67 lines
1.1 KiB
Markdown
67 lines
1.1 KiB
Markdown
# 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 JMQ
|
|
|
|
:here
|
|
< when not equal >
|
|
ee
|
|
BRK
|
|
|
|
:there
|
|
< when is equal >
|
|
ff
|
|
BRK
|
|
```
|
|
|
|
## Mission
|
|
|
|
- constants
|
|
- variables
|
|
- A Three-Way Decision Routine(http://www.6502.org/tutorials/compare_instructions.html)
|
|
- Carry flag?
|
|
- Loop
|
|
- Pointers/Literals
|
|
- Print word to stdout
|
|
- Draw pixel to screen
|
|
- Detect mouse click
|
|
- Jumps should be relative
|
|
- Catch overflow/underflow
|
|
- Audo-detect literals length.
|
|
- SDL Layer Emulator
|
|
- Build PPU
|
|
- Interrupts
|
|
|
|
### 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/ |