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/*
* Copyright (C) 2003-2014 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "config.h"
#include "PcmDsdUsb.hxx"
#include "PcmBuffer.hxx"
#include "AudioFormat.hxx"
#include "util/ConstBuffer.hxx"
#include <assert.h>
constexpr
static inline uint32_t
pcm_two_dsd_to_usb_marker1(uint8_t a, uint8_t b)
{
return 0xff050000 | (a << 8) | b;
}
constexpr
static inline uint32_t
pcm_two_dsd_to_usb_marker2(uint8_t a, uint8_t b)
{
return 0xfffa0000 | (a << 8) | b;
}
ConstBuffer<uint32_t>
pcm_dsd_to_usb(PcmBuffer &buffer, unsigned channels,
ConstBuffer<uint8_t> _src)
{
assert(audio_valid_channel_count(channels));
assert(!_src.IsNull());
assert(_src.size > 0);
assert(_src.size % channels == 0);
const unsigned num_src_samples = _src.size;
const unsigned num_src_frames = num_src_samples / channels;
/* this rounds down and discards the last odd frame; not
elegant, but good enough for now */
const unsigned num_frames = num_src_frames / 2;
const unsigned num_samples = num_frames * channels;
uint32_t *const dest0 = (uint32_t *)buffer.GetT<uint32_t>(num_samples),
*dest = dest0;
auto src = _src.data;
for (unsigned i = num_frames / 2; i > 0; --i) {
for (unsigned c = channels; c > 0; --c) {
/* each 24 bit sample has 16 DSD sample bits
plus the magic 0x05 marker */
*dest++ = pcm_two_dsd_to_usb_marker1(src[0], src[channels]);
/* seek the source pointer to the next
channel */
++src;
}
/* skip the second byte of each channel, because we
have already copied it */
src += channels;
for (unsigned c = channels; c > 0; --c) {
/* each 24 bit sample has 16 DSD sample bits
plus the magic 0xfa marker */
*dest++ = pcm_two_dsd_to_usb_marker2(src[0], src[channels]);
/* seek the source pointer to the next
channel */
++src;
}
/* skip the second byte of each channel, because we
have already copied it */
src += channels;
}
return { dest0, num_samples };
}
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