mirror of https://github.com/bsnes-emu/bsnes.git
132 lines
3.3 KiB
C++
132 lines
3.3 KiB
C++
auto DSP::calculateFIR(signed i, bool channel) -> signed {
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signed s = state.echoHistory[channel][state.echoHistoryOffset + i + 1];
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return (s * (int8)REG(FIR + i * 0x10)) >> 6;
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}
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auto DSP::echoOutput(bool channel) -> signed {
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signed output = (int16)((state._mainOut[channel] * (int8)REG(MVOLL + channel * 0x10)) >> 7)
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+ (int16)((state._echoIn [channel] * (int8)REG(EVOLL + channel * 0x10)) >> 7);
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return sclamp<16>(output);
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}
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auto DSP::echoRead(bool channel) -> void {
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unsigned addr = state._echoPointer + channel * 2;
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uint8 lo = smp.apuram[(uint16)(addr + 0)];
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uint8 hi = smp.apuram[(uint16)(addr + 1)];
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signed s = (int16)((hi << 8) + lo);
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state.echoHistory[channel].write(state.echoHistoryOffset, s >> 1);
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}
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auto DSP::echoWrite(bool channel) -> void {
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if(!(state._echoDisabled & 0x20)) {
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unsigned addr = state._echoPointer + channel * 2;
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signed s = state._echoOut[channel];
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smp.apuram[(uint16)(addr + 0)] = s;
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smp.apuram[(uint16)(addr + 1)] = s >> 8;
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}
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state._echoOut[channel] = 0;
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}
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auto DSP::echo22() -> void {
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//history
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state.echoHistoryOffset++;
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if(state.echoHistoryOffset >= EchoHistorySize) state.echoHistoryOffset = 0;
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state._echoPointer = (uint16)((state._esa << 8) + state.echoOffset);
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echoRead(0);
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//FIR
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signed l = calculateFIR(0, 0);
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signed r = calculateFIR(0, 1);
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state._echoIn[0] = l;
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state._echoIn[1] = r;
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}
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auto DSP::echo23() -> void {
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signed l = calculateFIR(1, 0) + calculateFIR(2, 0);
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signed r = calculateFIR(1, 1) + calculateFIR(2, 1);
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state._echoIn[0] += l;
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state._echoIn[1] += r;
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echoRead(1);
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}
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auto DSP::echo24() -> void {
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signed l = calculateFIR(3, 0) + calculateFIR(4, 0) + calculateFIR(5, 0);
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signed r = calculateFIR(3, 1) + calculateFIR(4, 1) + calculateFIR(5, 1);
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state._echoIn[0] += l;
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state._echoIn[1] += r;
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}
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auto DSP::echo25() -> void {
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signed l = state._echoIn[0] + calculateFIR(6, 0);
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signed r = state._echoIn[1] + calculateFIR(6, 1);
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l = (int16)l;
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r = (int16)r;
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l += (int16)calculateFIR(7, 0);
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r += (int16)calculateFIR(7, 1);
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state._echoIn[0] = sclamp<16>(l) & ~1;
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state._echoIn[1] = sclamp<16>(r) & ~1;
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}
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auto DSP::echo26() -> void {
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//left output volumes
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//(save sample for next clock so we can output both together)
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state._mainOut[0] = echoOutput(0);
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//echo feedback
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signed l = state._echoOut[0] + (int16)((state._echoIn[0] * (int8)REG(EFB)) >> 7);
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signed r = state._echoOut[1] + (int16)((state._echoIn[1] * (int8)REG(EFB)) >> 7);
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state._echoOut[0] = sclamp<16>(l) & ~1;
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state._echoOut[1] = sclamp<16>(r) & ~1;
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}
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auto DSP::echo27() -> void {
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//output
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signed outl = state._mainOut[0];
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signed outr = echoOutput(1);
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state._mainOut[0] = 0;
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state._mainOut[1] = 0;
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//TODO: global muting isn't this simple
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//(turns DAC on and off or something, causing small ~37-sample pulse when first muted)
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if(REG(FLG) & 0x40) {
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outl = 0;
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outr = 0;
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}
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//output sample to DAC
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audio.sample(outl, outr);
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}
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auto DSP::echo28() -> void {
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state._echoDisabled = REG(FLG);
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}
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auto DSP::echo29() -> void {
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state._esa = REG(ESA);
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if(!state.echoOffset) state.echoLength = (REG(EDL) & 0x0f) << 11;
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state.echoOffset += 4;
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if(state.echoOffset >= state.echoLength) state.echoOffset = 0;
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//write left echo
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echoWrite(0);
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state._echoDisabled = REG(FLG);
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}
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auto DSP::echo30() -> void {
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//write right echo
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echoWrite(1);
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}
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