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pcm/Dop: move the conversion loop to separate function

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This commit is contained in:
Max Kellermann 2019-06-16 12:22:07 +02:00
parent 96ff6b9b8b
commit 9fcd33cc8d
1 changed files with 29 additions and 21 deletions
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50
src/pcm/Dop.cxx
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@ -36,26 +36,15 @@ pcm_two_dsd_to_dop_marker2(uint8_t a, uint8_t b) noexcept
return 0xfffa0000 | (a << 8) | b;
}
ConstBuffer<uint32_t>
pcm_dsd_to_dop(PcmBuffer &buffer, unsigned channels,
ConstBuffer<uint8_t> _src) noexcept
/**
* @param num_dop_quads the number of "quad" bytes per channel in the
* source buffer; each "quad" will be converted to two 24 bit samples
* in the destination buffer, one for each marker
*/
static void
DsdToDop(uint32_t *dest, const uint8_t *src,
size_t num_dop_quads, unsigned channels) noexcept
{
assert(audio_valid_channel_count(channels));
assert(_src.size % channels == 0);
const size_t num_src_samples = _src.size;
const size_t num_src_frames = num_src_samples / channels;
/* this rounds down and discards up to 3 odd frames; not
elegant, but good enough for now */
const size_t num_dop_quads = num_src_frames / 4;
const size_t num_frames = num_dop_quads * 2;
const size_t num_samples = num_frames * channels;
uint32_t *const dest0 = (uint32_t *)buffer.GetT<uint32_t>(num_samples),
*dest = dest0;
auto src = _src.data;
for (size_t i = num_dop_quads; i > 0; --i) {
for (unsigned c = channels; c > 0; --c) {
/* each 24 bit sample has 16 DSD sample bits
@ -87,6 +76,25 @@ pcm_dsd_to_dop(PcmBuffer &buffer, unsigned channels,
have already copied it */
src += channels;
}
return { dest0, num_samples };
}
ConstBuffer<uint32_t>
pcm_dsd_to_dop(PcmBuffer &buffer, unsigned channels,
ConstBuffer<uint8_t> src) noexcept
{
assert(audio_valid_channel_count(channels));
assert(src.size % channels == 0);
const size_t num_src_samples = src.size;
const size_t num_src_frames = num_src_samples / channels;
/* this rounds down and discards up to 3 odd frames; not
elegant, but good enough for now */
const size_t num_dop_quads = num_src_frames / 4;
const size_t num_frames = num_dop_quads * 2;
const size_t num_samples = num_frames * channels;
uint32_t *const dest = (uint32_t *)buffer.GetT<uint32_t>(num_samples);
DsdToDop(dest, src.data, num_dop_quads, channels);
return { dest, num_samples };
}