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216 lines
5.6 KiB
Plaintext
216 lines
5.6 KiB
Plaintext
<!doctype linuxdoc system>
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<article>
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<title>PC-Engine (TurboGrafx) System specific information for cc65
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<author>
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<url url="mailto:groepaz@gmx.net" name="Groepaz/Hitmen">
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<date>2016-09-29
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<abstract>
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An overview over the PCE runtime system as it is implemented for the
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cc65 C compiler.
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</abstract>
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<!-- Table of contents -->
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<toc>
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<!-- Begin the document -->
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<sect>Overview<p>
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This file contains an overview of the PCE runtime system as it comes
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with the cc65 C compiler. It describes the memory layout, PCE specific header
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files, available drivers, and any pitfalls specific to that platform.
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Please note that PCE specific functions are just mentioned here, they are
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described in detail in the separate <url url="funcref.html" name="function
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reference">. Even functions marked as "platform dependent" may be available on
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more than one platform. Please see the function reference for more
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information.
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<sect>Binary format<p>
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The standard binary output format generated by the linker for the PCE target
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is a cartridge image with no header. It is of course possible to change this
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behaviour by using a modified startup file and linker config.
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<sect>Memory layout<p>
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cc65 generated programs with the default setup run with the I/O area and a
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CHR bank enabled, which gives a usable memory range of $8000 - $FFF3.
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All boot ROM entry points may be called directly without additional code.
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Special locations:
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<descrip>
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<tag/Text screen and Font/
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The text screen is located at VRAM $0000,
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the Font is located at VRAM $2000.
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<tag/Stack/
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The C runtime stack is located in system RAM at $3FFF and growing downwards.
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<tag/BSS and Data/
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The BSS (uninitialized variables) and Data (initialized variables) sections are
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placed one after the other into system RAM at $2000.
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<tag/Heap/
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The C heap is located after the end of the Data section and grows towards the C
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runtime stack.
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<tag/Code/
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The startup code is located at $E000 in the System/Hardware bank. Further
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code can be placed in other ROM banks, this must be done manually however.
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</descrip><p>
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<sect>Platform specific header files<p>
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Programs containing PCE specific code may use the <tt/pce.h/ header file.
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<sect1>PCE specific functions<p>
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<itemize>
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<item>waitvsync</item>
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<item>get_tv (since all PCE systems are NTSC, this always returns TV_NTSC)</item>
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</itemize>
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<sect1>Hardware access<p>
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The following pseudo variables declared in the <tt/pce.inc/ include file do
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allow access to hardware located in the address space.
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<descrip>
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<tag><tt/PSG/</tag>
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The <tt/PSG/ defines allow access to the PSG chip (Programmable Sound Generator).
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<tag><tt/VCE/</tag>
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The <tt/VCE/ defines allow access to the VCE chip (Video Color Encoder).
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<tag><tt/VDC/</tag>
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The <tt/VDC/ defines allow access to the VDC chip (Video Display Controller).
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</descrip><p>
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<sect>Loadable drivers<p>
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All drivers must be statically linked because no file I/O is available.
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The names in the parentheses denote the symbols to be used for static linking of the drivers.
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<sect1>Graphics drivers<p>
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No TGI graphics drivers are currently available for the PCE.
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<sect1>Extended memory drivers<p>
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No extended memory drivers are currently available for the PCE.
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<sect1>Joystick drivers<p>
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<descrip>
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<tag><tt/pce-stdjoy.joy (pce_stdjoy)/</tag>
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A joystick driver for the standard two buttons joypad is available.
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Note that the japanese 6-button pad is currently not supported.
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</descrip><p>
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<sect1>Mouse drivers<p>
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No mouse drivers are currently available for the PCE.
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<sect1>RS232 device drivers<p>
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No serial drivers are currently available for the PCE.
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<sect>Limitations<p>
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<itemize>
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<item>interruptor support in crt0 (and cfg) is missing
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</itemize>
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<sect1>Disk I/O<p>
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The existing library for the PCE doesn't implement C file
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I/O. There are no hacks for the <tt/read()/ and <tt/write()/ routines.
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To be more concrete, this limitation means that you cannot use any of the
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following functions (and a few others):
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<itemize>
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<item>printf
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<item>fclose
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<item>fopen
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<item>fread
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<item>fprintf
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<item>fputc
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<item>fscanf
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<item>fwrite
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<item>...
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</itemize>
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<sect>Other hints<p>
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<itemize>
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<item>a good emulator to use for PC-Engine is "mednafen" (<url url="http://mednafen.fobby.net/">)
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</itemize>
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some useful resources on PCE coding:
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<itemize>
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<item><url url="http://blog.blockos.org/?tag=pc-engine">
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<item><url url="http://pcedev.blockos.org/viewforum.php?f=5">
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<item><url url="http://www.romhacking.net/?page=documents&platform=4">
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<item><url url="http://archaicpixels.com/Main_Page">
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<item><url url="http://www.magicengine.com/mkit/doc.html">
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<item><url url="https://github.com/uli/huc">
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<item><url url="http://www.zeograd.com/parse.php?src=hucf">
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</itemize>
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<sect>License<p>
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This software is provided 'as-is', without any expressed or implied
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warranty. In no event will the authors be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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<enum>
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<item> The origin of this software must not be misrepresented; you must not
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claim that you wrote the original software. If you use this software
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in a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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<item> Altered source versions must be plainly marked as such, and must not
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be misrepresented as being the original software.
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<item> This notice may not be removed or altered from any source
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distribution.
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</enum>
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</article>
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