README
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halken
Video games are meant to be just one thing. Fun. Fun for everyone.
Satoru Iwata
Halken is a Game Boy emulator written in Go being developed during my time at the Recurse Center. The name is one used by HAL Laboratories for a time. HAL was the first company where Satoru Iwata was a video game programmer.
I intend to have lots of comments as well as a document regarding the process. Once I am happy with 32KB games generally working I'll be cleaning the code and writing documentation for others who want to tackle the same project.
Known working games
Usage: halken /path/to/rom
- Tetris
- Dr. Mario
- Flipull
- World Bowling
- Minesweeper
- Motorcross Maniacs
- Hyper Lode Runner
- Battlecity
Known bugs
- LCD STAT interrupt is only partially correct - need to make sure all cases are covered
- Breaks certain games like Game of Harmony, which gets weird graphics due to it not firing when it should
- Sprite color palettes besides default are unimplemented
- 8x16 sprites aren't drawn properly, get cut off
TODO
Implement CPU opcodesNon-CB opcodes implementedWrite dispatch loop- Use blargg's test output to fix instructions
01 - special- 02 - interrupts
03 - op sp,hl04 - op r,imm05 - op rp06 - ld r,r07 - jr,jp,call,ret,rst08 - misc instrs09 - op r,r10 - bit ops11 - op a,(hl)
Implement memoryTest GB bootstrap ROMDraw tilesDraw backgroundGraphics loop- Interrupts
VBlankLCDTimerSerialJoypad
TimerRefactor (direct memory access vs. abstractions), lower LOC, comment- Document process for learners
Documentation
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There is no documentation for this package.
Source Files
Directories
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| Path | Synopsis |
|---|---|
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Package cpu emulates the Sharp LR35902 executors contains implementations of assembly instructions registers contains register information and methods instructions contains all CPU instructions
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Package cpu emulates the Sharp LR35902 executors contains implementations of assembly instructions registers contains register information and methods instructions contains all CPU instructions |
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Package io handles reading keyboard inputs and returning them when requested by the CPU Input detection is provided by ebiten and ReadInput is called every frame
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Package io handles reading keyboard inputs and returning them when requested by the CPU Input detection is provided by ebiten and ReadInput is called every frame |
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Package lcd models all functionality related to the Game Boy's video output
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Package lcd models all functionality related to the Game Boy's video output |
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Package mmu contains the GBMMU struct which represents the Game Boy's memory and contains methods related to modifying memory TODO The WriteData and ReadData methods are pretty lean because I am modeling memory as a flat array of bytes.
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Package mmu contains the GBMMU struct which represents the Game Boy's memory and contains methods related to modifying memory TODO The WriteData and ReadData methods are pretty lean because I am modeling memory as a flat array of bytes. |
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Package timer contains functions to modify the GB's timer registers The timer is required to handle things like how quick tetromino should drop, and can provide pseudo-random numbers Realized timer implementation was necessary when Tetris would play correctly, but only would get square tetromino.
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Package timer contains functions to modify the GB's timer registers The timer is required to handle things like how quick tetromino should drop, and can provide pseudo-random numbers Realized timer implementation was necessary when Tetris would play correctly, but only would get square tetromino. |
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