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GB Audio: Re-optimize a bit

This commit is contained in:
Jeffrey Pfau 2016-02-09 00:36:07 -08:00
parent 755c1c66af
commit dd2fd9351c
1 changed files with 46 additions and 28 deletions
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36
src/gb/audio.c
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@ -51,10 +51,10 @@ void GBAudioReset(struct GBAudio* audio) {
audio->nextCh2 = 0;
audio->nextCh3 = 0;
audio->nextCh4 = 0;
audio->ch1 = (struct GBAudioChannel1) { .envelope = { .dead = 1 } };
audio->ch2 = (struct GBAudioChannel2) { .envelope = { .dead = 1 } };
audio->ch1 = (struct GBAudioChannel1) { .envelope = { .dead = 2 } };
audio->ch2 = (struct GBAudioChannel2) { .envelope = { .dead = 2 } };
audio->ch3 = (struct GBAudioChannel3) { .bank = 0 };
audio->ch4 = (struct GBAudioChannel4) { .envelope = { .dead = 1 } };
audio->ch4 = (struct GBAudioChannel4) { .envelope = { .dead = 2 } };
audio->eventDiff = 0;
audio->nextFrame = 0;
audio->frame = 0;
@ -443,8 +443,7 @@ int32_t GBAudioProcessEvents(struct GBAudio* audio, int32_t cycles) {
if (audio->playingCh1) {
audio->nextCh1 -= audio->eventDiff;
if (!audio->ch1.envelope.dead) {
if (frame == 7) {
if (!audio->ch1.envelope.dead && frame == 7) {
--audio->ch1.envelope.nextStep;
if (audio->ch1.envelope.nextStep == 0) {
int8_t sample = audio->ch1.control.hi * 0x10 - 0x8;
@ -452,7 +451,6 @@ int32_t GBAudioProcessEvents(struct GBAudio* audio, int32_t cycles) {
audio->ch1.sample = sample * audio->ch1.envelope.currentVolume;
}
}
}
if (audio->ch1.sweepEnable && (frame & 3) == 2) {
--audio->ch1.sweepStep;
@ -461,6 +459,7 @@ int32_t GBAudioProcessEvents(struct GBAudio* audio, int32_t cycles) {
}
}
if (audio->ch1.envelope.dead != 2) {
if (audio->nextCh1 <= 0) {
audio->nextCh1 += _updateChannel1(&audio->ch1);
}
@ -468,6 +467,7 @@ int32_t GBAudioProcessEvents(struct GBAudio* audio, int32_t cycles) {
audio->nextEvent = audio->nextCh1;
}
}
}
if (audio->ch1.control.length && audio->ch1.control.stop && !(frame & 1)) {
--audio->ch1.control.length;
@ -487,6 +487,7 @@ int32_t GBAudioProcessEvents(struct GBAudio* audio, int32_t cycles) {
}
}
if (audio->ch2.envelope.dead != 2) {
if (audio->nextCh2 <= 0) {
audio->nextCh2 += _updateChannel2(&audio->ch2);
}
@ -494,6 +495,7 @@ int32_t GBAudioProcessEvents(struct GBAudio* audio, int32_t cycles) {
audio->nextEvent = audio->nextCh2;
}
}
}
if (audio->ch2.control.length && audio->ch2.control.stop && !(frame & 1)) {
--audio->ch2.control.length;
@ -530,13 +532,21 @@ int32_t GBAudioProcessEvents(struct GBAudio* audio, int32_t cycles) {
}
}
if (audio->ch4.envelope.dead != 2) {
if (audio->nextCh4 <= 0) {
audio->nextCh4 += _updateChannel4(&audio->ch4);
int32_t timing = _updateChannel4(&audio->ch4);
if (audio->nextCh4 < -timing) {
int32_t bound = timing * 16;
// Perform negative modulo to cap to 16 iterations
audio->nextCh4 = bound - (audio->nextCh4 - 1) % bound - 1;
}
audio->nextCh4 += timing;
}
if (audio->nextCh4 < audio->nextEvent) {
audio->nextEvent = audio->nextCh4;
}
}
}
if (audio->ch4.length && audio->ch4.stop && !(frame & 1)) {
--audio->ch4.length;
@ -651,7 +661,15 @@ bool _writeSweep(struct GBAudioEnvelope* envelope, uint8_t value) {
envelope->stepTime = GBAudioRegisterSweepGetStepTime(value);
envelope->direction = GBAudioRegisterSweepGetDirection(value);
envelope->initialVolume = GBAudioRegisterSweepGetInitialVolume(value);
envelope->dead = envelope->stepTime == 0;
if (envelope->stepTime == 0) {
envelope->dead = envelope->currentVolume ? 1 : 2;
} else if (!envelope->direction && !envelope->currentVolume) {
envelope->dead = 2;
} else if (envelope->direction && envelope->currentVolume == 0xF) {
envelope->dead = 1;
} else {
envelope->dead = 0;
}
envelope->nextStep = envelope->stepTime;
return envelope->initialVolume || envelope->direction;
}
@ -685,7 +703,7 @@ static void _updateEnvelope(struct GBAudioEnvelope* envelope) {
envelope->dead = 1;
} else if (envelope->currentVolume <= 0) {
envelope->currentVolume = 0;
envelope->dead = 1;
envelope->dead = 2;
} else {
envelope->nextStep = envelope->stepTime;
}