<article>
<title>cc65 Users Guide
<author>Ullrich von Bassewitz, <htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">
-<date>03.09.2000
+<date>2000-09-03, 2001-10-02, 2005-08-01
<abstract>
cc65 is a C compiler for 6502 targets. It supports several 6502 based home
up the changes made by me. I have made many more changes in the meantime
(and rewritten major parts of the compiler), so I will no longer do that,
since the list would be too large and of no use to anyone. Instead I will
-describe the compiler in respect to the ANSI/ISO C standard. In fact, I'm
-planning a complete rewrite (that is, a complete new compiler) for the
-next release, since there are too many limitations in the current code,
-and removing these limitations would mean a rewrite of many more parts of
-the compiler.
+describe the compiler in respect to the ANSI/ISO C standard.
-There is a separate document named "library.txt" that covers the library
-available for the compiler. If you know C and are interested in doing
-actual programming, the library documentation is probably of much more use
-than this document.
+There are separate documents named <url url="library.html"> and <url
+url="funcref.html"> that cover the library that is available for the compiler.
+If you know C, and are interested in doing actual programming, the library
+documentation is probably of much more use than this document.
If you need some hints for getting the best code out of the compiler, you
-may have a look at "coding.txt" which covers some code generation issues.
+may have a look at <url url="coding.html"> which covers some code generation
+issues.
<sect>Usage<p>
-The compiler translates C files into files containing assembler code that
+The compiler translates C files into files containing assembly code that
may be translated by the ca65 macroassembler (for more information about
-the assembler, have a look at ca65.txt).
+the assembler, have a look at <url url="ca65.html">).
<sect1>Command line option overview<p>
---------------------------------------------------------------------------
Usage: cc65 [options] file
Short options:
- -d Debug mode
- -g Add debug info to object file
- -h Help (this text)
- -j Default characters are signed
- -o name Name the output file
- -t sys Set the target system
- -v Increase verbosity
- -A Strict ANSI mode
- -Cl Make local variables static
- -Dsym[=defn] Define a symbol
- -I dir Set an include directory search path
- -O Optimize code
- -Oi Optimize code, inline more code
- -Or Enable register variables
- -Os Inline some known functions
- -T Include source as comment
- -V Print the compiler version number
- -W Suppress warnings
+ -Cl Make local variables static
+ -Dsym[=defn] Define a symbol
+ -I dir Set an include directory search path
+ -O Optimize code
+ -Oi Optimize code, inline more code
+ -Or Enable register variables
+ -Os Inline some known functions
+ -T Include source as comment
+ -V Print the compiler version number
+ -W name[,name] Enable or disable warnings
+ -d Debug mode
+ -g Add debug info to object file
+ -h Help (this text)
+ -j Default characters are signed
+ -o name Name the output file
+ -r Enable register variables
+ -t sys Set the target system
+ -v Increase verbosity
Long options:
- --ansi Strict ANSI mode
- --cpu type Set cpu type
- --debug Debug mode
- --debug-info Add debug info to object file
- --help Help (this text)
- --include-dir dir Set an include directory search path
- --signed-chars Default characters are signed
- --static-locals Make local variables static
- --target sys Set the target system
- --verbose Increase verbosity
- --version Print the compiler version number
+ --add-source Include source as comment
+ --bss-name seg Set the name of the BSS segment
+ --check-stack Generate stack overflow checks
+ --code-name seg Set the name of the CODE segment
+ --codesize x Accept larger code by factor x
+ --cpu type Set cpu type
+ --create-dep Create a make dependency file
+ --data-name seg Set the name of the DATA segment
+ --debug Debug mode
+ --debug-info Add debug info to object file
+ --forget-inc-paths Forget include search paths
+ --help Help (this text)
+ --include-dir dir Set an include directory search path
+ --register-space b Set space available for register variables
+ --register-vars Enable register variables
+ --rodata-name seg Set the name of the RODATA segment
+ --signed-chars Default characters are signed
+ --standard std Language standard (c89, c99, cc65)
+ --static-locals Make local variables static
+ --target sys Set the target system
+ --verbose Increase verbosity
+ --version Print the compiler version number
+ --writable-strings Make string literals writable
---------------------------------------------------------------------------
</verb></tscreen>
<descrip>
- <tag><tt>-A, --ansi</tt></tag>
+ <label id="option-bss-name">
+ <tag><tt>--bss-name seg</tt></tag>
- This option disables any compiler exensions. Have a look at section 5
- for a discussion of compiler extensions. In addition, the macro
- <tt/__STRICT_ANSI__/ is defined, when using one of these options.
+ Set the name of the bss segment. See also <tt/<ref id="pragma-bss-name"
+ name="#pragma bss-name">/.
+ <label id="option-check-stack">
+ <tag><tt>--check-stack</tt></tag>
+
+ Tells the compiler to generate code that checks for stack overflows. See
+ <tt/<ref id="pragma-check-stack" name="#pragma check-stack">/ for an
+ explanation of this feature.
+
+
+ <label id="option-code-name">
+ <tag><tt>--code-name seg</tt></tag>
+
+ Set the name of the code segment. See also <tt/<ref id="pragma-code-name"
+ name="#pragma code-name">/
+
+
+ <label id="option-codesize">
+ <tag><tt>--codesize x</tt></tag>
+
+ This options allows finer control about speed vs. size decisions in the code
+ generation and optimization phases. It gives the allowed size increase
+ factor (in percent). The default is 100 when not using <tt/-Oi/ and 200 when
+ using <tt/-Oi/ (<tt/-Oi/ is the same as <tt/-O --codesize 200/).
+
+
+ <label id="option-cpu">
<tag><tt>--cpu CPU</tt></tag>
A new, still experimental option. You may specify "6502" or "65C02" as
overwhelming.
+ <label id="option-create-dep">
+ <tag><tt>--create-dep</tt></tag>
+
+ Tells the compiler to generate a file containing the dependency list for
+ the compiled module in makefile syntax. The file is named as the C input
+ file with the extension replaced by <tt/.u/.
+
+
+ <label id="option-data-name">
+ <tag><tt>--data-name seg</tt></tag>
+
+ Set the name of the data segment. See also <tt/<ref id="pragma-data-name"
+ name="#pragma data-name">/
+
+
<tag><tt>-d, --debug</tt></tag>
Enables debug mode, something that should not be needed for mere
is defined to the value "1".
+ <tag><tt>--forget-inc-paths</tt></tag>
+
+ Forget the builtin include paths. This is most useful when building
+ customized C or runtime libraries, in which case the standard header
+ files should be ignored.
+
+
<tag><tt>-g, --debug-info</tt></tag>
This will cause the compiler to insert a <tt/.DEBUGINFO/ command into the
Print the short option summary shown above.
+ <tag><tt>-o name</tt></tag>
+
+ Specify the name of the output file. If you don't specify a name, the
+ name of the C input file is used, with the extension replaced by ".s".
+
+
+ <label id="option-register-vars">
+ <tag><tt>-r, --register-vars</tt></tag>
+
+ <tt/-r/ will make the compiler honor the <tt/register/ keyword. Local
+ variables may be placed in registers (which are actually zero page
+ locations). There is some overhead involved with register variables, since
+ the old contents of the registers must be saved and restored. Since register
+ variables are of limited use without the optimizer, there is also a combined
+ switch: <tt/-Or/ will enable both, the optimizer and register variables.
+
+ For more information about register variables see <ref id="register-vars"
+ name="register variables">.
+
+ The compiler setting can also be changed within the source file by using
+ <tt/<ref id="pragma-register-vars" name="#pragma register-vars">/.
+
+
+ <label id="option-register-space">
+ <tag><tt>--register-space</tt></tag>
+
+ This option takes a numeric parameter and is used to specify, how much
+ zero page register space is available. Please note that just giving this
+ option will not increase or decrease by itself, it will just tell the
+ compiler about the available space. You will have to allocate that space
+ yourself using an assembler module with the necessary allocations, and a
+ linker configuration that matches the assembler module. The default value
+ for this option is 6 (bytes).
+
+ If you don't know what all this means, please don't use this option.
+
+
+ <label id="option-rodata-name">
+ <tag><tt>--rodata-name seg</tt></tag>
+
+ Set the name of the rodata segment (the segment used for readonly data).
+ See also <tt/<ref id="pragma-rodata-name" name="#pragma rodata-name">/
+
+ <label id="option-signed-chars">
<tag><tt>-j, --signed-chars</tt></tag>
Using this option, you can make the default characters signed. Since the
6502 has no provisions for sign extending characters (which is needed on
almost any load operation), this will make the code larger and slower. A
- better way is to declare characters explicitly as "signed" if needed.
- You can also use <tt/#pragma signedchars/ for better control of this option
- (see section <ref id="pragmas" name="#pragmas">).
+ better way is to declare characters explicitly as "signed" if needed. You
+ can also use <tt><ref id="pragma-signed-chars"
+ name="#pragma signed-chars"></tt> for better control of this option.
+
+ <label id="option--standard">
+ <tag><tt>--standard std</tt></tag>
+ This option allows to set the language standard supported. The argument is
+ one of
+ <itemize>
+ <item>c89
+ <item>c99
+ <item>cc65
+ </itemize>
+
+ Please note that the compiler does not support the c99 standard and never
+ will. c99 mode is actually c89 mode with a few selected c99 extensions
+ (// comments for example).
+
+
+ <label id="option-standard">
<tag><tt>-t target, --target target</tt></tag>
This option is used to set the target system. The target system
<itemize>
<item>none
+ <item>apple2
+ <item>apple2enh
<item>atari
+ <item>atmos
+ <item>c16 (works also for the c116 with memory up to 32K)
<item>c64
<item>c128
- <item>plus4
- <item>cbm610 (all CBM series-II computers with 80 column video)
- <item>pet (all CBM PET systems except the 2001)
- <item>apple2
+ <item>cbm510 (CBM-II series with 40 column video)
+ <item>cbm610 (all CBM-II II computers with 80 column video)
<item>geos
+ <item>lunix
+ <item>lynx
+ <item>nes
+ <item>pet (all CBM PET systems except the 2001)
+ <item>plus4
+ <item>supervision
+ <item>vic20
</itemize>
<tag><tt>-v, --verbose</tt></tag>
or warnings are encountered.
+ <label id="option-writable-strings">
+ <tag><tt>--writable-strings</tt></tag>
+
+ Make string literals writable by placing them into the data segment instead
+ of the rodata segment. You can also use <tt><ref id="pragma-writable-strings"
+ name="#pragma writable-strings"></tt> to control this option on a
+ per function basis.
+
+
+ <label id="option-static-locals">
<tag><tt>-Cl, --static-locals</tt></tag>
Use static storage for local variables instead of storage on the stack.
}
</verb></tscreen>
- the variable a will always have the value 1 when entering the function
- and using <tt/-Cl/, while in
+ the variable <tt/a/ will always have the value <tt/1/ when entering the
+ function and using <tt/-Cl/, while in
<tscreen><verb>
void f (void)
}
</verb></tscreen>
- the variable a will have the value 1 only the first time, the function
- is entered, and will keep the old value from one call of the function to
- the next.
+ the variable <tt/a/ will have the value <tt/1/ only the first time that the
+ function is entered, and will keep the old value from one call of the
+ function to the next.
- You may also use <tt/#pragma staticlocals/ to change this setting in your
- sources (see section <ref id="pragmas" name="#pragmas">).
+ You may also use <tt><ref id="pragma-static-locals"
+ name="#pragma static-locals"></tt> to change this setting in your
+ sources.
+ <label id="option-include-dir">
<tag><tt>-I dir, --include-dir dir</tt></tag>
Set a directory where the compiler searches for include files. You may
search list.
- <tag><tt>-o name</tt></tag>
-
- Specify the name of the output file. If you don't specify a name, the
- name of the C input file is used, with the extension replaced by ".s".
-
-
+ <label id="option-O">
<tag><tt>-O, -Oi, -Or, -Os</tt></tag>
Enable an optimizer run over the produced code.
Using <tt/-Oi/, the code generator will inline some code where otherwise a
runtime functions would have been called, even if the generated code is
larger. This will not only remove the overhead for a function call, but will
- make the code visible for the optimizer.
+ make the code visible for the optimizer. <tt/-Oi/ is an alias for
+ <tt/-O --codesize 200/.
<tt/-Or/ will make the compiler honor the <tt/register/ keyword. Local
variables may be placed in registers (which are actually zero page
- locations). There is some overhead involved with register variables, since
- the old contents of the registers must be saved and restored. In addition,
- the current implementation does not make good use of register variables, so
- using <tt/-Or/ may make your program even slower and larger. Use with care!
+ locations). See also the <tt/<ref id="option-register-vars"
+ name="--register-vars">/ command line option, and the <ref
+ id="register-vars" name="discussion of register variables"> below.
Using <tt/-Os/ will force the compiler to inline some known functions from
the C library like strlen. Note: This has two consequences:
<tt/-Os/ will actually break things.
<p>
<item>The inlined string and memory functions will not handle strings or
- memory areas larger than 255 bytes. Similar, the inlined <tt/is..()/
- functions will not work with values outside char range.
+ memory areas larger than 255 bytes. Similarly, the inlined <tt/is..()/
+ functions will not work with values outside the char. range (such as
+ <tt/EOF/).
<p>
</itemize>
<p>
<tt/-Ors/.
- <tag><tt>-T</tt></tag>
+ <tag><tt>-T, --add-source</tt></tag>
This include the source code as comments in the generated code. This is
normally not needed.
version.
- <tag><tt>-W</tt></tag>
-
- This option will suppress any warnings generated by the compiler. Since
- any source file may be written in a manner that it will not produce
- compiler warnings, using this option is usually not a good idea.
+ <label id="option-W">
+ <tag><tt>-W name[,name]</tt></tag>
+
+ This option allows to control warnings generated by the compiler. It is
+ followed by a comma separated list of warnings that should be enabled or
+ disabled. To disable a warning, its name is prefixed by a minus sign. If
+ no such prefix exists, or the name is prefixed by a plus sign, the warning
+ is enabled.
+
+ The following warning names are currently recognized:
+ <descrip>
+ <tag><tt/error/</tag>
+ Treat all warnings as errors.
+ <tag><tt/unknown-pragma/</tag>
+ Warn about known #pragmas.
+ <tag><tt/unused-label/</tag>
+ Warn about unused labels.
+ <tag><tt/unused-param/</tag>
+ Warn about unused function parameters.
+ <tag><tt/unused-var/</tag>
+ Warn about unused variables.
+ </descrip>
+
+ You may also use <tt><ref id="pragma-warn" name="#pragma warn"></tt> to
+ control this setting for smaller pieces of code from within your code.
</descrip><p>
file contains assembler code suitable for the use with the ca65 macro
assembler.
-In addition to the paths named in the <tt/-I/ option on the command line, the
-directory named in the environment variable <tt/CC65_INC/ is added to the
-search path for include files on startup.
+Include files in single quotes are searched in the following places:
+<enum>
+<item>The current directory.
+<item>The value of the environment variable <tt/CC65_INC/ if it is defined.
+<item>Any directory added with the <tt/-I/ option on the command line.
+</enum>
+
+Include files in angle brackets are searched in the following places:
+<enum>
+<item>A compiled in directory which is often <tt>/usr/lib/cc65/include</tt> on
+ Linux systems.
+<item>The value of the environment variable <tt/CC65_INC/ if it is defined.
+<item>A subdirectory named <tt/include/ of the directory defined in the
+ environment variable <tt/CC65_HOME/, if it is defined.
+<item>Any directory added with the <tt/-I/ option on the command line.
+</enum>
<sect>Differences to the ISO standard<p>
+Apart from the things listed below, the compiler does support additional
+keywords, has several functions in the standard headers with names outside the
+reserved namespace and a few syntax extensions. All these can be disabled with
+the <tt><ref id="option--standard" name="--standard"></tt> command line
+option. Its use for maximum standards compatibility is advised.
+
Here is a list of differences between the language, the compiler accepts,
and the one defined by the ISO standard:
<itemize>
-<item> The compiler allows single line comments that start with //. This
- feature is disabled in strict ANSI mode.
- <p>
-<item> The compiler allows unnamed parameters in parameter lists. The
- compiler will not issue warnings about unused parameters that don't
- have a name. This feature is disabled in strict ANSI mode.
- <p>
-<item> The compiler has some additional keywords:
- <p>
- <itemize>
- <item><tt/asm/
- <item><tt/__asm__/
- <item><tt/fastcall/
- <item><tt/__fastcall__/
- <item><tt/__AX__/
- <item><tt/__EAX__/
- <item><tt/__func__/
- <item><tt/__attribute__/
- </itemize>
- <p>
- The keywords without the underlines are disabled in strict ANSI mode.
- <p>
<item> The datatypes "float" and "double" are not available.
- <p>
-<item> The compiler does not support bit fields.
- <p>
-<item> Initialization of local variables is only possible for scalar data
- types (that is, not for arrays and structs).
- <p>
-<item> Because of the "wrong" order of the parameters on the stack, there is
- an additional macro needed to access parameters in a variable
- parameter list in a C function.
- <p>
-<item> Functions may not return structs. However, struct assignment *is*
- possible.
- <p>
+ <p>
+<item> C Functions may not return structs (or unions), and structs may not
+ be passed as parameters by value. However, struct assignment *is*
+ possible.
+ <p>
<item> Part of the C library is available only with fastcall calling
- conventions (see below). This means, that you may not mix pointers to
- those functions with pointers to user written functions.
+ conventions (see below). It means that you must not mix pointers to
+ those functions with pointers to user-written, not-fastcall functions.
+ <p>
+<item> The <tt/volatile/ keyword doesn't have an effect. This is not as bad
+ as it sounds, since the 6502 has so few registers that it isn't
+ possible to keep values in registers anyway.
<p>
</itemize>
-There may be some more minor differences, I'm currently not aware off. The
+There may be some more minor differences I'm currently not aware of. The
biggest problem is the missing float data type. With this limitation in
mind, you should be able to write fairly portable code.
<itemize>
-<item> The compiler allows // comments (like in C++ and in the proposed C9x
- standard). This feature is disabled by <tt/-A/.
-
<item> The compiler allows to insert assembler statements into the output
file. The syntax is
- <p>
- <tt/asm (<string literal>) ;/
- <p>
+
+ <tscreen><verb>
+ asm (<string literal>[, optional parameters]) ;
+ </verb></tscreen>
or
- <p>
- <tt/__asm__ (<string literal>) ;/
- <p>
+ <tscreen><verb>
+ __asm__ (<string literal>[, optional parameters]) ;
+ </verb></tscreen>
The first form is in the user namespace and is disabled if the <tt/-A/
switch is given.
- The given string is inserted literally into the output file, and a
- newline is appended. The statements in this string are not checked by
- the compiler, so be careful!
+ There is a whole section covering inline assembler statements,
+ <ref id="inline-asm" name="see there">.
+ <p>
- The asm statement may be used inside a function and on global file
- level.
+<item> There is a special calling convention named "fastcall".
+ The syntax for a function declaration using fastcall is
-<item> There is a special calling convention named "fastcall". This calling
- convention is currently only usable for functions written in
- assembler. The syntax for a function declaration using fastcall is
- <p>
- <tt/<return type> fastcall <function name> (<parameter list>)/
- <p>
+ <tscreen><verb>
+ <return type> fastcall <function name> (<parameter list>)
+ </verb></tscreen>
or
- <p>
- <tt/<return type> __fastcall__ <function name> (<parameter list>)/
- <p>
+ <tscreen><verb>
+ <return type> __fastcall__ <function name> (<parameter list>)
+ </verb></tscreen>
An example would be
- <p>
- <tt/void __fastcall__ f (unsigned char c)/
- <p>
- The first form of the fastcall keyword is in the user namespace and is
- therefore disabled in strict ANSI mode.
+ <tscreen><verb>
+ void __fastcall__ f (unsigned char c)
+ </verb></tscreen>
+ The first form of the fastcall keyword is in the user namespace and can
+ therefore be disabled with the <tt><ref id="option--standard"
+ name="--standard"></tt> command line option.
For functions declared as <tt/fastcall/, the rightmost parameter is not
pushed on the stack but left in the primary register when the function
is called. This will reduce the cost when calling assembler functions
significantly, especially when the function itself is rather small.
+ <p>
<item> There are two pseudo variables named <tt/__AX__/ and <tt/__EAX__/.
Both refer to the primary register that is used by the compiler to
sequences of assembler code. For example, the macro
<tscreen><verb>
- #define hi(x) (__AX__=(x),asm("\ttxa\n\tldx\t#$00",__AX__)
+ #define hi(x) \
+ (__AX__ = (x), \
+ asm ("txa"), \
+ asm ("ldx #$00"), \
+ __AX__)
</verb></tscreen>
will give the high byte of any unsigned value.
+ <p>
<item> Inside a function, the identifier <tt/__func__/ gives the name of the
current function as a string. Outside of functions, <tt/__func__/ is
Example:
<tscreen><verb>
- #define PRINT_DEBUG(s) printf ("%s: %s\n", __func__, s);
+ #define PRINT_DEBUG(s) printf ("%s: %s\n", __func__, s);
</verb></tscreen>
The macro will print the name of the current function plus a given
string.
+ <p>
+
+<item> cc65 allows the initialization of <tt/void/ variables. This may be
+ used to create variable structures that are more compatible with
+ interfaces written for assembler languages. Here is an example:
+
+ <tscreen><verb>
+ void GCmd = { (char)3, (unsigned)0x2000, (unsigned)0x3000 };
+ </verb></tscreen>
+
+ This will be translated as follows:
+
+ <tscreen><verb>
+ _GCmd:
+ .byte 3
+ .word $2000
+ .word $3000
+ </verb></tscreen>
+
+ Since the variable is of type <tt/void/ you may not use it as is.
+ However, taking the address of the variable results in a <tt/void*/
+ which may be passed to any function expecting a pointer.
+
+ See the <url url="geos.html" name="GEOS library document"> for examples
+ on how to use this feature.
+ <p>
+
+<item> cc65 implements flexible array struct members as defined in the C99 ISO
+ standard. As an extension, these fields may be initialized. There are
+ several exceptions, however (which is probably the reason why the
+ standard does not define this feature, because it is highly
+ unorthogonal). Flexible array members cannot be initialized ...
+
+ <itemize>
+ <item>... when defining an array of structs with flexible
+ members.
+ <item>... if such a struct is a member field of another struct
+ which is not the last field.
+ <item>... if the struct which contains a flexible array member is
+ declared as <tt/register/, and the size and compiler settings
+ do allow the compiler actually to place the struct into the
+ register bank in the zero page.
+ </itemize>
+
+ Please note that -- as defined in the ISO C standard -- the <tt/sizeof/
+ operator returns the struct size with the flexible array member having
+ size zero, even if it is initialized.
+ <p>
+
</itemize>
<p>
<tag><tt>__CC65__</tt></tag>
This macro is always defined. Its value is the version number of the
- compiler in hex. Version 2.0.1 of the compiler will have this macro defined
- as 0x0201.
+ compiler in hex. For example, version 2.10.1 of the compiler has this macro
+ defined as <tt/0x02A1/.
+
+ <tag><tt>__APPLE2__</tt></tag>
+
+ This macro is defined if the target is the Apple ][ (-t apple2).
+
+ <tag><tt>__APPLE2ENH__</tt></tag>
+
+ This macro is defined if the target is the enhanced Apple //e (-t apple2enh).
+
+ <tag><tt>__ATARI__</tt></tag>
+
+ This macro is defined if the target is one of the Atari computers
+ (400/800/130XL/800XL).
+
+ <tag><tt>__ATMOS__</tt></tag>
+
+ This macro is defined if the target is the Oric Atmos (-t atmos).
<tag><tt>__CBM__</tt></tag>
This macro is defined if the target system is one of the CBM targets.
+ <tag><tt>__C16__</tt></tag>
+
+ This macro is defined if the target is the c16 (-t c16).
+
<tag><tt>__C64__</tt></tag>
This macro is defined if the target is the c64 (-t c64).
This macro is defined if the target is the c128 (-t c128).
- <tag><tt>__PLUS4__</tt></tag>
+ <tag><tt>__CBM510__</tt></tag>
- This macro is defined if the target is the plus/4 (-t plus4).
+ This macro is defined if the target is the CBM 500 series of computers.
<tag><tt>__CBM610__</tt></tag>
This macro is defined if the target is one of the CBM 600/700 family of
computers (called B series in the US).
+ <tag><tt>__GEOS__</tt></tag>
+
+ This macro is defined if you are compiling for the GEOS system (-t geos).
+
+ <tag><tt>__LUNIX__</tt></tag>
+
+ This macro is defined if you are compiling for the LUnix system (-t lunix).
+
+ <tag><tt>__LYNX__</tt></tag>
+
+ This macro is defined if the target is the Atari Lynx (-t lynx).
+
+ <tag><tt>__NES__</tt></tag>
+
+ This macro is defined if the target is the NES (-t nes).
+
<tag><tt>__PET__</tt></tag>
This macro is defined if the target is the PET family of computers (-t pet).
- <tag><tt>__ATARI__</tt></tag>
+ <tag><tt>__PLUS4__</tt></tag>
- This macro is defined if the target is one of the Atari computers
- (400/800/130XL/800XL).
+ This macro is defined if the target is the plus/4 (-t plus4).
- <tag><tt>__APPLE2__</tt></tag>
+ <tag><tt>__SUPERVISION__</tt></tag>
- This macro is defined if the target is the Apple ][ (-t apple2).
+ This macro is defined if the target is the supervision (-t supervision).
- <tag><tt>__GEOS__</tt></tag>
+ <tag><tt>__VIC20__</tt></tag>
- This macro is defined if you are compiling for the GEOS system (-t geos).
+ This macro is defined if the target is the vic20 (-t vic20).
<tag><tt>__FILE__</tt></tag>
This macro expands to the current line number.
- <tag><tt>__STRICT_ANSI__</tt></tag>
+ <tag><tt>__CC65_STD__</tt></tag>
- This macro is defined to 1 if the <tt/-A/ compiler option was given, and
- undefined otherwise.
+ This macro is defined to one of the following depending on the <tt><ref
+ id="option--standard" name="--standard"></tt> command line option:
+ <itemize>
+ <item><tt/__CC65_STD_C89__/
+ <item><tt/__CC65_STD_C99__/
+ <item><tt/__CC65_STD_CC65__/
+ </itemize>
<tag><tt>__OPT__</tt></tag>
</descrip>
-<sect>
#pragmas<label id="pragmas"><p>
+<sect>
#pragmas<label id="pragmas"><p>
The compiler understands some pragmas that may be used to change code
-generation and other stuff.
-
-<descrip>
+generation and other stuff. Some of these pragmas understand a special form:
+If the first parameter is <tt/push/, the old value is saved onto a stack
+before changing it. The value may later be restored by using the <tt/pop/
+parameter with the <tt/#pragma/.
- <tag><tt>#pragma bssseg (<name>)</tt></tag>
+<sect1><tt>#pragma bss-name ([push,] <name>)</tt><label id="pragma-bss-name"><p>
This pragma changes the name used for the BSS segment (the BSS segment
is used to store uninitialized data). The argument is a string enclosed
use another BSS segment, you have to do that yourself, otherwise
uninitialized variables do not have the value zero.
+ The <tt/#pragma/ understands the push and pop parameters as explained above.
+
Example:
<tscreen><verb>
- #pragma bssseg ("MyBSS")
+ #pragma bss-name ("MyBSS")
</verb></tscreen>
- <tag><tt>#pragma codeseg (<name>)</tt></tag>
+<sect1><tt>#pragma charmap (<index>, <code>)</tt><label id="pragma-charmap"><p>
+
+ Each literal string and each literal character in the source is translated
+ by use of a translation table. This translation table is preset when the
+ compiler is started depending on the target system, for example to map
+ ISO-8859-1 characters into PETSCII if the target is a commodore machine.
+
+ This pragma allows to change entries in the translation table, so the
+ translation for individual characters, or even the complete table may be
+ adjusted.
+
+ Both arguments are assumed to be unsigned characters with a valid range of
+ 1-255.
+
+ Beware of two pitfalls:
+
+ <itemize>
+ <item>The character index is actually the code of the character in the
+ C source, so character mappings do always depend on the source
+ character set. This means that <tt/#pragma charmap/ is not
+ portable -- it depends on the build environment.
+ <item>While it is possible to use character literals as indices, the
+ result may be somewhat unexpected, since character literals are
+ itself translated. For this reason I would suggest to avoid
+ character literals and use numeric character codes instead.
+ </itemize>
+
+ Example:
+ <tscreen><verb>
+ /* Use a space wherever an 'a' occurs in ISO-8859-1 source */
+ #pragma charmap (0x61, 0x20);
+ </verb></tscreen>
+
+
+<sect1><tt>#pragma check-stack ([push,] on|off)</tt><label id="pragma-check-stack"><p>
+
+ Tells the compiler to insert calls to a stack checking subroutine to detect
+ stack overflows. The stack checking code will lead to somewhat larger and
+ slower programs, so you may want to use this pragma when debugging your
+ program and switch it off for the release version. If a stack overflow is
+ detected, the program is aborted.
+
+ If the argument is "off", stack checks are disabled (the default), otherwise
+ they're enabled.
+
+ The <tt/#pragma/ understands the push and pop parameters as explained above.
+
+<sect1><tt>#pragma code-name ([push,] <name>)</tt><label id="pragma-code-name"><p>
This pragma changes the name used for the CODE segment (the CODE segment
is used to store executable code). The argument is a string enclosed in
segments. If you use other segments, you have to create a new linker
configuration file.
+ The <tt/#pragma/ understands the push and pop parameters as explained above.
+
Example:
<tscreen><verb>
- #pragma bssseg ("MyCODE")
+ #pragma code-name ("MyCODE")
</verb></tscreen>
- <tag><tt>#pragma dataseg (<name>)</tt></tag>
+<sect1><tt>#pragma codesize ([push,] <int>)</tt><label id="pragma-codesize"><p>
+
+ This pragma allows finer control about speed vs. size decisions in the code
+ generation and optimization phase. It gives the allowed size increase factor
+ (in percent). The default is can be changed by use of the <tt/<ref
+ id="option-codesize" name="--codesize">/ compiler option.
+
+ The <tt/#pragma/ understands the push and pop parameters as explained above.
+
+
+<sect1><tt>#pragma data-name ([push,] <name>)</tt><label id="pragma-data-name"><p>
This pragma changes the name used for the DATA segment (the DATA segment
is used to store initialized data). The argument is a string enclosed in
segments. If you use other segments, you have to create a new linker
configuration file.
+ The <tt/#pragma/ understands the push and pop parameters as explained above.
+
Example:
<tscreen><verb>
- #pragma bssseg ("MyDATA")
+ #pragma data-name ("MyDATA")
</verb></tscreen>
- <tag><tt>#pragma rodataseg (<name>)</tt></tag>
+<sect1><tt>#pragma optimize ([push,] on|off)</tt><label id="pragma-optimize"><p>
+
+ Switch optimization on or off. If the argument is "off", optimization is
+ disabled, otherwise it is enabled. Please note that this pragma only effects
+ whole functions. The setting in effect when the function is encountered will
+ determine if the generated code is optimized or not.
+
+ Optimization and code generation is also controlled by the <ref
+ id="pragma-codesize" name="codesize pragma">.
+
+ The default is "off", but may be changed with the <tt/<ref name="-O"
+ id="option-O">/ compiler option.
+
+ The <tt/#pragma/ understands the push and pop parameters as explained above.
+
+
+<sect1><tt>#pragma rodata-name ([push,] <name>)</tt><label id="pragma-rodata-name"><p>
This pragma changes the name used for the RODATA segment (the RODATA
segment is used to store readonly data). The argument is a string
segments. If you use other segments, you have to create a new linker
configuration file.
+ The <tt/#pragma/ understands the push and pop parameters as explained above.
+
Example:
<tscreen><verb>
- #pragma bssseg ("MyRODATA")
+ #pragma rodata-name ("MyRODATA")
</verb></tscreen>
- <tag><tt>#pragma regvaraddr (<const int>)</tt></tag>
+<sect1><tt>#pragma regvaraddr ([push,] on|off)</tt><label id="pragma-regvaraddr"><p>
The compiler does not allow to take the address of register variables.
The regvaraddr pragma changes this. Taking the address of a register
- variable is allowed after using this pragma, if the argument is not
- zero. Using an argument of zero changes back to the default behaviour.
+ variable is allowed after using this pragma with "on" as argument.
+ Using "off" as an argument switches back to the default behaviour.
Beware: The C standard does not allow taking the address of a variable
declared as register. So your programs become non-portable if you use
this pragma. In addition, your program may not work. This is usually the
case if a subroutine is called with the address of a register variable,
- and this subroutine (or a subroutine called from there) uses itself
+ and this subroutine (or a subroutine called from there) uses
register variables. So be careful with this #pragma.
+ The <tt/#pragma/ understands the push and pop parameters as explained above.
+
Example:
<tscreen><verb>
- #pragma regvaraddr(1) /* Allow taking the address
- * of register variables
- */
+ #pragma regvaraddr(on) /* Allow taking the address
+ * of register variables
+ */
</verb></tscreen>
- <tag><tt>#pragma signedchars (<const int>)</tt></tag>
+<sect1><tt>#pragma register-vars ([push,] on|off)</tt><label id="pragma-register-vars"><p>
- Changed the signedness of the default character type. If the argument
- is not zero, default characters are signed, otherwise characters are
- unsigned. The compiler default is to make characters unsigned since this
- creates a lot better code. This default may be overridden by the
- <tt/--signed-chars/ command line option.
+ Enables or disables use of register variables. If register variables are
+ disabled (the default), the <tt/register/ keyword is ignored. Register
+ variables are explained in more detail in <ref id="register-vars" name="a separate
+ chapter">.
+ The <tt/#pragma/ understands the push and pop parameters as explained above.
- <tag><tt>#pragma staticlocals (<const int>)</tt></tag>
+
+<sect1><tt>#pragma signed-chars ([push,] on|off)</tt><label id="pragma-signed-chars"><p>
+
+ Changes the signedness of the default character type. If the argument is
+ "on", default characters are signed, otherwise characters are unsigned. The
+ compiler default is to make characters unsigned since this creates a lot
+ better code. This default may be overridden by the <tt/<ref
+ name="--signed-chars" id="option-signed-chars">/ command line option.
+
+ The <tt/#pragma/ understands the push and pop parameters as explained above.
+
+
+<sect1><tt>#pragma static-locals ([push,] on|off)</tt><label id="pragma-static-locals"<p>
Use variables in the bss segment instead of variables on the stack. This
- pragma changes the default set by the compiler option <tt/-Cl/. If the
- argument is not zero, local variables are allocated in the BSS segment,
- leading to shorter and in most cases faster, but non-reentrant code.
+ pragma changes the default set by the compiler option <tt/<ref
+ name="--static-locals" id="option-static-locals">/. If the argument is "on",
+ local variables are allocated in the BSS segment, leading to shorter and in
+ most cases faster, but non-reentrant code.
+
+ The <tt/#pragma/ understands the push and pop parameters as explained above.
+
+<sect1><tt>#pragma warn (name, [push,] on|off)</tt><label id="pragma-warn"><p>
- <tag><tt>#pragma zpsym (<name>)</tt></tag>
+ Switch compiler warnings on or off. "name" is the name of a warning (see the
+ <tt/<ref name="-W" id="option-W">/ compiler option for a list). The name is
+ either followed by "pop", which restores the last pushed state, or by "on" or
+ "off", optionally preceeded by "push" to push the current state before
+ changing it.
- Tell the compiler that the - previously as external declared - symbol with
+ Example:
+ <tscreen><verb>
+ /* Don't warn about the unused parameter in function func */
+ #pragma warn (unused-param, push, off)
+ static int func (int unused)
+ {
+ return 0;
+ }
+ #pragma warn (unused-param, pop)
+ </verb></tscreen>
+
+<sect1><tt>#pragma writable-strings ([push,] on|off)</tt><label id="pragma-writable-strings"><p>
+
+ Changes the storage location of string literals. For historical reasons,
+ the C standard defines that string literals are of type "char[]", but
+ writing to such a literal causes undefined behaviour. Most compilers
+ (including cc65) place string literals in the read-only data segment, which
+ may cause problems with old C code that writes to string literals.
+
+ Using this pragma (or the corresponding command line option <tt/<ref
+ name="--writable-strings" id="option-writable-strings">/) causes the
+ literals to be placed in the data segment so they can be written to without
+ worry.
+
+ Please note that the value of this flag that is in effect when a function
+ is encountered, determines where the literals are stored. Changing the
+ <tt/#pragma/ within a function doesn't have an effect for this function.
+
+ The <tt/#pragma/ understands the push and pop parameters as explained above.
+
+
+<sect1><tt>#pragma zpsym (<name>)</tt><p>
+
+ Tell the compiler that the -- previously as external declared -- symbol with
the given name is a zero page symbol (usually from an assembler file).
The compiler will create a matching import declaration for the assembler.
#pragma zpsym ("foo"); /* foo is in the zeropage */
</verb></tscreen>
-</descrip>
+<sect>Register variables<label id="register-vars"><p>
+
+The runtime for all supported platforms has 6 bytes of zero page space
+available for register variables (this could be increased, but I think it's a
+good value). So you can declare register variables up to a total size of 6 per
+function. The compiler will allocate register space on a "first come, first
+served" base and convert any <tt/register/ declarations that exceed the
+available register space silently to <tt/auto/. Parameters can also be
+declared as <tt/register/, this will in fact give slightly shorter code than
+using a register variable.
+
+Since a function must save the current values of the registers on entry and
+restore them on exit, there is an overhead associated with register variables,
+and this overhead is quite high (about 20 bytes per variable). This means that
+just declaring anything as <tt/register/ is not a good idea.
+
+The best use for register variables are pointers, especially those that point
+to structures. The magic number here is about 3 uses of a struct field: If the
+function contains this number or even more, the generated code will be usually
+shorter and faster when using a register variable for the struct pointer. The
+reason for this is that the register variable can in many cases be used as a
+pointer directly. Having a pointer in an auto variable means that this pointer
+must first be copied into a zero page location, before it can be dereferenced.
+
+Second best use for register variables are counters. However, there is not
+much difference in the code generated for counters, so you will need at least
+100 operations on this variable (for example in a loop) to make it worth the
+trouble. The only savings you get here are by the use of a zero page variable
+instead of one on the stack or in the data segment.
+
+Register variables must be explicitly enabled, either by using <tt/<ref
+name="-Or" id="option-O">/ or <tt/<ref name="--register-vars"
+id="option-register-vars">/ on the command line or by use of <tt/<ref
+name="#pragma register-vars" id="pragma-register-vars">/. Register variables
+are only accepted on function top level, register variables declared in
+interior blocks are silently converted to <tt/auto/. With register variables
+disabled, all variables declared as <tt/register/ are actually auto variables.
+
+Please take care when using register variables: While they are helpful and can
+lead to a tremendous speedup when used correctly, improper usage will cause
+bloated code and a slowdown.
+
+
+
+<sect>Inline assembler<label id="inline-asm"><p>
+
+The compiler allows to insert assembler statements into the output file. The
+syntax is
+
+<tscreen><verb>
+ asm (<string literal>[, optional parameters]) ;
+</verb></tscreen>
+or
+<tscreen><verb>
+ __asm__ (<string literal>[, optional parameters]) ;
+</verb></tscreen>
+<p>
+
+The first form is in the user namespace and is disabled by <tt><ref
+id="option--standard" name="--standard"></tt> if the argument is not <tt/cc65/.
+
+The asm statement may be used inside a function and on global file level. An
+inline assembler statement is a primary expression, so it may also be used as
+part of an expression. Please note however that the result of an expression
+containing just an inline assembler statement is always of type <tt/void/.
+
+The contents of the string literal are preparsed by the compiler and inserted
+into the generated assembly output, so that the can be further processed by
+the backend and especially the optimizer. For this reason, the compiler does
+only allow regular 6502 opcodes to be used with the inline assembler. Pseudo
+instructions (like <tt/.import/, <tt/.byte/ and so on) are <em/not/ allowed,
+even if the ca65 assembler (which is used to translate the generated assembler
+code) would accept them. The builtin inline assembler is not a replacement for
+the full blown macro assembler which comes with the compiler.
+
+Note: Inline assembler statements are subject to all optimizations done by the
+compiler. There is currently no way to protect an inline assembler statement
+from being moved or removed completely by the optimizer. If in doubt, check
+the generated assembler output, or disable optimizations.
+
+The string literal may contain format specifiers from the following list. For
+each format specifier, an argument is expected which is inserted instead of
+the format specifier before passing the assembly code line to the backend.
+
+<itemize>
+ <item><tt/%b/ - Numerical 8-bit value
+ <item><tt/%w/ - Numerical 16-bit value
+ <item><tt/%l/ - Numerical 32-bit value
+ <item><tt/%v/ - Assembler name of a (global) variable or function
+ <item><tt/%o/ - Stack offset of a (local) variable
+ <item><tt/%g/ - Assembler name of a C label
+ <item><tt/%s/ - The argument is converted to a string
+ <item><tt/%%/ - The % sign itself
+</itemize><p>
+
+Using these format specifiers, you can access C <tt/#defines/, variables or
+similar stuff from the inline assembler. For example, to load the value of
+a C <tt/#define/ into the Y register, one would use
+
+<tscreen><verb>
+ #define OFFS 23
+ __asm__ ("ldy #%b", OFFS);
+</verb></tscreen>
+
+Or, to access a struct member of a static variable:
+
+<tscreen><verb>
+ typedef struct {
+ unsigned char x;
+ unsigned char y;
+ unsigned char color;
+ } pixel_t;
+ static pixel_t pixel;
+ __asm__ ("ldy #%b", offsetof(pixel_t, color));
+ __asm__ ("lda %v,y", pixel);
+</verb></tscreen>
+<p>
+
+Note: Do not embed the assembler labels that are used as names of global
+variables or functions into your asm statements. Code like this
+
+<tscreen><verb>
+ int foo;
+ int bar () { return 1; }
+ __asm__ ("lda _foo"); /* DON'T DO THAT! */
+ ...
+ __asm__ ("jsr _bar"); /* DON'T DO THAT EITHER! */
+</verb></tscreen>
+<p>
+
+may stop working if the way, the compiler generates these names is changed in
+a future version. Instead use the format specifiers from the table above:
+
+<tscreen><verb>
+ __asm__ ("lda %v", foo); /* OK */
+ ...
+ __asm__ ("jsr %v", bar); /* OK */
+</verb></tscreen>
+<p>
+
+
+<sect>Implementation-defined behavior<p>
+
+This section describes the behavior of cc65 when the standard describes the
+behavior as implementation-defined.
+
+(to be done)
+
<sect>Bugs/Feedback<p>
If you have problems using the compiler, if you find any bugs, or if you're
doing something interesting with it, I would be glad to hear from you. Feel
-free to contact me by email (<htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">).
+free to contact me by email (<htmlurl url="mailto:uz@cc65.org"
+name="uz@cc65.org">).
--------------------------------------------------------------------------
</verb></tscreen>
-In acknowledgment of this copyright, I will place my own changes to the
-compiler under the same copyright. Please note however, that the library
-and all binutils are covered by another copyright, and that I'm planning
-to do a complete rewrite of the compiler, after which the compiler
-copyright will also change.
-
-For the list of changes requested by this copyright see newvers.txt.
-
+Small parts of the compiler (parts of the preprocessor and main parser) are
+still covered by this copyright. The main portion is covered by the usual
+cc65 license, which reads:
+
+This software is provided 'as-is', without any expressed or implied
+warranty. In no event will the authors be held liable for any damages
+arising from the use of this software.
+
+Permission is granted to anyone to use this software for any purpose,
+including commercial applications, and to alter it and redistribute it
+freely, subject to the following restrictions:
+
+<enum>
+<item> The origin of this software must not be misrepresented; you must not
+ claim that you wrote the original software. If you use this software
+ in a product, an acknowledgment in the product documentation would be
+ appreciated but is not required.
+<item> Altered source versions must be plainly marked as such, and must not
+ be misrepresented as being the original software.
+<item> This notice may not be removed or altered from any source
+ distribution.
+</enum>
</article>
projects / cc65 / blobdiff