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 --list-bytes n Maximum number of bytes per listing line
113 --listing Create a listing if assembly was ok
114 --pagelength n Set the page length for the listing
115 --smart Enable smart mode
116 --target sys Set the target system
117 --verbose Increase verbosity
118 --version Print the assembler version
119 ---------------------------------------------------------------------------
123 <sect1>Command line options in detail<p>
125 Here is a description of all the command line options:
129 <label id="option--cpu">
130 <tag><tt>--cpu type</tt></tag>
132 Set the default for the CPU type. The option takes a parameter, which
135 6502, 65SC02, 65C02, 65816 and sunplus
137 The last one (sunplus) is not available in the freeware version, because the
138 instruction set of the sunplus CPU is "proprietary and confidential".
141 <label id="option--feature">
142 <tag><tt>--feature name</tt></tag>
144 Enable an emulation feature. This is identical as using <tt/.FEATURE/
145 in the source with two exceptions: Feature names must be lower case, and
146 each feature must be specified by using an extra <tt/--feature/ option,
147 comma separated lists are not allowed.
149 See the discussion of the <tt><ref id=".FEATURE" name=".FEATURE"></tt>
150 command for a list of emulation features.
153 <label id="option-g">
154 <tag><tt>-g, --debug-info</tt></tag>
156 When this option (or the equivalent control command <tt/.DEBUGINFO/) is
157 used, the assembler will add a section to the object file that contains
158 all symbols (including local ones) together with the symbol values and
159 source file positions. The linker will put these additional symbols into
160 the VICE label file, so even local symbols can be seen in the VICE
164 <tag><tt>-h, --help</tt></tag>
166 Print the short option summary shown above.
169 <tag><tt>-i, --ignore-case</tt></tag>
171 This option makes the assembler case insensitive on identifiers and labels.
172 This option will override the default, but may itself be overriden by the
173 <tt><ref id=".CASE" name=".CASE"></tt> control command.
176 <tag><tt>-l, --listing</tt></tag>
178 Generate an assembler listing. The listing file will always have the
179 name of the main input file with the extension replaced by ".lst". This
180 may change in future versions.
183 <tag><tt>--list-bytes n</tt></tag>
185 Set the maximum number of bytes printed in the listing for one line of
186 input. See the <tt><ref id=".LISTBYTES" name=".LISTBYTES"></tt> directive
187 for more information. The value zero can be used to encode an unlimited
188 number of printed bytes.
191 <tag><tt>-o name</tt></tag>
193 The default output name is the name of the input file with the extension
194 replaced by ".o". If you don't like that, you may give another name with
195 the -o option. The output file will be placed in the same directory as
196 the source file, or, if -o is given, the full path in this name is used.
199 <tag><tt>--pagelength n</tt></tag>
201 sets the length of a listing page in lines. See the <tt><ref
202 id=".PAGELENGTH" name=".PAGELENGTH"></tt> directive for more information.
205 <tag><tt>-s, --smart-mode</tt></tag>
207 In smart mode (enabled by -s or the <tt><ref id=".SMART" name=".SMART"></tt>
208 pseudo instruction) the assembler will track usage of the <tt/REP/ and
209 <tt/SEP/ instructions in 65816 mode and update the operand sizes
210 accordingly. If the operand of such an instruction cannot be evaluated by
211 the assembler (for example, because the operand is an imported symbol), a
214 Beware: Since the assembler cannot trace the execution flow this may
215 lead to false results in some cases. If in doubt, use the .ixx and .axx
216 instructions to tell the assembler about the current settings. Smart
217 mode is off by default.
220 <label id="option-t">
221 <tag><tt>-t sys, --target sys</tt></tag>
223 Set the target system. This will enable translation of character strings
224 and character constants into the character set of the target platform.
225 The default for the target system is "none", which means that no translation
226 will take place. The assembler supports the same target systems as the
227 compiler, see there for a list.
230 <tag><tt>-v, --verbose</tt></tag>
232 Increase the assembler verbosity. Usually only needed for debugging
233 purposes. You may use this option more than one time for even more
237 <tag><tt>-D</tt></tag>
239 This option allows you to define symbols on the command line. Without a
240 value, the symbol is defined with the value zero. When giving a value,
241 you may use the '$' prefix for hexadecimal symbols. Please note
242 that for some operating systems, '$' has a special meaning, so
243 you may have to quote the expression.
246 <tag><tt>-I dir, --include-dir dir</tt></tag>
248 Name a directory which is searched for include files. The option may be
249 used more than once to specify more than one directory to search. The
250 current directory is always searched first before considering any
251 additional directores.
254 <tag><tt>-U, --auto-import</tt></tag>
256 Mark symbols that are not defined in the sources as imported symbols. This
257 should be used with care since it delays error messages about typos and such
258 until the linker is run. The compiler uses the equivalent of this switch
259 (<tt><ref id=".AUTOIMPORT" name=".AUTOIMPORT"></tt>) to enable auto imported
260 symbols for the runtime library. However, the compiler is supposed to
261 generate code that runs through the assembler without problems, something
262 which is not always true for assembler programmers.
265 <tag><tt>-V, --version</tt></tag>
267 Print the version number of the assembler. If you send any suggestions
268 or bugfixes, please include the version number.
271 <label id="option-W">
272 <tag><tt>-Wn</tt></tag>
274 Set the warning level for the assembler. Using -W2 the assembler will
275 even warn about such things like unused imported symbols. The default
276 warning level is 1, and it would probably be silly to set it to
283 <sect>Input format<p>
285 <sect1>Assembler syntax<p>
287 The assembler accepts the standard 6502/65816 assembler syntax. One line may
288 contain a label (which is identified by a colon), and, in addition to the
289 label, an assembler mnemonic, a macro, or a control command (see section <ref
290 id="control-commands" name="Control Commands"> for supported control
291 commands). Alternatively, the line may contain a symbol definition using the
292 '=' token. Everything after a semicolon is handled as a comment (that is, it
295 Here are some examples for valid input lines:
298 Label: ; A label and a comment
299 lda #$20 ; A 6502 instruction plus comment
300 L1: ldx #$20 ; Same with label
301 L2: .byte "Hello world" ; Label plus control command
302 mymac $20 ; Macro expansion
303 MySym = 3*L1 ; Symbol definition
304 MaSym = Label ; Another symbol
307 The assembler accepts
310 <item>all valid 6502 mnemonics when in 6502 mode (the default or after the
311 <tt><ref id=".P02" name=".P02"></tt> command was given).
312 <item>all valid 6502 mnemonics plus a set of illegal instructions when in
313 <ref id="6502X-mode" name="6502X mode">.
314 <item>all valid 65SC02 mnemonics when in 65SC02 mode (after the
315 <tt><ref id=".PSC02" name=".PSC02"></tt> command was given).
316 <item>all valid 65C02 mnemonics when in 65C02 mode (after the
317 <tt><ref id=".PC02" name=".PC02"></tt> command was given).
318 <item>all valid 65618 mnemonics when in 65816 mode (after the
319 <tt><ref id=".P816" name=".P816"></tt> command was given).
320 <item>all valid SunPlus mnemonics when in SunPlus mode (after the
321 <tt><ref id=".SUNPLUS" name=".SUNPLUS"></tt> command was given).
327 In 65816 mode several aliases are accepted in addition to the official
331 BGE is an alias for BCS
332 BLT is an alias for BCC
333 CPA is an alias for CMP
334 DEA is an alias for DEC A
335 INA is an alias for INC A
336 SWA is an alias for XBA
337 TAD is an alias for TCD
338 TAS is an alias for TCS
339 TDA is an alias for TDC
340 TSA is an alias for TSC
345 <sect1>6502X mode<label id="6502X-mode"><p>
347 6502X mode is an extension to the normal 6502 mode. In this mode, several
348 mnemomics for illegal instructions of the NMOS 6502 CPUs are accepted. Since
349 these instructions are illegal, there are no official mnemonics for them. The
350 unofficial ones are taken from <htmlurl
351 url="http://oxyron.net/graham/opcodes02.html"
352 name="http://oxyron.net/graham/opcodes02.html">. Please note that only the
353 ones marked as "stable" are supported. The following table uses information
354 from the mentioned web page, for more information, see there.
357 <item><tt>ALR: A:=(A and #{imm})*2;</tt>
358 <item><tt>ANC: A:=A and #{imm};</tt> Generates opcode $0B.
359 <item><tt>ARR: A:=(A and #{imm})/2;</tt>
360 <item><tt>AXS: X:=A and X-#{imm};</tt>
361 <item><tt>DCP: {adr}:={adr}-1; A-{adr};</tt>
362 <item><tt>ISC: {adr}:={adr}+1; A:=A-{adr};</tt>
363 <item><tt>LAS: A,X,S:={adr} and S;</tt>
364 <item><tt>LAX: A,X:={adr};</tt>
365 <item><tt>RLA: {adr}:={adr}rol; A:=A and {adr};</tt>
366 <item><tt>RRA: {adr}:={adr}ror; A:=A adc {adr};</tt>
367 <item><tt>SAX: {adr}:=A and X;</tt>
368 <item><tt>SLO: {adr}:={adr}*2; A:=A or {adr};</tt>
369 <item><tt>SRE: {adr}:={adr}/2; A:=A xor {adr};</tt>
374 <sect1>Number format<p>
376 For literal values, the assembler accepts the widely used number formats:
377 A preceeding '$' denotes a hex value, a preceeding '%' denotes a
378 binary value, and a bare number is interpeted as a decimal. There are
379 currently no octal values and no floats.
382 <sect1>Conditional assembly<p>
384 Please note that when using the conditional directives (<tt/.IF/ and friends),
385 the input must consist of valid assembler tokens, even in <tt/.IF/ branches
386 that are not assembled. The reason for this behaviour is that the assembler
387 must still be able to detect the ending tokens (like <tt/.ENDIF/), so
388 conversion of the input stream into tokens still takes place. As a consequence
389 conditional assembly directives may <bf/not/ be used to prevent normal text
390 (used as a comment or similar) from being assembled. <p>
396 <sect1>Expression evaluation<p>
398 All expressions are evaluated with (at least) 32 bit precision. An
399 expression may contain constant values and any combination of internal and
400 external symbols. Expressions that cannot be evaluated at assembly time
401 are stored inside the object file for evaluation by the linker.
402 Expressions referencing imported symbols must always be evaluated by the
406 <sect1>Size of an expression result<p>
408 Sometimes, the assembler must know about the size of the value that is the
409 result of an expression. This is usually the case, if a decision has to be
410 made, to generate a zero page or an absolute memory references. In this
411 case, the assembler has to make some assumptions about the result of an
415 <item> If the result of an expression is constant, the actual value is
416 checked to see if it's a byte sized expression or not.
417 <item> If the expression is explicitly casted to a byte sized expression by
418 one of the '>', '<' or '^' operators, it is a byte expression.
419 <item> If this is not the case, and the expression contains a symbol,
420 explicitly declared as zero page symbol (by one of the .importzp or
421 .exportzp instructions), then the whole expression is assumed to be
423 <item> If the expression contains symbols that are not defined, and these
424 symbols are local symbols, the enclosing scopes are searched for a
425 symbol with the same name. If one exists and this symbol is defined,
426 it's attributes are used to determine the result size.
427 <item> In all other cases the expression is assumed to be word sized.
430 Note: If the assembler is not able to evaluate the expression at assembly
431 time, the linker will evaluate it and check for range errors as soon as
435 <sect1>Boolean expressions<p>
437 In the context of a boolean expression, any non zero value is evaluated as
438 true, any other value to false. The result of a boolean expression is 1 if
439 it's true, and zero if it's false. There are boolean operators with extrem
440 low precedence with version 2.x (where x > 0). The <tt/.AND/ and <tt/.OR/
441 operators are shortcut operators. That is, if the result of the expression is
442 already known, after evaluating the left hand side, the right hand side is
446 <sect1>Constant expressions<p>
448 Sometimes an expression must evaluate to a constant without looking at any
449 further input. One such example is the <tt/<ref id=".IF" name=".IF">/ command
450 that decides if parts of the code are assembled or not. An expression used in
451 the <tt/.IF/ command cannot reference a symbol defined later, because the
452 decision about the <tt/.IF/ must be made at the point when it is read. If the
453 expression used in such a context contains only constant numerical values,
454 there is no problem. When unresolvable symbols are involved it may get harder
455 for the assembler to determine if the expression is actually constant, and it
456 is even possible to create expressions that aren't recognized as constant.
457 Simplifying the expressions will often help.
459 In cases where the result of the expression is not needed immediately, the
460 assembler will delay evaluation until all input is read, at which point all
461 symbols are known. So using arbitrary complex constant expressions is no
462 problem in most cases.
466 <sect1>Available operators<label id="operators"><p>
468 Available operators sorted by precedence:
471 Op Description Precedence
472 -------------------------------------------------------------------
473 Builtin string functions 0
475 Builtin pseudo variables 1
476 Builtin pseudo functions 1
479 ~ Unary bitwise not 1
480 .BITNOT Unary bitwise not 1
481 < Low byte operator 1
482 > High byte operator 1
483 ^ Bank byte operator 1
487 .MOD Modulo operation 2
489 .BITAND Bitwise and 2
491 .BITXOR Bitwise xor 2
492 << Shift left operator 2
493 .SHL Shift left operator 2
494 >> Shift right operator
495 .SHR Shift right operator 2
502 = Compare operation (equal) 4
503 <> Compare operation (not equal) 4
504 < Compare operation (less) 4
505 > Compare operation (greater) 4
506 <= Compare operation (less or equal) 4
507 >= Compare operation (greater or equal) 4
509 && Boolean and 5
521 To force a specific order of evaluation, braces may be used as usual.
527 <sect>Symbols and labels<p>
529 The assembler allows you to use symbols instead of naked values to make
530 the source more readable. There are a lot of different ways to define and
531 use symbols and labels, giving a lot of flexibility.
534 <sect1>Numeric constants<p>
536 Numeric constants are defined using the equal sign or the label assignment
537 operator. After doing
543 may use the symbol "two" in every place where a number is expected, and it is
544 evaluated to the value 2 in this context. The label assignment operator causes
545 the same, but causes the symbol to be marked as a label, which may cause a
546 different handling in the debugger:
552 The right side can of course be an expression:
559 <sect1>Standard labels<p>
561 A label is defined by writing the name of the label at the start of the line
562 (before any instruction mnemonic, macro or pseudo directive), followed by a
563 colon. This will declare a symbol with the given name and the value of the
564 current program counter.
567 <sect1>Local labels and symbols<p>
569 Using the <tt><ref id=".PROC" name=".PROC"></tt> directive, it is possible to
570 create regions of code where the names of labels and symbols are local to this
571 region. They are not known outside of this region and cannot be accessed from
572 there. Such regions may be nested like PROCEDUREs in Pascal.
574 See the description of the <tt><ref id=".PROC" name=".PROC"></tt>
575 directive for more information.
578 <sect1>Cheap local labels<p>
580 Cheap local labels are defined like standard labels, but the name of the
581 label must begin with a special symbol (usually '@', but this can be
582 changed by the <tt><ref id=".LOCALCHAR" name=".LOCALCHAR"></tt>
585 Cheap local labels are visible only between two non cheap labels. As soon as a
586 standard symbol is encountered (this may also be a local symbol if inside a
587 region defined with the <tt><ref id=".PROC" name=".PROC"></tt> directive), the
588 cheap local symbol goes out of scope.
590 You may use cheap local labels as an easy way to reuse common label
591 names like "Loop". Here is an example:
594 Clear: lda #$00 ; Global label
596 @Loop: sta Mem,y ; Local label
600 Sub: ... ; New global label
601 bne @Loop ; ERROR: Unknown identifier!
604 <sect1>Unnamed labels<p>
606 If you really want to write messy code, there are also unnamed
607 labels. These labels do not have a name (you guessed that already,
608 didn't you?). A colon is used to mark the absence of the name.
610 Unnamed labels may be accessed by using the colon plus several minus
611 or plus characters as a label designator. Using the '-' characters
612 will create a back reference (use the n'th label backwards), using
613 '+' will create a forward reference (use the n'th label in forward
614 direction). An example will help to understand this:
636 As you can see from the example, unnamed labels will make even short
637 sections of code hard to understand, because you have to count labels
638 to find branch targets (this is the reason why I for my part do
639 prefer the "cheap" local labels). Nevertheless, unnamed labels are
640 convenient in some situations, so it's your decision.
643 <sect1>Using macros to define labels and constants<p>
645 While there are drawbacks with this approach, it may be handy in some
646 situations. Using <tt><ref id=".DEFINE" name=".DEFINE"></tt>, it is
647 possible to define symbols or constants that may be used elsewhere. Since
648 the macro facility works on a very low level, there is no scoping. On the
649 other side, you may also define string constants this way (this is not
650 possible with the other symbol types).
656 .DEFINE version "SOS V2.3"
658 four = two * two ; Ok
661 .PROC ; Start local scope
662 two = 3 ; Will give "2 = 3" - invalid!
667 <sect1>Symbols and <tt>.DEBUGINFO</tt><p>
669 If <tt><ref id=".DEBUGINFO" name=".DEBUGINFO"></tt> is enabled (or <ref
670 id="option-g" name="-g"> is given on the command line), global, local and
671 cheap local labels are written to the object file and will be available in the
672 symbol file via the linker. Unnamed labels are not written to the object file,
673 because they don't have a name which would allow to access them.
677 <sect>Scopes<label id="scopes"><p>
679 ca65 implements several sorts of scopes for symbols.
681 <sect1>Global scope<p>
683 All (non cheap local) symbols that are declared outside of any nested scopes
687 <sect1>A special scope: cheap locals<p>
689 A special scope is the scope for cheap local symbols. It lasts from one non
690 local symbol to the next one, without any provisions made by the programmer.
691 All other scopes differ in usage but use the same concept internally.
694 <sect1>Generic nested scopes<p>
696 A nested scoped for generic use is started with <tt/<ref id=".SCOPE"
697 name=".SCOPE">/ and closed with <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/.
698 The scope can have a name, in which case it is accessible from the outside by
699 using <ref id="scopesyntax" name="explicit scopes">. If the scope does not
700 have a name, all symbols created within the scope are local to the scope, and
701 aren't accessible from the outside.
703 A nested scope can access symbols from the local or from enclosing scopes by
704 name without using explicit scope names. In some cases there may be
705 ambiguities, for example if there is a reference to a local symbol that is not
706 yet defined, but a symbol with the same name exists in outer scopes:
718 In the example above, the <tt/lda/ instruction will load the value 3 into the
719 accumulator, because <tt/foo/ is redefined in the scope. However:
731 Here, <tt/lda/ will still load from <tt/$12,x/, but since it is unknown to the
732 assembler that <tt/foo/ is a zeropage symbol when translating the instruction,
733 absolute mode is used instead. In fact, the assembler will not use absolute
734 mode by default, but it will search through the enclosing scopes for a symbol
735 with the given name. If one is found, the address size of this symbol is used.
736 This may lead to errors:
748 In this case, when the assembler sees the symbol <tt/foo/ in the <tt/lda/
749 instruction, it will search for an already defined symbol <tt/foo/. It will
750 find <tt/foo/ in scope <tt/outer/, and a close look reveals that it is a
751 zeropage symbol. So the assembler will use zeropage addressing mode. If
752 <tt/foo/ is redefined later in scope <tt/inner/, the assembler tries to change
753 the address in the <tt/lda/ instruction already translated, but since the new
754 value needs absolute addressing mode, this fails, and an error message "Range
757 Of course the most simple solution for the problem is to move the definition
758 of <tt/foo/ in scope <tt/inner/ upwards, so it preceeds its use. There may be
759 rare cases when this cannot be done. In these cases, you can use one of the
760 address size override operators:
772 This will cause the <tt/lda/ instruction to be translated using absolute
773 addressing mode, which means changing the symbol reference later does not
777 <sect1>Nested procedures<p>
779 A nested procedure is created by use of <tt/<ref id=".PROC" name=".PROC">/. It
780 differs from a <tt/<ref id=".SCOPE" name=".SCOPE">/ in that it must have a
781 name, and a it will introduce a symbol with this name in the enclosing scope.
790 is actually the same as
799 This is the reason why a procedure must have a name. If you want a scope
800 without a name, use <tt/<ref id=".SCOPE" name=".SCOPE">/.
802 <bf/Note:/ As you can see from the example above, scopes and symbols live in
803 different namespaces. There can be a symbol named <tt/foo/ and a scope named
804 <tt/foo/ without any conflicts (but see the section titled <ref
805 id="scopesearch" name=""Scope search order"">).
808 <sect1>Structs, unions and enums<p>
810 Structs, unions and enums are explained in a <ref id="structs" name="separate
811 section">, I do only cover them here, because if they are declared with a
812 name, they open a nested scope, similar to <tt/<ref id=".SCOPE"
813 name=".SCOPE">/. However, when no name is specified, the behaviour is
814 different: In this case, no new scope will be opened, symbols declared within
815 a struct, union, or enum declaration will then be added to the enclosing scope
819 <sect1>Explicit scope specification<label id="scopesyntax"><p>
821 Accessing symbols from other scopes is possible by using an explicit scope
822 specification, provided that the scope where the symbol lives in has a name.
823 The namespace token (<tt/::/) is used to access other scopes:
831 lda foo::bar ; Access foo in scope bar
834 The only way to deny access to a scope from the outside is to declare a scope
835 without a name (using the <tt/<ref id=".SCOPE" name=".SCOPE">/ command).
837 A special syntax is used to specify the global scope: If a symbol or scope is
838 preceeded by the namespace token, the global scope is searched:
845 lda #::bar ; Access the global bar (which is 3)
850 <sect1>Scope search order<label id="scopesearch"><p>
852 The assembler searches for a scope in a similar way as for a symbol. First, it
853 looks in the current scope, and then it walks up the enclosing scopes until
856 However, one important thing to note when using explicit scope syntax is, that
857 a symbol may be accessed before it is defined, but a scope may <bf/not/ be
858 used without a preceeding definition. This means that in the following
867 lda #foo::bar ; Will load 3, not 2!
874 the reference to the scope <tt/foo/ will use the global scope, and not the
875 local one, because the local one is not visible at the point where it is
878 Things get more complex if a complete chain of scopes is specified:
889 lda #outer::inner::bar ; 1
901 When <tt/outer::inner::bar/ is referenced in the <tt/lda/ instruction, the
902 assembler will first search in the local scope for a scope named <tt/outer/.
903 Since none is found, the enclosing scope (<tt/another/) is checked. There is
904 still no scope named <tt/outer/, so scope <tt/foo/ is checked, and finally
905 scope <tt/outer/ is found. Within this scope, <tt/inner/ is searched, and in
906 this scope, the assembler looks for a symbol named <tt/bar/.
908 Please note that once the anchor scope is found, all following scopes
909 (<tt/inner/ in this case) are expected to be found exactly in this scope. The
910 assembler will search the scope tree only for the first scope (if it is not
911 anchored in the root scope). Starting from there on, there is no flexibility,
912 so if the scope named <tt/outer/ found by the assembler does not contain a
913 scope named <tt/inner/, this would be an error, even if such a pair does exist
914 (one level up in global scope).
916 Ambiguities that may be introduced by this search algorithm may be removed by
917 anchoring the scope specification in the global scope. In the example above,
918 if you want to access the "other" symbol <tt/bar/, you would have to write:
929 lda #::outer::inner::bar ; 2
942 <sect>Address sizes and memory models<label id="address-sizes"><p>
944 <sect1>Address sizes<p>
946 ca65 assigns each segment and each symbol an address size. This is true, even
947 if the symbol is not used as an address. You may also think of a value range
948 of the symbol instead of an address size.
950 Possible address sizes are:
953 <item>Zeropage or direct (8 bits)
954 <item>Absolute (16 bits)
959 Since the assembler uses default address sizes for the segments and symbols,
960 it is usually not necessary to override the default behaviour. In cases, where
961 it is necessary, the following keywords may be used to specify address sizes:
964 <item>DIRECT, ZEROPAGE or ZP for zeropage addressing (8 bits).
965 <item>ABSOLUTE, ABS or NEAR for absolute addressing (16 bits).
966 <item>FAR for far addressing (24 bits).
967 <item>LONG or DWORD for long addressing (32 bits).
971 <sect1>Address sizes of segments<p>
973 The assembler assigns an address size to each segment. Since the
974 representation of a label within this segment is "segment start + offset",
975 labels will inherit the address size of the segment they are declared in.
977 The address size of a segment may be changed, by using an optional address
978 size modifier. See the <tt/<ref id=".SEGMENT" name="segment directive">/ for
979 an explanation on how this is done.
982 <sect1>Address sizes of symbols<p>
987 <sect1>Memory models<p>
989 The default address size of a segment depends on the memory model used. Since
990 labels inherit the address size from the segment they are declared in,
991 changing the memory model is an easy way to change the address size of many
997 <sect>Pseudo variables<label id="pseudo-variables"><p>
999 Pseudo variables are readable in all cases, and in some special cases also
1002 <sect1><tt>*</tt><p>
1004 Reading this pseudo variable will return the program counter at the start
1005 of the current input line.
1007 Assignment to this variable is possible when <tt/<ref id=".FEATURE"
1008 name=".FEATURE pc_assignment">/ is used. Note: You should not use
1009 assignments to <tt/*/, use <tt/<ref id=".ORG" name=".ORG">/ instead.
1012 <sect1><tt>.CPU</tt><label id=".CPU"><p>
1014 Reading this pseudo variable will give a constant integer value that
1015 tells which CPU is currently enabled. It can also tell which instruction
1016 set the CPU is able to translate. The value read from the pseudo variable
1017 should be further examined by using one of the constants defined by the
1018 "cpu" macro package (see <tt/<ref id=".MACPACK" name=".MACPACK">/).
1020 It may be used to replace the .IFPxx pseudo instructions or to construct
1021 even more complex expressions.
1027 .if (.cpu .bitand CPU_ISET_65816)
1039 <sect1><tt>.PARAMCOUNT</tt><label id=".PARAMCOUNT"><p>
1041 This builtin pseudo variable is only available in macros. It is replaced by
1042 the actual number of parameters that were given in the macro invocation.
1047 .macro foo arg1, arg2, arg3
1048 .if .paramcount <> 3
1049 .error "Too few parameters for macro foo"
1055 See section <ref id="macros" name="Macros">.
1058 <sect1><tt>.TIME</tt><label id=".TIME"><p>
1060 Reading this pseudo variable will give a constant integer value that
1061 represents the current time in POSIX standard (as seconds since the
1064 It may be used to encode the time of translation somewhere in the created
1070 .dword .time ; Place time here
1074 <sect1><tt>.VERSION</tt><label id=".VERSION"><p>
1076 Reading this pseudo variable will give the assembler version according to
1077 the following formula:
1079 VER_MAJOR*$100 + VER_MINOR*$10 + VER_PATCH
1081 It may be used to encode the assembler version or check the assembler for
1082 special features not available with older versions.
1086 Version 2.11.1 of the assembler will return $2B1 as numerical constant when
1087 reading the pseudo variable <tt/.VERSION/.
1091 <sect>Pseudo functions<label id="pseudo-functions"><p>
1093 Pseudo functions expect their arguments in parenthesis, and they have a result,
1094 either a string or an expression.
1097 <sect1><tt>.BANKBYTE</tt><label id=".BANKBYTE"><p>
1099 The function returns the bank byte (that is, bits 16-23) of its argument.
1100 It works identical to the '^' operator.
1102 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1103 <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>
1106 <sect1><tt>.BLANK</tt><label id=".BLANK"><p>
1108 Builtin function. The function evaluates its argument in braces and yields
1109 "false" if the argument is non blank (there is an argument), and "true" if
1110 there is no argument. The token list that makes up the function argument
1111 may optionally be enclosed in curly braces. This allows the inclusion of
1112 tokens that would otherwise terminate the list (the closing right
1113 parenthesis). The curly braces are not considered part of the list, a list
1114 just consisting of curly braces is considered to be empty.
1116 As an example, the <tt/.IFBLANK/ statement may be replaced by
1124 <sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
1126 Builtin string function. The function allows to concatenate a list of string
1127 constants separated by commas. The result is a string constant that is the
1128 concatentation of all arguments. This function is most useful in macros and
1129 when used together with the <tt/.STRING/ builtin function. The function may
1130 be used in any case where a string constant is expected.
1135 .include .concat ("myheader", ".", "inc")
1138 This is the same as the command
1141 .include "myheader.inc"
1145 <sect1><tt>.CONST</tt><label id=".CONST"><p>
1147 Builtin function. The function evaluates its argument in braces and
1148 yields "true" if the argument is a constant expression (that is, an
1149 expression that yields a constant value at assembly time) and "false"
1150 otherwise. As an example, the .IFCONST statement may be replaced by
1157 <sect1><tt>.HIBYTE</tt><label id=".HIBYTE"><p>
1159 The function returns the high byte (that is, bits 8-15) of its argument.
1160 It works identical to the '>' operator.
1162 See: <tt><ref id=".LOBYTE" name=".LOBYTE"></tt>,
1163 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1166 <sect1><tt>.HIWORD</tt><label id=".HIWORD"><p>
1168 The function returns the high word (that is, bits 16-31) of its argument.
1170 See: <tt><ref id=".LOWORD" name=".LOWORD"></tt>
1173 <sect1><tt>.LEFT</tt><label id=".LEFT"><p>
1175 Builtin function. Extracts the left part of a given token list.
1180 .LEFT (<int expr>, <token list>)
1183 The first integer expression gives the number of tokens to extract from
1184 the token list. The second argument is the token list itself. The token
1185 list may optionally be enclosed into curly braces. This allows the
1186 inclusion of tokens that would otherwise terminate the list (the closing
1187 right paren in the given case).
1191 To check in a macro if the given argument has a '#' as first token
1192 (immidiate addressing mode), use something like this:
1197 .if (.match (.left (1, {arg}), #))
1199 ; ldax called with immidiate operand
1207 See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
1208 name=".RIGHT"></tt> builtin functions.
1211 <sect1><tt>.LOBYTE</tt><label id=".LOBYTE"><p>
1213 The function returns the low byte (that is, bits 0-7) of its argument.
1214 It works identical to the '<' operator.
1216 See: <tt><ref id=".HIBYTE" name=".HIBYTE"></tt>,
1217 <tt><ref id=".BANKBYTE" name=".BANKBYTE"></tt>
1220 <sect1><tt>.LOWORD</tt><label id=".LOWORD"><p>
1222 The function returns the low word (that is, bits 0-15) of its argument.
1224 See: <tt><ref id=".HIWORD" name=".HIWORD"></tt>
1227 <sect1><tt>.MATCH</tt><label id=".MATCH"><p>
1229 Builtin function. Matches two token lists against each other. This is
1230 most useful within macros, since macros are not stored as strings, but
1236 .MATCH(<token list #1>, <token list #2>)
1239 Both token list may contain arbitrary tokens with the exception of the
1240 terminator token (comma resp. right parenthesis) and
1247 The token lists may optionally be enclosed into curly braces. This allows
1248 the inclusion of tokens that would otherwise terminate the list (the closing
1249 right paren in the given case). Often a macro parameter is used for any of
1252 Please note that the function does only compare tokens, not token
1253 attributes. So any number is equal to any other number, regardless of the
1254 actual value. The same is true for strings. If you need to compare tokens
1255 <em/and/ token attributes, use the <tt><ref id=".XMATCH"
1256 name=".XMATCH"></tt> function.
1260 Assume the macro <tt/ASR/, that will shift right the accumulator by one,
1261 while honoring the sign bit. The builtin processor instructions will allow
1262 an optional "A" for accu addressing for instructions like <tt/ROL/ and
1263 <tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
1264 to check for this and print and error for invalid calls.
1269 .if (.not .blank(arg)) .and (.not .match ({arg}, a))
1270 .error "Syntax error"
1273 cmp #$80 ; Bit 7 into carry
1274 lsr a ; Shift carry into bit 7
1279 The macro will only accept no arguments, or one argument that must be the
1280 reserved keyword "A".
1282 See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
1285 <sect1><tt>.MID</tt><label id=".MID"><p>
1287 Builtin function. Takes a starting index, a count and a token list as
1288 arguments. Will return part of the token list.
1293 .MID (<int expr>, <int expr>, <token list>)
1296 The first integer expression gives the starting token in the list (the first
1297 token has index 0). The second integer expression gives the number of tokens
1298 to extract from the token list. The third argument is the token list itself.
1299 The token list may optionally be enclosed into curly braces. This allows the
1300 inclusion of tokens that would otherwise terminate the list (the closing
1301 right paren in the given case).
1305 To check in a macro if the given argument has a '<tt/#/' as first token
1306 (immidiate addressing mode), use something like this:
1311 .if (.match (.mid (0, 1, {arg}), #))
1313 ; ldax called with immidiate operand
1321 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
1322 name=".RIGHT"></tt> builtin functions.
1325 <sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
1327 Builtin function. The function expects an identifier as argument in braces.
1328 The argument is evaluated, and the function yields "true" if the identifier
1329 is a symbol that has already been referenced somewhere in the source file up
1330 to the current position. Otherwise the function yields false. As an example,
1331 the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
1337 See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
1340 <sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
1342 Builtin function. Extracts the right part of a given token list.
1347 .RIGHT (<int expr>, <token list>)
1350 The first integer expression gives the number of tokens to extract from the
1351 token list. The second argument is the token list itself. The token list
1352 may optionally be enclosed into curly braces. This allows the inclusion of
1353 tokens that would otherwise terminate the list (the closing right paren in
1356 See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
1357 name=".MID"></tt> builtin functions.
1360 <sect1><tt>.SIZEOF</tt><label id=".SIZEOF"><p>
1362 <tt/.SIZEOF/ is a pseudo function that returns the size of its argument. The
1363 argument can be a struct/union, a struct member, a procedure, or a label. In
1364 case of a procedure or label, its size is defined by the amount of data
1365 placed in the segment where the label is relative to. If a line of code
1366 switches segments (for example in a macro) data placed in other segments
1367 does not count for the size.
1369 Please note that a symbol or scope must exist, before it is used together with
1370 <tt/.SIZEOF/ (this may get relaxed later, but will always be true for scopes).
1371 A scope has preference over a symbol with the same name, so if the last part
1372 of a name represents both, a scope and a symbol, the scope is choosen over the
1375 After the following code:
1378 .struct Point ; Struct size = 4
1383 P: .tag Point ; Declare a point
1384 @P: .tag Point ; Declare another point
1396 .data ; Segment switch!!!
1402 <tag><tt/.sizeof(Point)/</tag>
1403 will have the value 4, because this is the size of struct <tt/Point/.
1405 <tag><tt/.sizeof(Point::xcoord)/</tag>
1406 will have the value 2, because this is the size of the member <tt/xcoord/
1407 in struct <tt/Point/.
1409 <tag><tt/.sizeof(P)/</tag>
1410 will have the value 4, this is the size of the data declared on the same
1411 source line as the label <tt/P/, which is in the same segment that <tt/P/
1414 <tag><tt/.sizeof(@P)/</tag>
1415 will have the value 4, see above. The example demonstrates that <tt/.SIZEOF/
1416 does also work for cheap local symbols.
1418 <tag><tt/.sizeof(Code)/</tag>
1419 will have the value 3, since this is amount of data emitted into the code
1420 segment, the segment that was active when <tt/Code/ was entered. Note that
1421 this value includes the amount of data emitted in child scopes (in this
1422 case <tt/Code::Inner/).
1424 <tag><tt/.sizeof(Code::Inner)/</tag>
1425 will have the value 1 as expected.
1427 <tag><tt/.sizeof(Data)/</tag>
1428 will have the value 0. Data is emitted within the scope <tt/Data/, but since
1429 the segment is switched after entry, this data is emitted into another
1434 <sect1><tt>.STRAT</tt><label id=".STRAT"><p>
1436 Builtin function. The function accepts a string and an index as
1437 arguments and returns the value of the character at the given position
1438 as an integer value. The index is zero based.
1444 ; Check if the argument string starts with '#'
1445 .if (.strat (Arg, 0) = '#')
1452 <sect1><tt>.STRING</tt><label id=".STRING"><p>
1454 Builtin function. The function accepts an argument in braces and converts
1455 this argument into a string constant. The argument may be an identifier, or
1456 a constant numeric value.
1458 Since you can use a string in the first place, the use of the function may
1459 not be obvious. However, it is useful in macros, or more complex setups.
1464 ; Emulate other assemblers:
1466 .segment .string(name)
1471 <sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
1473 Builtin function. The function accepts a string argument in braces and
1474 eveluates to the length of the string.
1478 The following macro encodes a string as a pascal style string with
1479 a leading length byte.
1483 .byte .strlen(Arg), Arg
1488 <sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
1490 Builtin function. The function accepts a token list in braces. The function
1491 result is the number of tokens given as argument. The token list may
1492 optionally be enclosed into curly braces which are not considered part of
1493 the list and not counted. Enclosement in curly braces allows the inclusion
1494 of tokens that would otherwise terminate the list (the closing right paren
1499 The <tt/ldax/ macro accepts the '#' token to denote immidiate addressing (as
1500 with the normal 6502 instructions). To translate it into two separate 8 bit
1501 load instructions, the '#' token has to get stripped from the argument:
1505 .if (.match (.mid (0, 1, {arg}), #))
1506 ; ldax called with immidiate operand
1507 lda #<(.right (.tcount ({arg})-1, {arg}))
1508 ldx #>(.right (.tcount ({arg})-1, {arg}))
1516 <sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
1518 Builtin function. Matches two token lists against each other. This is
1519 most useful within macros, since macros are not stored as strings, but
1525 .XMATCH(<token list #1>, <token list #2>)
1528 Both token list may contain arbitrary tokens with the exception of the
1529 terminator token (comma resp. right parenthesis) and
1536 The token lists may optionally be enclosed into curly braces. This allows
1537 the inclusion of tokens that would otherwise terminate the list (the closing
1538 right paren in the given case). Often a macro parameter is used for any of
1541 The function compares tokens <em/and/ token values. If you need a function
1542 that just compares the type of tokens, have a look at the <tt><ref
1543 id=".MATCH" name=".MATCH"></tt> function.
1545 See: <tt><ref id=".MATCH" name=".MATCH"></tt>
1549 <sect>Control commands<label id="control-commands"><p>
1551 Here's a list of all control commands and a description, what they do:
1554 <sect1><tt>.A16</tt><label id=".A16"><p>
1556 Valid only in 65816 mode. Switch the accumulator to 16 bit.
1558 Note: This command will not emit any code, it will tell the assembler to
1559 create 16 bit operands for immediate accumulator adressing mode.
1561 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1564 <sect1><tt>.A8</tt><label id=".A8"><p>
1566 Valid only in 65816 mode. Switch the accumulator to 8 bit.
1568 Note: This command will not emit any code, it will tell the assembler to
1569 create 8 bit operands for immediate accu adressing mode.
1571 See also: <tt><ref id=".SMART" name=".SMART"></tt>
1574 <sect1><tt>.ADDR</tt><label id=".ADDR"><p>
1576 Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
1577 may be used for better readability if the data words are address values. In
1578 65816 mode, the address is forced to be 16 bit wide to fit into the current
1579 segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
1580 must be followed by a sequence of (not necessarily constant) expressions.
1585 .addr $0D00, $AF13, _Clear
1588 See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
1592 <sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
1594 Align data to a given boundary. The command expects a constant integer
1595 argument that must be a power of two, plus an optional second argument
1596 in byte range. If there is a second argument, it is used as fill value,
1597 otherwise the value defined in the linker configuration file is used
1598 (the default for this value is zero).
1600 Since alignment depends on the base address of the module, you must
1601 give the same (or a greater) alignment for the segment when linking.
1602 The linker will give you a warning, if you don't do that.
1611 <sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
1613 Define a string with a trailing zero.
1618 Msg: .asciiz "Hello world"
1621 This will put the string "Hello world" followed by a binary zero into
1622 the current segment. There may be more strings separated by commas, but
1623 the binary zero is only appended once (after the last one).
1626 <sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
1628 Add an assertion. The command is followed by an expression, an action
1629 specifier and a message that is output in case the assertion fails. The
1630 action specifier may be one of <tt/warning/ or <tt/error/. The assertion
1631 is passed to the linker and will be evaluated when segment placement has
1637 .assert * = $8000, error, "Code not at $8000"
1640 The example assertion will check that the current location is at $8000,
1641 when the output file is written, and abort with an error if this is not
1642 the case. More complex expressions are possible. The action specifier
1643 <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
1644 an error message. In the latter case, generation if the output file is
1648 <sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
1650 Is followed by a plus or a minus character. When switched on (using a
1651 +), undefined symbols are automatically marked as import instead of
1652 giving errors. When switched off (which is the default so this does not
1653 make much sense), this does not happen and an error message is
1654 displayed. The state of the autoimport flag is evaluated when the
1655 complete source was translated, before outputing actual code, so it is
1656 <em/not/ possible to switch this feature on or off for separate sections
1657 of code. The last setting is used for all symbols.
1659 You should probably not use this switch because it delays error
1660 messages about undefined symbols until the link stage. The cc65
1661 compiler (which is supposed to produce correct assembler code in all
1662 circumstances, something which is not true for most assembler
1663 programmers) will insert this command to avoid importing each and every
1664 routine from the runtime library.
1669 .autoimport + ; Switch on auto import
1673 <sect1><tt>.BSS</tt><label id=".BSS"><p>
1675 Switch to the BSS segment. The name of the BSS segment is always "BSS",
1676 so this is a shortcut for
1682 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1685 <sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
1687 Define byte sized data. Must be followed by a sequence of (byte ranged)
1688 expressions or strings.
1694 .byt "world", $0D, $00
1698 <sect1><tt>.CASE</tt><label id=".CASE"><p>
1700 Switch on or off case sensitivity on identifiers. The default is off
1701 (that is, identifiers are case sensitive), but may be changed by the
1702 -i switch on the command line.
1703 The command must be followed by a '+' or '-' character to switch the
1704 option on or off respectively.
1709 .case - ; Identifiers are not case sensitive
1713 <sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
1715 Apply a custom mapping for characters. The command is followed by two
1716 numbers in the range 1..255. The first one is the index of the source
1717 character, the second one is the mapping. The mapping applies to all
1718 character and string constants when they generate output, and overrides
1719 a mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
1720 command line switch.
1725 .charmap $41, $61 ; Map 'A' to 'a'
1729 <sect1><tt>.CODE</tt><label id=".CODE"><p>
1731 Switch to the CODE segment. The name of the CODE segment is always
1732 "CODE", so this is a shortcut for
1738 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1741 <sect1><tt>.CONDES</tt><label id=".CONDES"><p>
1743 Export a symbol and mark it in a special way. The linker is able to build
1744 tables of all such symbols. This may be used to automatically create a list
1745 of functions needed to initialize linked library modules.
1747 Note: The linker has a feature to build a table of marked routines, but it
1748 is your code that must call these routines, so just declaring a symbol with
1749 <tt/.CONDES/ does nothing by itself.
1751 All symbols are exported as an absolute (16 bit) symbol. You don't need to
1752 use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
1753 is implied by <tt/.CONDES/.
1755 <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
1756 <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
1757 specifiying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
1758 The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> and <tt><ref
1759 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands are actually shortcuts
1760 for <tt/.CONDES/ with a type of <tt/constructor/ resp. <tt/destructor/.
1762 After the type, an optional priority may be specified. Higher numeric values
1763 mean higher priority. If no priority is given, the default priority of 7 is
1764 used. Be careful when assigning priorities to your own module constructors
1765 so they won't interfere with the ones in the cc65 library.
1770 .condes ModuleInit, constructor
1771 .condes ModInit, 0, 16
1774 See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> and <tt><ref
1775 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
1776 <ref id="condes" name="Module constructors/destructors"> explaining the
1777 feature in more detail.
1780 <sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
1782 Export a symbol and mark it as a module constructor. This may be used
1783 together with the linker to build a table of constructor subroutines that
1784 are called by the startup code.
1786 Note: The linker has a feature to build a table of marked routines, but it
1787 is your code that must call these routines, so just declaring a symbol as
1788 constructor does nothing by itself.
1790 A constructor is always exported as an absolute (16 bit) symbol. You don't
1791 need to use an additional <tt/.export/ statement, this is implied by
1792 <tt/.constructor/. It may have an optional priority that is separated by a
1793 comma. Higher numeric values mean a higher priority. If no priority is
1794 given, the default priority of 7 is used. Be careful when assigning
1795 priorities to your own module constructors so they won't interfere with the
1796 ones in the cc65 library.
1801 .constructor ModuleInit
1802 .constructor ModInit, 16
1805 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
1806 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
1807 <ref id="condes" name="Module constructors/destructors"> explaining the
1808 feature in more detail.
1811 <sect1><tt>.DATA</tt><label id=".DATA"><p>
1813 Switch to the DATA segment. The name of the DATA segment is always
1814 "DATA", so this is a shortcut for
1820 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
1823 <sect1><tt>.DBYT</tt><label id=".DBYT"><p>
1825 Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
1826 create word sized data in native 65XX format). Must be followed by a
1827 sequence of (word ranged) expressions.
1835 This will emit the bytes
1841 into the current segment in that order.
1844 <sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
1846 Switch on or off debug info generation. The default is off (that is,
1847 the object file will not contain debug infos), but may be changed by the
1848 -g switch on the command line.
1849 The command must be followed by a '+' or '-' character to switch the
1850 option on or off respectively.
1855 .debuginfo + ; Generate debug info
1859 <sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
1861 Start a define style macro definition. The command is followed by an
1862 identifier (the macro name) and optionally by a list of formal arguments
1864 See section <ref id="macros" name="Macros">.
1867 <sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
1869 Builtin function. The function expects an identifier as argument in braces.
1870 The argument is evaluated, and the function yields "true" if the identifier
1871 is a symbol that is already defined somewhere in the source file up to the
1872 current position. Otherwise the function yields false. As an example, the
1873 <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
1880 <sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
1882 Export a symbol and mark it as a module destructor. This may be used
1883 together with the linker to build a table of destructor subroutines that
1884 are called by the startup code.
1886 Note: The linker has a feature to build a table of marked routines, but it
1887 is your code that must call these routines, so just declaring a symbol as
1888 constructor does nothing by itself.
1890 A destructor is always exported as an absolute (16 bit) symbol. You don't
1891 need to use an additional <tt/.export/ statement, this is implied by
1892 <tt/.destructor/. It may have an optional priority that is separated by a
1893 comma. Higher numerical values mean a higher priority. If no priority is
1894 given, the default priority of 7 is used. Be careful when assigning
1895 priorities to your own module destructors so they won't interfere with the
1896 ones in the cc65 library.
1901 .destructor ModuleDone
1902 .destructor ModDone, 16
1905 See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
1906 id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
1907 section <ref id="condes" name="Module constructors/destructors"> explaining
1908 the feature in more detail.
1911 <sect1><tt>.DWORD</tt><label id=".DWORD"><p>
1913 Define dword sized data (4 bytes) Must be followed by a sequence of
1919 .dword $12344512, $12FA489
1923 <sect1><tt>.ELSE</tt><label id=".ELSE"><p>
1925 Conditional assembly: Reverse the current condition.
1928 <sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
1930 Conditional assembly: Reverse current condition and test a new one.
1933 <sect1><tt>.END</tt><label id=".END"><p>
1935 Forced end of assembly. Assembly stops at this point, even if the command
1936 is read from an include file.
1939 <sect1><tt>.ENDENUM</tt><label id=".ENDENUM"><p>
1941 End a <tt><ref id=".ENUM" name=".ENUM"></tt> declaration.
1944 <sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
1946 Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
1947 <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
1950 <sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
1952 End of macro definition (see section <ref id="macros" name="Macros">).
1955 <sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
1957 End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
1960 <sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
1962 End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
1965 <sect1><tt>.ENDSCOPE</tt><label id=".ENDSCOPE"><p>
1967 End of local lexical level (see <tt/<ref id=".SCOPE" name=".SCOPE">/).
1970 <sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
1972 Ends a struct definition. See the <tt/<ref id=".STRUCT" name=".STRUCT">/
1973 command and the separate section named <ref id="structs" name=""Structs
1977 <sect1><tt>.ENUM</tt><label id=".ENUM"><p>
1979 Start an enumeration. This directive is very similar to the C <tt/enum/
1980 keyword. If a name is given, a new scope is created for the enumeration,
1981 otherwise the enumeration members are placed in the enclosing scope.
1983 In the enumeration body, symbols are declared. The first symbol has a value
1984 of zero, and each following symbol will get the value of the preceeding plus
1985 one. This behaviour may be overriden by an explicit assignment. Two symbols
1986 may have the same value.
1998 Above example will create a new scope named <tt/errorcodes/ with three
1999 symbols in it that get the values 0, 1 and 2 respectively. Another way
2000 to write this would have been:
2010 Please note that explicit scoping must be used to access the identifiers:
2013 .word errorcodes::no_error
2016 A more complex example:
2025 EWOULDBLOCK = EAGAIN
2029 In this example, the enumeration does not have a name, which means that the
2030 members will be visible in the enclosing scope and can be used in this scope
2031 without explicit scoping. The first member (<tt/EUNKNOWN/) has the value -1.
2032 The value for the following members is incremented by one, so <tt/EOK/ would
2033 be zero and so on. <tt/EWOULDBLOCK/ is an alias for <tt/EGAIN/, so it has an
2034 override for the value using an already defined symbol.
2037 <sect1><tt>.ERROR</tt><label id=".ERROR"><p>
2039 Force an assembly error. The assembler will output an error message
2040 preceeded by "User error" and will <em/not/ produce an object file.
2042 This command may be used to check for initial conditions that must be
2043 set before assembling a source file.
2053 .error "Must define foo or bar!"
2057 See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
2058 id=".OUT" name=".OUT"></tt> directives.
2061 <sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
2063 Abort a macro expansion immidiately. This command is often useful in
2064 recursive macros. See separate section <ref id="macros" name="Macros">.
2067 <sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
2069 Make symbols accessible from other modules. Must be followed by a comma
2070 separated list of symbols to export, with each one optionally followed by
2071 an address specification. The default is to export the symbol with the
2072 address size it actually has. The assembler will issue a warning, if the
2073 symbol is exported with an address size smaller than the actual address
2083 See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
2086 <sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
2088 Make symbols accessible from other modules. Must be followed by a comma
2089 separated list of symbols to export. The exported symbols are explicitly
2090 marked as zero page symols.
2098 See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
2101 <sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
2103 Define far (24 bit) address data. The command must be followed by a
2104 sequence of (not necessarily constant) expressions.
2109 .faraddr DrawCircle, DrawRectangle, DrawHexagon
2112 See: <tt><ref id=".ADDR" name=".ADDR"></tt>
2115 <sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
2117 This directive may be used to enable one or more compatibility features
2118 of the assembler. While the use of <tt/.FEATURE/ should be avoided when
2119 possible, it may be useful when porting sources written for other
2120 assemblers. There is no way to switch a feature off, once you have
2121 enabled it, so using
2127 will enable the feature until end of assembly is reached.
2129 The following features are available:
2133 <tag><tt>at_in_identifiers</tt></tag>
2135 Accept the at character (`@') as a valid character in identifiers. The
2136 at character is not allowed to start an identifier, even with this
2139 <tag><tt>dollar_in_identifiers</tt></tag>
2141 Accept the dollar sign (`$') as a valid character in identifiers. The
2142 at character is not allowed to start an identifier, even with this
2145 <tag><tt>dollar_is_pc</tt></tag>
2147 The dollar sign may be used as an alias for the star (`*'), which
2148 gives the value of the current PC in expressions.
2149 Note: Assignment to the pseudo variable is not allowed.
2151 <tag><tt>labels_without_colons</tt></tag>
2153 Allow labels without a trailing colon. These labels are only accepted,
2154 if they start at the beginning of a line (no leading white space).
2156 <tag><tt>leading_dot_in_identifiers</tt></tag>
2158 Accept the dot (`.') as the first character of an identifier. This may be
2159 used for example to create macro names that start with a dot emulating
2160 control directives of other assemblers. Note however, that none of the
2161 reserved keywords built into the assembler, that starts with a dot, may be
2162 overridden. When using this feature, you may also get into trouble if
2163 later versions of the assembler define new keywords starting with a dot.
2165 <tag><tt>loose_char_term</tt></tag>
2167 Accept single quotes as well as double quotes as terminators for char
2170 <tag><tt>loose_string_term</tt></tag>
2172 Accept single quotes as well as double quotes as terminators for string
2175 <tag><tt>missing_char_term</tt></tag>
2177 Accept single quoted character constants where the terminating quote is
2182 <bf/Note:/ This does not work in conjunction with <tt/.FEATURE
2183 loose_string_term/, since in this case the input would be ambigous.
2185 <tag><tt>pc_assignment</tt></tag>
2187 Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
2188 is enabled). Such an assignment is handled identical to the <tt><ref
2189 id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
2190 removing the lines with the assignments may also be an option when porting
2191 code written for older assemblers).
2193 <tag><tt>ubiquitous_idents</tt></tag>
2195 Allow the use of instructions names as names for macros and symbols. This
2196 makes it possible to "overload" instructions by defining a macro with the
2197 same name. This does also make it possible to introduce hard to find errors
2198 in your code, so be careful!
2202 It is also possible to specify features on the command line using the
2203 <tt><ref id="option--feature" name="--feature"></tt> command line option.
2204 This is useful when translating sources written for older assemblers, when
2205 you don't want to change the source code.
2207 As an example, to translate sources written for Andre Fachats xa65
2208 assembler, the features
2211 labels_without_colons, pc_assignment, loose_char_term
2214 may be helpful. They do not make ca65 completely compatible, so you may not
2215 be able to translate the sources without changes, even when enabling these
2216 features. However, I have found several sources that translate without
2217 problems when enabling these features on the command line.
2220 <sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
2222 Insert an option string into the object file. There are two forms of
2223 this command, one specifies the option by a keyword, the second
2224 specifies it as a number. Since usage of the second one needs knowledge
2225 of the internal encoding, its use is not recommended and I will only
2226 describe the first form here.
2228 The command is followed by one of the keywords
2236 a comma and a string. The option is written into the object file
2237 together with the string value. This is currently unidirectional and
2238 there is no way to actually use these options once they are in the
2244 .fileopt comment, "Code stolen from my brother"
2245 .fileopt compiler, "BASIC 2.0"
2246 .fopt author, "J. R. User"
2250 <sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
2252 Import an absolute symbol from another module. The command is followed by a
2253 comma separated list of symbols to import. The command is similar to <tt>
2254 <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
2255 written to the generated object file, even if the symbol is never referenced
2256 (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
2257 references for unused symbols).
2262 .forceimport needthisone, needthistoo
2265 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2268 <sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
2270 Declare symbols as global. Must be followed by a comma separated list of
2271 symbols to declare. Symbols from the list, that are defined somewhere in the
2272 source, are exported, all others are imported. Additional <tt><ref
2273 id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
2274 name=".EXPORT"></tt> commands for the same symbol are allowed.
2283 <sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
2285 Declare symbols as global. Must be followed by a comma separated list of
2286 symbols to declare. Symbols from the list, that are defined somewhere in the
2287 source, are exported, all others are imported. Additional <tt><ref
2288 id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
2289 name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
2290 in the list are explicitly marked as zero page symols.
2299 <sect1><tt>.I16</tt><label id=".I16"><p>
2301 Valid only in 65816 mode. Switch the index registers to 16 bit.
2303 Note: This command will not emit any code, it will tell the assembler to
2304 create 16 bit operands for immediate operands.
2306 See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
2307 name=".SMART"></tt> commands.
2310 <sect1><tt>.I8</tt><label id=".I8"><p>
2312 Valid only in 65816 mode. Switch the index registers to 8 bit.
2314 Note: This command will not emit any code, it will tell the assembler to
2315 create 8 bit operands for immediate operands.
2317 See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
2318 name=".SMART"></tt> commands.
2321 <sect1><tt>.IF</tt><label id=".IF"><p>
2323 Conditional assembly: Evalute an expression and switch assembler output
2324 on or off depending on the expression. The expression must be a constant
2325 expression, that is, all operands must be defined.
2327 A expression value of zero evaluates to FALSE, any other value evaluates
2331 <sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
2333 Conditional assembly: Check if there are any remaining tokens in this line,
2334 and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
2335 condition is not true, further lines are not assembled until an <tt><ref
2336 id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2337 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2339 This command is often used to check if a macro parameter was given. Since an
2340 empty macro parameter will evaluate to nothing, the condition will evaluate
2341 to FALSE if an empty parameter was given.
2355 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2358 <sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
2360 Conditional assembly: Evaluate an expression and switch assembler output
2361 on or off depending on the constness of the expression.
2363 A const expression evaluates to to TRUE, a non const expression (one
2364 containing an imported or currently undefined symbol) evaluates to
2367 See also: <tt><ref id=".CONST" name=".CONST"></tt>
2370 <sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
2372 Conditional assembly: Check if a symbol is defined. Must be followed by
2373 a symbol name. The condition is true if the the given symbol is already
2374 defined, and false otherwise.
2376 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2379 <sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
2381 Conditional assembly: Check if there are any remaining tokens in this line,
2382 and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
2383 condition is not true, further lines are not assembled until an <tt><ref
2384 id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
2385 <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
2387 This command is often used to check if a macro parameter was given.
2388 Since an empty macro parameter will evaluate to nothing, the condition
2389 will evaluate to FALSE if an empty parameter was given.
2402 See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
2405 <sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
2407 Conditional assembly: Check if a symbol is defined. Must be followed by
2408 a symbol name. The condition is true if the the given symbol is not
2409 defined, and false otherwise.
2411 See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
2414 <sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
2416 Conditional assembly: Check if a symbol is referenced. Must be followed
2417 by a symbol name. The condition is true if if the the given symbol was
2418 not referenced before, and false otherwise.
2420 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2423 <sect1><tt>.IFP02</tt><label id=".IFP02"><p>
2425 Conditional assembly: Check if the assembler is currently in 6502 mode
2426 (see <tt><ref id=".P02" name=".P02"></tt> command).
2429 <sect1><tt>.IFP816</tt><label id=".IFP816"><p>
2431 Conditional assembly: Check if the assembler is currently in 65816 mode
2432 (see <tt><ref id=".P816" name=".P816"></tt> command).
2435 <sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
2437 Conditional assembly: Check if the assembler is currently in 65C02 mode
2438 (see <tt><ref id=".PC02" name=".PC02"></tt> command).
2441 <sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
2443 Conditional assembly: Check if the assembler is currently in 65SC02 mode
2444 (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
2447 <sect1><tt>.IFREF</tt><label id=".IFREF"><p>
2449 Conditional assembly: Check if a symbol is referenced. Must be followed
2450 by a symbol name. The condition is true if if the the given symbol was
2451 referenced before, and false otherwise.
2453 This command may be used to build subroutine libraries in include files
2454 (you may use separate object modules for this purpose too).
2459 .ifref ToHex ; If someone used this subroutine
2460 ToHex: tay ; Define subroutine
2466 See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
2469 <sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
2471 Import a symbol from another module. The command is followed by a comma
2472 separated list of symbols to import, with each one optionally followed by
2473 an address specification.
2479 .import bar: zeropage
2482 See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
2485 <sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
2487 Import a symbol from another module. The command is followed by a comma
2488 separated list of symbols to import. The symbols are explicitly imported
2489 as zero page symbols (that is, symbols with values in byte range).
2497 See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
2500 <sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
2502 Include a file as binary data. The command expects a string argument
2503 that is the name of a file to include literally in the current segment.
2504 In addition to that, a start offset and a size value may be specified,
2505 separated by commas. If no size is specified, all of the file from the
2506 start offset to end-of-file is used. If no start position is specified
2507 either, zero is assume (which means that the whole file is inserted).
2512 ; Include whole file
2513 .incbin "sprites.dat"
2515 ; Include file starting at offset 256
2516 .incbin "music.dat", $100
2518 ; Read 100 bytes starting at offset 200
2519 .incbin "graphics.dat", 200, 100
2523 <sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
2525 Include another file. Include files may be nested up to a depth of 16.
2534 <sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
2536 Switch on or off line continuations using the backslash character
2537 before a newline. The option is off by default.
2538 Note: Line continuations do not work in a comment. A backslash at the
2539 end of a comment is treated as part of the comment and does not trigger
2541 The command must be followed by a '+' or '-' character to switch the
2542 option on or off respectively.
2547 .linecont + ; Allow line continuations
2550 #$20 ; This is legal now
2554 <sect1><tt>.LIST</tt><label id=".LIST"><p>
2556 Enable output to the listing. The command must be followed by a boolean
2557 switch ("on", "off", "+" or "-") and will enable or disable listing
2559 The option has no effect if the listing is not enabled by the command line
2560 switch -l. If -l is used, an internal counter is set to 1. Lines are output
2561 to the listing file, if the counter is greater than zero, and suppressed if
2562 the counter is zero. Each use of <tt/.LIST/ will increment or decrement the
2568 .list on ; Enable listing output
2572 <sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
2574 Set, how many bytes are shown in the listing for one source line. The
2575 default is 12, so the listing will show only the first 12 bytes for any
2576 source line that generates more than 12 bytes of code or data.
2577 The directive needs an argument, which is either "unlimited", or an
2578 integer constant in the range 4..255.
2583 .listbytes unlimited ; List all bytes
2584 .listbytes 12 ; List the first 12 bytes
2585 .incbin "data.bin" ; Include large binary file
2589 <sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
2591 This command may only be used inside a macro definition. It declares a
2592 list of identifiers as local to the macro expansion.
2594 A problem when using macros are labels: Since they don't change their name,
2595 you get a "duplicate symbol" error if the macro is expanded the second time.
2596 Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
2597 name mapped to an internal unique name (<tt/___ABCD__/) with each macro
2600 Some other assemblers start a new lexical block inside a macro expansion.
2601 This has some drawbacks however, since that will not allow <em/any/ symbol
2602 to be visible outside a macro, a feature that is sometimes useful. The
2603 <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
2604 to address the problem.
2606 You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
2610 <sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
2612 Defines the character that start "cheap" local labels. You may use one
2613 of '@' and '?' as start character. The default is '@'.
2615 Cheap local labels are labels that are visible only between two non
2616 cheap labels. This way you can reuse identifiers like "<tt/loop/" without
2617 using explicit lexical nesting.
2624 Clear: lda #$00 ; Global label
2625 ?Loop: sta Mem,y ; Local label
2629 Sub: ... ; New global label
2630 bne ?Loop ; ERROR: Unknown identifier!
2634 <sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
2636 Insert a predefined macro package. The command is followed by an
2637 identifier specifying the macro package to insert. Available macro
2641 generic Defines generic macros like add and sub.
2642 longbranch Defines conditional long jump macros.
2643 cbm Defines the scrcode macro
2644 cpu Defines constants for the .CPU variable
2647 Including a macro package twice, or including a macro package that
2648 redefines already existing macros will lead to an error.
2653 .macpack longbranch ; Include macro package
2655 cmp #$20 ; Set condition codes
2656 jne Label ; Jump long on condition
2659 Macro packages are explained in more detail in section <ref
2660 id="macropackages" name="Macro packages">.
2663 <sect1><tt>.MAC, .MACRO</tt><label id=".MAC"><p>
2665 Start a classic macro definition. The command is followed by an identifier
2666 (the macro name) and optionally by a comma separated list of identifiers
2667 that are macro parameters.
2669 See section <ref id="macros" name="Macros">.
2672 <sect1><tt>.ORG</tt><label id=".ORG"><p>
2674 Start a section of absolute code. The command is followed by a constant
2675 expression that gives the new PC counter location for which the code is
2676 assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
2679 Please note that you <em/do not need/ this command in most cases. Placing
2680 code at a specific address is the job of the linker, not the assembler, so
2681 there is usually no reason to assemble code to a specific address.
2683 You may not switch segments while inside a section of absolute code.
2688 .org $7FF ; Emit code starting at $7FF
2692 <sect1><tt>.OUT</tt><label id=".OUT"><p>
2694 Output a string to the console without producing an error. This command
2695 is similiar to <tt/.ERROR/, however, it does not force an assembler error
2696 that prevents the creation of an object file.
2701 .out "This code was written by the codebuster(tm)"
2704 See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
2705 id=".ERROR" name=".ERROR"></tt> directives.
2708 <sect1><tt>.P02</tt><label id=".P02"><p>
2710 Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
2711 instructions. This is the default if not overridden by the
2712 <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
2714 See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
2715 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
2718 <sect1><tt>.P816</tt><label id=".P816"><p>
2720 Enable the 65816 instruction set. This is a superset of the 65SC02 and
2721 6502 instruction sets.
2723 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
2724 name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
2727 <sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
2729 Set the page length for the listing. Must be followed by an integer
2730 constant. The value may be "unlimited", or in the range 32 to 127. The
2731 statement has no effect if no listing is generated. The default value is -1
2732 (unlimited) but may be overridden by the <tt/--pagelength/ command line
2733 option. Beware: Since ca65 is a one pass assembler, the listing is generated
2734 after assembly is complete, you cannot use multiple line lengths with one
2735 source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
2740 .pagelength 66 ; Use 66 lines per listing page
2742 .pagelength unlimited ; Unlimited page length
2746 <sect1><tt>.PC02</tt><label id=".PC02"><p>
2748 Enable the 65C02 instructions set. This instruction set includes all
2749 6502 and 65SC02 instructions.
2751 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
2752 name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
2755 <sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
2757 Pop the last pushed segment from the stack, and set it.
2759 This command will switch back to the segment that was last pushed onto the
2760 segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
2761 command, and remove this entry from the stack.
2763 The assembler will print an error message if the segment stack is empty
2764 when this command is issued.
2766 See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
2769 <sect1><tt>.PROC</tt><label id=".PROC"><p>
2771 Start a nested lexical level with the given name and adds a symbol with this
2772 name to the enclosing scope. All new symbols from now on are in the local
2773 lexical level and are accessible from outside only via <ref id="scopesyntax"
2774 name="explicit scope specification">. Symbols defined outside this local
2775 level may be accessed as long as their names are not used for new symbols
2776 inside the level. Symbols names in other lexical levels do not clash, so you
2777 may use the same names for identifiers. The lexical level ends when the
2778 <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
2779 may be nested up to a depth of 16 (this is an artificial limit to protect
2780 against errors in the source).
2782 Note: Macro names are always in the global level and in a separate name
2783 space. There is no special reason for this, it's just that I've never
2784 had any need for local macro definitions.
2789 .proc Clear ; Define Clear subroutine, start new level
2791 L1: sta Mem,y ; L1 is local and does not cause a
2792 ; duplicate symbol error if used in other
2795 bne L1 ; Reference local symbol
2797 .endproc ; Leave lexical level
2800 See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
2804 <sect1><tt>.PSC02</tt><label id=".PSC02"><p>
2806 Enable the 65SC02 instructions set. This instruction set includes all
2809 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
2810 name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
2813 <sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
2815 Push the currently active segment onto a stack. The entries on the stack
2816 include the name of the segment and the segment type. The stack has a size
2819 <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
2820 to switch to another segment and to restore the old segment later, without
2821 even knowing the name and type of the current segment.
2823 The assembler will print an error message if the segment stack is already
2824 full, when this command is issued.
2826 See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
2829 <sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
2831 Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
2832 name=".ENDREPEAT"></tt> constant number of times. The command is followed by
2833 a constant expression that tells how many times the commands in the body
2834 should get repeated. Optionally, a comma and an identifier may be specified.
2835 If this identifier is found in the body of the repeat statement, it is
2836 replaced by the current repeat count (starting with zero for the first time
2837 the body is repeated).
2839 <tt/.REPEAT/ statements may be nested. If you use the same repeat count
2840 identifier for a nested <tt/.REPEAT/ statement, the one from the inner
2841 level will be used, not the one from the outer level.
2845 The following macro will emit a string that is "encrypted" in that all
2846 characters of the string are XORed by the value $55.
2850 .repeat .strlen(Arg), I
2851 .byte .strat(Arg, I) .xor $55
2856 See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
2859 <sect1><tt>.RELOC</tt><label id=".RELOC"><p>
2861 Switch back to relocatable mode. See the <tt><ref id=".ORG"
2862 name=".ORG"></tt> command.
2865 <sect1><tt>.RES</tt><label id=".RES"><p>
2867 Reserve storage. The command is followed by one or two constant
2868 expressions. The first one is mandatory and defines, how many bytes of
2869 storage should be defined. The second, optional expression must by a
2870 constant byte value that will be used as value of the data. If there
2871 is no fill value given, the linker will use the value defined in the
2872 linker configuration file (default: zero).
2877 ; Reserve 12 bytes of memory with value $AA
2882 <sect1><tt>.RODATA</tt><label id=".RODATA"><p>
2884 Switch to the RODATA segment. The name of the RODATA segment is always
2885 "RODATA", so this is a shortcut for
2891 The RODATA segment is a segment that is used by the compiler for
2892 readonly data like string constants.
2894 See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
2897 <sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
2899 Start a nested lexical level with the given name. All new symbols from now
2900 on are in the local lexical level and are accessible from outside only via
2901 <ref id="scopesyntax" name="explicit scope specification">. Symbols defined
2902 outside this local level may be accessed as long as their names are not used
2903 for new symbols inside the level. Symbols names in other lexical levels do
2904 not clash, so you may use the same names for identifiers. The lexical level
2905 ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
2906 read. Lexical levels may be nested up to a depth of 16 (this is an
2907 artificial limit to protect against errors in the source).
2909 Note: Macro names are always in the global level and in a separate name
2910 space. There is no special reason for this, it's just that I've never
2911 had any need for local macro definitions.
2916 .scope Error ; Start new scope named Error
2918 File = 1 ; File error
2919 Parse = 2 ; Parse error
2920 .endproc ; Close lexical level
2923 lda #Error::File ; Use symbol from scope Error
2926 See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
2930 <sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
2932 Switch to another segment. Code and data is always emitted into a
2933 segment, that is, a named section of data. The default segment is
2934 "CODE". There may be up to 254 different segments per object file
2935 (and up to 65534 per executable). There are shortcut commands for
2936 the most common segments ("CODE", "DATA" and "BSS").
2938 The command is followed by a string containing the segment name (there are
2939 some constraints for the name - as a rule of thumb use only those segment
2940 names that would also be valid identifiers). There may also be an optional
2941 address size separated by a colon. See the section covering <tt/<ref
2942 id="address-sizes" name="address sizes">/ for more information.
2944 The default address size for a segment depends on the memory model specified
2945 on the command line. The default is "absolute", which means that you don't
2946 have to use an address size modifier in most cases.
2948 "absolute" means that the is a segment with 16 bit (absolute) addressing.
2949 That is, the segment will reside somewhere in core memory outside the zero
2950 page. "zeropage" (8 bit) means that the segment will be placed in the zero
2951 page and direct (short) addressing is possible for data in this segment.
2953 Beware: Only labels in a segment with the zeropage attribute are marked
2954 as reachable by short addressing. The `*' (PC counter) operator will
2955 work as in other segments and will create absolute variable values.
2957 Please note that a segment cannot have two different address sizes. A
2958 segment specified as zeropage cannot be declared as being absolute later.
2963 .segment "ROM2" ; Switch to ROM2 segment
2964 .segment "ZP2": zeropage ; New direct segment
2965 .segment "ZP2" ; Ok, will use last attribute
2966 .segment "ZP2": absolute ; Error, redecl mismatch
2969 See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
2970 name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt> and <tt><ref
2971 id=".RODATA" name=".RODATA"></tt>
2974 <sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
2976 Switch the CPU instruction set. The command is followed by a string that
2977 specifies the CPU. Possible values are those that can also be supplied to
2978 the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
2979 namely: 6502, 6502X, 65SC02, 65C02, 65816 and sunplus. Please note that
2980 support for the sunplus CPU is not available in the freeware version,
2981 because the instruction set of the sunplus CPU is "proprietary and
2984 See: <tt><ref id=".CPU" name=".CPU"></tt>,
2985 <tt><ref id=".IFP02" name=".IFP02"></tt>,
2986 <tt><ref id=".IFP816" name=".IFP816"></tt>,
2987 <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
2988 <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
2989 <tt><ref id=".P02" name=".P02"></tt>,
2990 <tt><ref id=".P816" name=".P816"></tt>,
2991 <tt><ref id=".PC02" name=".PC02"></tt>,
2992 <tt><ref id=".PSC02" name=".PSC02"></tt>
2995 <sect1><tt>.SMART</tt><label id=".SMART"><p>
2997 Switch on or off smart mode. The command must be followed by a '+' or
2998 '-' character to switch the option on or off respectively. The default
2999 is off (that is, the assembler doesn't try to be smart), but this
3000 default may be changed by the -s switch on the command line.
3002 In smart mode the assembler will do the following:
3005 <item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
3006 and update the operand sizes accordingly. If the operand of such an
3007 instruction cannot be evaluated by the assembler (for example, because
3008 the operand is an imported symbol), a warning is issued. Beware: Since
3009 the assembler cannot trace the execution flow this may lead to false
3010 results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
3011 instructions to tell the assembler about the current settings.
3012 <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
3013 used within a procedure declared as <tt/far/, or if the procedure has
3014 no explicit address specification, but it is <tt/far/ because of the
3022 .smart - ; Stop being smart
3025 See: <tt><ref id=".A16" name=".A16"></tt>,
3026 <tt><ref id=".A8" name=".A8"></tt>,
3027 <tt><ref id=".I16" name=".I16"></tt>,
3028 <tt><ref id=".I8" name=".I8"></tt>
3031 <sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
3033 Starts a struct definition. Structs are covered in a separate section named
3034 <ref id="structs" name=""Structs and unions"">.
3036 See: <tt><ref id=".ENDSTRUCT" name=".ENDSTRUCT"></tt>
3039 <sect1><tt>.SUNPLUS</tt><label id=".SUNPLUS"><p>
3041 Enable the SunPlus instructions set. This command will not work in the
3042 freeware version of the assembler, because the instruction set is
3043 "proprietary and confidential".
3045 See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
3046 name=".PSC02"></tt>, <tt><ref id=".PC02" name=".PC02"></tt>, and
3047 <tt><ref id=".P816" name=".P816"></tt>
3050 <sect1><tt>.TAG</tt><label id=".TAG"><p>
3052 Allocate space for a struct or union.
3063 .tag Point ; Allocate 4 bytes
3067 <sect1><tt>.WARNING</tt><label id=".WARNING"><p>
3069 Force an assembly warning. The assembler will output a warning message
3070 preceeded by "User warning". This warning will always be output, even if
3071 other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
3072 command line option.
3074 This command may be used to output possible problems when assembling
3083 .warning "Forward jump in jne, cannot optimize!"
3093 See also the <tt><ref id=".ERROR" name=".ERROR"></tt> and <tt><ref id=".OUT"
3094 name=".OUT"></tt> directives.
3097 <sect1><tt>.WORD</tt><label id=".WORD"><p>
3099 Define word sized data. Must be followed by a sequence of (word ranged,
3100 but not necessarily constant) expressions.
3105 .word $0D00, $AF13, _Clear
3109 <sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
3111 Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
3112 The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
3116 .segment "ZEROPAGE", zeropage
3119 Because of the "zeropage" attribute, labels declared in this segment are
3120 addressed using direct addressing mode if possible. You <em/must/ instruct
3121 the linker to place this segment somewhere in the address range 0..$FF
3122 otherwise you will get errors.
3124 See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
3128 <sect>Macros<label id="macros"><p>
3131 <sect1>Introduction<p>
3133 Macros may be thought of as "parametrized super instructions". Macros are
3134 sequences of tokens that have a name. If that name is used in the source
3135 file, the macro is "expanded", that is, it is replaced by the tokens that
3136 were specified when the macro was defined.
3139 <sect1>Macros without parameters<p>
3141 In it's simplest form, a macro does not have parameters. Here's an
3145 .macro asr ; Arithmetic shift right
3146 cmp #$80 ; Put bit 7 into carry
3147 ror ; Rotate right with carry
3151 The macro above consists of two real instructions, that are inserted into
3152 the code, whenever the macro is expanded. Macro expansion is simply done
3153 by using the name, like this:
3162 <sect1>Parametrized macros<p>
3164 When using macro parameters, macros can be even more useful:
3178 When calling the macro, you may give a parameter, and each occurence of
3179 the name "addr" in the macro definition will be replaced by the given
3198 A macro may have more than one parameter, in this case, the parameters
3199 are separated by commas. You are free to give less parameters than the
3200 macro actually takes in the definition. You may also leave intermediate
3201 parameters empty. Empty parameters are replaced by empty space (that is,
3202 they are removed when the macro is exanded). If you have a look at our
3203 macro definition above, you will see, that replacing the "addr" parameter
3204 by nothing will lead to wrong code in most lines. To help you, writing
3205 macros with a variable parameter list, there are some control commands:
3207 <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
3208 returns true, if there are any tokens on the remainder of the line. Since
3209 empty parameters are replaced by nothing, this may be used to test if a given
3210 parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
3213 Look at this example:
3216 .macro ldaxy a, x, y
3229 This macro may be called as follows:
3232 ldaxy 1, 2, 3 ; Load all three registers
3234 ldaxy 1, , 3 ; Load only a and y
3236 ldaxy , , 3 ; Load y only
3239 There's another helper command for determining, which macro parameters are
3240 valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt> This command is
3241 replaced by the parameter count given, <em/including/ intermediate empty macro
3245 ldaxy 1 ; .PARAMCOUNT = 1
3246 ldaxy 1,,3 ; .PARAMCOUNT = 3
3247 ldaxy 1,2 ; .PARAMCOUNT = 2
3248 ldaxy 1, ; .PARAMCOUNT = 2
3249 ldaxy 1,2,3 ; .PARAMCOUNT = 3
3252 Macro parameters may optionally be enclosed into curly braces. This allows the
3253 inclusion of tokens that would otherwise terminate the parameter (the comma in
3254 case of a macro parameter).
3257 .macro foo arg1, arg2
3261 foo ($00,x) ; Two parameters passed
3262 foo {($00,x)} ; One parameter passed
3265 In the first case, the macro is called with two parameters: '<tt/($00/'
3266 and 'x)'. The comma is not passed to the macro, since it is part of the
3267 calling sequence, not the parameters.
3269 In the second case, '($00,x)' is passed to the macro, this time
3270 including the comma.
3273 <sect1>Detecting parameter types<p>
3275 Sometimes it is nice to write a macro that acts differently depending on the
3276 type of the argument supplied. An example would be a macro that loads a 16 bit
3277 value from either an immediate operand, or from memory. The <tt/<ref
3278 id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
3279 functions will allow you to do exactly this:
3283 .if (.match (.left (1, {arg}), #))
3285 lda #<(.right (.tcount ({arg})-1, {arg}))
3286 ldx #>(.right (.tcount ({arg})-1, {arg}))
3288 ; assume absolute or zero page
3295 Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
3296 check if its argument begins with a hash mark. If so, two immediate loads are
3297 emitted, Otherwise a load from an absolute zero page memory location is
3298 assumed. Please note how the curly braces are used to enclose parameters to
3299 pseudo functions handling token lists. This is necessary, because the token
3300 lists may include commas or parens, which would be treated by the assembler
3303 The macro can be used as
3308 ldax #$1234 ; X=$12, A=$34
3310 ldax foo ; X=$56, A=$78
3314 <sect1>Recursive macros<p>
3316 Macros may be used recursively:
3319 .macro push r1, r2, r3
3328 There's also a special macro to help writing recursive macros: <tt><ref
3329 id=".EXITMACRO" name=".EXITMACRO"></tt> This command will stop macro expansion
3333 .macro push r1, r2, r3, r4, r5, r6, r7
3335 ; First parameter is empty
3341 push r2, r3, r4, r5, r6, r7
3345 When expanding this macro, the expansion will push all given parameters
3346 until an empty one is encountered. The macro may be called like this:
3349 push $20, $21, $32 ; Push 3 ZP locations
3350 push $21 ; Push one ZP location
3354 <sect1>Local symbols inside macros<p>
3356 Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
3357 <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
3358 Have a look at the inc16 macro above. Here is it again:
3372 If you have a closer look at the code, you will notice, that it could be
3373 written more efficiently, like this:
3384 But imagine what happens, if you use this macro twice? Since the label
3385 "Skip" has the same name both times, you get a "duplicate symbol" error.
3386 Without a way to circumvent this problem, macros are not as useful, as
3387 they could be. One solution is, to start a new lexical block inside the
3401 Now the label is local to the block and not visible outside. However,
3402 sometimes you want a label inside the macro to be visible outside. To make
3403 that possible, there's a new command that's only usable inside a macro
3404 definition: <tt><ref id=".LOCAL" name=".LOCAL"></tt>. <tt/.LOCAL/ declares one
3405 or more symbols as local to the macro expansion. The names of local variables
3406 are replaced by a unique name in each separate macro expansion. So we could
3407 also solve the problem above by using <tt/.LOCAL/:
3411 .local Skip ; Make Skip a local symbol
3418 Skip: ; Not visible outside
3423 <sect1>C style macros<p>
3425 Starting with version 2.5 of the assembler, there is a second macro type
3426 available: C style macros using the <tt/.DEFINE/ directive. These macros are
3427 similar to the classic macro type described above, but behaviour is sometimes
3432 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
3433 span more than a line. You may use line continuation (see <tt><ref
3434 id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
3435 more than one line for increased readability, but the macro itself
3436 may not contain an end-of-line token.
3438 <item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
3439 the name space with classic macros, but they are detected and replaced
3440 at the scanner level. While classic macros may be used in every place,
3441 where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
3442 name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
3443 they are more versatile in some situations.
3445 <item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
3446 parameters. While classic macros may have empty parameters, this is
3447 not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
3448 For this macro type, the number of actual parameters must match
3449 exactly the number of formal parameters.
3451 To make this possible, formal parameters are enclosed in braces when
3452 defining the macro. If there are no parameters, the empty braces may
3455 <item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
3456 contain end-of-line tokens, there are things that cannot be done. They
3457 may not contain several processor instructions for example. So, while
3458 some things may be done with both macro types, each type has special
3459 usages. The types complement each other.
3463 Let's look at a few examples to make the advantages and disadvantages
3466 To emulate assemblers that use "<tt/EQU/" instead of "<tt/=/" you may use the
3467 following <tt/.DEFINE/:
3472 foo EQU $1234 ; This is accepted now
3475 You may use the directive to define string constants used elsewhere:
3478 ; Define the version number
3479 .define VERSION "12.3a"
3485 Macros with parameters may also be useful:
3488 .define DEBUG(message) .out message
3490 DEBUG "Assembling include file #3"
3493 Note that, while formal parameters have to be placed in braces, this is
3494 not true for the actual parameters. Beware: Since the assembler cannot
3495 detect the end of one parameter, only the first token is used. If you
3496 don't like that, use classic macros instead:
3504 (This is an example where a problem can be solved with both macro types).
3507 <sect1>Characters in macros<p>
3509 When using the <ref id="option-t" name="-t"> option, characters are translated
3510 into the target character set of the specific machine. However, this happens
3511 as late as possible. This means that strings are translated if they are part
3512 of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
3513 name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
3514 used as part of an expression.
3516 This behaviour is very intuitive outside of macros but may be confusing when
3517 doing more complex macros. If you compare characters against numeric values,
3518 be sure to take the translation into account.
3523 <sect>Macro packages<label id="macropackages"><p>
3525 Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
3526 macro packages may be included with just one command. Available macro packages
3530 <sect1><tt>.MACPACK generic</tt><p>
3532 This macro package defines macros that are useful in almost any program.
3533 Currently, two macros are defined:
3548 <sect1><tt>.MACPACK longbranch</tt><p>
3550 This macro package defines long conditional jumps. They are named like the
3551 short counterpart but with the 'b' replaced by a 'j'. Here is a sample
3552 definition for the "<tt/jeq/" macro, the other macros are built using the same
3557 .if .def(Target) .and ((*+2)-(Target) <= 127)
3566 All macros expand to a short branch, if the label is already defined (back
3567 jump) and is reachable with a short jump. Otherwise the macro expands to a
3568 conditional branch with the branch condition inverted, followed by an absolute
3569 jump to the actual branch target.
3571 The package defines the following macros:
3574 jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
3579 <sect1><tt>.MACPACK cbm</tt><p>
3581 The cbm macro package will define a macro named <tt/scrcode/. It takes a
3582 string as argument and places this string into memory translated into screen
3586 <sect1><tt>.MACPACK cpu</tt><p>
3588 This macro package does not define any macros but constants used to examine
3589 the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
3590 each supported CPU a constant similar to
3600 is defined. These constants may be used to determine the exact type of the
3601 currently enabled CPU. In addition to that, for each CPU instruction set,
3602 another constant is defined:
3612 The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
3613 be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
3614 currently enabled CPU supports a specific instruction set. For example the
3615 65C02 supports all instructions of the 65SC02 CPU, so it has the
3616 <tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
3620 .if (.cpu .bitand CPU_ISET_65SC02)
3628 it is possible to determine if the
3634 instruction is supported, which is the case for the 65SC02, 65C02 and 65816
3635 CPUs (the latter two are upwards compatible to the 65SC02).
3639 <sect>Structs and unions<label id="structs"><p>
3641 Structs and unions are special forms of <ref id="scopes" name="scopes">. They
3642 are to some degree comparable to their C counterparts. Both have a list of
3643 members. Each member allocates storage and may optionally have a name, which,
3644 in case of a struct, is the offset from the beginning and, in case of a union,
3647 Here is an example for a very simple struct with two members and a total size
3657 A union shares the total space between all its members, its size is the same
3658 as that of the largest member.
3660 A struct or union must not necessarily have a name. If it is anonymous, no
3661 local scope is opened, the identifiers used to name the members are placed
3662 into the current scope instead.
3664 A struct may contain unnamed members and definitions of local structs. The
3665 storage allocators may contain a multiplier, as in the example below:
3670 .word 2 ; Allocate two words
3676 Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to embedd
3677 already defined structs or unions in structs:
3691 Space for a struct or union may be allocated using the <ref id=".TAG"
3692 name=".TAG"> directive.
3698 Currently, members are just offsets from the start of the struct or union. To
3699 access a field of a struct, the member offset has to be added to the address
3700 of the struct itself:
3703 lda C+Circle::Radius ; Load circle radius into A
3706 This may change in a future version of the assembler.
3709 <sect>Module constructors/destructors<label id="condes"><p>
3711 <em>Note:</em> This section applies mostly to C programs, so the explanation
3712 below uses examples from the C libraries. However, the feature may also be
3713 useful for assembler programs.
3716 <sect1>Module overview<p>
3718 Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> and <tt><ref
3719 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> keywords it it possible to export
3720 functions in a special way. The linker is able to generate tables with all
3721 functions of a specific type. Such a table will <em>only</em> include symbols
3722 from object files that are linked into a specific executable. This may be used
3723 to add initialization and cleanup code for library modules.
3725 The C heap functions are an example where module initialization code is used.
3726 All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
3727 variables that contain the start and the end of the heap, pointers to the free
3728 list and so on. Since the end of the heap depends on the size and start of the
3729 stack, it must be initialized at runtime. However, initializing these
3730 variables for programs that do not use the heap are a waste of time and
3733 So the central module defines a function that contains initialization code and
3734 exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
3735 this module is added to an executable by the linker, the initialization
3736 function will be placed into the table of constructors by the linker. The C
3737 startup code will call all constructors before <tt/main/ and all destructors
3738 after <tt/main/, so without any further work, the heap initialization code is
3739 called once the module is linked in.
3741 While it would be possible to add explicit calls to initialization functions
3742 in the startup code, the new approach has several advantages:
3746 If a module is not included, the initialization code is not linked in and not
3747 called. So you don't pay for things you don't need.
3750 Adding another library that needs initialization does not mean that the
3751 startup code has to be changed. Before we had module constructors and
3752 destructors, the startup code for all systems had to be adjusted to call the
3753 new initialization code.
3756 The feature saves memory: Each additional initialization function needs just
3757 two bytes in the table (a pointer to the function).
3762 <sect1>Calling order<p>
3764 Both, constructors and destructors are sorted in increasing priority order by
3765 the linker when using one of the builtin linker configurations, so the
3766 functions with lower priorities come first and are followed by those with
3767 higher priorities. The C library runtime subroutine that walks over the
3768 constructor and destructor tables calls the functions starting from the top of
3769 the table - which means that functions with a high priority are called first.
3771 So when using the C runtime, both constructors and destructors are called with
3772 high priority functions first, followed by low priority functions.
3777 When creating and using module constructors and destructors, please take care
3783 The linker will only generate function tables, it will not generate code to
3784 call these functions. If you're using the feature in some other than the
3785 existing C environments, you have to write code to call all functions in a
3786 linker generated table yourself. See the <tt>condes</tt> module in the C
3787 runtime for an example on how to do this.
3790 The linker will only add addresses of functions that are in modules linked to
3791 the executable. This means that you have to be careful where to place the
3792 condes functions. If initialization is needed for a group of functions, be
3793 sure to place the initialization function into a module that is linked in
3794 regardless of which function is called by the user.
3797 The linker will generate the tables only when requested to do so by the
3798 <tt/FEATURE CONDES/ statement in the linker config file. Each table has to
3799 be requested separately.
3802 Constructors and destructors may have priorities. These priorities determine
3803 the order of the functions in the table. If your intialization or cleanup code
3804 does depend on other initialization or cleanup code, you have to choose the
3805 priority for the functions accordingly.
3808 Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> and <tt><ref
3809 id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> statements, there is also a more
3810 generic command: <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to
3811 specify an additional type. Predefined types are 0 (constructor) and 1
3812 (destructor). The linker generates a separate table for each type on request.
3817 <sect>Porting sources from other assemblers<p>
3819 Sometimes it is necessary to port code written for older assemblers to ca65.
3820 In some cases, this can be done without any changes to the source code by
3821 using the emulation features of ca65 (see <tt><ref id=".FEATURE"
3822 name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
3825 Probably the biggest difference is the handling of the <tt><ref id=".ORG"
3826 name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
3827 done by the linker. Most other assemblers generate absolute code, placement is
3828 done within the assembler and there is no external linker.
3830 In general it is not a good idea to write new code using the emulation
3831 features of the assembler, but there may be situations where even this rule is
3836 You need to use some of the ca65 emulation features to simulate the behaviour
3837 of such simple assemblers.
3840 <item>Prepare your sourcecode like this:
3843 ; if you want TASS style labels without colons
3844 .feature labels_without_colons
3846 ; if you want TASS style character constants
3847 ; ("a" instead of the default 'a')
3848 .feature loose_char_term
3850 .word *+2 ; the cbm load address
3855 notice that the two emulation features are mostly useful for porting
3856 sources originally written in/for TASS, they are not needed for the
3857 actual "simple assembler operation" and are not recommended if you are
3858 writing new code from scratch.
3860 <item>Replace all program counter assignments (which are not possible in ca65
3861 by default, and the respective emulation feature works different from what
3862 you'd expect) by another way to skip to another memory location, for example
3863 the <tt><ref id=".RES" name=".RES"></tt>directive.
3867 .res $2000-* ; reserve memory up to $2000
3870 notice that other than the original TASS, ca65 can never move the
3871 programmcounter backwards - think of it as if you are assembling to disc with
3874 <item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
3875 rewritten to match ca65 syntax. Most importantly notice that due to the lack
3876 of <tt/.goto/, everything involving loops must be replaced by
3877 <tt><ref id=".REPEAT" name=".REPEAT"></tt>.
3879 <item>To assemble code to a different address than it is executed at, use the
3880 <tt><ref id=".ORG" name=".ORG"></tt> directive instead of
3881 <tt/.offs/-constructs.
3888 .reloc ; back to normal
3891 <item>Then assemble like this:
3894 cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
3897 notice that you need to use the actual start address minus two, since two
3898 bytes are used for the cbm load address.
3903 <sect>Bugs/Feedback<p>
3905 If you have problems using the assembler, if you find any bugs, or if
3906 you're doing something interesting with the assembler, I would be glad to
3907 hear from you. Feel free to contact me by email
3908 (<htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">).
3914 ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
3915 Bassewitz. For usage of the binaries and/or sources the following
3916 conditions do apply:
3918 This software is provided 'as-is', without any expressed or implied
3919 warranty. In no event will the authors be held liable for any damages
3920 arising from the use of this software.
3922 Permission is granted to anyone to use this software for any purpose,
3923 including commercial applications, and to alter it and redistribute it
3924 freely, subject to the following restrictions:
3927 <item> The origin of this software must not be misrepresented; you must not
3928 claim that you wrote the original software. If you use this software
3929 in a product, an acknowledgment in the product documentation would be
3930 appreciated but is not required.
3931 <item> Altered source versions must be plainly marked as such, and must not
3932 be misrepresented as being the original software.
3933 <item> This notice may not be removed or altered from any source