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Add channel 4 envelope, fix audio timing

This commit is contained in:
Jeffrey Pfau 2013-10-18 09:33:07 -07:00
parent a55b4dc87f
commit 093c86c943
2 changed files with 73 additions and 5 deletions
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74
src/gba/gba-audio.c
View File

@ -9,6 +9,7 @@
const unsigned GBA_AUDIO_SAMPLES = 512;
const unsigned GBA_AUDIO_FIFO_SIZE = 8 * sizeof(int32_t);
static void _updateEnvelope(struct GBAAudioEnvelope* envelope);
static int32_t _updateChannel1(struct GBAAudioChannel1* ch);
static int32_t _updateChannel2(struct GBAAudioChannel2* ch);
static int32_t _updateChannel3(struct GBAAudioChannel3* ch);
@ -21,7 +22,10 @@ void GBAAudioInit(struct GBAAudio* audio) {
audio->nextCh2 = 0;
audio->nextCh3 = 0;
audio->nextCh4 = 0;
audio->ch1.envelope.nextStep = INT_MAX;
audio->ch2.envelope.nextStep = INT_MAX;
audio->ch4.sample = 0;
audio->ch4.envelope.nextStep = INT_MAX;
audio->eventDiff = 0;
audio->nextSample = 0;
audio->sampleRate = 0x8000;
@ -48,7 +52,8 @@ void GBAAudioDeinit(struct GBAAudio* audio) {
int32_t GBAAudioProcessEvents(struct GBAAudio* audio, int32_t cycles) {
audio->nextEvent -= cycles;
if (audio->nextEvent <= 0) {
audio->eventDiff += cycles;
while (audio->nextEvent <= 0) {
audio->nextEvent = INT_MAX;
audio->nextCh1 -= audio->eventDiff;
@ -56,6 +61,30 @@ int32_t GBAAudioProcessEvents(struct GBAAudio* audio, int32_t cycles) {
audio->nextCh3 -= audio->eventDiff;
audio->nextCh4 -= audio->eventDiff;
if (audio->ch1.envelope.nextStep != INT_MAX) {
audio->ch1.envelope.nextStep -= audio->eventDiff;
if (audio->ch1.envelope.nextStep <= 0) {
_updateEnvelope(&audio->ch1.envelope);
}
}
if (audio->ch2.envelope.nextStep != INT_MAX) {
audio->ch2.envelope.nextStep -= audio->eventDiff;
if (audio->ch2.envelope.nextStep <= 0) {
_updateEnvelope(&audio->ch2.envelope);
}
}
if (audio->ch4.envelope.nextStep != INT_MAX) {
audio->ch4.envelope.nextStep -= audio->eventDiff;
if (audio->ch4.envelope.nextStep <= 0) {
_updateEnvelope(&audio->ch4.envelope);
if (audio->ch4.envelope.nextStep < audio->nextEvent) {
audio->nextEvent = audio->nextCh4;
}
}
}
if ((audio->ch1Right || audio->ch1Left) && audio->nextCh1 <= 0) {
audio->nextCh1 += _updateChannel1(&audio->ch1);
}
@ -84,7 +113,7 @@ int32_t GBAAudioProcessEvents(struct GBAAudio* audio, int32_t cycles) {
if (audio->nextSample < audio->nextEvent) {
audio->nextEvent = audio->nextSample;
}
audio->eventDiff = audio->nextEvent;
audio->eventDiff = 0;
}
return audio->nextEvent;
}
@ -110,6 +139,11 @@ void GBAAudioWriteSOUND1CNT_LO(struct GBAAudio* audio, uint16_t value) {
void GBAAudioWriteSOUND1CNT_HI(struct GBAAudio* audio, uint16_t value) {
audio->ch1.envelope.packed = value;
if (audio->ch1.envelope.stepTime) {
audio->ch1.envelope.nextStep = 0;
} else {
audio->ch1.envelope.nextStep = INT_MAX;
}
}
void GBAAudioWriteSOUND1CNT_X(struct GBAAudio* audio, uint16_t value) {
@ -118,6 +152,11 @@ void GBAAudioWriteSOUND1CNT_X(struct GBAAudio* audio, uint16_t value) {
void GBAAudioWriteSOUND2CNT_LO(struct GBAAudio* audio, uint16_t value) {
audio->ch2.envelope.packed = value;
if (audio->ch2.envelope.stepTime) {
audio->ch2.envelope.nextStep = 0;
} else {
audio->ch2.envelope.nextStep = INT_MAX;
}
}
void GBAAudioWriteSOUND2CNT_HI(struct GBAAudio* audio, uint16_t value) {
@ -138,11 +177,22 @@ void GBAAudioWriteSOUND3CNT_X(struct GBAAudio* audio, uint16_t value) {
void GBAAudioWriteSOUND4CNT_LO(struct GBAAudio* audio, uint16_t value) {
audio->ch4.envelope.packed = value;
if (audio->ch4.envelope.stepTime) {
audio->ch4.envelope.nextStep = 0;
} else {
audio->ch4.envelope.nextStep = INT_MAX;
}
}
void GBAAudioWriteSOUND4CNT_HI(struct GBAAudio* audio, uint16_t value) {
audio->ch4.control.packed = value;
if (audio->ch4.control.restart) {
audio->ch4.envelope.currentVolume = audio->ch4.envelope.initialVolume;
if (audio->ch4.envelope.stepTime) {
audio->ch4.envelope.nextStep = 0;
} else {
audio->ch4.envelope.nextStep = INT_MAX;
}
if (audio->ch4.control.power) {
audio->ch4.lfsr = 0x40;
} else {
@ -205,6 +255,23 @@ void GBAAudioSampleFIFO(struct GBAAudio* audio, int fifoId) {
CircleBufferRead8(&channel->fifo, &channel->sample);
}
static void _updateEnvelope(struct GBAAudioEnvelope* envelope) {
if (envelope->direction) {
++envelope->currentVolume;
} else {
--envelope->currentVolume;
}
if (envelope->currentVolume >= 15) {
envelope->currentVolume = 15;
envelope->nextStep = INT_MAX;
} else if (envelope->currentVolume <= 0) {
envelope->currentVolume = 0;
envelope->nextStep = INT_MAX;
} else {
envelope->nextStep += envelope->stepTime * (GBA_ARM7TDMI_FREQUENCY >> 6);
}
}
static int32_t _updateChannel1(struct GBAAudioChannel1* ch) {
return INT_MAX / 4;
}
@ -219,7 +286,8 @@ static int32_t _updateChannel3(struct GBAAudioChannel3* ch) {
static int32_t _updateChannel4(struct GBAAudioChannel4* ch) {
int lsb = ch->lfsr & 1;
ch->sample = lsb * 0xFF - 0x80;
ch->sample = lsb * 0x10 - 0x8;
ch->sample *= ch->envelope.currentVolume;
ch->lfsr >>= 1;
ch->lfsr ^= (lsb * 0x60) << (ch->control.power ? 0 : 8);
int timing = ch->control.ratio ? 2 * ch->control.ratio : 1;

4
src/platform/sdl/sdl-audio.c
View File

@ -37,12 +37,12 @@ void GBASDLDeinitAudio(struct GBASDLAudio* context) {
static void _pulldownResample(struct GBASDLAudio* context) {
int32_t value;
if (CircleBufferRead32(&context->audio->left, &value)) {
context->currentSample.left = value << 7;
context->currentSample.left = value << 5;
} else {
context->currentSample.left = 0;
}
if (CircleBufferRead32(&context->audio->right, &value)) {
context->currentSample.right = value << 7;
context->currentSample.right = value << 5;
} else {
context->currentSample.right = 0;
}