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pcm/Normalizer: split the normalization loop

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Performance improvement because the ramp code is now moved out of the
hot code path, allowing the compiler to vectorize.
This commit is contained in:
Max Kellermann 2023-03-13 13:31:46 +01:00
parent d7f2d90fd3
commit c0d38d941a
1 changed files with 10 additions and 6 deletions
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16
src/pcm/Normalizer.cxx
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@ -71,15 +71,19 @@ PcmNormalizer::ProcessS16(int16_t *gcc_restrict dest,
curGain = 1 << 10;
const int delta = (newGain - curGain) / (int)ramp;
for (std::size_t i = 0; i < src.size(); i++) {
for (const auto sample : src.first(ramp)) {
//! Amplify the sample
*dest++ = PcmClamp<format>(src[i] * curGain >> 10);
*dest++ = PcmClamp<format>(sample * curGain >> 10);
//! Adjust the gain
if (i < ramp)
curGain += delta;
else
curGain = newGain;
curGain += delta;
}
curGain = newGain;
for (const auto sample : src.subspan(ramp)) {
//! Amplify the sample
*dest++ = PcmClamp<format>(sample * curGain >> 10);
}
pos = slot;