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113 lines
3.6 KiB
Plaintext
113 lines
3.6 KiB
Plaintext
xasm - 6502 cross-assembler
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===========================
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xasm is a free tool for programming
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http://en.wikipedia.org/wiki/Atari_8-bit_family[Atari 8-bit family computers].
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History
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-------
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First version of xasm was written in 1998. I needed a cross-assembler
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that could understand the syntax of Quick Assembler
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which I used for 8-bit Atari programming before I got a PC.
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Initially xasm supported the syntax of QA and nothing more.
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I quickly realized that I could extend the syntax to make it more expressive.
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This led to xasm 2.0, still in 1998. I added some more features
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next year. In 2002 I released many versions which contained
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mostly bugfixes. In 2005 there were some minor enhancements and bug fixes,
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as well as the whole assembler was rewritten from the x86 assembly language
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it was initially written in to the http://www.digitalmars.com/d/[D programming language].
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Current version 3.0.2 was released 17th October 2009.
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Syntax
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------
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6502 assembler code is usually full of LDA, STA, LDA, STA sequences.
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With xasm you can use MVA as a shortcut for LDA/STA pair
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or even MWA for 16-bit transfers. You can avoid defining labels
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when you need short jumps, thanks to conditional skip
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and repeat pseudo-instructions. You can put two instructions
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that share their argument in one line.
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These are just some of the features that help you program
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in a more concise way. Let's look at typical 6502 code
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(which is also valid in xasm):
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-----------------------------
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lda #<dest
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sta ptr
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lda #>dest
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sta ptr+1
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ldx #192
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do_line
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ldy #39
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do_byte
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lda pattern,y
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sta (ptr),y
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dey
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bpl do_byte
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lda #40
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clc
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adc ptr
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sta ptr
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bcc skip
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inc ptr+1
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skip
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dex
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bne do_line
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-----------------------------
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Using xasm's features this code can be rewritten to:
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-----------------------------
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mwa #dest ptr
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ldx #192
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do_line
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ldy #39
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mva:rpl pattern,y (ptr),y-
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lda #40
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add:sta ptr
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scc:inc ptr+1
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dex:bne do_line
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-----------------------------
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Usage
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-----
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xasm is a command-line tool.
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Therefore you additionally need a programmer's text editor.
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I use http://www.scintilla.org/SciTE.html[SciTE].
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Syntax highlighting definition for it is included with xasm.
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To install it, copy `xasm.properties` to the SciTE directory,
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select _Options / Open Global Options File_, type `import xasm`
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at the end and save the global configuration file.
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image::scite.png[xasm code in SciTE]
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Download
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--------
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- link:xasm-3.0.2-windows.zip[xasm 3.0.2 for Windows]
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- link:xasm-3.0.2-src.zip[xasm 3.0.2 source code]
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- link:xasm261.zip[xasm 2.6.1 for DOS]
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For other systems, such as GNU/Linux and MacOS X, install a D 1.x compiler
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and compile xasm from source code.
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Inflate
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-------
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Do you need a good decompression routine for 6502?
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See my link:inflate.html[inflate routine].
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Links
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-----
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- http://atari800.sourceforge.net/[Atari800 emulator] - portable emulator of Atari 8-bit computers
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- http://sources.pigwa.net/[Atari XL/XE Source Archive] - source code of Atari demos, utilities and games
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- http://www.cc65.org/[cc65] - C cross-compiler targeting 6502-based systems
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- http://epi.atari8.info/hcasm.php[HardCore Assembler] - 6502/65816 cross-assembler, partially supporting xasm's syntax
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- http://mads.atari8.info/[MADS] - another 6502/65816 cross-assembler, partially supporting xasm's syntax
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- http://wudsn.com/[WUDSN IDE] - Eclipse plugin, front-end to several 6502 cross-assemblers including xasm
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