uxn/README.md

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 address
• +literal, a numeric value
• .pointer, pointer to a label

< conditionals >

0302	ADD 
05		EQU

.there	JMZ

:here
	< when not equal >
	ee
	BRK

:there
	< when is equal >
	ff
	BRK

Mission

• Catch overflow/underflow
• Jumps should be relative
• constants
• variables
• Pointers/Literals
• A Three-Way Decision Routine(http://www.6502.org/tutorials/compare_instructions.html)
• Carry flag?
• Print word to stdout
• Draw pixel to screen
• Detect mouse click
• SDL Layer Emulator
• Build PPU
• Interrupts

16 Bit Missions

• 16 bits addressing
• jumping to subroutine should be relative
• Implement addressing
• Implement 16 bits operations

Notes

• Forth logic operators pop 2 items and add a bool to the stack, is that viable in uxn?

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/