<article>
<title>ca65 Users Guide
-<author>Ullrich von Bassewitz, <tt/uz@musoftware.de/
-<date>19.07.2000
-<abstract>ca65 is a macro assembler for the 6502, 65C02 and 65816 CPUs.
+<author>Ullrich von Bassewitz, <htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">
+<date>19.07.2000, 29.11.2000, 02.10.2001
+
+<abstract>
+ca65 is a powerful macro assembler for the 6502, 65C02 and 65816 CPUs. It is
+used as a companion assembler for the cc65 crosscompiler, but it may also be
+used as a standalone product.
</abstract>
<!-- Table of contents -->
<sect>Overview<p>
ca65 is a replacement for the ra65 assembler that was part of the cc65 C
-compiler developed by John R. Dunning. I had some problems with ra65 and
-the copyright does not permit some things which I wanted to be possible,
-so I decided to write a completely new assembler/linker/archiver suite for
-the cc65 compiler. ca65 is part of this suite.
+compiler, originally developed by John R. Dunning. I had some problems with
+ra65 and the copyright does not permit some things which I wanted to be
+possible, so I decided to write a completely new assembler/linker/archiver
+suite for the cc65 compiler. ca65 is part of this suite.
Some parts of the assembler (code generation and some routines for symbol
table handling) are taken from an older crossassembler named a816 written
by me a long time ago.
-Here's a list of the design criteria, that were important for the
+
+<sect1>Design criteria<p>
+
+Here's a list of the design criteria, that I considered important for the
development:
<itemize>
thinking about a 65816 backend for the C compiler, and even my old
a816 assembler had support for these CPUs, so this wasn't really a
problem.
-<item> The assembler must produce relocatable code. This necessary for the
+<item> The assembler must produce relocatable code. This is necessary for the
compiler support, and it is more convenient.
<item> Conditional assembly must be supported. This is a must for bigger
projects written in assembler (like Elite128).
three segments (this is the count, most other assemblers support).
Having more than one code segments helps developing code for systems
with a divided ROM area (like the C64).
-<item> The linker must be able to resolve arbitrary expressions. Years ago I
- spent half a day to convince Borlands Turbo Assembler to let me use
- the size of a structure I had created. So I decided that this is a
- must. The linker should be able to get things like
+<item> The linker must be able to resolve arbitrary expressions. It should
+ be able to get things like
<tscreen><verb>
- .import S1, S2
- .export Special
- Special = 2*S1 + S2/7
+ .import S1, S2
+ .export Special
+ Special = 2*S1 + S2/7
</verb></tscreen>
right.
<item> True lexical nesting for symbols. This is very convenient for larger
started to get boring. A one pass assembler needs much more elaborated
data structures, and because of that it's much more fun:-)
<item> Non-GPLed code that may be used in any project without restrictions or
- fear of "GPL infecting" other code.
+ fear of "GPL infecting" other code.
</itemize>
+<p>
<sect>Usage<p>
+
+<sect1>Command line option overview<p>
+
The assembler accepts the following options:
<tscreen><verb>
---------------------------------------------------------------------------
Usage: ca65 [options] file
Short options:
- -g Add debug info to object file
- -h Help (this text)
- -i Ignore case of symbols
- -l Create a listing if assembly was ok
- -o name Name the output file
- -s Enable smart mode
- -v Increase verbosity
-D name[=value] Define a symbol
- -I dir Set an include directory search path
- -U Mark unresolved symbols as import
- -V Print the assembler version
- -W n Set warning level n
+ -I dir Set an include directory search path
+ -U Mark unresolved symbols as import
+ -V Print the assembler version
+ -W n Set warning level n
+ -g Add debug info to object file
+ -h Help (this text)
+ -i Ignore case of symbols
+ -l Create a listing if assembly was ok
+ -o name Name the output file
+ -s Enable smart mode
+ -t sys Set the target system
+ -v Increase verbosity
Long options:
--auto-import Mark unresolved symbols as import
- --cpu type Set cpu type
+ --cpu type Set cpu type
--debug-info Add debug info to object file
+ --feature name Set an emulation feature
--help Help (this text)
--ignore-case Ignore case of symbols
--include-dir dir Set an include directory search path
- --listing Create a listing if assembly was ok
+ --listing Create a listing if assembly was ok
--pagelength n Set the page length for the listing
- --smart Enable smart mode
- --verbose Increase verbosity
+ --smart Enable smart mode
+ --target sys Set the target system
+ --verbose Increase verbosity
--version Print the assembler version
---------------------------------------------------------------------------
</verb></tscreen>
+
+<sect1>Command line options in detail<p>
+
Here is a description of all the command line options:
<descrip>
+ <label id="option--cpu">
<tag><tt>--cpu type</tt></tag>
Set the default for the CPU type. The option takes a parameter, which
may be one of
- 6502, 65C02, 65816 and sunplus
+ 6502, 65SC02, 65C02, 65816 and sunplus
- (the latter is not available in the freeware version).
+ The last one (sunplus) is not available in the freeware version, because the
+ instruction set of the sunplus CPU is "proprietary and confidential".
+ <label id="option--feature">
+ <tag><tt>--feature name</tt></tag>
+
+ Enable an emulation feature. This is identical as using <tt/.FEATURE/
+ in the source with two exceptions: Feature names must be lower case, and
+ each feature must be specified by using an extra <tt/--feature/ option,
+ comma separated lists are not allowed.
+
+ See the discussion of the <tt><ref id=".FEATURE" name=".FEATURE"></tt>
+ command for a list of emulation features.
+
+
+ <label id="option-g">
<tag><tt>-g, --debug-info</tt></tag>
When this option (or the equivalent control command <tt/.DEBUGINFO/) is
<tag><tt>-i, --ignore-case</tt></tag>
- This option makes the assembler case insensitive on identifiers and
- labels. This option will override the default, but may itself be
- overriden by the <tt/.CASE/ control command (see section 6).
+ This option makes the assembler case insensitive on identifiers and labels.
+ This option will override the default, but may itself be overriden by the
+ <tt><ref id=".CASE" name=".CASE"></tt> control command.
<tag><tt>-l, --listing</tt></tag>
<tag><tt>--pagelength n</tt></tag>
- sets the length of a listing page in lines. See the <tt/.PAGELENGTH/
- directive for more information.
+ sets the length of a listing page in lines. See the <tt><ref
+ id=".PAGELENGTH" name=".PAGELENGTH"></tt> directive for more information.
<tag><tt>-s, --smart-mode</tt></tag>
- In smart mode (enabled by -s or the <tt/.SMART/ pseudo instruction) the
- assembler will track usage of the REP and SEP instructions in 65816 mode
- and update the operand sizes accordingly. If the operand of such an
- instruction cannot be evaluated by the assembler (for example, because
- the operand is an imported symbol), a warning is issued.
+ In smart mode (enabled by -s or the <tt><ref id=".SMART" name=".SMART"></tt>
+ pseudo instruction) the assembler will track usage of the <tt/REP/ and
+ <tt/SEP/ instructions in 65816 mode and update the operand sizes
+ accordingly. If the operand of such an instruction cannot be evaluated by
+ the assembler (for example, because the operand is an imported symbol), a
+ warning is issued.
Beware: Since the assembler cannot trace the execution flow this may
lead to false results in some cases. If in doubt, use the .ixx and .axx
mode is off by default.
+ <label id="option-t">
+ <tag><tt>-t sys, --target sys</tt></tag>
+
+ Set the target system. This will enable translation of character strings
+ and character constants into the character set of the target platform.
+ The default for the target system is "none", which means that no translation
+ will take place. The assembler supports the same target systems as the
+ compiler, see there for a list.
+
+
<tag><tt>-v, --verbose</tt></tag>
Increase the assembler verbosity. Usually only needed for debugging
<tag><tt>-U, --auto-import</tt></tag>
- Mark symbols that are not defined in the sources as imported symbols.
- This should be used with care since it delays error messages about typos
- and such until the linker is run. The compiler uses the equivalent of
- this switch (<tt/.AUTOIMPORT/, see control command section below) to enable
- auto imported symbols for the runtime library. However, the compiler is
- supposed to generate code that runs through the assembler without
- problems, something which is not always true for assembler programmers.
+ Mark symbols that are not defined in the sources as imported symbols. This
+ should be used with care since it delays error messages about typos and such
+ until the linker is run. The compiler uses the equivalent of this switch
+ (<tt><ref id=".AUTOIMPORT" name=".AUTOIMPORT"></tt>) to enable auto imported
+ symbols for the runtime library. However, the compiler is supposed to
+ generate code that runs through the assembler without problems, something
+ which is not always true for assembler programmers.
<tag><tt>-V, --version</tt></tag>
or bugfixes, please include the version number.
+ <label id="option-W">
<tag><tt>-Wn</tt></tag>
Set the warning level for the assembler. Using -W2 the assembler will
something lower.
</descrip>
-
+<p>
<sect>Input format<p>
-The assembler accepts the standard 6502/65816 assembler syntax. One line
-may contain a label (which is identified by a colon), and, in addition to
-the label, an assembler mnemonic, a macro, or a control command (see
-section 6 for supported control commands). Alternatively, the line may
-contain a symbol definition using the '=' token. Everything after a
-semicolon is handled as a comment (that is, it is ignored).
+<sect1>Assembler syntax<p>
+
+The assembler accepts the standard 6502/65816 assembler syntax. One line may
+contain a label (which is identified by a colon), and, in addition to the
+label, an assembler mnemonic, a macro, or a control command (see section <ref
+id="control-commands" name="Control Commands"> for supported control
+commands). Alternatively, the line may contain a symbol definition using the
+'=' token. Everything after a semicolon is handled as a comment (that is, it
+is ignored).
Here are some examples for valid input lines:
MaSym = Label ; Another symbol
</verb></tscreen>
-The assembler accepts all valid 6502 mnemonics when in 6502 mode (the
-default). The assembler accepts all valid 65SC02 mnemonics when in 65SC02
-mode (after a <tt/.PC02/ command is found). The assembler accepts all valid
-65816 mnemonics with a few exceptions after a .P816 command is found.
-These exceptions are listed below.
+The assembler accepts
+
+<itemize>
+<item>all valid 6502 mnemonics when in 6502 mode (the default or after the
+ <tt><ref id=".P02" name=".P02"></tt> command was given).
+<item>all valid 65SC02 mnemonics when in 65SC02 mode (after the
+ <tt><ref id=".PSC02" name=".PSC02"></tt> command was given).
+<item>all valid 65C02 mnemonics when in 65C02 mode (after the
+ <tt><ref id=".PC02" name=".PC02"></tt> command was given).
+<item>all valid 65618 mnemonics when in 65816 mode (after the
+ <tt><ref id=".P816" name=".P816"></tt> command was given).
+<item>all valid SunPlus mnemonics when in SunPlus mode (after the
+ <tt><ref id=".SUNPLUS" name=".SUNPLUS"></tt> command was given).
+</itemize>
+
+
+<sect1>65816 mode<p>
In 65816 mode several aliases are accepted in addition to the official
mnemonics:
separated by a dot:
<tscreen><verb>
- jsl 3.$1234 ; Call subroutine at $1234 in bank 3
+ jsl 3.$1234 ; Call subroutine at $1234 in bank 3
</verb></tscreen>
+<sect1>Number format<p>
+
For literal values, the assembler accepts the widely used number formats:
A preceeding '$' denotes a hex value, a preceeding '%' denotes a
binary value, and a bare number is interpeted as a decimal. There are
currently no octal values and no floats.
+<sect1>Conditional assembly<p>
-<sect>Expressions
+Please note that when using the conditional directives (<tt/.IF/ and friends),
+the input must consist of valid assembler tokens, even in <tt/.IF/ branches
+that are not assembled. The reason for this behaviour is that the assembler
+must still be able to detect the ending tokens (like <tt/.ENDIF/), so
+conversion of the input stream into tokens still takes place. As a consequence
+conditional assembly directives may <bf/not/ be used to prevent normal text
+(used as a comment or similar) from being assembled. <p>
+
+
+<sect>Expressions<p>
+
+
+<sect1>Expression evaluation<p>
-<p>
All expressions are evaluated with (at least) 32 bit precision. An
expression may contain constant values and any combination of internal and
external symbols. Expressions that cannot be evaluated at assembly time
Expressions referencing imported symbols must always be evaluated by the
linker.
+
+<sect1>Size of an expression result<p>
+
Sometimes, the assembler must know about the size of the value that is the
result of an expression. This is usually the case, if a decision has to be
made, to generate a zero page or an absolute memory references. In this
<item> If the result of an expression is constant, the actual value is
checked to see if it's a byte sized expression or not.
<item> If the expression is explicitly casted to a byte sized expression by
- one of the '>'/'<' operators, it is a byte expression.
+ one of the '>', '<' or '^' operators, it is a byte expression.
<item> If this is not the case, and the expression contains a symbol,
explicitly declared as zero page symbol (by one of the .importzp or
.exportzp instructions), then the whole expression is assumed to be
the result is known.
-<bf>Boolean expressions:</bf>
+<sect1>Boolean expressions<p>
In the context of a boolean expression, any non zero value is evaluated as
true, any other value to false. The result of a boolean expression is 1 if
not evaluated.
+<sect1>Constant expressions<p>
+
+Sometimes an expression must evaluate to a constant without looking at any
+further input. One such example is the <tt/<ref id=".IF" name=".IF">/ command
+that decides if parts of the code are assembled or not. An expression used in
+the <tt/.IF/ command cannot reference a symbol defined later, because the
+decision about the <tt/.IF/ must be made at the point when it is read. If the
+expression used in such a context contains only constant numerical values,
+there is no problem. When unresolvable symbols are involved it may get harder
+for the assembler to determine if the expression is actually constant, and it
+is even possible to create expressions that aren't recognized as constant.
+Simplifying the expressions will often help.
+
+In cases where the result of the expression is not needed immediately, the
+assembler will delay evaluation until all input is read, at which point all
+symbols are known. So using arbitrary complex constant expressions is no
+problem in most cases.
+
+
+
+<sect1>Available operators<label id="operators"><p>
+
Available operators sorted by precedence:
<tscreen><verb>
Op Description Precedence
-------------------------------------------------------------------
.CONCAT Builtin function 0
- .LEFT Builtin function 0
- .MID Builtin function 0
- .RIGHT Builtin function 0
- .STRING Builtin function 0
+ .LEFT Builtin function 0
+ .MID Builtin function 0
+ .RIGHT Builtin function 0
+ .STRING Builtin function 0
* Builtin pseudo variable (r/o) 1
- .BLANK Builtin function 1
- .CONST Builtin function 1
- .CPU Builtin pseudo variable (r/o) 1
- .DEFINED Builtin function 1
- .MATCH Builtin function 1
- .TCOUNT Builtin function 1
- .XMATCH Builtin function 1
- .PARAMCOUNT Builtin pseudo variable (r/o) 1
- .REFERENCED Builtin function 1
- :: Global namespace override 1
- + Unary plus 1
- - Unary minus 1
- ~ Unary bitwise not 1
+ .BLANK Builtin function 1
+ .CONST Builtin function 1
+ .CPU Builtin pseudo variable (r/o) 1
+ .DEFINED Builtin function 1
+ .MATCH Builtin function 1
+ .TCOUNT Builtin function 1
+ .TIME Builtin function 1
+ .VERSION Builtin function 1
+ .XMATCH Builtin function 1
+ .PARAMCOUNT Builtin pseudo variable (r/o) 1
+ .REFERENCED Builtin function 1
+ + Unary plus 1
+ - Unary minus 1
+ ~ Unary bitwise not 1
.BITNOT Unary bitwise not 1
- < Low byte operator 1
- > High byte operator 1
-
- * Multiplication 2
- / Division 2
- .MOD Modulo operation 2
- & Bitwise and 2
- .BITAND Bitwise and 2
- ^ Bitwise xor 2
- .BITXOR Bitwise xor 2
- << Shift left operator 2
- .SHL Shift left operator 2
- >> Shift right operator 2
- .SHR Shift right operator 2
-
- + Binary plus 3
- - Binary minus 3
+ < Low byte operator 1
+ > High byte operator 1
+ ^ Bank byte operator 1
+
+ * Multiplication 2
+ / Division 2
+ .MOD Modulo operation 2
+ & Bitwise and 2
+ .BITAND Bitwise and 2
+ ^ Bitwise xor 2
+ .BITXOR Bitwise xor 2
+ << Shift left operator 2
+ .SHL Shift left operator 2
+ >> Shift right operator
+ .SHR Shift right operator 2
+
+ + Binary plus 3
+ - Binary minus 3
| Binary or 3
- .BITOR Binary or 3
+ .BITOR Binary or 3
= Compare operation (equal) 4
- <> Compare operation (not equal) 4
- < Compare operation (less) 4
- > Compare operation (greater) 4
- <= Compare operation (less or equal) 4
- >= Compare operation (greater or equal) 4
+ <> Compare operation (not equal) 4
+ < Compare operation (less) 4
+ > Compare operation (greater) 4
+ <= Compare operation (less or equal) 4
+ >= Compare operation (greater or equal) 4
- && Boolean and 5
- .AND Boolean and 5
- .XOR Boolean xor 5
+ && Boolean and 5
+ .AND Boolean and 5
+ .XOR Boolean xor 5
- || Boolean or 6
- .OR Boolean or 6
+ || Boolean or 6
+ .OR Boolean or 6
- ! Boolean not 7
- .NOT Boolean not 7
+ ! Boolean not 7
+ .NOT Boolean not 7
</verb></tscreen>
Some of the pseudo variables mentioned above need some more explanation:
+<tscreen><verb>
* This symbol is replaced by the value of the program
counter at start of the current instruction. Note, that
'*' yields a rvalue, that means, you cannot assign to it.
- Use <tt/.ORG/ to set the program counter in sections with
+ Use .ORG to set the program counter in sections with
absolute code.
+</verb></tscreen>
+<p>
-<sect>Symbols and labels
+<sect>Symbols and labels<p>
-<p>
The assembler allows you to use symbols instead of naked values to make
the source more readable. There are a lot of different ways to define and
use symbols and labels, giving a lot of flexibility.
-<descrip>
+<sect1>Numeric constants<p>
-<tag/Numeric constants/
+Numeric constants are defined using the equal sign or the label assignment
+operator. After doing
- Numeric constants are defined using the equal sign. After doing
+<tscreen><verb>
+ two = 2
+</verb></tscreen>
- <tscreen><verb>
- two = 2
- </verb></tscreen>
+may use the symbol "two" in every place where a number is expected, and it is
+evaluated to the value 2 in this context. The label assignment operator causes
+the same, but causes the symbol to be marked as a label, which may cause a
+different handling in the debugger:
- may use the symbol "two" in every place where a number is expected,
- and it is evaluated to the value 2 in this context. An example would be
+<tscreen><verb>
+ io := $d000
+</verb></tscreen>
- <tscreen><verb>
- four = two * two
- </verb></tscreen>
+The right side can of course be an expression:
+<tscreen><verb>
+ four = two * two
+</verb></tscreen>
-<tag/Standard labels/
- A label is defined by writing the name of the label at the start of
- the line (before any instruction mnemonic, macro or pseudo
- directive), followed by a colon. This will declare a symbol with the
- given name and the value of the current program counter.
+<sect1>Standard labels<p>
+A label is defined by writing the name of the label at the start of the line
+(before any instruction mnemonic, macro or pseudo directive), followed by a
+colon. This will declare a symbol with the given name and the value of the
+current program counter.
-<tag/Local labels and symbols/
- Using the <tt/.PROC/ directive, it is possible to create regions of code
- where the names of labels and symbols are local to this region. They
- are not know outside and cannot be accessed from there. Such regions
- may be nested like PROCEDUREs in Pascal.
+<sect1>Local labels and symbols<p>
- See the description of the <tt/.PROC/ directive for more information.
+Using the <tt><ref id=".PROC" name=".PROC"></tt> directive, it is possible to
+create regions of code where the names of labels and symbols are local to this
+region. They are not known outside of this region and cannot be accessed from
+there. Such regions may be nested like PROCEDUREs in Pascal.
-<tag/Cheap local labels/
+See the description of the <tt><ref id=".PROC" name=".PROC"></tt>
+directive for more information.
- Cheap local labels are defined like standard labels, but the name of
- the label must begin with a special symbol (usually '@', but this can
- be changed by the <tt/.LOCALCHAR/ directive).
- Cheap local labels are visible only between two no cheap labels. As
- soon as a standard symbol is encountered (this may also be a local
- symbol if inside a region defined with the .PROC directive), the
- cheap local symbol goes out of scope.
+<sect1>Cheap local labels<p>
- You may use cheap local labels as an easy way to reuse common label
- names like "Loop". Here is an example:
+Cheap local labels are defined like standard labels, but the name of the
+label must begin with a special symbol (usually '@', but this can be
+changed by the <tt><ref id=".LOCALCHAR" name=".LOCALCHAR"></tt>
+directive).
- <tscreen><verb>
- Clear: lda #$00 ; Global label
- ldy #$20
- @Loop: sta Mem,y ; Local label
- dey
- bne @Loop ; Ok
- rts
- Sub: ... ; New global label
- bne @Loop ; ERROR: Unknown identifier!
- </verb></tscreen>
-
-<tag/Unnamed labels/
-
- If you really want to write messy code, there are also unnamed
- labels. These labels do not have a name (you guessed that already,
- didn't you?). A colon is used to mark the absence of the name.
-
- Unnamed labels may be accessed by using the colon plus several minus
- or plus characters as a label designator. Using the '-' characters
- will create a back reference (use the n'th label backwards), using
- '+' will create a forward reference (use the n'th label in forward
- direction). An example will help to understand this:
+Cheap local labels are visible only between two non cheap labels. As soon as a
+standard symbol is encountered (this may also be a local symbol if inside a
+region defined with the <tt><ref id=".PROC" name=".PROC"></tt> directive), the
+cheap local symbol goes out of scope.
- <tscreen><verb>
- : lda (ptr1),y ; #1
- cmp (ptr2),y
- bne :+ ; -> #2
- tax
- beq :+++ ; -> #4
- iny
- bne :- ; -> #1
- inc ptr1+1
- inc ptr2+1
- bne :- ; -> #1
-
- : bcs :+ ; #2 -> #3
- ldx #$FF
- rts
-
- : ldx #$01 ; #3
- : rts ; #4
- </verb></tscreen>
-
- As you can see from the example, unnamed labels will make even short
- sections of code hard to understand, because you have to count labels
- to find branch targets (this is the reason why I for my part do
- prefer the "cheap" local labels). Nevertheless, unnamed labels are
- convenient in some situations, so it's your decision.
-
-<tag/Using macros to define labels and constants/
-
- While there are drawbacks with this approach, it may be handy in some
- situations. Using <tt/.DEFINE/, it is possible to define symbols or
- constants that may be used elsewhere. Since the macro facility works
- on a very low level, there is no scoping. On the other side, you may
- also define string constants this way (this is not possible with the
- other symbol types).
-
- Example:
+You may use cheap local labels as an easy way to reuse common label
+names like "Loop". Here is an example:
- <tscreen><verb>
+<tscreen><verb>
+ Clear: lda #$00 ; Global label
+ ldy #$20
+ @Loop: sta Mem,y ; Local label
+ dey
+ bne @Loop ; Ok
+ rts
+ Sub: ... ; New global label
+ bne @Loop ; ERROR: Unknown identifier!
+</verb></tscreen>
+
+<sect1>Unnamed labels<p>
+
+If you really want to write messy code, there are also unnamed
+labels. These labels do not have a name (you guessed that already,
+didn't you?). A colon is used to mark the absence of the name.
+
+Unnamed labels may be accessed by using the colon plus several minus
+or plus characters as a label designator. Using the '-' characters
+will create a back reference (use the n'th label backwards), using
+'+' will create a forward reference (use the n'th label in forward
+direction). An example will help to understand this:
+
+<tscreen><verb>
+ : lda (ptr1),y ; #1
+ cmp (ptr2),y
+ bne :+ ; -> #2
+ tax
+ beq :+++ ; -> #4
+ iny
+ bne :- ; -> #1
+ inc ptr1+1
+ inc ptr2+1
+ bne :- ; -> #1
+
+ : bcs :+ ; #2 -> #3
+ ldx #$FF
+ rts
+
+ : ldx #$01 ; #3
+ : rts ; #4
+</verb></tscreen>
+
+As you can see from the example, unnamed labels will make even short
+sections of code hard to understand, because you have to count labels
+to find branch targets (this is the reason why I for my part do
+prefer the "cheap" local labels). Nevertheless, unnamed labels are
+convenient in some situations, so it's your decision.
+
+
+<sect1>Using macros to define labels and constants<p>
+
+While there are drawbacks with this approach, it may be handy in some
+situations. Using <tt><ref id=".DEFINE" name=".DEFINE"></tt>, it is
+possible to define symbols or constants that may be used elsewhere. Since
+the macro facility works on a very low level, there is no scoping. On the
+other side, you may also define string constants this way (this is not
+possible with the other symbol types).
+
+Example:
+
+<tscreen><verb>
.DEFINE two 2
.DEFINE version "SOS V2.3"
four = two * two ; Ok
- .byte version ; Ok
+ .byte version ; Ok
- .PROC ; Start local scope
- two = 3 ; Will give "2 = 3" - invalid!
+ .PROC ; Start local scope
+ two = 3 ; Will give "2 = 3" - invalid!
.ENDPROC
- </verb></tscreen>
+</verb></tscreen>
-</descrip>
+<sect1>Symbols and <tt>.DEBUGINFO</tt><p>
+
+If <tt><ref id=".DEBUGINFO" name=".DEBUGINFO"></tt> is enabled (or <ref
+id="option-g" name="-g"> is given on the command line), global, local and
+cheap local labels are written to the object file and will be available in the
+symbol file via the linker. Unnamed labels are not written to the object file,
+because they don't have a name which would allow to access them.
+
+
+
+<sect>Scopes<label id="scopes"><p>
+
+ca65 implements several sorts of scopes for symbols.
+
+<sect1>Global scope<p>
+
+All (non cheap local) symbols that are declared outside of any nested scopes
+are in global scope.
+
+
+<sect1>A special scope: cheap locals<p>
+
+A special scope is the scope for cheap local symbols. It lasts from one non
+local symbol to the next one, without any provisions made by the programmer.
+All other scopes differ in usage but use the same concept internally.
+
+
+<sect1>Generic nested scopes<p>
+
+A nested scoped for generic use is started with <tt/<ref id=".SCOPE"
+name=".SCOPE">/ and closed with <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/.
+The scope can have a name, in which case it is accessible from the outside by
+using <ref id="scopesyntax" name="explicit scopes">. If the scope does not
+have a name, all symbols created within the scope are local to the scope, and
+aren't accessible from the outside.
+
+A nested scope can access symbols from the local or from enclosing scopes by
+name without using explicit scope names. In some cases there may be
+ambiguities, for example if there is a reference to a local symbol that is not
+yet defined, but a symbol with the same name exists in outer scopes:
+
+<tscreen><verb>
+ .scope outer
+ foo = 2
+ .scope inner
+ lda #foo
+ foo = 3
+ .endscope
+ .endscope
+</verb></tscreen>
+
+In the example above, the <tt/lda/ instruction will load the value 3 into the
+accumulator, because <tt/foo/ is redefined in the scope. However:
+
+<tscreen><verb>
+ .scope outer
+ foo = $1234
+ .scope inner
+ lda foo,x
+ foo = $12
+ .endscope
+ .endscope
+</verb></tscreen>
+
+Here, <tt/lda/ will still load from <tt/$12,x/, but since it is unknown to the
+assembler that <tt/foo/ is a zeropage symbol when translating the instruction,
+absolute mode is used instead. In fact, the assembler will not use absolute
+mode by default, but it will search through the enclosing scopes for a symbol
+with the given name. If one is found, the address size of this symbol is used.
+This may lead to errors:
+
+<tscreen><verb>
+ .scope outer
+ foo = $12
+ .scope inner
+ lda foo,x
+ foo = $1234
+ .endscope
+ .endscope
+</verb></tscreen>
+
+In this case, when the assembler sees the symbol <tt/foo/ in the <tt/lda/
+instruction, it will search for an already defined symbol <tt/foo/. It will
+find <tt/foo/ in scope <tt/outer/, and a close look reveals that it is a
+zeropage symbol. So the assembler will use zeropage addressing mode. If
+<tt/foo/ is redefined later in scope <tt/inner/, the assembler tries to change
+the address in the <tt/lda/ instruction already translated, but since the new
+value needs absolute addressing mode, this fails, and an error message "Range
+error" is output.
+
+Of course the most simple solution for the problem is to move the definition
+of <tt/foo/ in scope <tt/inner/ upwards, so it preceeds its use. There may be
+rare cases when this cannot be done. In these cases, you can use one of the
+address size override operators:
+
+<tscreen><verb>
+ .scope outer
+ foo = $12
+ .scope inner
+ lda a:foo,x
+ foo = $1234
+ .endscope
+ .endscope
+</verb></tscreen>
+
+This will cause the <tt/lda/ instruction to be translated using absolute
+addressing mode, which means changing the symbol reference later does not
+cause any errors.
+
+
+<sect1>Nested procedures<p>
+
+A nested procedure is created by use of <tt/<ref id=".PROC" name=".PROC">/. It
+differs from a <tt/<ref id=".SCOPE" name=".SCOPE">/ in that it must have a
+name, and a it will introduce a symbol with this name in the enclosing scope.
+So
+
+<tscreen><verb>
+ .proc foo
+ ...
+ .endscope
+</verb></tscreen>
+
+is actually the same as
+
+<tscreen><verb>
+ foo:
+ .scope foo
+ ...
+ .endscope
+</verb></tscreen>
+
+This is the reason why a procedure must have a name. If you want a scope
+without a name, use <tt/<ref id=".SCOPE" name=".SCOPE">/.
+
+<bf/Note:/ As you can see from the example above, scopes and symbols live in
+different namespaces. There can be a symbol named <tt/foo/ and a scope named
+<tt/foo/ without any conflicts (but see the section titled <ref
+id="scopesearch" name=""Scope search order"">).
+
+
+<sect1>Structs, unions and enums<p>
+
+Structs, unions and enums are explained in a <ref id="structs" name="separate
+section">, I do only cover them here, because if they are declared with a
+name, they open a nested scope, similar to <tt/<ref id=".SCOPE"
+name=".SCOPE">/. However, when no name is specified, the behaviour is
+different: In this case, no new scope will be opened, symbols declared within
+a struct, union, or enum declaration will then be added to the enclosing scope
+instead.
+
+
+<sect1>Explicit scope specification<label id="scopesyntax"><p>
+
+Accessing symbols from other scopes is possible by using an explicit scope
+specification, provided that the scope where the symbol lives in has a name.
+The namespace token (<tt/::/) is used to access other scopes:
+
+<tscreen><verb>
+ .scope foo
+ bar: .word 0
+ .endscope
+
+ ...
+ lda foo::bar ; Access foo in scope bar
+</verb></tscreen>
+
+The only way to deny access to a scope from the outside is to declare a scope
+without a name (using the <tt/<ref id=".SCOPE" name=".SCOPE">/ command).
+
+A special syntax is used to specify the global scope: If a symbol or scope is
+preceeded by the namespace token, the global scope is searched:
+
+<tscreen><verb>
+ bar = 3
+
+ .scope foo
+ bar = 2
+ lda #::bar ; Access the global bar (which is 3)
+ .endscope
+</verb></tscreen>
+
+
+<sect1>Scope search order<label id="scopesearch"><p>
+
+The assembler searches for a scope in a similar way as for a symbol. First, it
+looks in the current scope, and then it walks up the enclosing scopes until
+the scope is found.
+
+However, one important thing to note when using explicit scope syntax is, that
+a symbol may be accessed before it is defined, but a scope may <bf/not/ be
+used without a preceeding definition. This means that in the following
+example:
+
+<tscreen><verb>
+ .scope foo
+ bar = 3
+ .endscope
+
+ .scope outer
+ lda #foo::bar ; Will load 3, not 2!
+ .scope foo
+ bar = 2
+ .endscope
+ .endscope
+</verb></tscreen>
+
+the reference to the scope <tt/foo/ will use the global scope, and not the
+local one, because the local one is not visible at the point where it is
+referenced.
+
+Things get more complex if a complete chain of scopes is specified:
+
+<tscreen><verb>
+ .scope foo
+ .scope outer
+ .scope inner
+ bar = 1
+ .endscope
+ .endscope
+ .scope another
+ .scope nested
+ lda #outer::inner::bar ; 1
+ .endscope
+ .endscope
+ .endscope
+
+ .scope outer
+ .scope inner
+ bar = 2
+ .endscope
+ .endscope
+</verb></tscreen>
+
+When <tt/outer::inner::bar/ is referenced in the <tt/lda/ instruction, the
+assembler will first search in the local scope for a scope named <tt/outer/.
+Since none is found, the enclosing scope (<tt/another/) is checked. There is
+still no scope named <tt/outer/, so scope <tt/foo/ is checked, and finally
+scope <tt/outer/ is found. Within this scope, <tt/inner/ is searched, and in
+this scope, the assembler looks for a symbol named <tt/bar/.
+
+Please note that once the anchor scope is found, all following scopes
+(<tt/inner/ in this case) are expected to be found exactly in this scope. The
+assembler will search the scope tree only for the first scope (if it is not
+anchored in the root scope). Starting from there on, there is no flexibility,
+so if the scope named <tt/outer/ found by the assembler does not contain a
+scope named <tt/inner/, this would be an error, even if such a pair does exist
+(one level up in global scope).
+
+Ambiguities that may be introduced by this search algorithm may be removed by
+anchoring the scope specification in the global scope. In the example above,
+if you want to access the "other" symbol <tt/bar/, you would have to write:
+
+<tscreen><verb>
+ .scope foo
+ .scope outer
+ .scope inner
+ bar = 1
+ .endscope
+ .endscope
+ .scope another
+ .scope nested
+ lda #::outer::inner::bar ; 2
+ .endscope
+ .endscope
+ .endscope
+
+ .scope outer
+ .scope inner
+ bar = 2
+ .endscope
+ .endscope
+</verb></tscreen>
+
+
+<sect>Address sizes<label id="address-sizes"><p>
-If <tt/.DEBUGINFO/ is enabled (or -g is given on the command line), global,
-local and cheap local labels are written to the object file and will be
-available in the symbol file via the linker. Unnamed labels are not
-written to the object file, because they don't have a name which would
-allow to access them.
-<sect>Control commands
+
+
+<sect>Control commands<label id="control-commands">
<p>
Here's a list of all control commands and a description, what they do:
-<descrip>
-<tag><tt><idx>.A16</idx></tt></tag>
+<sect1><tt>.A16</tt><label id=".A16"><p>
Valid only in 65816 mode. Switch the accumulator to 16 bit.
Note: This command will not emit any code, it will tell the assembler to
create 16 bit operands for immediate accumulator adressing mode.
- See also: <tt/.SMART/
+ See also: <tt><ref id=".SMART" name=".SMART"></tt>
-<tag><tt><idx>.A8</idx></tt></tag>
+<sect1><tt>.A8</tt><label id=".A8"><p>
Valid only in 65816 mode. Switch the accumulator to 8 bit.
Note: This command will not emit any code, it will tell the assembler to
create 8 bit operands for immediate accu adressing mode.
- See also: <tt/.SMART/
+ See also: <tt><ref id=".SMART" name=".SMART"></tt>
-<tag><tt><idx>.ADDR</idx></tt></tag>
+<sect1><tt>.ADDR</tt><label id=".ADDR"><p>
Define word sized data. In 6502 mode, this is an alias for <tt/.WORD/ and
- may be used for better readability if the data words are address values.
- In 65816 mode, the address is forced to be 16 bit wide to fit into the
- current segment. See also <tt/.FARADDR/. The command must be followed by a
- sequence of (not necessarily constant) expressions.
+ may be used for better readability if the data words are address values. In
+ 65816 mode, the address is forced to be 16 bit wide to fit into the current
+ segment. See also <tt><ref id=".FARADDR" name=".FARADDR"></tt>. The command
+ must be followed by a sequence of (not necessarily constant) expressions.
Example:
.addr $0D00, $AF13, _Clear
</verb></tscreen>
+ See: <tt><ref id=".FARADDR" name=".FARADDR"></tt>, <tt><ref id=".WORD"
+ name=".WORD"></tt>
-<tag><tt><idx>.ALIGN</idx></tt></tag>
+
+<sect1><tt>.ALIGN</tt><label id=".ALIGN"><p>
Align data to a given boundary. The command expects a constant integer
argument that must be a power of two, plus an optional second argument
</verb></tscreen>
-<tag><tt><idx>.ASCIIZ</idx></tt></tag>
+<sect1><tt>.ASCIIZ</tt><label id=".ASCIIZ"><p>
Define a string with a trailing zero.
the binary zero is only appended once (after the last one).
-<tag><tt><idx>.AUTOIMPORT</idx></tt></tag>
+<sect1><tt>.ASSERT</tt><label id=".ASSERT"><p>
+
+ Add an assertion. The command is followed by an expression, an action
+ specifier and a message that is output in case the assertion fails. The
+ action specifier may be one of <tt/warning/ or <tt/error/. The assertion
+ is passed to the linker and will be evaluated when segment placement has
+ been done.
+
+ Example:
+
+ <tscreen><verb>
+ .assert * = $8000, error, "Code not at $8000"
+ </verb></tscreen>
+
+ The example assertion will check that the current location is at $8000,
+ when the output file is written, and abort with an error if this is not
+ the case. More complex expressions are possible. The action specifier
+ <tt/warning/ outputs a warning, while the <tt/error/ specifier outputs
+ an error message. In the latter case, generation if the output file is
+ suppressed.
+
+
+<sect1><tt>.AUTOIMPORT</tt><label id=".AUTOIMPORT"><p>
- Is followd by a plus or a minus character. When switched on (using a
+ Is followed by a plus or a minus character. When switched on (using a
+), undefined symbols are automatically marked as import instead of
giving errors. When switched off (which is the default so this does not
make much sense), this does not happen and an error message is
</verb></tscreen>
-<tag><tt><idx>.BLANK</idx></tt></tag>
+<sect1><tt>.BLANK</tt><label id=".BLANK"><p>
Builtin function. The function evaluates its argument in braces and
yields "false" if the argument is non blank (there is an argument), and
</verb></tscreen>
-<tag><tt><idx>.BSS</idx></tt></tag>
+<sect1><tt>.BSS</tt><label id=".BSS"><p>
Switch to the BSS segment. The name of the BSS segment is always "BSS",
so this is a shortcut for
.segment "BSS"
</verb></tscreen>
- See also the <tt/.SEGMENT/ command.
+ See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
-<tag><tt><idx>.BYTE</idx></tt></tag>
+<sect1><tt>.BYT, .BYTE</tt><label id=".BYTE"><p>
Define byte sized data. Must be followed by a sequence of (byte ranged)
expressions or strings.
Example:
<tscreen><verb>
- .byte "Hello world", $0D, $00
+ .byte "Hello "
+ .byt "world", $0D, $00
</verb></tscreen>
-<tag><tt><idx>.CASE</idx></tt></tag>
+<sect1><tt>.CASE</tt><label id=".CASE"><p>
Switch on or off case sensitivity on identifiers. The default is off
(that is, identifiers are case sensitive), but may be changed by the
Example:
<tscreen><verb>
- .case - ; Identifiers are not case sensitive
+ .case - ; Identifiers are not case sensitive
+ </verb></tscreen>
+
+
+<sect1><tt>.CHARMAP</tt><label id=".CHARMAP"><p>
+
+ Apply a custom mapping for characters. The command is followed by two
+ numbers in the range 1..255. The first one is the index of the source
+ character, the second one is the mapping. The mapping applies to all
+ character and string constants when they generate output, and overrides
+ a mapping table specified with the <tt><ref id="option-t" name="-t"></tt>
+ command line switch.
+
+ Example:
+
+ <tscreen><verb>
+ .charmap $41, $61 ; Map 'A' to 'a'
</verb></tscreen>
-<tag><tt><idx>.CODE</idx></tt></tag>
+<sect1><tt>.CODE</tt><label id=".CODE"><p>
Switch to the CODE segment. The name of the CODE segment is always
"CODE", so this is a shortcut for
.segment "CODE"
</verb></tscreen>
- See also the <tt/.SEGMENT/ command.
+ See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
+
+
+<sect1><tt>.CONDES</tt><label id=".CONDES"><p>
+
+ Export a symbol and mark it in a special way. The linker is able to build
+ tables of all such symbols. This may be used to automatically create a list
+ of functions needed to initialize linked library modules.
+
+ Note: The linker has a feature to build a table of marked routines, but it
+ is your code that must call these routines, so just declaring a symbol with
+ <tt/.CONDES/ does nothing by itself.
+
+ All symbols are exported as an absolute (16 bit) symbol. You don't need to
+ use an additional <tt><ref id=".EXPORT" name=".EXPORT"></tt> statement, this
+ is implied by <tt/.CONDES/.
+
+ <tt/.CONDES/ is followed by the type, which may be <tt/constructor/,
+ <tt/destructor/ or a numeric value between 0 and 6 (where 0 is the same as
+ specifiying <tt/constructor/ and 1 is equal to specifying <tt/destructor/).
+ The <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> and <tt><ref
+ id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands are actually shortcuts
+ for <tt/.CONDES/ with a type of <tt/constructor/ resp. <tt/destructor/.
+
+ After the type, an optional priority may be specified. Higher numeric values
+ mean higher priority. If no priority is given, the default priority of 7 is
+ used. Be careful when assigning priorities to your own module constructors
+ so they won't interfere with the ones in the cc65 library.
+
+ Example:
+
+ <tscreen><verb>
+ .condes ModuleInit, constructor
+ .condes ModInit, 0, 16
+ </verb></tscreen>
+
+ See the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> and <tt><ref
+ id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
+ <ref id="condes" name="Module constructors/destructors"> explaining the
+ feature in more detail.
-<tag><tt><idx>.CONCAT</idx></tt></tag>
+<sect1><tt>.CONCAT</tt><label id=".CONCAT"><p>
Builtin function. The function allows to concatenate a list of string
constants separated by commas. The result is a string constant that
Example:
<tscreen><verb>
- .include .concat ("myheader", ".", "inc)
+ .include .concat ("myheader", ".", "inc")
</verb></tscreen>
This is the same as the command
</verb></tscreen>
-<tag><tt><idx>.CONST</idx></tt></tag>
+<sect1><tt>.CONST</tt><label id=".CONST"><p>
Builtin function. The function evaluates its argument in braces and
yields "true" if the argument is a constant expression (that is, an
</verb></tscreen>
-<tag><tt><idx>.CPU</idx></tt></tag>
+<sect1><tt>.CONSTRUCTOR</tt><label id=".CONSTRUCTOR"><p>
- Reading this pseudo variable will give a constant integer value that
- tells which instruction set is currently enabled. Possible values are:
+ Export a symbol and mark it as a module constructor. This may be used
+ together with the linker to build a table of constructor subroutines that
+ are called by the startup code.
+
+ Note: The linker has a feature to build a table of marked routines, but it
+ is your code that must call these routines, so just declaring a symbol as
+ constructor does nothing by itself.
+
+ A constructor is always exported as an absolute (16 bit) symbol. You don't
+ need to use an additional <tt/.export/ statement, this is implied by
+ <tt/.constructor/. It may have an optional priority that is separated by a
+ comma. Higher numeric values mean a higher priority. If no priority is
+ given, the default priority of 7 is used. Be careful when assigning
+ priorities to your own module constructors so they won't interfere with the
+ ones in the cc65 library.
+
+ Example:
<tscreen><verb>
- 0 --> 6502
- 1 --> 65SC02
- 2 --> 65SC816
- 3 --> SunPlus SPC
+ .constructor ModuleInit
+ .constructor ModInit, 16
</verb></tscreen>
+ See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
+ id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> commands and the separate section
+ <ref id="condes" name="Module constructors/destructors"> explaining the
+ feature in more detail.
+
+
+<sect1><tt>.CPU</tt><label id=".CPU"><p>
+
+ Reading this pseudo variable will give a constant integer value that
+ tells which CPU is currently enabled. It can also tell which instruction
+ set the CPU is able to translate. The value read from the pseudo variable
+ should be further examined by using one of the constants defined by the
+ "cpu" macro package (see <tt/<ref id=".MACPACK" name=".MACPACK">/).
+
It may be used to replace the .IFPxx pseudo instructions or to construct
even more complex expressions.
Example:
<tscreen><verb>
- .if (.cpu = 0) .or (.cpu = 1)
- txa
- pha
- tya
- pha
- .else
- phx
- phy
- .endif
+ .macpack cpu
+ .if (.cpu .bitand CPU_ISET_65816)
+ phx
+ phy
+ .else
+ txa
+ pha
+ tya
+ pha
+ .endif
</verb></tscreen>
-<tag><tt><idx>.DATA</idx></tt></tag>
+<sect1><tt>.DATA</tt><label id=".DATA"><p>
Switch to the DATA segment. The name of the DATA segment is always
"DATA", so this is a shortcut for
.segment "DATA"
</verb></tscreen>
- See also the <tt/.SEGMENT/ command.
+ See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
-<tag><tt><idx>.DBYT</idx></tt></tag>
+<sect1><tt>.DBYT</tt><label id=".DBYT"><p>
Define word sized data with the hi and lo bytes swapped (use <tt/.WORD/ to
create word sized data in native 65XX format). Must be followed by a
into the current segment in that order.
-<tag><tt><idx>.DEBUGINFO</idx></tt></tag>
+<sect1><tt>.DEBUGINFO</tt><label id=".DEBUGINFO"><p>
Switch on or off debug info generation. The default is off (that is,
the object file will not contain debug infos), but may be changed by the
</verb></tscreen>
-<tag><tt><idx>.DEFINE</idx></tt></tag>
+<sect1><tt>.DEFINE</tt><label id=".DEFINE"><p>
Start a define style macro definition. The command is followed by an
identifier (the macro name) and optionally by a list of formal arguments
in braces.
- See separate section about macros.
+ See section <ref id="macros" name="Macros">.
-<tag><tt><idx>.DEF,</idx> <idx>.DEFINED</idx></tt></tag>
+<sect1><tt>.DEF, .DEFINED</tt><label id=".DEFINED"><p>
- Builtin function. The function expects an identifier as argument in
- braces. The argument is evaluated, and the function yields "true" if the
- identifier is a symbol that is already defined somewhere in the source
- file up to the current position. Otherwise the function yields false. As
- an example, the <tt/.IFDEF/ statement may be replaced by
+ Builtin function. The function expects an identifier as argument in braces.
+ The argument is evaluated, and the function yields "true" if the identifier
+ is a symbol that is already defined somewhere in the source file up to the
+ current position. Otherwise the function yields false. As an example, the
+ <tt><ref id=".IFDEF" name=".IFDEF"></tt> statement may be replaced by
<tscreen><verb>
.if .defined(a)
</verb></tscreen>
-<tag><tt><idx>.DWORD</idx></tt></tag>
+<sect1><tt>.DESTRUCTOR</tt><label id=".DESTRUCTOR"><p>
+
+ Export a symbol and mark it as a module destructor. This may be used
+ together with the linker to build a table of destructor subroutines that
+ are called by the startup code.
+
+ Note: The linker has a feature to build a table of marked routines, but it
+ is your code that must call these routines, so just declaring a symbol as
+ constructor does nothing by itself.
+
+ A destructor is always exported as an absolute (16 bit) symbol. You don't
+ need to use an additional <tt/.export/ statement, this is implied by
+ <tt/.destructor/. It may have an optional priority that is separated by a
+ comma. Higher numerical values mean a higher priority. If no priority is
+ given, the default priority of 7 is used. Be careful when assigning
+ priorities to your own module destructors so they won't interfere with the
+ ones in the cc65 library.
+
+ Example:
+
+ <tscreen><verb>
+ .destructor ModuleDone
+ .destructor ModDone, 16
+ </verb></tscreen>
+
+ See the <tt><ref id=".CONDES" name=".CONDES"></tt> and <tt><ref
+ id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> commands and the separate
+ section <ref id="condes" name="Module constructors/destructors"> explaining
+ the feature in more detail.
+
+
+<sect1><tt>.DWORD</tt><label id=".DWORD"><p>
Define dword sized data (4 bytes) Must be followed by a sequence of
expressions.
</verb></tscreen>
-<tag><tt><idx>.ELSE</idx></tt></tag>
+<sect1><tt>.ELSE</tt><label id=".ELSE"><p>
Conditional assembly: Reverse the current condition.
-<tag><tt><idx>.ELSEIF</idx></tt></tag>
+<sect1><tt>.ELSEIF</tt><label id=".ELSEIF"><p>
Conditional assembly: Reverse current condition and test a new one.
-<tag><tt><idx>.END</idx></tt></tag>
+<sect1><tt>.END</tt><label id=".END"><p>
Forced end of assembly. Assembly stops at this point, even if the command
is read from an include file.
-<tag><tt><idx>.ENDIF</idx></tt></tag>
+<sect1><tt>.ENDENUM</tt><label id=".ENDENUM"><p>
+
+ End a <tt><ref id=".ENUM" name=".ENUM"></tt> declaration.
+
+
+<sect1><tt>.ENDIF</tt><label id=".ENDIF"><p>
+
+ Conditional assembly: Close a <tt><ref id=".IF" name=".IF..."></tt> or
+ <tt><ref id=".ELSE" name=".ELSE"></tt> branch.
+
+
+<sect1><tt>.ENDMAC, .ENDMACRO</tt><label id=".ENDMACRO"><p>
+
+ End of macro definition (see section <ref id="macros" name="Macros">).
+
+
+<sect1><tt>.ENDPROC</tt><label id=".ENDPROC"><p>
+
+ End of local lexical level (see <tt><ref id=".PROC" name=".PROC"></tt>).
+
+
+<sect1><tt>.ENDREP, .ENDREPEAT</tt><label id=".ENDREPEAT"><p>
+
+ End a <tt><ref id=".REPEAT" name=".REPEAT"></tt> block.
+
+
+<sect1><tt>.ENDSCOPE</tt><label id=".ENDSCOPE"><p>
+
+ End of local lexical level (see <tt/<ref id=".SCOPE" name=".SCOPE">/).
- Conditional assembly: Close a <tt/.IF.../ or <tt/.ELSE/ branch.
+<sect1><tt>.ENDSTRUCT</tt><label id=".ENDSTRUCT"><p>
-<tag><tt><idx>.ENDMAC,</idx> <idx>.ENDMACRO</idx></tt></tag>
+ Ends a struct definition. See the section named <ref id="structs"
+ name="Structs and unions">.
- End of macro definition (see separate section).
+<sect1><tt>.ENUM</tt><label id=".ENUM"><p>
-<tag><tt><idx>.ENDPROC</idx></tt></tag>
+ Start an enumeration. This directive is very similar to the C <tt/enum/
+ keyword. If a name is given, a new scope is created for the enumeration,
+ otherwise the enumeration members are placed in the enclosing scope.
- End of local lexical level (see <tt/.PROC/).
+ In the enumeration body, symbols are declared. The first symbol has a value
+ of zero, and each following symbol will get the value of the preceeding plus
+ one. This behaviour may be overriden by an explicit assignment. Two symbols
+ may have the same value.
+ Example:
+
+ <tscreen><verb>
+ .enum errorcodes
+ no_error
+ file_error
+ parse_error
+ .endenum
+ </verb></tscreen>
+
+ Above example will create a new scope named <tt/errorcodes/ with three
+ symbols in it that get the values 0, 1 and 2 respectively. Another way
+ to write this would have been:
+
+ <tscreen><verb>
+ .scope errorcodes
+ no_error = 0
+ file_error = 1
+ parse_error = 2
+ .endscope
+ </verb></tscreen>
-<tag><tt><idx>.ENDREP,</idx> <idx>.ENDREPEAT</idx></tt></tag>
+ Please note that explicit scoping must be used to access the identifiers:
- End a <tt/.REPEAT/ block. See the <tt/.REPEAT/ command.
+ <tscreen><verb>
+ .word errorcodes::no_error
+ </verb></tscreen>
+
+ A more complex example:
+
+ <tscreen><verb>
+ .enum
+ EUNKNOWN = -1
+ EOK
+ EFILE
+ EBUSY
+ EAGAIN
+ EWOULDBLOCK = EAGAIN
+ .endenum
+ </verb></tscreen>
+ In this example, the enumeration does not have a name, which means that the
+ members will be visible in the enclosing scope and can be used in this scope
+ without explicit scoping. The first member (<tt/EUNKNOWN/) has the value -1.
+ The value for the following members is incremented by one, so <tt/EOK/ would
+ be zero and so on. <tt/EWOULDBLOCK/ is an alias for <tt/EGAIN/, so it has an
+ override for the value using an already defined symbol.
-<tag><tt><idx>.ERROR</idx></tt></tag>
+
+<sect1><tt>.ERROR</tt><label id=".ERROR"><p>
Force an assembly error. The assembler will output an error message
preceeded by "User error" and will <em/not/ produce an object file.
.endif
</verb></tscreen>
- See also the <tt/.WARNING/ and <tt/.OUT/ directives.
+ See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
+ id=".OUT" name=".OUT"></tt> directives.
-<tag><tt><idx>.EXITMAC,</idx> <idx>.EXITMACRO</idx></tt></tag>
+<sect1><tt>.EXITMAC, .EXITMACRO</tt><label id=".EXITMACRO"><p>
Abort a macro expansion immidiately. This command is often useful in
- recursive macros. See separate chapter about macros.
+ recursive macros. See separate section <ref id="macros" name="Macros">.
-<tag><tt><idx>.EXPORT</idx></tt></tag>
+<sect1><tt>.EXPORT</tt><label id=".EXPORT"><p>
Make symbols accessible from other modules. Must be followed by a comma
separated list of symbols to export.
.export foo, bar
</verb></tscreen>
+ See: <tt><ref id=".EXPORTZP" name=".EXPORTZP"></tt>
+
-<tag><tt><idx>.EXPORTZP</idx></tt></tag>
+<sect1><tt>.EXPORTZP</tt><label id=".EXPORTZP"><p>
Make symbols accessible from other modules. Must be followed by a comma
separated list of symbols to export. The exported symbols are explicitly
.exportzp foo, bar
</verb></tscreen>
+ See: <tt><ref id=".EXPORT" name=".EXPORT"></tt>
-<tag><tt><idx>.FARADDR</idx></tt></tag>
+
+<sect1><tt>.FARADDR</tt><label id=".FARADDR"><p>
Define far (24 bit) address data. The command must be followed by a
sequence of (not necessarily constant) expressions.
.faraddr DrawCircle, DrawRectangle, DrawHexagon
</verb></tscreen>
+ See: <tt><ref id=".ADDR" name=".ADDR"></tt>
+
-<tag><tt><idx>.FEATURE</idx></tt></tag>
+<sect1><tt>.FEATURE</tt><label id=".FEATURE"><p>
This directive may be used to enable one or more compatibility features
of the assembler. While the use of <tt/.FEATURE/ should be avoided when
<descrip>
- <tag><tt<idx>>dollar_is_pc</idx></tt></tag>
+ <tag><tt>dollar_is_pc</tt></tag>
The dollar sign may be used as an alias for the star (`*'), which
gives the value of the current PC in expressions.
Note: Assignment to the pseudo variable is not allowed.
- <tag><tt<idx>>labels_without_colons</idx></tt></tag>
+ <tag><tt>labels_without_colons</tt></tag>
Allow labels without a trailing colon. These labels are only accepted,
if they start at the beginning of a line (no leading white space).
- <tag><tt<idx>>loose_string_term</idx></tt></tag>
+ <tag><tt>loose_string_term</tt></tag>
Accept single quotes as well as double quotes as terminators for string
constants.
- <tag><tt<idx>>at_in_identifiers</idx></tt></tag>
+ <tag><tt>loose_char_term</tt></tag>
+
+ Accept single quotes as well as double quotes as terminators for char
+ constants.
+
+ <tag><tt>at_in_identifiers</tt></tag>
Accept the at character (`@') as a valid character in identifiers. The
at character is not allowed to start an identifier, even with this
feature enabled.
- <tag><tt<idx>>dollar_in_identifiers</idx></tt></tag>
+ <tag><tt>dollar_in_identifiers</tt></tag>
Accept the dollar sign (`$') as a valid character in identifiers. The
at character is not allowed to start an identifier, even with this
feature enabled.
+ <tag><tt>leading_dot_in_identifiers</tt></tag>
+
+ Accept the dot (`.') as the first character of an identifier. This may be
+ used for example to create macro names that start with a dot emulating
+ control directives of other assemblers. Note however, that none of the
+ reserved keywords built into the assembler, that starts with a dot, may be
+ overridden. When using this feature, you may also get into trouble if
+ later versions of the assembler define new keywords starting with a dot.
+
+ <tag><tt>pc_assignment</tt></tag>
+
+ Allow assignments to the PC symbol (`*' or `$' if <tt/dollar_is_pc/
+ is enabled). Such an assignment is handled identical to the <tt><ref
+ id=".ORG" name=".ORG"></tt> command (which is usually not needed, so just
+ removing the lines with the assignments may also be an option when porting
+ code written for older assemblers).
+
</descrip>
+ It is also possible to specify features on the command line using the
+ <tt><ref id="option--feature" name="--feature"></tt> command line option.
+ This is useful when translating sources written for older assemblers, when
+ you don't want to change the source code.
+
+ As an example, to translate sources written for Andre Fachats xa65
+ assembler, the features
+
+ <verb>
+ labels_without_colons, pc_assignment, loose_char_term
+ </verb>
+
+ may be helpful. They do not make ca65 completely compatible, so you may not
+ be able to translate the sources without changes, even when enabling these
+ features. However, I have found several sources that translate without
+ problems when enabling these features on the command line.
-<tag><tt><idx>.FILEOPT,</idx> <idx>.FOPT</idx></tt></tag>
+
+<sect1><tt>.FILEOPT, .FOPT</tt><label id=".FOPT"><p>
Insert an option string into the object file. There are two forms of
this command, one specifies the option by a keyword, the second
</verb></tscreen>
-<tag><tt><idx>.GLOBAL</idx></tt></tag>
+<sect1><tt>.FORCEIMPORT</tt><label id=".FORCEIMPORT"><p>
- Declare symbols as global. Must be followed by a comma separated list
- of symbols to declare. Symbols from the list, that are defined somewhere
- in the source, are exported, all others are imported. An additional
- explicit <tt/.IMPORT/ or <tt/.EXPORT/ command for the same symbol is
- allowed.
+ Import an absolute symbol from another module. The command is followed by a
+ comma separated list of symbols to import. The command is similar to <tt>
+ <ref id=".IMPORT" name=".IMPORT"></tt>, but the import reference is always
+ written to the generated object file, even if the symbol is never referenced
+ (<tt><ref id=".IMPORT" name=".IMPORT"></tt> will not generate import
+ references for unused symbols).
Example:
<tscreen><verb>
- .global foo, bar
+ .forceimport needthisone, needthistoo
</verb></tscreen>
+ See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
-<tag><tt><idx>.GLOBALZP</idx></tt></tag>
- Declare symbols as global. Must be followed by a comma separated list
- of symbols to declare. Symbols from the list, that are defined
- somewhere in the source, are exported, all others are imported. An
- additional explicit <tt/.IMPORT/ or <tt/.EXPORT/ command for the same
- symbol is explicitly allowed. The symbols in the list are explicitly
- marked as zero page symols.
+<sect1><tt>.GLOBAL</tt><label id=".GLOBAL"><p>
+
+ Declare symbols as global. Must be followed by a comma separated list of
+ symbols to declare. Symbols from the list, that are defined somewhere in the
+ source, are exported, all others are imported. Additional <tt><ref
+ id=".IMPORT" name=".IMPORT"></tt> or <tt><ref id=".EXPORT"
+ name=".EXPORT"></tt> commands for the same symbol are allowed.
+
+ Example:
+
+ <tscreen><verb>
+ .global foo, bar
+ </verb></tscreen>
+
+
+<sect1><tt>.GLOBALZP</tt><label id=".GLOBALZP"><p>
+
+ Declare symbols as global. Must be followed by a comma separated list of
+ symbols to declare. Symbols from the list, that are defined somewhere in the
+ source, are exported, all others are imported. Additional <tt><ref
+ id=".IMPORTZP" name=".IMPORTZP"></tt> or <tt><ref id=".EXPORTZP"
+ name=".EXPORTZP"></tt> commands for the same symbol are allowed. The symbols
+ in the list are explicitly marked as zero page symols.
Example:
</verb></tscreen>
-<tag><tt><idx>.I16</idx></tt></tag>
+<sect1><tt>.I16</tt><label id=".I16"><p>
Valid only in 65816 mode. Switch the index registers to 16 bit.
Note: This command will not emit any code, it will tell the assembler to
create 16 bit operands for immediate operands.
- See also the <tt/.SMART/ command.
+ See also the <tt><ref id=".I8" name=".I8"></tt> and <tt><ref id=".SMART"
+ name=".SMART"></tt> commands.
-<tag><tt><idx>.I8</idx></tt></tag>
+<sect1><tt>.I8</tt><label id=".I8"><p>
Valid only in 65816 mode. Switch the index registers to 8 bit.
Note: This command will not emit any code, it will tell the assembler to
create 8 bit operands for immediate operands.
- See also the <tt/.SMART/ command.
+ See also the <tt><ref id=".I16" name=".I16"></tt> and <tt><ref id=".SMART"
+ name=".SMART"></tt> commands.
-<tag><tt><idx>.IF</idx></tt></tag>
+<sect1><tt>.IF</tt><label id=".IF"><p>
Conditional assembly: Evalute an expression and switch assembler output
on or off depending on the expression. The expression must be a constant
to TRUE.
-<tag><tt><idx>.IFBLANK</idx></tt></tag>
+<sect1><tt>.IFBLANK</tt><label id=".IFBLANK"><p>
- Conditional assembly: Check if there are any remaining tokens in this
- line, and evaluate to FALSE if this is the case, and to TRUE otherwise.
- If the condition is not true, further lines are not assembled until
- an <tt/.ELSE/, <tt/.ELSEIF/ or <tt/.ENDIF/ directive.
+ Conditional assembly: Check if there are any remaining tokens in this line,
+ and evaluate to FALSE if this is the case, and to TRUE otherwise. If the
+ condition is not true, further lines are not assembled until an <tt><ref
+ id=".ELSE" name=".ESLE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
+ <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
- This command is often used to check if a macro parameter was given.
- Since an empty macro parameter will evaluate to nothing, the condition
- will evaluate to FALSE if an empty parameter was given.
+ This command is often used to check if a macro parameter was given. Since an
+ empty macro parameter will evaluate to nothing, the condition will evaluate
+ to FALSE if an empty parameter was given.
Example:
<tscreen><verb>
- .macro arg1, arg2
- .ifblank arg2
- lda #arg1
- .else
- lda #arg2
- .endif
- .endmacro
+ .macro arg1, arg2
+ .ifblank arg2
+ lda #arg1
+ .else
+ lda #arg2
+ .endif
+ .endmacro
</verb></tscreen>
- See also: <tt/.BLANK/
+ See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
-<tag><tt><idx>.IFCONST</idx></tt></tag>
+<sect1><tt>.IFCONST</tt><label id=".IFCONST"><p>
Conditional assembly: Evaluate an expression and switch assembler output
on or off depending on the constness of the expression.
containing an imported or currently undefined symbol) evaluates to
FALSE.
- See also: <tt/.CONST/
+ See also: <tt><ref id=".CONST" name=".CONST"></tt>
-<tag><tt><idx>.IFDEF</idx></tt></tag>
+<sect1><tt>.IFDEF</tt><label id=".IFDEF"><p>
Conditional assembly: Check if a symbol is defined. Must be followed by
a symbol name. The condition is true if the the given symbol is already
defined, and false otherwise.
- See also: <tt/.DEFINED/
+ See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
-<tag><tt><idx>.IFNBLANK</idx></tt></tag>
+<sect1><tt>.IFNBLANK</tt><label id=".IFNBLANK"><p>
- Conditional assembly: Check if there are any remaining tokens in this
- line, and evaluate to TRUE if this is the case, and to FALSE otherwise.
- If the condition is not true, further lines are not assembled until
- an <tt/.ELSE/, <tt/.ELSEIF/ or <tt/.ENDIF/ directive.
+ Conditional assembly: Check if there are any remaining tokens in this line,
+ and evaluate to TRUE if this is the case, and to FALSE otherwise. If the
+ condition is not true, further lines are not assembled until an <tt><ref
+ id=".ELSE" name=".ELSE"></tt>, <tt><ref id=".ELSEIF" name=".ELSEIF"></tt> or
+ <tt><ref id=".ENDIF" name=".ENDIF"></tt> directive.
This command is often used to check if a macro parameter was given.
Since an empty macro parameter will evaluate to nothing, the condition
.endmacro
</verb></tscreen>
- See also: <tt/.BLANK/
+ See also: <tt><ref id=".BLANK" name=".BLANK"></tt>
-<tag><tt><idx>.IFNDEF</idx></tt></tag>
+<sect1><tt>.IFNDEF</tt><label id=".IFNDEF"><p>
Conditional assembly: Check if a symbol is defined. Must be followed by
a symbol name. The condition is true if the the given symbol is not
defined, and false otherwise.
- See also: <tt/.DEFINED/
+ See also: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
-<tag><tt><idx>.IFNREF</idx></tt></tag>
+<sect1><tt>.IFNREF</tt><label id=".IFNREF"><p>
Conditional assembly: Check if a symbol is referenced. Must be followed
by a symbol name. The condition is true if if the the given symbol was
not referenced before, and false otherwise.
- See also: <tt/.REFERENCED/
+ See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
-<tag><tt><idx>.IFP02</idx></tt></tag>
+<sect1><tt>.IFP02</tt><label id=".IFP02"><p>
Conditional assembly: Check if the assembler is currently in 6502 mode
- (see <tt/.P02/ command).
+ (see <tt><ref id=".P02" name=".P02"></tt> command).
-<tag><tt><idx>.IFP816</idx></tt></tag>
+<sect1><tt>.IFP816</tt><label id=".IFP816"><p>
Conditional assembly: Check if the assembler is currently in 65816 mode
- (see <tt/.P816/ command).
+ (see <tt><ref id=".P816" name=".P816"></tt> command).
-<tag><tt><idx>.IFPC02</idx></tt></tag>
+<sect1><tt>.IFPC02</tt><label id=".IFPC02"><p>
Conditional assembly: Check if the assembler is currently in 65C02 mode
- (see <tt/.PC02/ command).
+ (see <tt><ref id=".PC02" name=".PC02"></tt> command).
+
+
+<sect1><tt>.IFPSC02</tt><label id=".IFPSC02"><p>
+ Conditional assembly: Check if the assembler is currently in 65SC02 mode
+ (see <tt><ref id=".PSC02" name=".PSC02"></tt> command).
-<tag><tt><idx>.IFREF</idx></tt></tag>
+
+<sect1><tt>.IFREF</tt><label id=".IFREF"><p>
Conditional assembly: Check if a symbol is referenced. Must be followed
by a symbol name. The condition is true if if the the given symbol was
.endif
</verb></tscreen>
- See also: <tt/.REFERENCED/
+ See also: <tt><ref id=".REFERENCED" name=".REFERENCED"></tt>
-<tag><tt><idx>.IMPORT</idx></tt></tag>
+<sect1><tt>.IMPORT</tt><label id=".IMPORT"><p>
Import a symbol from another module. The command is followed by a comma
separated list of symbols to import.
.import foo, bar
</verb></tscreen>
+ See: <tt><ref id=".IMPORTZP" name=".IMPORTZP"></tt>
+
-<tag><tt><idx>.IMPORTZP</idx></tt></tag>
+<sect1><tt>.IMPORTZP</tt><label id=".IMPORTZP"><p>
Import a symbol from another module. The command is followed by a comma
separated list of symbols to import. The symbols are explicitly imported
Example:
<tscreen><verb>
- .includezp foo, bar
+ .importzp foo, bar
</verb></tscreen>
+ See: <tt><ref id=".IMPORT" name=".IMPORT"></tt>
-<tag><tt><idx>.INCBIN</idx></tt></tag>
+
+<sect1><tt>.INCBIN</tt><label id=".INCBIN"><p>
Include a file as binary data. The command expects a string argument
that is the name of a file to include literally in the current segment.
+ In addition to that, a start offset and a size value may be specified,
+ separated by commas. If no size is specified, all of the file from the
+ start offset to end-of-file is used. If no start position is specified
+ either, zero is assume (which means that the whole file is inserted).
Example:
<tscreen><verb>
- .incbin "sprites.dat"
+ ; Include whole file
+ .incbin "sprites.dat"
+
+ ; Include file starting at offset 256
+ .incbin "music.dat", $100
+
+ ; Read 100 bytes starting at offset 200
+ .incbin "graphics.dat", 200, 100
</verb></tscreen>
-<tag><tt><idx>.INCLUDE</idx></tt></tag>
+<sect1><tt>.INCLUDE</tt><label id=".INCLUDE"><p>
Include another file. Include files may be nested up to a depth of 16.
</verb></tscreen>
-<tag><tt><idx>.LEFT</idx></tt></tag>
+<sect1><tt>.LEFT</tt><label id=".LEFT"><p>
Builtin function. Extracts the left part of a given token list.
.endmacro
</verb></tscreen>
- See also the <tt/.MID/ and <tt/.RIGHT/ builtin functions.
+ See also the <tt><ref id=".MID" name=".MID"></tt> and <tt><ref id=".RIGHT"
+ name=".RIGHT"></tt> builtin functions.
-<tag><tt><idx>.LINECONT</idx></tt></tag>
+<sect1><tt>.LINECONT</tt><label id=".LINECONT"><p>
Switch on or off line continuations using the backslash character
before a newline. The option is off by default.
</verb></tscreen>
-<tag><tt><idx>.LIST</idx></tt></tag>
+<sect1><tt>.LIST</tt><label id=".LIST"><p>
Enable output to the listing. The command must be followed by a boolean
switch ("on", "off", "+" or "-") and will enable or disable listing
</verb></tscreen>
-<tag><tt><idx>.LISTBYTES</idx></tt></tag>
+<sect1><tt>.LISTBYTES</tt><label id=".LISTBYTES"><p>
Set, how many bytes are shown in the listing for one source line. The
default is 12, so the listing will show only the first 12 bytes for any
</verb></tscreen>
-<tag><tt><idx>.LOCAL</idx></tt></tag>
+<sect1><tt>.LOCAL</tt><label id=".LOCAL"><p>
This command may only be used inside a macro definition. It declares a
list of identifiers as local to the macro expansion.
- A problem when using macros are labels: Since they don't change their
- name, you get a "duplicate symbol" error if the macro is expanded the
- second time. Labels declared with <tt/.LOCAL/ have their name mapped to
- an internal unique name (<tt/___ABCD__/) with each macro invocation.
+ A problem when using macros are labels: Since they don't change their name,
+ you get a "duplicate symbol" error if the macro is expanded the second time.
+ Labels declared with <tt><ref id=".LOCAL" name=".LOCAL"></tt> have their
+ name mapped to an internal unique name (<tt/___ABCD__/) with each macro
+ invocation.
- Some other assemblers start a new lexical block inside a macro
- expansion. This has some drawbacks however, since that will not allow
- <em/any/ symbol to be visible outside a macro, a feature that is sometimes
- useful. The <tt/.LOCAL/ command is in my eyes a better way to address
- the problem.
+ Some other assemblers start a new lexical block inside a macro expansion.
+ This has some drawbacks however, since that will not allow <em/any/ symbol
+ to be visible outside a macro, a feature that is sometimes useful. The
+ <tt><ref id=".LOCAL" name=".LOCAL"></tt> command is in my eyes a better way
+ to address the problem.
- You get an error when using <tt/.LOCAL/ outside a macro.
+ You get an error when using <tt><ref id=".LOCAL" name=".LOCAL"></tt> outside
+ a macro.
-<tag><tt><idx>.LOCALCHAR</idx></tt></tag>
+<sect1><tt>.LOCALCHAR</tt><label id=".LOCALCHAR"><p>
Defines the character that start "cheap" local labels. You may use one
of '@' and '?' as start character. The default is '@'.
</verb></tscreen>
-<tag><tt><idx>.MACPACK</idx></tt></tag>
+<sect1><tt>.MACPACK</tt><label id=".MACPACK"><p>
Insert a predefined macro package. The command is followed by an
identifier specifying the macro package to insert. Available macro
packages are:
+ <tscreen><verb>
generic Defines generic macros like add and sub.
longbranch Defines conditional long jump macros.
+ cbm Defines the scrcode macro
+ cpu Defines constants for the .CPU variable
+ </verb></tscreen>
Including a macro package twice, or including a macro package that
redefines already existing macros will lead to an error.
jne Label ; Jump long on condition
</verb></tscreen>
- See separate section about macros packages.
+ Macro packages are explained in more detail in section <ref
+ id="macropackages" name="Macro packages">.
-<tag><tt><idx>.MAC,</idx> <idx>.MACRO</idx></tt></tag>
+<sect1><tt>.MAC, .MACRO</tt><label id=".MAC"><p>
Start a classic macro definition. The command is followed by an identifier
(the macro name) and optionally by a comma separated list of identifiers
that are macro parameters.
- See separate section about macros.
+
+ See section <ref id="macros" name="Macros">.
-<tag><tt><idx>.MATCH</idx></tt></tag>
+<sect1><tt>.MATCH</tt><label id=".MATCH"><p>
Builtin function. Matches two token lists against each other. This is
most useful within macros, since macros are not stored as strings, but
Often a macro parameter is used for any of the token lists.
Please note that the function does only compare tokens, not token
- attributes. So any number is equal to any other number, regardless of
- the actual value. The same is true for strings. If you need to compare
- tokens <em/and/ token attributes, use the <tt/.XMATCH/ function.
+ attributes. So any number is equal to any other number, regardless of the
+ actual value. The same is true for strings. If you need to compare tokens
+ <em/and/ token attributes, use the <tt><ref id=".XMATCH"
+ name=".XMATCH"></tt> function.
Example:
- Assume the macro <tt/ASR/, that will shift right the accumulator by one, while
- honoring the sign bit. The builtin processor instructions will allow an
- optional "A" for accu addressing for instructions like <tt/ROL/ and <tt/ROR/.
- We will use the <tt/.MATCH/ function to check for this and print and error
- for invalid calls.
+ Assume the macro <tt/ASR/, that will shift right the accumulator by one,
+ while honoring the sign bit. The builtin processor instructions will allow
+ an optional "A" for accu addressing for instructions like <tt/ROL/ and
+ <tt/ROR/. We will use the <tt><ref id=".MATCH" name=".MATCH"></tt> function
+ to check for this and print and error for invalid calls.
<tscreen><verb>
- .macro asr arg
+ .macro asr arg
.if (.not .blank(arg)) .and (.not .match (arg, a))
.error "Syntax error"
.endif
cmp #$80 ; Bit 7 into carry
- lsr a ; Shit carry into bit 7
+ lsr a ; Shift carry into bit 7
.endmacro
</verb></tscreen>
The macro will only accept no arguments, or one argument that must be the
reserved keyword "A".
+ See: <tt><ref id=".XMATCH" name=".XMATCH"></tt>
+
-<tag><tt><idx>.MID</idx></tt></tag>
+<sect1><tt>.MID</tt><label id=".MID"><p>
Builtin function. Takes a starting index, a count and a token list as
arguments. Will return part of the token list.
.endmacro
</verb></tscreen>
- See also the <tt/.LEFT/ and <tt/.RIGHT/ builtin functions.
+ See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".RIGHT"
+ name=".RIGHT"></tt> builtin functions.
-<tag><tt><idx>.ORG</idx></tt></tag>
+<sect1><tt>.ORG</tt><label id=".ORG"><p>
Start a section of absolute code. The command is followed by a constant
expression that gives the new PC counter location for which the code is
- assembled. Use <tt/.RELOC/ to switch back to relocatable code.
+ assembled. Use <tt><ref id=".RELOC" name=".RELOC"></tt> to switch back to
+ relocatable code.
+
+ Please note that you <em/do not need/ this command in most cases. Placing
+ code at a specific address is the job of the linker, not the assembler, so
+ there is usually no reason to assemble code to a specific address.
You may not switch segments while inside a section of absolute code.
</verb></tscreen>
-<tag><tt><idx>.OUT</idx></tt></tag>
+<sect1><tt>.OUT</tt><label id=".OUT"><p>
Output a string to the console without producing an error. This command
is similiar to <tt/.ERROR/, however, it does not force an assembler error
.out "This code was written by the codebuster(tm)"
</verb></tscreen>
- See also the <tt/.WARNING/ and <tt/.ERROR/ directives.
+ See also the <tt><ref id=".WARNING" name=".WARNING"></tt> and <tt><ref
+ id=".ERROR" name=".ERROR"></tt> directives.
+
+<sect1><tt>.P02</tt><label id=".P02"><p>
-<tag><tt><idx>.P02</idx></tt></tag>
+ Enable the 6502 instruction set, disable 65SC02, 65C02 and 65816
+ instructions. This is the default if not overridden by the
+ <tt><ref id="option--cpu" name="--cpu"></tt> command line option.
- Enable the 6502 instruction set, disable 65C02 and 65816 instructions.
- This is the default if not overridden by the <tt/--cpu/ command line
- option.
+ See: <tt><ref id=".PC02" name=".PC02"></tt>, <tt><ref id=".PSC02"
+ name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
-<tag><tt><idx>.P816</idx></tt></tag>
+<sect1><tt>.P816</tt><label id=".P816"><p>
- Enable the 65816 instruction set. This is a superset of the 65C02 and
+ Enable the 65816 instruction set. This is a superset of the 65SC02 and
6502 instruction sets.
+ See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
+ name=".PSC02"></tt> and <tt><ref id=".PC02" name=".PC02"></tt>
-<tag><tt><idx>.PAGELEN,</idx> <idx>.PAGELENGTH</idx></tt></tag>
+
+<sect1><tt>.PAGELEN, .PAGELENGTH</tt><label id=".PAGELENGTH"><p>
Set the page length for the listing. Must be followed by an integer
constant. The value may be "unlimited", or in the range 32 to 127. The
- statement has no effect if no listing is generated. The default value
- is -1 but may be overridden by the <tt/--pagelength/ command line option.
- Beware: Since the listing is generated after assembly is complete, you
- cannot use multiple line lengths with one source. Instead, the value
- set with the last <tt/.PAGELENGTH/ is used.
+ statement has no effect if no listing is generated. The default value is -1
+ (unlimited) but may be overridden by the <tt/--pagelength/ command line
+ option. Beware: Since ca65 is a one pass assembler, the listing is generated
+ after assembly is complete, you cannot use multiple line lengths with one
+ source. Instead, the value set with the last <tt/.PAGELENGTH/ is used.
Examples:
</verb></tscreen>
-<tag><tt><idx>.PARAMCOUNT</idx></tt></tag>
+<sect1><tt>.PARAMCOUNT</tt><label id=".PARAMCOUNT"><p>
- This builtin pseudo variable is only available in macros. It is replaced
- by the actual number of parameters that were given in the macro
- invocation.
+ This builtin pseudo variable is only available in macros. It is replaced by
+ the actual number of parameters that were given in the macro invocation.
Example:
.endmacro
</verb></tscreen>
+ See section <ref id="macros" name="Macros">.
+
-<tag><tt><idx>.PC02</idx></tt></tag>
+<sect1><tt>.PC02</tt><label id=".PC02"><p>
Enable the 65C02 instructions set. This instruction set includes all
- 6502 instructions.
+ 6502 and 65SC02 instructions.
+
+ See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
+ name=".PSC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
+
+
+<sect1><tt>.POPSEG</tt><label id=".POPSEG"><p>
+
+ Pop the last pushed segment from the stack, and set it.
+
+ This command will switch back to the segment that was last pushed onto the
+ segment stack using the <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
+ command, and remove this entry from the stack.
+
+ The assembler will print an error message if the segment stack is empty
+ when this command is issued.
+ See: <tt><ref id=".PUSHSEG" name=".PUSHSEG"></tt>
-<tag><tt><idx>.PROC</idx></tt></tag>
- Start a nested lexical level. All new symbols from now on are in the
- local lexical level and are not accessible from outside. Symbols defined
- outside this local level may be accessed as long as their names are not
- used for new symbols inside the level. Symbols names in other lexical
- levels do not clash, so you may use the same names for identifiers. The
- lexical level ends when the <tt/.ENDPROC/ command is read. Lexical levels
- may be nested up to a depth of 16.
+<sect1><tt>.PROC</tt><label id=".PROC"><p>
- The command may be followed by an identifier, in this case the
- identifier is declared in the outer level as a label having the value of
- the program counter at the start of the lexical level.
+ Start a nested lexical level with the given name and adds a symbol with this
+ name to the enclosing scope. All new symbols from now on are in the local
+ lexical level and are accessible from outside only via <ref id="scopesyntax"
+ name="explicit scope specification">. Symbols defined outside this local
+ level may be accessed as long as their names are not used for new symbols
+ inside the level. Symbols names in other lexical levels do not clash, so you
+ may use the same names for identifiers. The lexical level ends when the
+ <tt><ref id=".ENDPROC" name=".ENDPROC"></tt> command is read. Lexical levels
+ may be nested up to a depth of 16 (this is an artificial limit to protect
+ against errors in the source).
Note: Macro names are always in the global level and in a separate name
space. There is no special reason for this, it's just that I've never
dey
bne L1 ; Reference local symbol
rts
- .endproc ; Leave lexical level
+ .endproc ; Leave lexical level
</verb></tscreen>
+ See: <tt/<ref id=".ENDPROC" name=".ENDPROC">/ and <tt/<ref id=".SCOPE"
+ name=".SCOPE">/
-<tag><tt><idx>.REF,</idx> <idx>.REFERENCED</idx></tt></tag>
- Builtin function. The function expects an identifier as argument in
- braces. The argument is evaluated, and the function yields "true" if the
- identifier is a symbol that has already been referenced somewhere in the
- source file up to the current position. Otherwise the function yields
- false. As an example, the <tt/.IFREF/ statement may be replaced by
+<sect1><tt>.PSC02</tt><label id=".PSC02"><p>
+
+ Enable the 65SC02 instructions set. This instruction set includes all
+ 6502 instructions.
+
+ See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PC02"
+ name=".PC02"></tt> and <tt><ref id=".P816" name=".P816"></tt>
+
+
+<sect1><tt>.PUSHSEG</tt><label id=".PUSHSEG"><p>
+
+ Push the currently active segment onto a stack. The entries on the stack
+ include the name of the segment and the segment type. The stack has a size
+ of 16 entries.
+
+ <tt/.PUSHSEG/ allows together with <tt><ref id=".POPSEG" name=".POPSEG"></tt>
+ to switch to another segment and to restore the old segment later, without
+ even knowing the name and type of the current segment.
+
+ The assembler will print an error message if the segment stack is already
+ full, when this command is issued.
+
+ See: <tt><ref id=".POPSEG" name=".POPSEG"></tt>
+
+
+<sect1><tt>.REF, .REFERENCED</tt><label id=".REFERENCED"><p>
+
+ Builtin function. The function expects an identifier as argument in braces.
+ The argument is evaluated, and the function yields "true" if the identifier
+ is a symbol that has already been referenced somewhere in the source file up
+ to the current position. Otherwise the function yields false. As an example,
+ the <tt><ref id=".IFREF" name=".IFREF"></tt> statement may be replaced by
<tscreen><verb>
.if .referenced(a)
</verb></tscreen>
+ See: <tt><ref id=".DEFINED" name=".DEFINED"></tt>
+
-<tag><tt><idx>.REPEAT</idx></tt></tag>
+<sect1><tt>.REPEAT</tt><label id=".REPEAT"><p>
- Repeat all commands between <tt/.REPEAT/ and <tt/.ENDREPEAT/ a constant
- number of times. The command is followed by a constant expression that tells
- how many times the commands in the body should get repeated. Optionally, a
- comma and an identifier may be specified. If this identifier is found in
- the body of the repeat statement, it is replaced by the current repeat
- count (starting with zero for the first time the body is repeated).
+ Repeat all commands between <tt/.REPEAT/ and <tt><ref id=".ENDREPEAT"
+ name=".ENDREPEAT"></tt> constant number of times. The command is followed by
+ a constant expression that tells how many times the commands in the body
+ should get repeated. Optionally, a comma and an identifier may be specified.
+ If this identifier is found in the body of the repeat statement, it is
+ replaced by the current repeat count (starting with zero for the first time
+ the body is repeated).
<tt/.REPEAT/ statements may be nested. If you use the same repeat count
identifier for a nested <tt/.REPEAT/ statement, the one from the inner
characters of the string are XORed by the value $55.
<tscreen><verb>
- .macro Crypt Arg
- .repeat strlen(Arg), I
- .byte strat(Arg, I) .xor $55
+ .macro Crypt Arg
+ .repeat .strlen(Arg), I
+ .byte .strat(Arg, I) .xor $55
.endrep
.endmacro
</verb></tscreen>
+ See: <tt><ref id=".ENDREPEAT" name=".ENDREPEAT"></tt>
-<tag><tt><idx>.RELOC</idx></tt></tag>
- Switch back to relocatable mode. See the <tt/.ORG/ command.
+<sect1><tt>.RELOC</tt><label id=".RELOC"><p>
+ Switch back to relocatable mode. See the <tt><ref id=".ORG"
+ name=".ORG"></tt> command.
-<tag><tt><idx>.RES</idx></tt></tag>
+
+<sect1><tt>.RES</tt><label id=".RES"><p>
Reserve storage. The command is followed by one or two constant
expressions. The first one is mandatory and defines, how many bytes of
<tscreen><verb>
; Reserve 12 bytes of memory with value $AA
- .res 12, $AA
+ .res 12, $AA
</verb></tscreen>
-<tag><tt><idx>.RIGHT</idx></tt></tag>
+<sect1><tt>.RIGHT</tt><label id=".RIGHT"><p>
Builtin function. Extracts the right part of a given token list.
The first integer expression gives the number of tokens to extract from
the token list. The second argument is the token list itself.
- See also the <tt/.LEFT/ and <tt/.MID/ builtin functions.
+ See also the <tt><ref id=".LEFT" name=".LEFT"></tt> and <tt><ref id=".MID"
+ name=".MID"></tt> builtin functions.
-<tag><tt><idx>.RODATA</idx></tt></tag>
+<sect1><tt>.RODATA</tt><label id=".RODATA"><p>
Switch to the RODATA segment. The name of the RODATA segment is always
"RODATA", so this is a shortcut for
</verb></tscreen>
The RODATA segment is a segment that is used by the compiler for
- readonly data like string constants. See also the <tt/.SEGMENT/ command.
+ readonly data like string constants.
+
+ See also the <tt><ref id=".SEGMENT" name=".SEGMENT"></tt> command.
+
+
+<sect1><tt>.SCOPE</tt><label id=".SCOPE"><p>
+
+ Start a nested lexical level with the given name. All new symbols from now
+ on are in the local lexical level and are accessible from outside only via
+ <ref id="scopesyntax" name="explicit scope specification">. Symbols defined
+ outside this local level may be accessed as long as their names are not used
+ for new symbols inside the level. Symbols names in other lexical levels do
+ not clash, so you may use the same names for identifiers. The lexical level
+ ends when the <tt><ref id=".ENDSCOPE" name=".ENDSCOPE"></tt> command is
+ read. Lexical levels may be nested up to a depth of 16 (this is an
+ artificial limit to protect against errors in the source).
+
+ Note: Macro names are always in the global level and in a separate name
+ space. There is no special reason for this, it's just that I've never
+ had any need for local macro definitions.
+
+ Example:
+
+ <tscreen><verb>
+ .scope Error ; Start new scope named Error
+ None = 0 ; No error
+ File = 1 ; File error
+ Parse = 2 ; Parse error
+ .endproc ; Close lexical level
+
+ ...
+ lda #Error::File ; Use symbol from scope Error
+ </verb></tscreen>
+ See: <tt/<ref id=".ENDSCOPE" name=".ENDSCOPE">/ and <tt/<ref id=".PROC"
+ name=".PROC">/
-<tag><tt><idx>.SEGMENT</idx></tt></tag>
+
+<sect1><tt>.SEGMENT</tt><label id=".SEGMENT"><p>
Switch to another segment. Code and data is always emitted into a
segment, that is, a named section of data. The default segment is
.segment "ZP2", absolute ; Error, redecl mismatch
</verb></tscreen>
+ See: <tt><ref id=".BSS" name=".BSS"></tt>, <tt><ref id=".CODE"
+ name=".CODE"></tt>, <tt><ref id=".DATA" name=".DATA"></tt> and <tt><ref
+ id=".RODATA" name=".RODATA"></tt>
+
+
+<sect1><tt>.SETCPU</tt><label id=".SETCPU"><p>
+
+ Switch the CPU instruction set. The command is followed by a string that
+ specifies the CPU. Possible values are those that can also be supplied to
+ the <tt><ref id="option--cpu" name="--cpu"></tt> command line option,
+ namely: 6502, 65SC02, 65C02, 65816 and sunplus. Please note that support
+ for the sunplus CPU is not available in the freeware version, because the
+ instruction set of the sunplus CPU is "proprietary and confidential".
+
+ See: <tt><ref id=".CPU" name=".CPU"></tt>,
+ <tt><ref id=".IFP02" name=".IFP02"></tt>,
+ <tt><ref id=".IFP816" name=".IFP816"></tt>,
+ <tt><ref id=".IFPC02" name=".IFPC02"></tt>,
+ <tt><ref id=".IFPSC02" name=".IFPSC02"></tt>,
+ <tt><ref id=".P02" name=".P02"></tt>,
+ <tt><ref id=".P816" name=".P816"></tt>,
+ <tt><ref id=".PC02" name=".PC02"></tt>,
+ <tt><ref id=".PSC02" name=".PSC02"></tt>
+
+
+<sect1><tt>.SIZEOF</tt><label id=".SIZEOF"><p>
+
+ <tt/.SIZEOF/ is a pseudo function that returns the size of its argument. The
+ argument can be a struct/union, a struct member, a procedure, or a label. In
+ case of a procedure or label, its size is defined by the amount of data
+ placed in the segment where the label is relative to. If a line of code
+ switches segments (for example in a macro) data placed in other segments
+ does not count for the size.
+
+ Please note that a symbol or scope must exist, before it is used together with
+ <tt/.SIZEOF/ (this may get relaxed later, but will always be true for scopes).
+ A scope has preference over a symbol with the same name, so if the last part
+ of a name represents both, a scope and a symbol, the scope is choosen over the
+ symbol.
+
+ After the following code:
+
+ <tscreen><verb>
+ .struct Point ; Struct size = 4
+ xcoord .word
+ xcoord .word
+ .endstruct
-<tag><tt><idx>.SMART</idx></tt></tag>
+ P: .tag Point ; Declare a point
+ @P: .tag Point ; Declare another point
+
+ .code
+ .proc Code
+ nop
+ .proc Inner
+ nop
+ .endproc
+ nop
+ .endproc
+
+ .proc Data
+ .data ; Segment switch!!!
+ .res 4
+ .endproc
+ </verb></tscreen>
+
+ <descrip>
+ <tag><tt/.sizeof(Point)/</tag>
+ will have the value 4, because this is the size of struct <tt/Point/.
+
+ <tag><tt/.sizeof(Point::xcoord)/</tag>
+ will have the value 2, because this is the size of the member <tt/xcoord/
+ in struct <tt/Point/.
+
+ <tag><tt/.sizeof(P)/</tag>
+ will have the value 4, this is the size of the data declared on the same
+ source line as the label <tt/P/, which is in the same segment that <tt/P/
+ is relative to.
+
+ <tag><tt/.sizeof(@P)/</tag>
+ will have the value 4, see above. The example demonstrates that <tt/.SIZEOF/
+ does also work for cheap local symbols.
+
+ <tag><tt/.sizeof(Code)/</tag>
+ will have the value 3, since this is amount of data emitted into the code
+ segment, the segment that was active when <tt/Code/ was entered. Note that
+ this value includes the amount of data emitted in child scopes (in this
+ case <tt/Code::Inner/).
+
+ <tag><tt/.sizeof(Code::Inner)/</tag>
+ will have the value 1 as expected.
+
+ <tag><tt/.sizeof(Data)/</tag>
+ will have the value 0. Data is emitted within the scope <tt/Data/, but since
+ the segment is switched after entry, this data is emitted into another
+ segment.
+ </descrip>
+
+
+<sect1><tt>.SMART</tt><label id=".SMART"><p>
Switch on or off smart mode. The command must be followed by a '+' or
'-' character to switch the option on or off respectively. The default
is off (that is, the assembler doesn't try to be smart), but this
default may be changed by the -s switch on the command line.
- In smart mode the assembler will track usage of the <tt/REP/ and <tt/SEP/
- instructions in 65816 mode and update the operand sizes accordingly. If
- the operand of such an instruction cannot be evaluated by the assembler
- (for example, because the operand is an imported symbol), a warning is
- issued. Beware: Since the assembler cannot trace the execution flow this
- may lead to false results in some cases. If in doubt, use the <tt/.Inn/ and
- <tt/.Ann/ instructions to tell the assembler about the current settings.
+ In smart mode the assembler will do the following:
+
+ <itemize>
+ <item>Track usage of the <tt/REP/ and <tt/SEP/ instructions in 65816 mode
+ and update the operand sizes accordingly. If the operand of such an
+ instruction cannot be evaluated by the assembler (for example, because
+ the operand is an imported symbol), a warning is issued. Beware: Since
+ the assembler cannot trace the execution flow this may lead to false
+ results in some cases. If in doubt, use the <tt/.Inn/ and <tt/.Ann/
+ instructions to tell the assembler about the current settings.
+ <item>In 65816 mode, replace a <tt/RTS/ instruction by <tt/RTL/ if it is
+ used within a procedure declared as <tt/far/, or if the procedure has
+ no explicit address specification, but it is <tt/far/ because of the
+ memory model used.
+ </itemize>
Example:
.smart - ; Stop being smart
</verb></tscreen>
+ See: <tt><ref id=".A16" name=".A16"></tt>,
+ <tt><ref id=".A8" name=".A8"></tt>,
+ <tt><ref id=".I16" name=".I16"></tt>,
+ <tt><ref id=".I8" name=".I8"></tt>
+
-<tag><tt><idx>.STRAT</idx></tt></tag>
+<sect1><tt>.STRAT</tt><label id=".STRAT"><p>
Builtin function. The function accepts a string and an index as
arguments and returns the value of the character at the given position
</verb></tscreen>
-<tag><tt><idx>.STRING</idx></tt></tag>
+<sect1><tt>.STRING</tt><label id=".STRING"><p>
+
+ Builtin function. The function accepts an argument in braces and converts
+ this argument into a string constant. The argument may be an identifier, or
+ a constant numeric value.
- Builtin function. The function accepts an argument in braces and
- converts this argument into a string constant. The argument may be an
- identifier, or a constant numeric value.
- Since you can use a string in the first place, the use of the function
- may not be obvious. However, it is useful in macros, or more complex
- setups.
+ Since you can use a string in the first place, the use of the function may
+ not be obvious. However, it is useful in macros, or more complex setups.
Example:
</verb></tscreen>
-<tag><tt><idx>.STRLEN</idx></tt></tag>
+<sect1><tt>.STRLEN</tt><label id=".STRLEN"><p>
Builtin function. The function accepts a string argument in braces and
eveluates to the length of the string.
</verb></tscreen>
-<tag><tt><idx>.TCOUNT</idx></tt></tag>
+<sect1><tt>.STRUCT</tt><label id=".STRUCT"><p>
+
+ Starts a struct definition. See the section named <ref id="structs"
+ name="Structs and unions">.
+
+
+<sect1><tt>.SUNPLUS</tt><label id=".SUNPLUS"><p>
+
+ Enable the SunPlus instructions set. This command will not work in the
+ freeware version of the assembler, because the instruction set is
+ "proprietary and confidential".
+
+ See: <tt><ref id=".P02" name=".P02"></tt>, <tt><ref id=".PSC02"
+ name=".PSC02"></tt>, <tt><ref id=".PC02" name=".PC02"></tt>, and
+ <tt><ref id=".P816" name=".P816"></tt>
+
+
+<sect1><tt>.TAG</tt><label id=".TAG"><p>
+
+ Allocate space for a struct or union.
+
+ Example:
+
+ <tscreen><verb>
+ .struct Point
+ xcoord .word
+ ycoord .word
+ .endstruct
+
+ .bss
+ .tag Point ; Allocate 4 bytes
+ </verb></tscreen>
+
+
+<sect1><tt>.TCOUNT</tt><label id=".TCOUNT"><p>
Builtin function. The function accepts a token list in braces. The
function result is the number of tokens given as argument.
<tscreen><verb>
.macro ldax arg
- .if (.match (.mid (0, 1, arg), #))
- ; ldax called with immidiate operand
- lda #<(.right (.tcount (arg)-1, arg))
- ldx #>(.right (.tcount (arg)-1, arg))
- .else
- ...
- .endif
+ .if (.match (.mid (0, 1, arg), #))
+ ; ldax called with immidiate operand
+ lda #<(.right (.tcount (arg)-1, arg))
+ ldx #>(.right (.tcount (arg)-1, arg))
+ .else
+ ...
+ .endif
.endmacro
</verb></tscreen>
-<tag><tt><idx>.WARNING</idx></tt></tag>
+<sect1><tt>.TIME</tt><label id=".TIME"><p>
+
+ Reading this pseudo variable will give a constant integer value that
+ represents the current time in POSIX standard (as seconds since the
+ Epoch).
+
+ It may be used to encode the time of translation somewhere in the created
+ code.
+
+ Example:
+
+ <tscreen><verb>
+ .dword .time ; Place time here
+ </verb></tscreen>
+
+
+<sect1><tt>.VERSION</tt><label id=".VERSION"><p>
+
+ Reading this pseudo variable will give the assembler version according to
+ the following formula:
+
+ VER_MAJOR*$100 + VER_MINOR*$10 + VER_PATCH
+
+ It may be used to encode the assembler version or check the assembler for
+ special features not available with older versions.
+
+ Example:
+
+ Version 2.11.1 of the assembler will return $2B1 as numerical constant when
+ reading the pseudo variable <tt/.VERSION/.
+
+
+<sect1><tt>.WARNING</tt><label id=".WARNING"><p>
Force an assembly warning. The assembler will output a warning message
- preceeded by "User warning". This warning will always be output, even
- if other warnings are disabled with the <tt/-W0/ command line option.
+ preceeded by "User warning". This warning will always be output, even if
+ other warnings are disabled with the <tt><ref id="option-W" name="-W0"></tt>
+ command line option.
This command may be used to output possible problems when assembling
the source file.
.endmacro
</verb></tscreen>
- See also the <tt/.ERROR/ and <tt/.OUT/ directives.
+ See also the <tt><ref id=".ERROR" name=".ERROR"></tt> and <tt><ref id=".OUT"
+ name=".OUT"></tt> directives.
-<tag><tt><idx>.WORD</idx></tt></tag>
+<sect1><tt>.WORD</tt><label id=".WORD"><p>
Define word sized data. Must be followed by a sequence of (word ranged,
but not necessarily constant) expressions.
</verb></tscreen>
-<tag><tt><idx>.ZEROPAGE</idx></tt></tag>
+<sect1><tt>.XMATCH</tt><label id=".XMATCH"><p>
+
+ Builtin function. Matches two token lists against each other. This is
+ most useful within macros, since macros are not stored as strings, but
+ as lists of tokens.
+
+ The syntax is
+
+ <tscreen><verb>
+ .XMATCH(<token list #1>, <token list #2>)
+ </verb></tscreen>
+
+ Both token list may contain arbitrary tokens with the exception of the
+ terminator token (comma resp. right parenthesis) and
+
+ <itemize>
+ <item>end-of-line
+ <item>end-of-file
+ </itemize>
+
+ Often a macro parameter is used for any of the token lists.
+
+ The function compares tokens <em/and/ token values. If you need a function
+ that just compares the type of tokens, have a look at the <tt><ref
+ id=".MATCH" name=".MATCH"></tt> function.
+
+ See: <tt><ref id=".MATCH" name=".MATCH"></tt>
+
+
+<sect1><tt>.ZEROPAGE</tt><label id=".ZEROPAGE"><p>
Switch to the ZEROPAGE segment and mark it as direct (zeropage) segment.
The name of the ZEROPAGE segment is always "ZEROPAGE", so this is a
the linker to place this segment somewhere in the address range 0..$FF
otherwise you will get errors.
-</descrip>
+ See: <tt><ref id=".SEGMENT" name=".SEGMENT"></tt>
-<sect>Macros
+<sect>Macros<label id="macros"><p>
+
+
+<sect1>Introduction<p>
-<p>
Macros may be thought of as "parametrized super instructions". Macros are
sequences of tokens that have a name. If that name is used in the source
file, the macro is "expanded", that is, it is replaced by the tokens that
were specified when the macro was defined.
+
+<sect1>Macros without parameters<p>
+
In it's simplest form, a macro does not have parameters. Here's an
example:
sta $2010
</verb></tscreen>
+
+<sect1>Parametrized macros<p>
+
When using macro parameters, macros can be even more useful:
<tscreen><verb>
.macro inc16 addr
clc
- lda addr
+ lda addr
adc #$01
sta addr
lda addr+1
by nothing will lead to wrong code in most lines. To help you, writing
macros with a variable parameter list, there are some control commands:
-<tt/.IFBLANK/ tests the rest of the line and returns true, if there are any
-tokens on the remainder of the line. Since empty parameters are replaced by
-nothing, this may be used to test if a given parameter is empty.
-<tt/.IFNBLANK/ tests the opposite.
+<tt><ref id=".IFBLANK" name=".IFBLANK"></tt> tests the rest of the line and
+returns true, if there are any tokens on the remainder of the line. Since
+empty parameters are replaced by nothing, this may be used to test if a given
+parameter is empty. <tt><ref id=".IFNBLANK" name=".IFNBLANK"></tt> tests the
+opposite.
Look at this example:
</verb></tscreen>
There's another helper command for determining, which macro parameters are
-valid: <tt/.PARAMCOUNT/. This command is replaced by the parameter count
-given, <em/including/ intermediate empty macro parameters:
+valid: <tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt> This command is
+replaced by the parameter count given, <em/including/ intermediate empty macro
+parameters:
+
+<tscreen><verb>
+ ldaxy 1 ; .PARAMCOUNT = 1
+ ldaxy 1,,3 ; .PARAMCOUNT = 3
+ ldaxy 1,2 ; .PARAMCOUNT = 2
+ ldaxy 1, ; .PARAMCOUNT = 2
+ ldaxy 1,2,3 ; .PARAMCOUNT = 3
+</verb></tscreen>
+
+
+<sect1>Detecting parameter types<p>
+
+Sometimes it is nice to write a macro that acts differently depending on the
+type of the argument supplied. An example would be a macro that loads a 16 bit
+value from either an immediate operand, or from memory. The <tt/<ref
+id=".MATCH" name=".MATCH">/ and <tt/<ref id=".XMATCH" name=".XMATCH">/
+functions will allow you to do exactly this:
+
+<tscreen><verb>
+ .macro ldax arg
+ .if (.match (.left (1, arg), #))
+ ; immediate mode
+ lda #<(.right (.tcount (arg)-1, arg))
+ ldx #>(.right (.tcount (arg)-1, arg))
+ .else
+ ; assume absolute or zero page
+ lda arg
+ ldx 1+(arg)
+ .endif
+ .endmacro
+</verb></tscreen>
+
+Using the <tt/<ref id=".MATCH" name=".MATCH">/ function, the macro is able to
+check if its argument begins with a hash mark. If so, two immediate loads are
+emitted, Otherwise a load from an absolute zero page memory location is
+assumed. So this macro can be used as
<tscreen><verb>
- ldaxy 1 ; .PARAMCOUNT = 1
- ldaxy 1,,3 ; .PARAMCOUNT = 3
- ldaxy 1,2 ; .PARAMCOUNT = 2
- ldaxy 1, ; .PARAMCOUNT = 2
- ldaxy 1,2,3 ; .PARAMCOUNT = 3
+ foo: .word $5678
+ ...
+ ldax #$1234 ; X=$12, A=$34
+ ...
+ ldax foo ; X=$56, A=$78
</verb></tscreen>
+
+<sect1>Recursive macros<p>
+
Macros may be used recursively:
<tscreen><verb>
.endmacro
</verb></tscreen>
-There's also a special macro to help writing recursive macros:
-<tt/.EXITMACRO/. This command will stop macro expansion immidiately:
+There's also a special macro to help writing recursive macros: <tt><ref
+id=".EXITMACRO" name=".EXITMACRO"></tt> This command will stop macro expansion
+immidiately:
<tscreen><verb>
.macro push r1, r2, r3, r4, r5, r6, r7
.ifblank r1
- ; First parameter is empty
- .exitmacro
+ ; First parameter is empty
+ .exitmacro
.else
- lda r1
- pha
+ lda r1
+ pha
.endif
- push r2, r3, r4, r5, r6, r7
+ push r2, r3, r4, r5, r6, r7
.endmacro
</verb></tscreen>
<tscreen><verb>
push $20, $21, $32 ; Push 3 ZP locations
- push $21 ; Push one ZP location
+ push $21 ; Push one ZP location
</verb></tscreen>
-Now, with recursive macros, <tt/.IFBLANK/ and <tt/.PARAMCOUNT/, what else do
-you need? Have a look at the inc16 macro above. Here is it again:
+
+<sect1>Local symbols inside macros<p>
+
+Now, with recursive macros, <tt><ref id=".IFBLANK" name=".IFBLANK"></tt> and
+<tt><ref id=".PARAMCOUNT" name=".PARAMCOUNT"></tt>, what else do you need?
+Have a look at the inc16 macro above. Here is it again:
<tscreen><verb>
- .macro inc16 addr
- clc
- lda addr
- adc #$01
- sta addr
- lda addr+1
- adc #$00
- sta addr+1
- .endmacro
+ .macro inc16 addr
+ clc
+ lda addr
+ adc #$01
+ sta addr
+ lda addr+1
+ adc #$00
+ sta addr+1
+ .endmacro
</verb></tscreen>
If you have a closer look at the code, you will notice, that it could be
written more efficiently, like this:
<tscreen><verb>
- .macro inc16 addr
- clc
- lda addr
- adc #$01
- sta addr
- bcc Skip
- inc addr+1
- Skip:
- .endmacro
+ .macro inc16 addr
+ inc addr
+ bne Skip
+ inc addr+1
+ Skip:
+ .endmacro
</verb></tscreen>
But imagine what happens, if you use this macro twice? Since the label
<tscreen><verb>
.macro inc16 addr
.proc
- clc
- lda addr
- adc #$01
- sta addr
- bcc Skip
- inc addr+1
+ inc addr
+ bne Skip
+ inc addr+1
Skip:
.endproc
.endmacro
Now the label is local to the block and not visible outside. However,
sometimes you want a label inside the macro to be visible outside. To make
that possible, there's a new command that's only usable inside a macro
-definition: <tt/.LOCAL/. <tt/.LOCAL/ declares one or more symbols as local to
-the macro expansion. The names of local variables are replaced by a unique
-name in each separate macro expansion. So we could also solve the problem
-above by using <tt/.LOCAL/:
+definition: <tt><ref id=".LOCAL" name=".LOCAL"></tt>. <tt/.LOCAL/ declares one
+or more symbols as local to the macro expansion. The names of local variables
+are replaced by a unique name in each separate macro expansion. So we could
+also solve the problem above by using <tt/.LOCAL/:
<tscreen><verb>
.macro inc16 addr
.endmacro
</verb></tscreen>
+
+<sect1>C style macros<p>
+
Starting with version 2.5 of the assembler, there is a second macro type
available: C style macros using the <tt/.DEFINE/ directive. These macros are
-similar to the classic macro type speified above, but behaviour is sometimes
+similar to the classic macro type described above, but behaviour is sometimes
different:
<itemize>
-<item> Macros defined with <tt/.DEFINE/ may not span more than a line. You
- may use line continuation (see <tt/.LINECONT/) to spread the
- definition over more than one line for increased readability, but the
- macro itself does not contain an end-of-line token.
-
-<item> Macros defined with <tt/.DEFINE/ share the name space with classic
- macros, but they are detected and replaced at the scanner level. While
- classic macros may be used in every place, where a mnemonic or other
- directive is allowed, <tt/.DEFINE/ style macros are allowed anywhere
- in a line. So they are more versatile in some situations.
-
-<item> <tt/.DEFINE/ style macros may take parameters. While classic macros
- may have empty parameters, this is not true for <tt/.DEFINE/ style
- macros. For this macro type, the number of actual parameters must
- match exactly the number of formal parameters.
+<item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> may not
+ span more than a line. You may use line continuation (see <tt><ref
+ id=".LINECONT" name=".LINECONT"></tt>) to spread the definition over
+ more than one line for increased readability, but the macro itself
+ may not contain an end-of-line token.
+
+<item> Macros defined with <tt><ref id=".DEFINE" name=".DEFINE"></tt> share
+ the name space with classic macros, but they are detected and replaced
+ at the scanner level. While classic macros may be used in every place,
+ where a mnemonic or other directive is allowed, <tt><ref id=".DEFINE"
+ name=".DEFINE"></tt> style macros are allowed anywhere in a line. So
+ they are more versatile in some situations.
+
+<item> <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may take
+ parameters. While classic macros may have empty parameters, this is
+ not true for <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros.
+ For this macro type, the number of actual parameters must match
+ exactly the number of formal parameters.
To make this possible, formal parameters are enclosed in braces when
defining the macro. If there are no parameters, the empty braces may
be omitted.
-<item> Since <tt/.DEFINE/ style macros may not contain end-of-line tokens,
- there are things that cannot be done. They may not contain several
- processor instructions for example. So, while some things may be done
- with both macro types, each type has special usages. The types
- complement each other.
+<item> Since <tt><ref id=".DEFINE" name=".DEFINE"></tt> style macros may not
+ contain end-of-line tokens, there are things that cannot be done. They
+ may not contain several processor instructions for example. So, while
+ some things may be done with both macro types, each type has special
+ usages. The types complement each other.
</itemize>
<tscreen><verb>
.define EQU =
- foo EQU $1234 ; This is accepted now
+ foo EQU $1234 ; This is accepted now
</verb></tscreen>
You may use the directive to define string constants used elsewhere:
<tscreen><verb>
.macro message
- .out message
+ .out message
.endmacro
</verb></tscreen>
(This is an example where a problem can be solved with both macro types).
+<sect1>Characters in macros<p>
-<sect>Macro packages
+When using the <ref id="option-t" name="-t"> option, characters are translated
+into the target character set of the specific machine. However, this happens
+as late as possible. This means that strings are translated if they are part
+of a <tt><ref id=".BYTE" name=".BYTE"></tt> or <tt><ref id=".ASCIIZ"
+name=".ASCIIZ"></tt> command. Characters are translated as soon as they are
+used as part of an expression.
-<p>
-Using the <tt/.MACPACK/ directive, predefined macro packages may be included
-with just one command. Available macro packages are:
+This behaviour is very intuitive outside of macros but may be confusing when
+doing more complex macros. If you compare characters against numeric values,
+be sure to take the translation into account.
-<descrip>
-<tag><tt><idx>generic</idx></tt></tag>
- This macro package defines macros that are useful in almost any program.
- Currently, two macros are defined:
- <tscreen><verb>
- .macro add Arg
- clc
+<sect>Macro packages<label id="macropackages"><p>
+
+Using the <tt><ref id=".MACPACK" name=".MACPACK"></tt> directive, predefined
+macro packages may be included with just one command. Available macro packages
+are:
+
+
+<sect1><tt>.MACPACK generic</tt><p>
+
+This macro package defines macros that are useful in almost any program.
+Currently, two macros are defined:
+
+<tscreen><verb>
+ .macro add Arg
+ clc
adc Arg
.endmacro
sec
sbc Arg
.endmacro
- </verb></tscreen>
+</verb></tscreen>
-<tag><tt><idx>longbranch</idx></tt></tag>
+<sect1><tt>.MACPACK longbranch</tt><p>
- This macro package defines long conditional jumps. They are named like the
- short counterpart but with the 'b' replaced by a 'j'. Here is a sample
- definition for the "<tt/jeq/" macro, the other macros are built using the
- same scheme:
+This macro package defines long conditional jumps. They are named like the
+short counterpart but with the 'b' replaced by a 'j'. Here is a sample
+definition for the "<tt/jeq/" macro, the other macros are built using the same
+scheme:
- <tscreen><verb>
+<tscreen><verb>
.macro jeq Target
.if .def(Target) .and ((*+2)-(Target) <= 127)
beq Target
jmp Target
.endif
.endmacro
- </verb></tscreen>
+</verb></tscreen>
- All macros expand to a short branch, if the label is already defined (back
- jump) and is reachable with a short jump. Otherwise the macro expands to a
- conditional branch with the branch condition inverted, followed by an
- absolute jump to the actual branch target.
+All macros expand to a short branch, if the label is already defined (back
+jump) and is reachable with a short jump. Otherwise the macro expands to a
+conditional branch with the branch condition inverted, followed by an absolute
+jump to the actual branch target.
- The package defines the following macros:
+The package defines the following macros:
- <tscreen><verb>
+<tscreen><verb>
jeq, jne, jmi, jpl, jcs, jcc, jvs, jvc
- </verb></tscreen>
+</verb></tscreen>
-</descrip>
+
+
+<sect1><tt>.MACPACK cbm</tt><p>
+
+The cbm macro package will define a macro named <tt/scrcode/. It takes a
+string as argument and places this string into memory translated into screen
+codes.
+
+
+<sect1><tt>.MACPACK cpu</tt><p>
+
+This macro package does not define any macros but constants used to examine
+the value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable. For
+each supported CPU a constant similar to
+
+<tscreen><verb>
+ CPU_6502
+ CPU_65SC02
+ CPU_65C02
+ CPU_65816
+ CPU_SUNPLUS
+</verb></tscreen>
+
+is defined. These constants may be used to determine the exact type of the
+currently enabled CPU. In addition to that, for each CPU instruction set,
+another constant is defined:
+
+<tscreen><verb>
+ CPU_ISET_6502
+ CPU_ISET_65SC02
+ CPU_ISET_65C02
+ CPU_ISET_65816
+ CPU_ISET_SUNPLUS
+</verb></tscreen>
+
+The value read from the <tt/<ref id=".CPU" name=".CPU">/ pseudo variable may
+be checked with <tt/<ref id="operators" name=".BITAND">/ to determine if the
+currently enabled CPU supports a specific instruction set. For example the
+65C02 supports all instructions of the 65SC02 CPU, so it has the
+<tt/CPU_ISET_65SC02/ bit set in addition to its native <tt/CPU_ISET_65C02/
+bit. Using
+
+<tscreen><verb>
+ .if (.cpu .bitand CPU_ISET_65SC02)
+ lda (sp)
+ .else
+ ldy #$00
+ lda (sp),y
+ .endif
+</verb></tscreen>
+
+it is possible to determine if the
+
+<tscreen><verb>
+ lda (sp)
+</verb></tscreen>
+
+instruction is supported, which is the case for the 65SC02, 65C02 and 65816
+CPUs (the latter two are upwards compatible to the 65SC02).
+
+
+
+<sect>Structs and unions<label id="structs"><p>
+
+Structs and unions are special forms of <ref id="scopes" name="scopes">. They
+are to some degree comparable to their C counterparts. Both have a list of
+members. Each member allocates storage and may optionally have a name, which,
+in case of a struct, is the offset from the beginning and, in case of a union
+is always zero.
+
+Here is an example for a very simple struct with two members and a total size
+of 4 bytes:
+
+<tscreen><verb>
+ .struct Point
+ xcoord .word
+ ycoord .word
+ .endstruct
+</verb></tscreen>
+
+A union shares the total space between all its members, its size is the same
+as that of the largest member.
+
+A struct or union must not necessarily have a name. If it is anonymous, no
+local scope is opened, the identifiers used to name the members are placed
+into the current scope instead.
+
+A struct may contain unnamed members and definitions of local structs. The
+storage allocators may contain a multiplier, as in the example below:
+
+<tscreen><verb>
+ .struct Circle
+ .struct Point
+ .word 2 ; Allocate two words
+ .endstruct
+ Radius .word
+ .endstruct
+</verb></tscreen>
+
+Using the <ref id=".TAG" name=".TAG"> keyword, it is possible to embedd
+already defined structs or unions in structs:
+
+<tscreen><verb>
+ .struct Point
+ xcoord .word
+ ycoord .word
+ .endstruct
+
+ .struct Circle
+ Origin .tag Point
+ Radius .word
+ .endstruct
+</verb></tscreen>
+
+Space for a struct or union may be allocated using the <ref id=".TAG"
+name=".TAG"> directive.
+
+
+
+<sect>Module constructors/destructors<label id="condes"><p>
+
+<em>Note:</em> This section applies mostly to C programs, so the explanation
+below uses examples from the C libraries. However, the feature may also be
+useful for assembler programs.
+
+
+<sect1>Module overview<p>
+
+Using the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> and <tt><ref
+id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> keywords it it possible to export
+functions in a special way. The linker is able to generate tables with all
+functions of a specific type. Such a table will <em>only</em> include symbols
+from object files that are linked into a specific executable. This may be used
+to add initialization and cleanup code for library modules.
+
+The C heap functions are an example where module initialization code is used.
+All heap functions (<tt>malloc</tt>, <tt>free</tt>, ...) work with a few
+variables that contain the start and the end of the heap, pointers to the free
+list and so on. Since the end of the heap depends on the size and start of the
+stack, it must be initialized at runtime. However, initializing these
+variables for programs that do not use the heap are a waste of time and
+memory.
+
+So the central module defines a function that contains initialization code and
+exports this function using the <tt/.CONSTRUCTOR/ statement. If (and only if)
+this module is added to an executable by the linker, the initialization
+function will be placed into the table of constructors by the linker. The C
+startup code will call all constructors before <tt/main/ and all destructors
+after <tt/main/, so without any further work, the heap initialization code is
+called once the module is linked in.
+
+While it would be possible to add explicit calls to initialization functions
+in the startup code, the new approach has several advantages:
+
+<enum>
+<item>
+If a module is not included, the initialization code is not linked in and not
+called. So you don't pay for things you don't need.
+
+<item>
+Adding another library that needs initialization does not mean that the
+startup code has to be changed. Before we had module constructors and
+destructors, the startup code for all systems had to be adjusted to call the
+new initialization code.
+
+<item>
+The feature saves memory: Each additional initialization function needs just
+two bytes in the table (a pointer to the function).
+
+</enum>
+
+
+<sect1>Calling order<p>
+
+Both, constructors and destructors are sorted in increasing priority order by
+the linker when using one of the builtin linker configurations, so the
+functions with lower priorities come first and are followed by those with
+higher priorities. The C library runtime subroutine that walks over the
+constructor and destructor tables calls the functions starting from the top of
+the table - which means that functions with a high priority are called first.
+
+So when using the C runtime, both constructors and destructors are called with
+high priority functions first, followed by low priority functions.
+
+
+<sect1>Pitfalls<p>
+
+When creating and using module constructors and destructors, please take care
+of the following:
+
+<itemize>
+
+<item>
+The linker will only generate function tables, it will not generate code to
+call these functions. If you're using the feature in some other than the
+existing C environments, you have to write code to call all functions in a
+linker generated table yourself. See the <tt>condes</tt> module in the C
+runtime for an example on how to do this.
+
+<item>
+The linker will only add addresses of functions that are in modules linked to
+the executable. This means that you have to be careful where to place the
+condes functions. If initialization is needed for a group of functions, be
+sure to place the initialization function into a module that is linked in
+regardless of which function is called by the user.
+
+<item>
+The linker will generate the tables only when requested to do so by the
+<tt/FEATURE CONDES/ statement in the linker config file. Each table has to
+be requested separately.
+
+<item>
+Constructors and destructors may have priorities. These priorities determine
+the order of the functions in the table. If your intialization or cleanup code
+does depend on other initialization or cleanup code, you have to choose the
+priority for the functions accordingly.
+
+<item>
+Besides the <tt><ref id=".CONSTRUCTOR" name=".CONSTRUCTOR"></tt> and <tt><ref
+id=".DESTRUCTOR" name=".DESTRUCTOR"></tt> statements, there is also a more
+generic command: <tt><ref id=".CONDES" name=".CONDES"></tt>. This allows to
+specify an additional type. Predefined types are 0 (constructor) and 1
+(destructor). The linker generates a separate table for each type on request.
+
+</itemize>
+
+
+<sect>Porting sources from other assemblers<p>
+
+Sometimes it is necessary to port code written for older assemblers to ca65.
+In some cases, this can be done without any changes to the source code by
+using the emulation features of ca65 (see <tt><ref id=".FEATURE"
+name=".FEATURE"></tt>). In other cases, it is necessary to make changes to the
+source code.
+
+Probably the biggest difference is the handling of the <tt><ref id=".ORG"
+name=".ORG"></tt> directive. ca65 generates relocatable code, and placement is
+done by the linker. Most other assemblers generate absolute code, placement is
+done within the assembler and there is no external linker.
+
+In general it is not a good idea to write new code using the emulation
+features of the assembler, but there may be situations where even this rule is
+not valid.
+
+<sect1>TASS<p>
+
+You need to use some of the ca65 emulation features to simulate the behaviour
+of such simple assemblers.
+
+<enum>
+<item>Prepare your sourcecode like this:
+
+<tscreen><verb>
+ ; if you want TASS style labels without colons
+ .feature labels_without_colons
+
+ ; if you want TASS style character constants
+ ; ("a" instead of the default 'a')
+ .feature loose_char_term
+
+ .word *+2 ; the cbm load address
+
+ [yourcode here]
+</verb></tscreen>
+
+notice that the two emulation features are mostly useful for porting
+sources originally written in/for TASS, they are not needed for the
+actual "simple assembler operation" and are not recommended if you are
+writing new code from scratch.
+
+<item>Replace all program counter assignments (which are not possible in ca65
+by default, and the respective emulation feature works different from what
+you'd expect) by another way to skip to another memory location, for example
+the <tt><ref id=".RES" name=".RES"></tt>directive.
+
+<tscreen><verb>
+ ; *=$2000
+ .res $2000-* ; reserve memory up to $2000
+</verb></tscreen>
+
+notice that other than the original TASS, ca65 can never move the
+programmcounter backwards - think of it as if you are assembling to disc with
+TASS.
+
+<item>Conditional assembly (<tt/.ifeq//<tt/.endif//<tt/.goto/ etc.) must be
+rewritten to match ca65 syntax. Most importantly notice that due to the lack
+of <tt/.goto/, everything involving loops must be replaced by
+<tt><ref id=".REPEAT" name=".REPEAT"></tt>.
+
+<item>To assemble code to a different address than it is executed at, use the
+<tt><ref id=".ORG" name=".ORG"></tt> directive instead of
+<tt/.offs/-constructs.
+
+<tscreen><verb>
+ .org $1800
+
+ [floppy code here]
+
+ .reloc ; back to normal
+</verb></tscreen>
+
+<item>Then assemble like this:
+
+<tscreen><verb>
+ cl65 --start-addr 0x0ffe -t none myprog.s -o myprog.prg
+</verb></tscreen>
+
+notice that you need to use the actual start address minus two, since two
+bytes are used for the cbm load address.
+
+</enum>
<sect>Bugs/Feedback<p>
<sect>Copyright<p>
-ca65 (and all cc65 binutils) are (C) Copyright 1998-2000 Ullrich von
+ca65 (and all cc65 binutils) are (C) Copyright 1998-2003 Ullrich von
Bassewitz. For usage of the binaries and/or sources the following
conditions do apply:
projects / cc65 / blobdiff