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# Uxn
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A stack-based VM, written in ANSI C.
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## Build
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```
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cc uxn.c -std=c89 -Os -DNDEBUG -g0 -s -Wall -Wno-unknown-pragmas -o uxn
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```
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2021-01-29 14:35:59 -05:00
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2021-01-29 20:49:10 -05:00
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## Assembly Syntax
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- `:label`, a named address
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- `+literal`, a numeric value
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- `.pointer`, pointer to a label
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```
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< conditionals >
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2021-02-01 23:21:27 -05:00
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0302 ADD
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05 EQU
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2021-02-01 23:21:27 -05:00
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.there JMQ
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:here
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< when not equal >
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ee
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BRK
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:there
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< when is equal >
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ff
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BRK
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```
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2021-02-01 14:58:47 -05:00
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## Mission
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- constants
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- variables
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- A Three-Way Decision Routine(http://www.6502.org/tutorials/compare_instructions.html)
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- Carry flag?
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- Loop
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- Pointers/Literals
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- Print word to stdout
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- Draw pixel to screen
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- Detect mouse click
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- Jumps should be relative
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- Catch overflow/underflow
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- Audo-detect literals length.
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- SDL Layer Emulator
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- Build PPU
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- Interrupts
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### 16 Bit Missions
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- 16 bits addressing
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- jumping to subroutine should be relative
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- Implement addressing
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- Implement 16 bits operations
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2021-01-30 17:25:48 -05:00
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## Refs
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https://code.9front.org/hg/plan9front/file/a7f9946e238f/sys/src/games/nes/cpu.c
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http://www.w3group.de/stable_glossar.html
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http://www.emulator101.com/6502-addressing-modes.html
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http://forth.works/8f0c04f616b6c34496eb2141785b4454
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https://justinmeiners.github.io/lc3-vm/
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