Profiling GameBoyAdvance::frame shows that it spends way too much time idleing
on SoundController::update & Gpu::step waiting for the cycle count to
reach to the next event, Consuming cpu time for the Arm7tdmi core.
This commit changes the implementation of the main loop functions so
that the CPU will run as many cycles as possible and the peripherals
will only be updated when needed.
The is a performance improvement of roughly 50% in fps in some games!
Former-commit-id: 937e097f958423934c70b7face6b6b02926b7a51
1) Decouple SysBus from Gpu
2) Split Gpu rendering function into separate modules
3) Cleanup
Former-commit-id: 0435ad1c9c1de72ed50769fabfea7c5f33b670e0
The symptom of the problem was in the form of a rythmic click sound popping in the left channel.
Diving deep into Kirby's binary, I found out that channel B and channel
A are playing too different pcm buffers simultationsly: A is enabled for
the right channel and B is enabled for the left.
I found out that the game's sound driver was using VCOUNT in order to syncornize the audio,
but in some occassions the fifo DMA was not disabled in time, causing the DMA to
fill the fifo in additional 16 bytes of garbage residing next to channel
B's pcmBuffer.
After a thorough check-up of the GPU state machine, I find out that I
stay in VBLANK for 1 line too long, and that's what caused the audio
buffer to de-sync with the gpu emulation.
This commit fixes this issue.
Former-commit-id: e0f20bd01b8abf62da486e2501cff197a9a22763
This fixes the glitch in dma_demo.gba where the rendering of the circle
was off by a scanline.
Former-commit-id: 907fefd548b6557ce46e06a99d0bc6ab83a8f332
I have fought very hard against the rust ownership model,
In the end for DMA to play nice with my code, I had to resort to use
unsafe code for now..
The DMA implementation itself is not accurate to say the least, but will
have to do for now.
Tonc's dma_demo.gba plays but with a visual glitch.
Former-commit-id: 3b9cdcb2d09c78701290f2c48b77f9f3487e85c9
