<title>cc65 Users Guide
<author><url url="mailto:uz@cc65.org" name="Ullrich von Bassewitz">,<newline>
<url url="mailto:gregdk@users.sf.net" name="Greg King">
-<date>2017-03-21
+<date>2017-05-20
<abstract>
cc65 is a C compiler for 6502 targets. It supports several 6502 based home
-O Optimize code
-Oi Optimize code, inline more code
-Or Enable register variables
- -Os Inline some known functions
+ -Os Inline some standard functions
-T Include source as comment
-V Print the compiler version number
-W warning[,...] Suppress warnings
--debug-opt name Debug optimization steps
--dep-target target Use this dependency target
--disable-opt name Disable an optimization step
+ --eagerly-inline-funcs Eagerly inline some known functions
--enable-opt name Enable an optimization step
--help Help (this text)
--include-dir dir Set an include directory search path
+ --inline-stdfuncs Inline some standard functions
--list-opt-steps List all optimizer steps and exit
--list-warnings List available warning types for -W
--local-strings Emit string literals immediately
symbols in a special section in the object file.
+ <label id="option-eagerly-inline-funcs">
+ <tag><tt>--eagerly-inline-funcs</tt></tag>
+
+ Have the compiler eagerly inline these functions from the C library:
+ <itemize>
+ <item><tt/memcpy()/
+ <item><tt/memset()/
+ <item><tt/strcmp()/
+ <item><tt/strcpy()/
+ <item><tt/strlen()/
+ <item>most of the functions declared in <tt/<ctype.h>/
+ </itemize>
+
+ Note: This has two consequences:
+ <itemize>
+ <item>You may not use names of standard C functions for your own functions.
+ If you do that, your program is not standard-compliant anyway; but,
+ using <tt/--eagerly-inline-funcs/ actually will break things.
+ <p>
+ <item>The inlined string and memory functions will not handle strings or
+ 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>
+
+ <tt/--eagerly-inline-funcs/ implies the <tt><ref id="option-inline-stdfuncs"
+ name="--inline-stdfuncs"></tt> command line option.
+
+ See also <tt><ref id="pragma-allow-eager-inline" name="#pragma allow-eager-inline"></tt>.
+
+
<tag><tt>-h, --help</tt></tag>
Print the short option summary shown above.
+ <label id="option-inline-stdfuncs">
+ <tag><tt>--inline-stdfuncs</tt></tag>
+
+ Allow the compiler to inline some standard functions from the C library like
+ strlen. This will not only remove the overhead for a function call, but will
+ make the code visible for the optimizer. See also the <tt><ref id="option-O"
+ name="-Os"></tt> command line option and <tt><ref id="pragma-inline-stdfuncs"
+ name="#pragma inline-stdfuncs"></tt>.
+
+
<label id="option-list-warnings">
<tag><tt>--list-warnings</tt></tag>
<item>sim6502
<item>sim65c02
<item>supervision
+ <item>telestrat
<item>vic20
</itemize>
using
<tscreen><verb>
- void f (void)
- {
- unsigned a = 1;
- ...
- }
+ void f (void)
+ {
+ unsigned a = 1;
+ ...
+ }
</verb></tscreen>
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)
- {
- static unsigned a = 1;
- ....
- }
+ void f (void)
+ {
+ static unsigned a = 1;
+ ....
+ }
</verb></tscreen>
the variable <tt/a/ will have the value <tt/1/ only the first time that the
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:
- <p>
- <itemize>
- <item>You may not use names of standard C functions in your own code. If you
- do that, your program is not standard compliant anyway, but using
- <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. Similarly, the inlined <tt/is..()/
- functions will not work with values outside the char. range (such as
- <tt/EOF/).
- <p>
- </itemize>
- <p>
+ Using <tt/-Os/ will allow the compiler to inline some standard functions
+ from the C library like strlen. This will not only remove the overhead
+ for a function call, but will make the code visible for the optimizer.
+ See also the <tt/<ref id="option-inline-stdfuncs" name="--inline-stdfuncs">/
+ command line option.
+
It is possible to concatenate the modifiers for <tt/-O/. For example, to
- enable register variables and inlining of known functions, you may use
+ enable register variables and inlining of standard functions, you may use
<tt/-Ors/.
</descrip><p>
+
<sect>Input and output<p>
The compiler will accept one C file per invocation and create a file with
<itemize>
-<item> The datatypes "float" and "double" are not available.
- <p>
-<item> C Functions may not return structs (or unions), and structs may not
+<item> The datatypes "float" and "double" are not available.
+ <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> Most of the C library is available with only the fastcall calling
- convention (<ref id="extension-fastcall" name="see below">). It means
- that you must not mix pointers to those functions with pointers to
- user-written, cdecl functions (the calling conventions are incompatible).
- <p>
-<item> The <tt/volatile/ keyword has almost no effect. That is not as bad
+ possible.
+ <p>
+<item> Most of the C library is available with only the fastcall calling
+ convention (<ref id="extension-fastcall" name="see below">). It means
+ that you must not mix pointers to those functions with pointers to
+ user-written, cdecl functions (the calling conventions are incompatible).
+ <p>
+<item> The <tt/volatile/ keyword has almost no effect. That 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>
+ <p>
</itemize>
There may be some more minor differences I'm currently not aware of. The
<itemize>
-<item> The compiler allows to insert assembler statements into the output
- file. The syntax is
+<item> The compiler allows to insert assembler statements into the output
+ file. The syntax is
- <tscreen><verb>
- asm [optional volatile] (<string literal>[, optional parameters]) ;
- </verb></tscreen>
- or
- <tscreen><verb>
+ <tscreen><verb>
+ asm [optional volatile] (<string literal>[, optional parameters]) ;
+ </verb></tscreen>
+ or
+ <tscreen><verb>
__asm__ [optional volatile] (<string literal>[, optional parameters]) ;
- </verb></tscreen>
+ </verb></tscreen>
- The first form is in the user namespace; and, is disabled if the <tt/-A/
- switch is given.
+ The first form is in the user namespace; and, is disabled if the <tt/-A/
+ switch is given.
- There is a whole section covering inline assembler statements,
- <ref id="inline-asm" name="see there">.
- <p>
+ There is a whole section covering inline assembler statements,
+ <ref id="inline-asm" name="see there">.
+ <p>
<label id="extension-fastcall">
-<item> The normal calling convention -- for non-variadic functions -- is
- named "fastcall". The syntax for a function declaration that
- <em/explicitly/ uses fastcall is
-
- <tscreen><verb>
- <return type> fastcall <function name> (<parameter list>)
- </verb></tscreen>
- or
- <tscreen><verb>
- <return type> __fastcall__ <function name> (<parameter list>)
- </verb></tscreen>
- An example is
- <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"
+<item> The normal calling convention -- for non-variadic functions -- is
+ named "fastcall". The syntax for a function declaration that
+ <em/explicitly/ uses fastcall is
+
+ <tscreen><verb>
+ <return type> fastcall <function name> (<parameter list>)
+ </verb></tscreen>
+ or
+ <tscreen><verb>
+ <return type> __fastcall__ <function name> (<parameter list>)
+ </verb></tscreen>
+ An example is
+ <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 that are <tt/fastcall/, the rightmost parameter is not
- pushed on the stack but left in the primary register when the function
- is called. That significantly reduces the cost of calling those functions.
- <newline><newline>
- <p>
+ For functions that are <tt/fastcall/, the rightmost parameter is not
+ pushed on the stack but left in the primary register when the function
+ is called. That significantly reduces the cost of calling those functions.
+ <p>
<item> There is another calling convention named "cdecl". Variadic functions
(their prototypes have an ellipsis [<tt/.../]) always use that
For functions that are <tt/cdecl/, the rightmost parameter is pushed
onto the stack before the function is called. That increases the cost
of calling those functions, especially when they are called from many
- places.<newline><newline>
+ places.
<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
- evaluate expressions or return function results. <tt/__AX__/ is of
- type <tt/unsigned int/ and <tt/__EAX__/ of type <tt/long unsigned int/
- respectively. The pseudo variables may be used as lvalue and rvalue as
- every other variable. They are most useful together with short
- sequences of assembler code. For example, the macro
+<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
+ evaluate expressions or return function results. <tt/__AX__/ is of
+ type <tt/unsigned int/ and <tt/__EAX__/ of type <tt/long unsigned int/
+ respectively. The pseudo variables may be used as lvalue and rvalue as
+ every other variable. They are most useful together with short
+ sequences of assembler code. For example, the macro
- <tscreen><verb>
- #define hi(x) \
+ <tscreen><verb>
+ #define hi(x) \
(__AX__ = (x), \
asm ("txa"), \
asm ("ldx #$00"), \
__AX__)
- </verb></tscreen>
+ </verb></tscreen>
- will give the high byte of any unsigned value.
- <p>
+ 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
- undefined.
- Example:
+<item> Inside a function, the identifier <tt/__func__/ gives the name of the
+ current function as a string. Outside of functions, <tt/__func__/ is
+ undefined.
+ Example:
- <tscreen><verb>
- #define PRINT_DEBUG(s) printf ("%s: %s\n", __func__, s);
- </verb></tscreen>
+ <tscreen><verb>
+ #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>
+ 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 arbitrary structures that are more compatible with
This macro expands to the date of translation of the preprocessing
translation unit in the form "Mmm dd yyyy".
+ <tag><tt>__EAGERLY_INLINE_FUNCS__</tt></tag>
+
+ Is defined if the compiler was called with the <tt><ref id="option-eagerly-inline-funcs"
+ name="--eagerly-inline-funcs"></tt> command line option.
+
<tag><tt>__FILE__</tt></tag>
This macro expands to a string containing the name of the C source file.
This macro is defined if the target is the Supervision (-t supervision).
+ <tag><tt>__TELESTRAT__</tt></tag>
+
+ This macro is defined if the target is the Telestrat (-t telestrat).
+
<tag><tt>__TIME__</tt></tag>
This macro expands to the time of translation of the preprocessing
</descrip>
+
<sect>#pragmas<label id="pragmas"><p>
The compiler understands some pragmas that may be used to change code
before changing it. The value may later be restored by using the <tt/pop/
parameter with the <tt/#pragma/.
+
+<sect1><tt>#pragma allow-eager-inline ([push,] on|off)</tt><label id="pragma-allow-eager-inline"><p>
+
+ Allow eager inlining of known functions. If the argument is "off", eager
+ inlining is disabled, otherwise it is enabled. Please note that (in contrast
+ to the <tt><ref id="option-eagerly-inline-funcs" name="--eagerly-inline-funcs"></tt>
+ command line option) this pragma does not imply the <tt><ref id="option-inline-stdfuncs"
+ name="--inline-stdfuncs"></tt> command line option. Rather it marks code to be safe for
+ eager inlining of known functions if inlining of standard functions is enabled.
+
+ The <tt/#pragma/ understands the push and pop parameters as explained above.
+
+
<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
Example:
<tscreen><verb>
- #pragma bss-name ("MyBSS")
+ #pragma bss-name ("MyBSS")
</verb></tscreen>
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
Example:
<tscreen><verb>
- #pragma code-name ("MyCODE")
+ #pragma code-name ("MyCODE")
</verb></tscreen>
Example:
<tscreen><verb>
- #pragma data-name ("MyDATA")
+ #pragma data-name ("MyDATA")
</verb></tscreen>
+<sect1><tt>#pragma inline-stdfuncs ([push,] on|off)</tt><label id="pragma-inline-stdfuncs"><p>
+
+ Allow the compiler to inline some standard functions from the C library like
+ strlen. If the argument is "off", inlining is disabled, otherwise it is enabled.
+
+ See also the <tt/<ref id="option-inline-stdfuncs" name="--inline-stdfuncs">/
+ command line option.
+
+ The <tt/#pragma/ understands the push and pop parameters as explained above.
+
+
<sect1><tt>#pragma local-strings ([push,] on|off)</tt><label id="pragma-local-strings"><p>
When "on", emit string literals to the data segment when they're encountered
remembered and output as a whole when translation is finished.
+<sect1><tt>#pragma message (<message>)</tt><label id="pragma-message"><p>
+
+ This pragma is used to display informational messages at compile-time.
+
+ The message intented to be displayed must be a string literal.
+
+ Example:
+ <tscreen><verb>
+ #pragma message ("in a bottle")
+ </verb></tscreen>
+
+ Results in the compiler outputting the following to stderr:
+ <tscreen><verb>
+ example.c(42): Note: in a bottle
+ </verb></tscreen>
+
+
<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
Example:
<tscreen><verb>
- #pragma rodata-name ("MyRODATA")
+ #pragma rodata-name ("MyRODATA")
</verb></tscreen>
Example:
<tscreen><verb>
- #pragma regvaraddr(on) /* Allow taking the address
- * of register variables
- */
+ #pragma regvaraddr(on) /* Allow taking the address
+ * of register variables
+ */
</verb></tscreen>
Example:
<tscreen><verb>
/* Don't warn about the unused parameter in function func */
- #pragma warn (unused-param, push, off)
+ #pragma warn (unused-param, push, off)
static int func (int unused)
{
return 0;
</verb></tscreen>
+<sect1><tt>#pragma wrapped-call (push, <name>, <identifier>)</tt><label id="pragma-wrapped-call"><p>
+
+ This pragma sets a wrapper for functions, often used for trampolines.
+
+ The name is a function returning <tt/void/, and taking no parameters.
+ It must preserve the CPU's <tt/A/ and <tt/X/ registers if it wraps any
+ <tt/__fastcall__/ functions that have parameters. It must preserve
+ the <tt/Y/ register if it wraps any variadic functions (they have "<tt/.../"
+ in their prototypes).
+
+ The identifier is an 8-bit number that's set into <tt/tmp4/.
+
+ The address of a wrapped function is passed in <tt/ptr4/. The wrapper can
+ call that function by using "<tt/jsr callptr4/".
+
+ This feature is useful, for example, with banked memory, to switch banks
+ automatically to where a wrapped function resides, and then to restore the
+ previous bank when it returns.
+
+ The <tt/#pragma/ requires the push or pop argument as explained above.
+
+ Example:
+ <tscreen><verb>
+/* Note that this code can be in a header. */
+void mytrampoline(void); /* Doesn't corrupt __AX__ */
+
+#pragma wrapped-call (push, mytrampoline, 5)
+void somefunc1(void);
+void somefunc2(int, char *);
+#pragma wrapped-call (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,
Example:
<tscreen><verb>
- extern int foo;
- #pragma zpsym ("foo"); /* foo is in the zeropage */
+ extern int foo;
+ #pragma zpsym ("foo"); /* foo is in the zeropage */
</verb></tscreen>
-
<sect>Register variables<label id="register-vars"><p>
The runtime for all supported platforms has 6 bytes of zero page space
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.
+<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>