mirror of https://git.sr.ht/~rabbits/uxn
96 lines
1.6 KiB
Markdown
96 lines
1.6 KiB
Markdown
# Uxn
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A [stack-based VM](https://wiki.xxiivv.com/site/uxn.html), written in ANSI C.
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## Setup
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If you wish to build your own emulator, you can create a new instance of Uxn like:
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```
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#include "uxn.h"
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Uxn u;
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if(!bootuxn(&u))
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return error("Boot", "Failed");
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if(!loaduxn(&u, argv[1]))
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return error("Load", "Failed");
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if(!init())
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return error("Init", "Failed");
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evaluxn(u, u->vreset); /* Once on start */
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evaluxn(u, u->vframe); /* Each frame
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```
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## Uxambly
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Read more in the [Uxambly Guide](https://wiki.xxiivv.com/site/uxambly.html).
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```
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( hello world )
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%RTN { JMP2r }
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( devices )
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|0100 ;Console { pad 8 char 1 byte 1 short 2 }
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|01F0 .RESET .FRAME .ERROR ( vectors )
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|01F8 [ 13fd 1ef3 1bf2 ] ( palette )
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( program )
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|0200 @RESET
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,text1 ,print-label JSR2
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,text2 ,print-label JSR2
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#ab =Console.byte
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#cdef =Console.short
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BRK
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@print-label ( text )
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$loop NOP
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( send ) DUP2 LDR =Console.char
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( incr ) #0001 ADD2
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( loop ) DUP2 LDR #00 NEQ ^$loop MUL JMP
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POP2
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RTN
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@text1 [ Welcome 20 to 20 UxnVM 0a00 ]
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@text2 [ Hello 20 World 0a00 ]
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|c000 @FRAME
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|d000 @ERROR
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```
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## TODOs
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### OS Boot Disk
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- Load external disk in disk2
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### Assembler
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- Includes
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- Defines
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- Jump helpers
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- LDRS should load from the zeropage?
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- A fast way(2 bytes) to read from the zero page #aa LDR.
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## Notes
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## Palettes
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- `[ 6a03 4a0d aa0c ]`, purple/cyan
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- `[ a1f3 a14d a16c ]`, grey-pink/teal
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## Refs
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https://code.9front.org/hg/plan9front/file/a7f9946e238f/sys/src/games/nes/cpu.c
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http://www.w3group.de/stable_glossar.html
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http://www.emulator101.com/6502-addressing-modes.html
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http://forth.works/8f0c04f616b6c34496eb2141785b4454
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https://justinmeiners.github.io/lc3-vm/
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