# Uxn

A [stack-based VM](https://wiki.xxiivv.com/site/uxn.html), written in ANSI C.

## Setup

If you wish to build your own emulator, you can create a new instance of Uxn like:

```
#include "uxn.h"

Uxn u;

if(!bootuxn(&u))
	return error("Boot", "Failed");
if(!loaduxn(&u, argv[1]))
	return error("Load", "Failed");
if(!init())
	return error("Init", "Failed");

evaluxn(u, u->vreset); /* Once on start */
evaluxn(u, u->vframe); /* Each frame
```

## Uxambly

Read more in the [Uxambly Guide](https://wiki.xxiivv.com/site/uxambly.html).

```
( hello world )

%RTN { JMP2r }

( devices )

|0100 ;Console { pad 8 char 1 byte 1 short 2 }
|01F0 .RESET .FRAME .ERROR ( vectors )
|01F8 [ 13fd 1ef3 1bf2 ] ( palette )

( program )

|0200 @RESET 
	
	,text1 ,print-label JSR2
	,text2 ,print-label JSR2
	#ab =Console.byte
	#cdef =Console.short

BRK

@print-label ( text )
	
	$loop NOP
		( send ) DUP2 LDR =Console.char
		( incr ) #0001 ADD2
		( loop ) DUP2 LDR #00 NEQ ^$loop MUL JMP 
	POP2

RTN    

@text1 [ Welcome 20 to 20 UxnVM 0a00 ]
@text2 [ Hello 20 World 0a00 ] 

|c000 @FRAME
|d000 @ERROR 
```

## TODOs

### OS Boot Disk

- Load external disk in disk2

### Assembler

- Includes
- Defines
- Jump helpers
- Implement Peek/Pook to helpers
- Create a theme designer application
- DateTime device
- Document controller.player2

## Notes

## Palettes

- `[ 6a03 4a0d aa0c ]`, purple/cyan
- `[ a1f3 a14d a16c ]`, grey-pink/teal

## 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/