NESEmulator save fixes

2025-12-08 18:24:55 +00:00 · 2018-02-02 14:35:19 -10:00
parent c42fe06233
commit 15e5b4bbb8
11 changed files with 414 additions and 66 deletions
--- a/NESEmulator/apu.c
+++ b/NESEmulator/apu.c
@@ -0,0 +1,172 @@
+#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(curBufPos == apuBufSize)
+    {
+        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;
+        }
+        curBufPos = 0;
+    }
+    uint8_t p1Out = lastP1Out, p2Out = lastP2Out,
+        triOut = lastTriOut, noiseOut = lastNoiseOut;
+    if(p1LengthCtr && (APU_IO_Reg[0x15] & P1_ENABLE))
+    {
+        if(p1seq[p1Cycle] && !p1Sweep.mute && freq1 >= 8 && freq1 < 0x7FF)
+            lastP1Out = p1Out = (p1Env.constant ? p1Env.vol : p1Env.decay);
+        else
+            p1Out = 0;
+    }
+    if(p2LengthCtr && (APU_IO_Reg[0x15] & P2_ENABLE))
+    {
+        if(p2seq[p2Cycle] && !p2Sweep.mute && freq2 >= 8 && freq2 < 0x7FF)
+            lastP2Out = p2Out = (p2Env.constant ? p2Env.vol : p2Env.decay);
+        else
+            p2Out = 0;
+    }
+    if(triLengthCtr && triCurLinearCtr && (APU_IO_Reg[0x15] & TRI_ENABLE))
+    {
+        if(triSeq[triCycle] && triFreq >= 2)
+            lastTriOut = triOut = triSeq[triCycle];
+        else
+            triOut = 0;
+    }
+    if(noiseLengthCtr && (APU_IO_Reg[0x15] & NOISE_ENABLE))
+    {
+        if((noiseShiftReg&1) == 0 && noiseFreq > 0)
+            lastNoiseOut = noiseOut = (noiseEnv.constant ? noiseEnv.vol : noiseEnv.decay);
+        else
+            noiseOut = 0;
+    }
+#if AUDIO_FLOAT
+    float curIn = pulseLookupTbl[p1Out + p2Out] + tndLookupTbl[(3*triOut) + (2*noiseOut) + dmcVol];
+    //very rough still
+    if(vrc6enabled)
+    {
+        vrc6AudioCycle();
+        curIn += ((float)vrc6Out)*0.008f;
+        curIn *= 0.6667f;
+    }
+    if(fdsEnabled)
+    {
+        fdsAudioCycle();
+        curIn += ((float)fdsOut)*0.00617f;
+        curIn *= 0.75f;
+    }
+    if(mmc5enabled)
+    {
+        mmc5AudioCycle();
+        curIn += pulseLookupTbl[mmc5Out]+(mmc5pcm*0.002f);
+        curIn *= 0.75f;
+    }
+    if(vrc7enabled)
+    {
+        curIn += (((float)(vrc7Out>>7))/32768.f);
+        curIn *= 0.75f;
+    }
+    if(n163enabled)
+    {
+        curIn += ((float)n163Out)*0.0008f;
+        curIn *= 0.6667f;
+    }
+    if(s5Benabled)
+    {
+        s5BAudioCycle();
+        curIn += ((float)s5BOut)/32768.f;
+        curIn *= 0.6667f;
+    }
+    //amplify input
+    curIn *= 3.0f;
+    float curLPout = lastLPOut+(lpVal*(curIn-lastLPOut));
+    float curHPOut = hpVal*(lastHPOut+lastLPOut-curLPout);
+    //set output
+    apuOutBuf[curBufPos] = curHPOut;
+    lastLPOut = curLPout;
+    lastHPOut = curHPOut;
+#else
+    int32_t curIn = pulseLookupTbl[p1Out + p2Out] + tndLookupTbl[(3*triOut) + (2*noiseOut) + dmcVol];
+    //very rough still
+    if(vrc6enabled)
+    {
+        vrc6AudioCycle();
+        curIn += ((int32_t)vrc6Out)*262;
+        curIn <<= 1; curIn /= 3;
+    }
+    if(fdsEnabled)
+    {
+        fdsAudioCycle();
+        curIn += ((int32_t)fdsOut)*202;
+        curIn *= 3; curIn >>= 2;
+    }
+    if(mmc5enabled)
+    {
+        mmc5AudioCycle();
+        curIn += pulseLookupTbl[mmc5Out]+(mmc5pcm<<6);
+        curIn *= 3; curIn >>= 2;
+    }
+    if(vrc7enabled)
+    {
+        curIn += vrc7Out>>7;
+        curIn *= 3; curIn >>= 2;
+    }
+    if(n163enabled)
+    {
+        curIn += n163Out*26;
+        curIn <<= 1; curIn /= 3;
+    }
+    if(s5Benabled)
+    {
+        s5BAudioCycle();
+        curIn += s5BOut;
+        curIn <<= 1; curIn /= 3;
+    }
+    //amplify input
+    curIn *= 3;
+    int32_t curOut;
+    //gen output
+    curOut = lastLPOut+((lpVal*(curIn-lastLPOut))>>15); //Set Lowpass Output
+    curIn = (lastHPOut+lastLPOut-curOut); //Set Highpass Input
+    curIn += (curIn>>31)&1; //Add Sign Bit for proper Downshift later
+    lastLPOut = curOut; //Save Lowpass Output
+    curOut = (hpVal*curIn)>>15; //Set Highpass Output
+    lastHPOut = curOut; //Save Highpass Output
+    //Save Clipped Highpass Output
+    apuOutBuf[curBufPos] = (curOut > 32767)?(32767):((curOut < -32768)?(-32768):curOut);
+#endif
+    apuOutBuf[curBufPos+1] = apuOutBuf[curBufPos];
+    curBufPos+=2;
+    return true;
+}