewhere:
3282 ; Define the version number
3283 .define VERSION "12.3a"
3289 Macros with parameters may also be useful:
3292 .define DEBUG(message) .out message
3294 DEBUG "Assembling include file #3"
3297 Note that, while formal parameters have to be placed in braces, this is
3298 not true for the actual parameters. Beware: Since the assembler cannot
3299 detect the end of one parameter, only the first token is used. If you
3300 don't like that, use classic macros instead:
3308 (This is an example where a problem can be solved with both macro types).
3311 <sect1>Characters in macros<p>
3313 When using the <ref id="option-t" name="-t"> option, characters are translated
3314 into the target character set of the specific machine. However, this happens
3315 as late as possible. This means that strings are translated if they are part
3316 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
3317 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
3318 used as part of an expression.
3320 This behaviour is very intuitive outside of macros but may be confusing when
3321 doing more complex macros. If you compare characters against numeric values,
3322 be sure to take the translation into account.
3327 <sect>Macro packages<label id="macropackages"><p>
3329 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
3330 macro packages may be included with just one command. Available macro packages
3334 <sect1><tt>.MACPACK generic</tt><p>
3336 This macro package defines macros that are useful in almost any program.
3337 Currently, two macros are defined:
3352 <sect1><tt>.MACPACK longbranch</tt><p>
3354 This macro package defines long conditional jumps. They are named like the
3355 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
3356 definition for the "<tt/jeq/" macro, the other macros are built using the same
3361 .if .def(Target) .and ((*+2)-(Target) <= 127)
3370 All macros expand to a short branch, if the label is already defined (back
3371 jump) and is reachable with a short jump. Otherwise the macro expands to a
3372 conditional branch with the branch condition inverted, followed by an absolute
3373 jump to the actual branch target.
3375 The package defines the following macros:
3378 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
3383 <sect1><tt>.MACPACK cbm</tt><p>
3385 The cbm macro package will define a macro named <tt/scrcode/. It takes a
3386 string as argument and places this string into memory translated into screen
3390 <sect1><tt>.MACPACK cpu</tt><p>
3392 This macro package does not define any macros but constants used to examine
3393 the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
3394 each supported CPU a constant similar to
3404 is defined. These constants may be used to determine the exact type of the
3405 currently enabled CPU. In addition to that, for each CPU instruction set,
3406 another constant is defined:
3416 The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
3417 be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
3418 currently enabled CPU supports a specific instruction set. For example the
3419 65C02 supports all instructions of the 65SC02 CPU, so it has the
3420 <tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
3424 .if (.cpu .bitand CPU_ISET_65SC02)
3432 it is possible to determine if the
3438 instruction is supported, which is the case for the 65SC02, 65C02 and 65816
3439 CPUs (the latter two are upwards compatible to the 65SC02).
3443 <sect>Structs and unions<label id="structs"><p>
3445 Structs and unions are special forms of <ref id="scopes" name="scopes">. They
3446 are to some degree comparable to their C counterparts. Both have a list of
3447 members. Each member allocates storage and may optionally have a name, which,
3448 in case of a struct, is the offset from the beginning and, in case of a union
3451 Here is an example for a very simple struct with two members and a total size
3461 A union shares the total space between all its members, its size is the same
3462 as that of the largest member.
3464 A struct or union must not necessarily have a name. If it is anonymous, no
3465 local scope is opened, the identifiers used to name the members are placed
3466 into the current scope instead.
3468 A struct may contain unnamed members and definitions of local structs. The
3469 storage allocators may contain a multiplier, as in the example below:
3474 .word 2 ; Allocate two words
3480 Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to embedd
3481 already defined structs or unions in structs:
3495 Space for a struct or union may be allocated using the <ref id=".TAG"
3496 name=".TAG"> directive.
3500 <sect>Module constructors/destructors<label id="condes"><p>
3502 <em>Note:</em> This section applies mostly to C programs, so the explanation
3503 below uses examples from the C libraries. However, the feature may also be
3504 useful for assembler programs.
3507 <sect1>Module overview<p>
3509 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> and <tt><ref
3510 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> keywords it it possible to export
3511 functions in a special way. The linker is able to generate tables with all
3512 functions of a specific type. Such a table will <em>only</em> include symbols
3513 from object files that are linked into a specific executable. This may be used
3514 to add initialization and cleanup code for library modules.
3516 The C heap functions are an example where module initialization code is used.
3517 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
3518 variables that contain the start and the end of the heap, pointers to the free
3519 list and so on. Since the end of the heap depends on the size and start of the
3520 stack, it must be initialized at runtime. However, initializing these
3521 variables for programs that do not use the heap are a waste of time and
3524 So the central module defines a function that contains initialization code and
3525 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
3526 this module is added to an executable by the linker, the initialization
3527 function will be placed into the table of constructors by the linker. The C
3528 startup code will call all constructors before <tt/main/ and all destructors
3529 after <tt/main/, so without any further work, the heap initialization code is
3530 called once the module is linked in.
3532 While it would be possible to add explicit calls to initialization functions
3533 in the startup code, the new approach has several advantages:
3537 If a module is not included, the initialization code is not linked in and not
3538 called. So you don't pay for things you don't need.
3541 Adding another library that needs initialization does not mean that the
3542 startup code has to be changed. Before we had module constructors and
3543 destructors, the startup code for all systems had to be adjusted to call the
3544 new initialization code.
3547 The feature saves memory: Each additional initialization function needs just
3548 two bytes in the table (a pointer to the function).
3553 <sect1>Calling order<p>
3555 Both, constructors and destructors are sorted in increasing priority order by
3556 the linker when using one of the builtin linker configurations, so the
3557 functions with lower priorities come first and are followed by those with
3558 higher priorities. The C library runtime subroutine that walks over the
3559 constructor and destructor tables calls the functions starting from the top of
3560 the table - which means that functions with a high priority are called first.
3562 So when using the C runtime, both constructors and destructors are called with
3563 high priority functions first, followed by low priority functions.
3568 When creating and using module constructors and destructors, please take care
3574 The linker will only generate function tables, it will not generate code to
3575 call these functions. If you're using the feature in some other than the
3576 existing C environments, you have to write code to call all functions in a
3577 linker generated table yourself. See the <tt>condes</tt> module in the C
3578 runtime for an example on how to do this.
3581 The linker will only add addresses of functions that are in modules linked to
3582 the executable. This means that you have to be careful where to place the
3583 condes functions. If initialization is needed for a group of functions, be
3584 sure to place the initialization function into a module that is linked in
3585 regardless of which function is called by the user.
3588 The linker will generate the tables only when requested to do so by the
3589 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
3590 be requested separately.
3593 Constructors and destructors may have priorities. These priorities determine
3594 the order of the functions in the table. If your intialization or cleanup code
3595 does depend on other initialization or cleanup code, you have to choose the
3596 priority for the functions accordingly.
3599 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> and <tt><ref
3600 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> statements, there is also a more
3601 generic command: <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to
3602 specify an additional type. Predefined types are 0 (constructor) and 1
3603 (destructor). The linker generates a separate table for each type on request.
3608 <sect>Porting sources from other assemblers<p>
3610 Sometimes it is necessary to port code written for older assemblers to ca65.
3611 In some cases, this can be done without any changes to the source code by
3612 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
3613 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
3616 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
3617 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
3618 done by the linker. Most other assemblers generate absolute code, placement is
3619 done within the assembler and there is no external linker.
3621 In general it is not a good idea to write new code using the emulation
3622 features of the assembler, but there may be situations where even this rule is
3627 You need to use some of the ca65 emulation features to simulate the behaviour
3628 of such simple assemblers.
3631 <item>Prepare your sourcecode like this:
3634 ; if you want TASS style labels without colons
3635 .feature labels_without_colons
3637 ; if you want TASS style character constants
3638 ; ("a" instead of the default 'a')
3639 .feature loose_char_term
3641 .word *+2 ; the cbm load address
3646 notice that the two emulation features are mostly useful for porting
3647 sources originally written in/for TASS, they are not needed for the
3648 actual "simple assembler operation" and are not recommended if you are
3649 writing new code from scratch.
3651 <item>Replace all program counter assignments (which are not possible in ca65
3652 by default, and the respective emulation feature works different from what
3653 you'd expect) by another way to skip to another memory location, for example
3654 the <tt><ref id=".RES" name=".RES"></tt>directive.
3658 .res $2000-* ; reserve memory up to $2000
3661 notice that other than the original TASS, ca65 can never move the
3662 programmcounter backwards - think of it as if you are assembling to disc with
3665 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
3666 rewritten to match ca65 syntax. Most importantly notice that due to the lack
3667 of <tt/.goto/, everything involving loops must be replaced by
3668 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
3670 <item>To assemble code to a different address than it is executed at, use the
3671 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
3672 <tt/.offs/-constructs.
3679 .reloc ; back to normal
3682 <item>Then assemble like this:
3685 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
3688 notice that you need to use the actual start address minus two, since two
3689 bytes are used for the cbm load address.
3694 <sect>Bugs/Feedback<p>
3696 If you have problems using the assembler, if you find any bugs, or if
3697 you're doing something interesting with the assembler, I would be glad to
3698 hear from you. Feel free to contact me by email
3699 (<htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">).
3705 ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
3706 Bassewitz. For usage of the binaries and/or sources the following
3707 conditions do apply:
3709 This software is provided 'as-is', without any expressed or implied
3710 warranty. In no event will the authors be held liable for any damages
3711 arising from the use of this software.
3713 Permission is granted to anyone to use this software for any purpose,
3714 including commercial applications, and to alter it and redistribute it
3715 freely, subject to the following restrictions:
3718 <item> The origin of this software must not be misrepresented; you must not
3719 claim that you wrote the original software. If you use this software
3720 in a product, an acknowledgment in the product documentation would be
3721 appreciated but is not required.
3722 <item> Altered source versions must be plainly marked as such, and must not
3723 be misrepresented as being the original software.
3724 <item> This notice may not be removed or altered from any source