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troubleshooting

This commit is contained in:
Theron 2019-12-31 19:03:29 -06:00
parent 8f3ab6e751
commit 24be0586e6
2 changed files with 4 additions and 16 deletions
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19
src/apu/mod.rs
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@ -12,26 +12,14 @@ use dmc::DMC;
// Frame counter only ticks every 3728.5 APU ticks, and in audio frames of 4 or 5.
// Length counter controls note durations.
// How to sync clock to audio?
// Measure time slept to see if it will be a problem.
// What if the APU kept a ring buffer of audio data way longer than the audio device's sample size,
// and that was in a struct with some markers, so the audio device can just consume what it needs during PPU's sleep and mark
// where it left off? But wouldn't it catch up and consume buffer? It won't catch up if it's big enough, and the APU can
// change the markers somehow as it needs to? Or audio callback truncates what it consumed and adjusts head? No, audio device doesn't
// need all samples, it needs one from the stream 44100 time per second. So just an if statement, if time has passed grab a sample.
// But then that won't be running during PPU 60Hz sleep... So run audio in its own thread... Except then it won't work on Windows because of SDL...
// So just run the console in its own thread and video/audio in the main thread... But that's annoying.
// No. Don't have to be concerned about the audio device, that's solved by the buffer, and the 44100 samples get fed in batches of 4096 from the large buffer,
// when the device needs them, which is accomplished just by calling .resume() before the main loop starts. So a large buffer really should allow for the 60Hz sleep lock.
// We need to take a sample 44100 times per second. The CPU clocks (not steps) at 1.789773 MHz. Meaning the APU, going half as fast,
// clocks 894,886.5 times per second. 894,886.5/44,100=20.29 APU clocks per audio sample.
// TODO: organize APU structs
const FRAME_COUNTER_STEPS: [usize; 5] = [3728, 7456, 11185, 14914, 18640];
// const CYCLES_PER_SAMPLE: f32 = 894_886.5/44_100.0; // APU frequency over sample frequency. May need to turn this down slightly as it's outputting less than 44_100Hz.
const CYCLES_PER_SAMPLE: f32 = 19.65;
const CYCLES_PER_SAMPLE: f32 = 894_886.5/44_100.0; // APU frequency over sample frequency. May need to turn this down slightly as it's outputting less than 44_100Hz.
// const CYCLES_PER_SAMPLE: f32 = 20.0;
const LENGTH_COUNTER_TABLE: [u8; 32] = [
10, 254, 20, 2, 40, 4, 80, 6, 160, 8, 60, 10, 14, 12, 26, 14,
12, 16, 24, 18, 48, 20, 96, 22, 192, 24, 72, 26, 16, 28, 32, 30,
@ -96,7 +84,7 @@ impl Apu {
if self.remainder > CYCLES_PER_SAMPLE {
// send sample to buffer
sample = Some(self.mix());
self.remainder -= CYCLES_PER_SAMPLE;
self.remainder -= 20.0;
}
self.remainder += 1.0;
@ -143,7 +131,6 @@ impl Apu {
fn mix(&self) -> f32 {
let square_out = self.square_table[(self.square1.sample + self.square2.sample) as usize];
let tnd_out = self.tnd_table[((3*self.triangle.sample)+(2*self.noise.sample) + self.dmc.sample) as usize];
// println!("square: {}, tnd: {}", square_out, tnd_out);
square_out + tnd_out
}

1
src/apu/square.rs
View File

@ -199,6 +199,7 @@ impl Square {
// When the enabled bit is cleared (via $4015), the length counter is forced to 0 and cannot be changed until enabled is set again (the length counter's previous value is lost).
if self.enabled {
self.length_counter = super::LENGTH_COUNTER_TABLE[value as usize >> 3];
println!("val: 0b{:08b}, wrote length_counter {}", value, self.length_counter);
}
let timer_high = value as u16 & 0b0000_0111;
self.timer_period &= 0b11111000_11111111; // mask off high 3 bits of 11-bit timer