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metaforce/NESEmulator/apu.c

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#include "fixNES/apu.c"
/*
* Alternate apuCycle implementation to avoid processing multiple
* NES frames per URDE frame (costly and jarring to player).
*
* This implementation nominally fills 6/10 buffers, allowing
* emulation to "catch up" by having more buffer headroom available
* (and also reducing audio latency somewhat).
*
* URDE's NesEmuMainLoop uses emuSkipVsync as a signal to proceed
* with the emulation, allowing audio buffers to be pre-filled with
* generated tones independent of the emulated CPU. Granted, this
* compromises accuracy, but doesn't affect NEStroid's behavior and
* reduces audio discontinuities.
*/
bool apuCycleURDE()
{
if(apu.curBufPos == apu.BufSize)
{
int updateRes = audioUpdate();
if(updateRes == 0)
{
emuSkipFrame = false;
emuSkipVsync = false;
return false;
}
if(updateRes > 6)
{
emuSkipVsync = true;
emuSkipFrame = true;
}
else
{
emuSkipFrame = false;
if(updateRes > 4) // 6 buffers filled, stop here
emuSkipVsync = true;
else
emuSkipVsync = false;
}
apu.curBufPos = 0;
}
uint8_t aExp = audioExpansion;
if(!(apu.apuClock&7))
{
if(apu.p1LengthCtr && (apu.reg[0x15] & P1_ENABLE))
{
if(!apu.p1Sweep.mute && apu.freq1 >= 8 && apu.freq1 < 0x7FF)
apu.p1Out = apu.p1seq[apu.p1Cycle] ? (apu.p1Env.constant ? apu.p1Env.vol : apu.p1Env.decay) : 0;
}
if(apu.p2LengthCtr && (apu.reg[0x15] & P2_ENABLE))
{
if(!apu.p2Sweep.mute && apu.freq2 >= 8 && apu.freq2 < 0x7FF)
apu.p2Out = apu.p2seq[apu.p2Cycle] ? (apu.p2Env.constant ? apu.p2Env.vol : apu.p2Env.decay) : 0;
}
if(apu.triLengthCtr && apu.triCurLinearCtr && (apu.reg[0x15] & TRI_ENABLE))
{
if(apu.triFreq >= 2)
apu.triOut = apu.triSeq[apu.triCycle];
}
if(apu.noiseLengthCtr && (apu.reg[0x15] & NOISE_ENABLE))
{
if(apu.noiseFreq > 0)
apu.noiseOut = (apu.noiseShiftReg&1) == 0 ? (apu.noiseEnv.constant ? apu.noiseEnv.vol : apu.noiseEnv.decay) : 0;
}
#if AUDIO_FLOAT
float curIn = apu.pulseLookupTbl[apu.p1Out + apu.p2Out] + apu.tndLookupTbl[(3*apu.triOut) + (2*apu.noiseOut) + apu.dmcVol];
uint8_t ampVolPos = 0;
//very rough still
if(aExp & EXP_VRC6)
{
vrc6AudioCycle();
curIn += ((float)vrc6Out)*0.008f;
ampVolPos++;
}
if(aExp & EXP_FDS)
{
fdsAudioCycle();
curIn += ((float)fdsOut)*0.00617f;
ampVolPos++;
}
if(aExp & EXP_MMC5)
{
mmc5AudioCycle();
curIn += apu.pulseLookupTbl[mmc5Out]+(mmc5pcm*0.002f);
ampVolPos++;
}
if(aExp & EXP_VRC7)
{
curIn += (((float)(vrc7Out>>7))/32768.f);
ampVolPos++;
}
if(aExp & EXP_N163)
{
curIn += ((float)n163Out)*0.0008f;
ampVolPos++;
}
if(aExp & EXP_S5B)
{
s5BAudioCycle();
curIn += ((float)s5BOut)/32768.f;
ampVolPos++;
}
//amplify input
curIn *= ampVol[ampVolPos];
float curLPout = apu.lastLPOut+(apu.lpVal*(curIn-apu.lastLPOut));
float curHPOut = apu.hpVal*(apu.lastHPOut+apu.lastLPOut-curLPout);
//set output
apu.OutBuf[apu.curBufPos] = curHPOut;
apu.lastLPOut = curLPout;
apu.lastHPOut = curHPOut;
#else
int32_t curIn = apu.pulseLookupTbl[apu.p1Out + apu.p2Out] + apu.tndLookupTbl[(3*apu.triOut) + (2*apu.noiseOut) + apu.dmcVol];
uint8_t ampVolPos = 0;
//very rough still
if(aExp & EXP_VRC6)
{
vrc6AudioCycle();
curIn += ((int32_t)vrc6Out)*262;
ampVolPos++;
}
if(aExp & EXP_FDS)
{
fdsAudioCycle();
curIn += ((int32_t)fdsOut)*202;
ampVolPos++;
}
if(aExp & EXP_MMC5)
{
mmc5AudioCycle();
curIn += apu.pulseLookupTbl[mmc5Out]+(mmc5pcm<<6);
ampVolPos++;
}
if(aExp & EXP_VRC7)
{
curIn += vrc7Out>>7;
ampVolPos++;
}
if(aExp & EXP_N163)
{
curIn += n163Out*26;
ampVolPos++;
}
if(aExp & EXP_S5B)
{
s5BAudioCycle();
curIn += s5BOut;
ampVolPos++;
}
//amplify input
curIn *= apu.ampVol[ampVolPos];
int32_t curOut;
//gen output
curOut = apu.lastLPOut+((apu.lpVal*((curIn>>6)-apu.lastLPOut))>>15); //Set Lowpass Output
curIn = (apu.lastHPOut+apu.lastLPOut-curOut); //Set Highpass Input
curIn += (curIn>>31)&1; //Add Sign Bit for proper Downshift later
apu.lastLPOut = curOut; //Save Lowpass Output
curOut = (apu.hpVal*curIn)>>15; //Set Highpass Output
apu.lastHPOut = curOut; //Save Highpass Output
//Save Clipped Highpass Output
apu.OutBuf[apu.curBufPos] = (curOut > 32767)?(32767):((curOut < -32768)?(-32768):curOut);
#endif
apu.OutBuf[apu.curBufPos+1] = apu.OutBuf[apu.curBufPos];
apu.curBufPos+=2;
}
apu.apuClock++;
if(apu.p1freqCtr == 0)
{
apu.p1freqCtr = (apu.freq1<<1)+1;
apu.p1Cycle = (apu.p1Cycle+1)&7;
}
else
apu.p1freqCtr--;
if(apu.p2freqCtr == 0)
{
apu.p2freqCtr = (apu.freq2<<1)+1;
apu.p2Cycle = (apu.p2Cycle+1)&7;
}
else
apu.p2freqCtr--;
if(apu.triFreqCtr == 0)
{
apu.triFreqCtr = apu.triFreq;
apu.triCycle = (apu.triCycle+1)&31;
}
else
apu.triFreqCtr--;
if(apu.noiseFreqCtr == 0)
{
apu.noiseFreqCtr = apu.noiseFreq;
uint8_t cmpBit = apu.noiseMode1 ? (apu.noiseShiftReg>>6)&1 : (apu.noiseShiftReg>>1)&1;
uint8_t cmpRes = (apu.noiseShiftReg&1)^cmpBit;
apu.noiseShiftReg >>= 1;
apu.noiseShiftReg |= cmpRes<<14;
}
else
apu.noiseFreqCtr--;
if(apu.dmcFreqCtr == 0)
{
apu.dmcFreqCtr = apu.dmcFreq;
if(apu.dmcenabled)
{
if(apu.dmcSampleBuf&1)
{
if(apu.dmcVol <= 125)
apu.dmcVol += 2;
}
else if(apu.dmcVol >= 2)
apu.dmcVol -= 2;
apu.dmcSampleBuf>>=1;
}
if(apu.dmcSampleRemain == 0)
{
if(apu.dmcready)
{
apu.dmcSampleBuf = apu.dmcCpuBuf;
apu.dmcenabled = true;
apu.dmcready = false;
}
else
apu.dmcenabled = false;
apu.dmcSampleRemain = 7;
}
else
apu.dmcSampleRemain--;
}
else
apu.dmcFreqCtr--;
if(!apu.dmcready && !cpuInDMC_DMA() && apu.dmcCurLen)
{
cpuDoDMC_DMA(apu.dmcCurAddr);
apu.dmcCurLen--;
}
if(aExp&EXP_VRC7)
{
if(apu.vrc7Clock == vrc7CycleTimer)
{
vrc7AudioCycle();
apu.vrc7Clock = 1;
}
else
apu.vrc7Clock++;
}
if(aExp&EXP_FDS)
fdsAudioMasterUpdate();
if(aExp&EXP_MMC5)
mmc5AudioLenCycle();
if(apu.mode_change)
apuChangeMode();
if(apu.mode5 == false)
{
if(apu.modeCurCtr == 0)
{
if(apu.modePos == 5)
apu.modePos = 0;
else
apu.modePos++;
apu.modeCurCtr = apu.mode4Ctr[apu.modePos]-1;
if(apu.modePos == 3 || apu.modePos == 5)
{
if(apu.enable_irq)
apu.irq = 1;
}
else
{
if(apu.modePos == 1)
apuClockA();
else if(apu.modePos == 4)
{
apuClockA();
if(apu.enable_irq)
{
apu.irq = 1;
//actually set for cpu
interrupt |= APU_IRQ;
}
}
apuClockB();
}
}
else
apu.modeCurCtr--;
}
else
{
if(apu.modeCurCtr == 0)
{
if(apu.modePos == 5)
apu.modePos = 0;
else
apu.modePos++;
apu.modeCurCtr = apu.mode5Ctr[apu.modePos]-1;
if(apu.modePos != 1 && apu.modePos != 5)
{
if(apu.modePos == 0 || apu.modePos == 3)
apuClockA();
apuClockB();
}
}
else
apu.modeCurCtr--;
}
return true;
}
uint32_t apuGetMaxBufSize()
{
return apu.BufSizeBytes;
}
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