mirror of
https://github.com/cc65/cc65.git
synced 2024-12-23 04:30:10 +00:00
318 lines
9.4 KiB
Plaintext
318 lines
9.4 KiB
Plaintext
<!doctype linuxdoc system>
|
|
|
|
<article>
|
|
|
|
<title>Commodore 64 specific information for cc65
|
|
<author>Ullrich von Bassewitz, <htmlurl url="mailto:uz@cc65.org" name="uz@cc65.org">
|
|
<date>2003-09-23
|
|
|
|
<abstract>
|
|
An overview over the C64 runtime system as it is implemented for the cc65 C
|
|
compiler.
|
|
</abstract>
|
|
|
|
<!-- Table of contents -->
|
|
<toc>
|
|
|
|
<!-- Begin the document -->
|
|
|
|
<sect>Overview<p>
|
|
|
|
This file contains an overview of the C64 runtime system as it comes with the
|
|
cc65 C compiler. It describes the memory layout, C64 specific header files,
|
|
available drivers, and any pitfalls specific to that platform.
|
|
|
|
Please note that C64 specific functions are just mentioned here, they are
|
|
described in detail in the separate <htmlurl url="funcref.html" name="function
|
|
reference">. Even functions marked as "platform dependent" may be available on
|
|
more than one platform. Please see the function reference for more
|
|
information.
|
|
|
|
|
|
<sect>Binary format<p>
|
|
|
|
The standard binary output format generated by the linker for the C64 target
|
|
is a machine language program with a one line BASIC stub. This means that a
|
|
program can be loaded as BASIC program and started with RUN. It is of course
|
|
possible to change this behaviour by using a modified startup file and linker
|
|
config.
|
|
|
|
|
|
<sect>Memory layout<p>
|
|
|
|
cc65 generated programs with the default setup run with the I/O area and the
|
|
kernal ROM enabled (memory under the kernal may be used for graphics or as
|
|
extended memory - see the sections about graphics and extended memory
|
|
drivers). The BASIC ROM is disabled, which gives a usable memory range of
|
|
$0800 - $CFFF. This means that kernal entry points may be called
|
|
directly, but using the BASIC ROM is not possible without additional code.
|
|
|
|
Special locations:
|
|
|
|
<descrip>
|
|
<tag/Text screen/
|
|
The text screen is located at $400 (as in the standard setup).
|
|
|
|
<tag/Stack/
|
|
The C runtime stack is located at $CFFF and growing downwards.
|
|
|
|
<tag/Heap/
|
|
The C heap is located at the end of the program and grows towards the C
|
|
runtime stack.
|
|
|
|
</descrip><p>
|
|
|
|
|
|
|
|
<sect>Platform specific header files<p>
|
|
|
|
Programs containing C64 specific code may use the <tt/c64.h/ or <tt/cbm.h/
|
|
header files. Using the later may be an option when writing code for more than
|
|
one CBM platform, since it includes <tt/c64.h/ and declares several functions
|
|
common to all CBM platforms.
|
|
|
|
|
|
<sect1>C64 specific functions<p>
|
|
|
|
The functions listed below are special for the C64. See the <htmlurl
|
|
url="funcref.html" name="function reference"> for declaration and usage.
|
|
|
|
<itemize>
|
|
<item>get_ostype
|
|
</itemize>
|
|
|
|
|
|
<sect1>CBM specific functions<p>
|
|
|
|
Some functions are available for all (or at least most) of the Commodore
|
|
machines. See the <htmlurl url="funcref.html" name="function reference"> for
|
|
declaration and usage.
|
|
|
|
<itemize>
|
|
<item>cbm_close
|
|
<item>cbm_closedir
|
|
<item>cbm_k_setlfs
|
|
<item>cbm_k_setnam
|
|
<item>cbm_k_load
|
|
<item>cbm_k_save
|
|
<item>cbm_k_open
|
|
<item>cbm_k_close
|
|
<item>cbm_k_readst
|
|
<item>cbm_k_chkin
|
|
<item>cbm_k_ckout
|
|
<item>cbm_k_basin
|
|
<item>cbm_k_bsout
|
|
<item>cbm_k_clrch
|
|
<item>cbm_load
|
|
<item>cbm_open
|
|
<item>cbm_opendir
|
|
<item>cbm_read
|
|
<item>cbm_readdir
|
|
<item>cbm_save
|
|
<item>cbm_write
|
|
<item>get_tv
|
|
</itemize>
|
|
|
|
|
|
<sect1>Hardware access<p>
|
|
|
|
The following pseudo variables declared in the <tt/c64.h/ header file do allow
|
|
access to hardware located in the address space. Some variables are
|
|
structures, accessing the struct fields will access the chip registers.
|
|
|
|
<descrip>
|
|
|
|
<tag><tt/VIC/</tag>
|
|
The <tt/VIC/ structure allows access to the VIC II (the graphics
|
|
controller). See the <tt/_vic2.h/ header file located in the include
|
|
directory for the declaration of the structure.
|
|
|
|
<tag><tt/SID/</tag>
|
|
The <tt/SID/ structure allows access to the SID (the sound interface
|
|
device). See the <tt/_sid.h/ header file located in the include directory
|
|
for the declaration of the structure.
|
|
|
|
<tag><tt/CIA1, CIA2/</tag>
|
|
Access to the two CIA (complex interface adapter) chips is available via
|
|
the <tt/CIA1/ and <tt/CIA2/ variables. The structure behind these variables
|
|
is explained in <tt/_6526.h/.
|
|
|
|
<tag><tt/COLOR_RAM/</tag>
|
|
A character array that mirrors the color RAM of the C64 at $D800.
|
|
|
|
</descrip><p>
|
|
|
|
|
|
|
|
<sect>Loadable drivers<p>
|
|
|
|
<sect1>Graphics drivers<p>
|
|
|
|
<em>Note:</em> All available graphics drivers for the TGI interface will use
|
|
the space below the I/O area and kernal ROM, so you can have hires graphics in
|
|
the standard setup without any memory loss or need for a changed
|
|
configuration.
|
|
|
|
<descrip>
|
|
<tag><tt/c64-hi.tgi/</tag>
|
|
This driver features a resolution of 320*200 with two colors and an
|
|
adjustable palette (that means that the two colors can be chosen out of a
|
|
palette of the 16 C64 colors).
|
|
</descrip><p>
|
|
|
|
|
|
<sect1>Extended memory drivers<p>
|
|
|
|
<descrip>
|
|
|
|
<tag><tt/c64-georam.emd/</tag>
|
|
A driver for the GeoRam cartridge. The driver will always assume 2048 pages
|
|
of 256 bytes each. There are no checks, so if your program knows better,
|
|
just go ahead.
|
|
|
|
<tag><tt/c64-ram.emd/</tag>
|
|
A driver for the hidden RAM below the I/O area and kernal ROM. Supports 48
|
|
256 byte pages. Please note that this driver is incompatible with any of the
|
|
graphics drivers!
|
|
|
|
<tag><tt/c64-ramcart.emd/</tag>
|
|
A driver for the RamCart 64/128 written and contributed by Maciej Witkowiak.
|
|
Will test the hardware for the available RAM.
|
|
|
|
<tag><tt/c64-reu.emd/</tag>
|
|
A driver for the CBM REUs. The driver will determine from the connected REU
|
|
if it supports 128KB of RAM or more. In the latter case, 256KB are assumed,
|
|
but since there are no range checks, the application can use more memory if
|
|
it has better knowledge about the hardware than the driver.
|
|
|
|
<tag><tt/c64-vdc.emd/</tag>
|
|
A driver for the VDC memory of the C128. Written and contributed by Maciej
|
|
WitkowiakCan be used if the program is running in C64 mode of the C128.
|
|
Autodetects the amount of memory available (16 or 64K) and offers 64 or 256
|
|
pages of 256 bytes each.
|
|
|
|
</descrip><p>
|
|
|
|
|
|
<sect1>Joystick drivers<p>
|
|
|
|
<descrip>
|
|
|
|
<tag><tt/c64-hitjoy.joy/</tag>
|
|
Driver for the Digital Excess & Hitmen adapter contributed by Groepaz. See
|
|
<htmlurl url="http://www.digitalexcess.de/downloads/productions.php"
|
|
name="http://www.digitalexcess.de/downloads/productions.php"> on
|
|
instructions how to build one. Up to four joysticks are supported.
|
|
|
|
<tag><tt/c64-ptvjoy.joy/</tag>
|
|
Driver for the Protovision 4-player adapter contributed by Groepaz. See
|
|
<htmlurl url="http://www.protovision-online.de/hardw/hardwstart.htm"
|
|
name="http://www.protovision-online.de/hardw/hardwstart.htm"> for prices and
|
|
building instructions. Up to four joysticks are supported.
|
|
|
|
<tag><tt/c64-stdjoy.joy/</tag>
|
|
Supports up to two standard joysticks connected to the joysticks port of
|
|
the C64.
|
|
|
|
</descrip><p>
|
|
|
|
|
|
|
|
<sect1>Mouse drivers<p>
|
|
|
|
Currently no drivers available (in fact, the API for loadable mouse drivers
|
|
does not exist).
|
|
|
|
|
|
<sect1>RS232 device drivers<p>
|
|
|
|
<descrip>
|
|
|
|
<tag><tt/c64-swlink.ser/</tag>
|
|
Driver for the SwiftLink cartridge. Supports up to 38400 baud, hardware flow
|
|
control (RTS/CTS) and interrupt driven receives. Note that because of the
|
|
peculiarities of the 6551 chip together with the use of the NMI, transmits
|
|
are not interrupt driven, and the transceiver blocks if the receiver asserts
|
|
flow control because of a full buffer.
|
|
|
|
</descrip><p>
|
|
|
|
|
|
|
|
<sect>Limitations<p>
|
|
|
|
|
|
|
|
<sect>Other hints<p>
|
|
|
|
<sect1>Passing arguments to the program<p>
|
|
|
|
Command line arguments can be passed to <tt/main()/. Since this is not
|
|
supported by BASIC, the following syntax was chosen:
|
|
|
|
<tscreen><verb>
|
|
RUN:REM ARG1 " ARG2 IS QUOTED" ARG3 "" ARG5
|
|
</verb></tscreen>
|
|
|
|
<enum>
|
|
<item>Arguments are separated by spaces.
|
|
<item>Arguments may be quoted.
|
|
<item>Leading and trailing spaces around an argument are ignored. Spaces within
|
|
a quoted argument are allowed.
|
|
<item>The first argument passed to <tt/main/ is the program name.
|
|
<item>A maximum number of 10 arguments (including the program name) are
|
|
supported.
|
|
</enum>
|
|
|
|
|
|
<sect1>Program return code<p>
|
|
|
|
The program return code (low byte) is passed back to BASIC by use of the
|
|
<tt/ST/ variable.
|
|
|
|
|
|
<sect1>Interrupts<p>
|
|
|
|
The runtime for the C64 uses routines marked as <tt/.CONDES/ type 2 for
|
|
interrupt handlers. Such routines must be written as simple machine language
|
|
subroutines and will be called automatically by the interrupt handler code
|
|
when they are linked into a program. See the discussion of the <tt/.CONDES/
|
|
feature in the <htmlurl url="ca65.html" name="assembler manual">.
|
|
|
|
|
|
|
|
<sect>Bugs/Feedback<p>
|
|
|
|
If you have problems using the library, 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">).
|
|
|
|
|
|
|
|
<sect>License<p>
|
|
|
|
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>
|
|
|
|
|
|
|