Uxn

A stack-based VM, written in ANSI C.

Build

cc uxn.c -std=c89 -Os -DNDEBUG -g0 -s -Wall -Wno-unknown-pragmas -o uxn

Assembly Syntax

• :label, a named offset
• +literal, a numeric value
• .pointer, pointer to a label

< comment >

+01 < literal >

[ 01 02 03 04 ] < block of literals >

$01 < pointer8 >

{ 01 02 03 04 } < block of pointer8 >

~ff0f < pointer16 >

( ff00 ff01 ff02 ff03 ) < block of pointer16 >

=const +ff

:label ADD RTS

Mission

• Loop
• Conditional example
• Pointers/Literals
• Print word to stdout
• Draw pixel to screen
• Detect mouse click
• 16 bits addressing
• jumping to subroutine should be relative

TODOs

• Implement addressing
• Implement 16 bits operations
• Jumps should be relative
• Catch overflow/underflow
• Implement literals like [2], and [ 2 3 ].
• Audo-detect literals length.
• SDL Layer Emulator
• Build PPU
• Interrupts

Refs

https://code.9front.org/hg/plan9front/file/a7f9946e238f/sys/src/games/nes/cpu.c http://www.w3group.de/stable_glossar.html http://www.emulator101.com/6502-addressing-modes.html http://forth.works/8f0c04f616b6c34496eb2141785b4454 https://justinmeiners.github.io/lc3-vm/