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Merge pull request #1957 from unknownbrackets/perf

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Small performance improvement in VAG decoding
This commit is contained in:
Henrik Rydgård committed 2013-05-28 00:39:43 -07:00
2 parents d6135ed452 1107571af5
commit d76d05b338
2 files changed
+29 -16
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Core/HW/SasAudio.cpp
+28 -16
View File
@@ -22,12 +22,26 @@
// #define AUDIO_TO_FILE
static const s8 f[5][2] =
{ { 0, 0 },
{ 60, 0 },
{ 115, -52 },
{ 98, -55 },
{ 122, -60 } };
static const s8 f[16][2] = {
{ 0, 0 },
{ 60, 0 },
{ 115, -52 },
{ 98, -55 },
{ 122, -60 },
// Padding to prevent overflow.
{ 0, 0 },
{ 0, 0 },
{ 0, 0 },
{ 0, 0 },
{ 0, 0 },
{ 0, 0 },
{ 0, 0 },
{ 0, 0 },
{ 0, 0 },
{ 0, 0 },
{ 0, 0 },
};
void VagDecoder::Start(u32 data, int vagSize, bool loopEnabled) {
loopEnabled_ = loopEnabled;
@@ -47,9 +61,6 @@ void VagDecoder::DecodeBlock(u8 *&readp) {
int predict_nr = *readp++;
int shift_factor = predict_nr & 0xf;
predict_nr >>= 4;
if (predict_nr >= sizeof(f) / sizeof(f[0])) {
predict_nr = 0;
}
int flags = *readp++;
if (flags == 7) {
end_ = true;
@@ -66,14 +77,9 @@ void VagDecoder::DecodeBlock(u8 *&readp) {
for (int i = 0; i < 28; i += 2) {
int d = *readp++;
int s = (short)((d & 0xf) << 12);
samples[i] = s >> shift_factor;
DecodeSample(i, s >> shift_factor, predict_nr);
s = (short)((d & 0xf0) << 8);
samples[i + 1] = s >> shift_factor;
}
for (int i = 0; i < 28; i++) {
samples[i] = (int) (samples[i] + ((s_1 * f[predict_nr][0] + s_2 * f[predict_nr][1]) >> 6));
s_2 = s_1;
s_1 = samples[i];
DecodeSample(i + 1, s >> shift_factor, predict_nr);
}
curSample = 0;
curBlock_++;
@@ -82,6 +88,12 @@ void VagDecoder::DecodeBlock(u8 *&readp) {
}
}
inline void VagDecoder::DecodeSample(int i, int sample, int predict_nr) {
samples[i] = (int) (sample + ((s_1 * f[predict_nr][0] + s_2 * f[predict_nr][1]) >> 6));
s_2 = s_1;
s_1 = samples[i];
}
void VagDecoder::GetSamples(s16 *outSamples, int numSamples) {
if (end_) {
memset(outSamples, 0, numSamples * sizeof(s16));
Core/HW/SasAudio.h
+1
View File
@@ -86,6 +86,7 @@ public:
void DoState(PointerWrap &p);
private:
void DecodeSample(int i, int sample, int predict_nr);
int samples[28];
int curSample;