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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

Write

;variable, set a name to address on the zero-page
:label, set a name to an address

Read

,literal, get a literal pointer
.pointer, get a raw pointer

Special

@0010, move to position in the program
( comment )

( comment )

;variable1
;variable2
;variable3

.there ( 0a 05 GTH ) JMC

:here
	< when not equal >
	ee
	BRK

:there
	< when is equal >
	ff
	BRK

Mission

Assembler

Crash on missing label
Catch overflow/underflow
Constants
Jumps should be relative

CPU

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, vectors

16 Bit Missions

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

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/