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implement ring modulation

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This commit is contained in:
Dennis Ranke
2022-04-02 18:19:45 +02:00
parent 1917057b81
commit 8ad2885a55
1 changed files with 25 additions and 1 deletions
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26
platform/src/ges.cwa
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@@ -55,7 +55,7 @@ export fn gesSnd(t: i32) -> f32 {
i32.store16(envVol, channelState, GesChannelState.EnvVol);
let inline note = i32.load16_u(channelReg, 2);
let inline freq = 440 as f32 * pow(2.0, (note - 69*256) as f32 / (12*256) as f32);
let lazy freq = 440 as f32 * pow(2.0, (note - 69*256) as f32 / (12*256) as f32);
let phaseInc = (freq * (65536.0 / 44100.0)) as i32;
let phase = channelState!GesChannelState.Phase;
@@ -120,6 +120,30 @@ export fn gesSnd(t: i32) -> f32 {
channelState!GesChannelState.Phase = phase;
if ctrl & 32 {
let lazy modSrc = (ch - 1) & 3;
let inline channelState = GesStateOffset + modSrc * GesChannelState.Size;
let inline channelReg = 80 + modSrc * 6;
let inline note = i32.load16_u(channelReg, 2);
let inline freq = 440 as f32 * pow(2.0, (note - 69*256) as f32 / (12*256) as f32);
let phaseInc = (freq * (65536.0 / 44100.0)) as i32;
let phase = channelState!GesChannelState.Phase;
if modSrc > ch {
phase = phase - (phaseInc << 6);
}
i = 0;
loop ringLoop {
let s = phase << 16;
s = (s ^ (s >> 31));
i!(GesBufferOffset + 128*4) = (i!(GesBufferOffset + 128*4) * ((s >> 15) - 32768)) >> 15;
phase = phase + phaseInc;
branch_if (i := i + 4) < 64*4: ringLoop;
}
}
let channelVol = ((ch >> 1)?0x68 >> ((ch & 1) * 4)) & 15;
envVol = envVol * channelVol / 15;