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83 lines
2.1 KiB
Markdown
83 lines
2.1 KiB
Markdown
## Synopsis
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A sprite compiler that targets 16-bit 65816 assembly code on the Apple IIgs computer. The sprite compiler uses informed search techniques to generate optimal code for whole-sprite rendering.
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## Example
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The compiler takes a simple masked, sparse byte sequence which are represented by (data, mask, offset) tuples. During the search, it tracks the state of the 65816 CPU registers in order to find an optimal sequence of operations to generated the sprite data. The space of possible actions are defined by the subclasses of the CodeSequence class.
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Currently, the compiler can only handle short, unmasked sequences, but it does correctly find optimal code sequences. Here is a sample of the code that the compiler generates
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### Data = $11 ###
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```
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TCS ; 2 cycles
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SEP #$10 ; 3 cycles
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LDA #$11 ; 2 cycles
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STA 00,s ; 4 cycles
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REP #$10 ; 3 cycles
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; Total Cost = 14 cycles
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```
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### Data = $11 $22 ###
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```
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TCS ; 2 cycles
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LDA #$2211 ; 3 cycles
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STA 00,s ; 5 cycles
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; Total Cost = 10 cycles
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```
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### Data = $11 $22 $22
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```
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TCS ; 2 cycles
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LDA #$2222 ; 3 cycles
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STA 02,s ; 5 cycles
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LDA #$2211 ; 3 cycles
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STA 01,s ; 5 cycles
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; Total Cost = 18 cycles
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```
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### Data = $11 $22 $11 $22 ###
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```
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TCS ; 2 cycles
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LDA #$2211 ; 3 cycles
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STA 00,s ; 5 cycles
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STA 02,s ; 5 cycles
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; Total Cost = 15 cycles
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```
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### Data = $11 $22 $33 $44 $55 $66 ###
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```
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ADC #5 ; 3 cycles
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TCS ; 2 cycles
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PEA $6655 ; 5 cycles
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PEA $4433 ; 5 cycles
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PEA $2211 ; 5 cycles
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; Total Cost = 20 cycles
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```
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### Data = $11 $22 $11 $22 $11 $22 $11 $22 ###
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```
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ADC #7 ; 3 cycles
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TCS ; 2 cycles
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LDA #$2211 ; 3 cycles
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PHA ; 4 cycles
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PHA ; 4 cycles
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PHA ; 4 cycles
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PHA ; 4 cycles
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; Total Cost = 24 cycles
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```
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## Limitations ##
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The search is quite memory intensive and grows too fast to handle multi-line sprite data yet. Future versions will
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incorporate more aggressive heuristic and Iterative Deepening A-Star search to mitigate the memory usage.
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## License
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MIT License
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