bsnes/higan/sfc/dsp/voice.cpp

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inline auto DSP::voiceOutput(Voice& v, bool channel) -> void {
//apply left/right volume
int amp = (state._output * (int8)VREG(VOLL + channel)) >> 7;
//add to output total
state._mainOut[channel] += amp;
state._mainOut[channel] = sclamp<16>(state._mainOut[channel]);
//optionally add to echo total
if(state._eon & v.vbit) {
state._echoOut[channel] += amp;
state._echoOut[channel] = sclamp<16>(state._echoOut[channel]);
}
}
auto DSP::voice1(Voice& v) -> void {
state._dirAddress = (state._dir << 8) + (state._srcn << 2);
state._srcn = VREG(SRCN);
}
auto DSP::voice2(Voice& v) -> void {
//read sample pointer (ignored if not needed)
uint16 addr = state._dirAddress;
if(!v.konDelay) addr += 2;
uint8 lo = apuram[(uint16)(addr + 0)];
uint8 hi = apuram[(uint16)(addr + 1)];
state._brrNextAddress = ((hi << 8) + lo);
state._adsr0 = VREG(ADSR0);
//read pitch, spread over two clocks
state._pitch = VREG(PITCHL);
}
auto DSP::voice3(Voice& v) -> void {
voice3a(v);
voice3b(v);
voice3c(v);
}
auto DSP::voice3a(Voice& v) -> void {
state._pitch += (VREG(PITCHH) & 0x3f) << 8;
}
auto DSP::voice3b(Voice& v) -> void {
state._brrByte = apuram[(uint16)(v.brrAddress + v.brrOffset)];
state._brrHeader = apuram[(uint16)(v.brrAddress)];
}
auto DSP::voice3c(Voice& v) -> void {
//pitch modulation using previous voice's output
if(state._pmon & v.vbit) {
state._pitch += ((state._output >> 5) * state._pitch) >> 10;
}
if(v.konDelay) {
//get ready to start BRR decoding on next sample
if(v.konDelay == 5) {
v.brrAddress = state._brrNextAddress;
v.brrOffset = 1;
v.bufferOffset = 0;
state._brrHeader = 0; //header is ignored on this sample
}
//envelope is never run during KON
v.envelope = 0;
v.hiddenEnvelope = 0;
//disable BRR decoding until last three samples
v.gaussianOffset = 0;
v.konDelay--;
if(v.konDelay & 3) v.gaussianOffset = 0x4000;
//pitch is never added during KON
state._pitch = 0;
}
//gaussian interpolation
int output = gaussianInterpolate(v);
//noise
if(state._non & v.vbit) {
output = (int16)(state.noise << 1);
}
//apply envelope
state._output = ((output * v.envelope) >> 11) & ~1;
v._envxOut = v.envelope >> 4;
//immediate silence due to end of sample or soft reset
if(REG(FLG) & 0x80 || (state._brrHeader & 3) == 1) {
v.envelopeMode = EnvelopeRelease;
v.envelope = 0;
}
if(state.everyOtherSample) {
//KOFF
if(state._koff & v.vbit) {
v.envelopeMode = EnvelopeRelease;
}
//KON
if(state.kon & v.vbit) {
v.konDelay = 5;
v.envelopeMode = EnvelopeAttack;
}
}
//run envelope for next sample
if(!v.konDelay) envelopeRun(v);
}
auto DSP::voice4(Voice& v) -> void {
//decode BRR
state._looped = 0;
if(v.gaussianOffset >= 0x4000) {
brrDecode(v);
v.brrOffset += 2;
if(v.brrOffset >= 9) {
//start decoding next BRR block
v.brrAddress = (uint16)(v.brrAddress + 9);
if(state._brrHeader & 1) {
v.brrAddress = state._brrNextAddress;
state._looped = v.vbit;
}
v.brrOffset = 1;
}
}
//apply pitch
v.gaussianOffset = (v.gaussianOffset & 0x3fff) + state._pitch;
//keep from getting too far ahead (when using pitch modulation)
if(v.gaussianOffset > 0x7fff) v.gaussianOffset = 0x7fff;
//output left
voiceOutput(v, 0);
}
auto DSP::voice5(Voice& v) -> void {
//output right
voiceOutput(v, 1);
//ENDX, OUTX and ENVX won't update if you wrote to them 1-2 clocks earlier
state.endxBuffer = REG(ENDX) | state._looped;
//clear bit in ENDX if KON just began
if(v.konDelay == 5) state.endxBuffer &= ~v.vbit;
}
auto DSP::voice6(Voice& v) -> void {
state.outxBuffer = state._output >> 8;
}
auto DSP::voice7(Voice& v) -> void {
//update ENDX
REG(ENDX) = (uint8)state.endxBuffer;
state.envxBuffer = v._envxOut;
}
auto DSP::voice8(Voice& v) -> void {
//update OUTX
VREG(OUTX) = (uint8)state.outxBuffer;
}
auto DSP::voice9(Voice& v) -> void {
//update ENVX
VREG(ENVX) = (uint8)state.envxBuffer;
}