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pcm/Dsd2Pcm: add optimized stereo version 

This code path is 2% faster.
This commit is contained in:
Max Kellermann 2020-01-14 23:38:46 +01:00
parent ee46150329
commit 235b6980b8
2 changed files with 30 additions and 0 deletions
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18
src/pcm/Dsd2Pcm.cxx
View File

@ -213,9 +213,27 @@ MultiDsd2Pcm::Translate(unsigned channels, size_t n_frames,
{
assert(channels <= per_channel.max_size());
if (channels == 2) {
TranslateStereo(n_frames, src, dest);
return;
}
for (unsigned i = 0; i < channels; ++i) {
per_channel[i].Translate(n_frames,
src++, channels,
dest++, channels);
}
}
inline void
MultiDsd2Pcm::TranslateStereo(size_t n_frames,
const uint8_t *src, float *dest) noexcept
{
size_t ffp = fifopos;
while (n_frames-- > 0) {
*dest++ = per_channel[0].TranslateSample(ffp, *src++);
*dest++ = per_channel[1].TranslateSample(ffp, *src++);
ffp = (ffp + 1) & Dsd2Pcm::FIFOMASK;
}
fifopos = ffp;
}

12
src/pcm/Dsd2Pcm.hxx
View File

@ -42,6 +42,8 @@ or implied, of Sebastian Gesemann.
* A "dsd2pcm engine" for one channel.
*/
class Dsd2Pcm {
friend class MultiDsd2Pcm;
public:
/* must be a power of two */
static constexpr size_t FIFOSIZE = 16;
@ -86,14 +88,24 @@ private:
class MultiDsd2Pcm {
std::array<Dsd2Pcm, MAX_CHANNELS> per_channel;
size_t fifopos = 0;
public:
void Reset() noexcept {
for (auto &i : per_channel)
i.Reset();
fifopos = 0;
}
void Translate(unsigned channels, size_t n_frames,
const uint8_t *src, float *dest) noexcept;
private:
/**
* Optimized implementation for the common case.
*/
void TranslateStereo(size_t n_frames,
const uint8_t *src, float *dest) noexcept;
};
#endif /* include guard DSD2PCM_H_INCLUDED */