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Refactor pow() usage

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Refactor pow() usage:
- use base of 0.5^k instead of 1/(2^k)
- skip pow if using INTEGER_SAMPLES
This commit is contained in:
Olli 2025-02-23 12:54:41 +02:00
parent e31e1715fb
commit 5dede763ff
4 changed files with 13 additions and 20 deletions
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2
source/SoundTouch/BPMDetect.cpp
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@ -301,7 +301,7 @@ void BPMDetect::updateXCorr(int process_samples)
pBuffer = buffer->ptrBegin();
// calculate decay factor for xcorr filtering
float xcorr_decay = (float)pow(0.5, 1.0 / (XCORR_DECAY_TIME_CONSTANT * TARGET_SRATE / process_samples));
float xcorr_decay = (float)pow(0.5, process_samples / (XCORR_DECAY_TIME_CONSTANT * TARGET_SRATE));
// prescale pbuffer
float tmp[XCORR_UPDATE_SEQUENCE];

17
source/SoundTouch/FIRFilter.cpp
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@ -56,7 +56,6 @@ using namespace soundtouch;
FIRFilter::FIRFilter()
{
resultDivFactor = 0;
resultDivider = 0;
length = 0;
lengthDiv8 = 0;
filterCoeffs = nullptr;
@ -207,24 +206,24 @@ void FIRFilter::setCoefficients(const SAMPLETYPE *coeffs, uint newLength, uint u
assert(newLength > 0);
if (newLength % 8) ST_THROW_RT_ERROR("FIR filter length not divisible by 8");
#ifdef SOUNDTOUCH_FLOAT_SAMPLES
// scale coefficients already here if using floating samples
double scale = 1.0 / resultDivider;
#else
short scale = 1;
#endif
lengthDiv8 = newLength / 8;
length = lengthDiv8 * 8;
assert(length == newLength);
resultDivFactor = uResultDivFactor;
resultDivider = (SAMPLETYPE)::pow(2.0, (int)resultDivFactor);
delete[] filterCoeffs;
filterCoeffs = new SAMPLETYPE[length];
delete[] filterCoeffsStereo;
filterCoeffsStereo = new SAMPLETYPE[length*2];
#ifdef SOUNDTOUCH_FLOAT_SAMPLES
// scale coefficients already here if using floating samples
const double scale = ::pow(0.5, (int)resultDivFactor);;
#else
const short scale = 1;
#endif
for (uint i = 0; i < length; i ++)
{
filterCoeffs[i] = (SAMPLETYPE)(coeffs[i] * scale);

3
source/SoundTouch/FIRFilter.h
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@ -52,9 +52,6 @@ protected:
// Result divider factor in 2^k format
uint resultDivFactor;
// Result divider value.
SAMPLETYPE resultDivider;
// Memory for filter coefficients
SAMPLETYPE *filterCoeffs;
SAMPLETYPE *filterCoeffsStereo;

11
source/SoundTouch/sse_optimized.cpp
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@ -211,9 +211,6 @@ FIRFilterSSE::~FIRFilterSSE()
// (overloaded) Calculates filter coefficients for SSE routine
void FIRFilterSSE::setCoefficients(const float *coeffs, uint newLength, uint uResultDivFactor)
{
uint i;
float fDivider;
FIRFilter::setCoefficients(coeffs, newLength, uResultDivFactor);
// Scale the filter coefficients so that it won't be necessary to scale the filtering result
@ -223,13 +220,13 @@ void FIRFilterSSE::setCoefficients(const float *coeffs, uint newLength, uint uRe
filterCoeffsUnalign = new float[2 * newLength + 4];
filterCoeffsAlign = (float *)SOUNDTOUCH_ALIGN_POINTER_16(filterCoeffsUnalign);
fDivider = (float)resultDivider;
const float scale = ::pow(0.5, (int)resultDivFactor);
// rearrange the filter coefficients for mmx routines
for (i = 0; i < newLength; i ++)
// rearrange the filter coefficients for sse routines
for (auto i = 0U; i < newLength; i ++)
{
filterCoeffsAlign[2 * i + 0] =
filterCoeffsAlign[2 * i + 1] = coeffs[i + 0] / fDivider;
filterCoeffsAlign[2 * i + 1] = coeffs[i] * scale;
}
}