2021-01-29 14:17:59 -05:00
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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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2021-02-04 15:22:08 -05:00
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### Write
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- `;variable`, set a name to address on the zero-page
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- `:label`, set a name to an address
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### Read
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- `,literal`, get a literal pointer
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- `.pointer`, get a raw pointer
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### Special
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- `@0010`, move to position in the program
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- `( comment )`
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2021-01-31 00:31:49 -05:00
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2021-01-29 14:35:59 -05:00
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```
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2021-02-04 15:22:08 -05:00
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( comment )
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;variable1
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;variable2
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;variable3
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2021-01-29 20:49:10 -05:00
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2021-02-04 00:53:56 -05:00
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.there ( 0a 05 GTH ) JMC
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2021-01-30 17:25:48 -05:00
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2021-02-01 17:49:09 -05:00
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:here
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2021-02-01 23:21:27 -05:00
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< when not equal >
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ee
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BRK
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2021-02-01 17:49:09 -05:00
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:there
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2021-02-01 23:21:27 -05:00
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< when is equal >
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ff
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BRK
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2021-01-29 14:35:59 -05:00
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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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2021-02-04 00:53:56 -05:00
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### Assembler
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- Crash on missing label
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- Catch overflow/underflow
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- Constants
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- Jumps should be relative
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### CPU
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- Pointers/Literals
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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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- Print word to stdout
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- Draw pixel to screen
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- Detect mouse click
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- SDL Layer Emulator
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- Build PPU
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- Interrupts, vectors
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2021-02-01 23:21:27 -05:00
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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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