# 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 ) @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 JMPS POP2 RTS @text1 [ Welcome 20 to 20 UxnVM 0a00 ] @text2 [ Hello 20 World 0a00 ] |c000 @FRAME |d000 @ERROR |FF00 ;Console { pad 8 char 1 byte 1 short 2 } |FFF0 .RESET .FRAME .ERROR ( vectors ) |FFF8 [ 13fd 1ef3 1bf2 ] ( palette ) ``` ## TODOs ### OS Boot Disk - Load external disk in disk2 - Build hex editor ### Assembler - Includes - Defines - Jump helpers ## Notes ### Conditional Jumping I've considered automatically popping an amount of items from the stack equal to the offset between the opcode's push/pop to make the stack length more predictable, and making the pattern JMP? POP2 unecessary, but that idea would make DUP? unusable. That change was reverted. ## 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/