98 lines
2.7 KiB
C
98 lines
2.7 KiB
C
/*
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* Copyright (C) 2003-2012 The Music Player Daemon Project
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* http://www.musicpd.org
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include "config.h"
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#include "pcm_dsd_usb.h"
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#include "pcm_buffer.h"
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#include "audio_format.h"
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G_GNUC_CONST
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static inline uint32_t
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pcm_two_dsd_to_usb_marker1(uint8_t a, uint8_t b)
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{
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return 0xff050000 | (a << 8) | b;
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}
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G_GNUC_CONST
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static inline uint32_t
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pcm_two_dsd_to_usb_marker2(uint8_t a, uint8_t b)
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{
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return 0xfffa0000 | (a << 8) | b;
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}
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const uint32_t *
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pcm_dsd_to_usb(struct pcm_buffer *buffer, unsigned channels,
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const uint8_t *src, size_t src_size,
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size_t *dest_size_r)
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{
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assert(buffer != NULL);
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assert(audio_valid_channel_count(channels));
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assert(src != NULL);
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assert(src_size > 0);
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assert(src_size % channels == 0);
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const unsigned num_src_samples = src_size;
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const unsigned num_src_frames = num_src_samples / channels;
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/* this rounds down and discards the last odd frame; not
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elegant, but good enough for now */
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const unsigned num_frames = num_src_frames / 2;
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const unsigned num_samples = num_frames * channels;
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const size_t dest_size = num_samples * 4;
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*dest_size_r = dest_size;
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uint32_t *const dest0 = pcm_buffer_get(buffer, dest_size),
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*dest = dest0;
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for (unsigned i = num_frames / 2; i > 0; --i) {
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for (unsigned c = channels; c > 0; --c) {
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/* each 24 bit sample has 16 DSD sample bits
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plus the magic 0x05 marker */
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*dest++ = pcm_two_dsd_to_usb_marker1(src[0], src[channels]);
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/* seek the source pointer to the next
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channel */
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++src;
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}
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/* skip the second byte of each channel, because we
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have already copied it */
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src += channels;
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for (unsigned c = channels; c > 0; --c) {
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/* each 24 bit sample has 16 DSD sample bits
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plus the magic 0xfa marker */
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*dest++ = pcm_two_dsd_to_usb_marker2(src[0], src[channels]);
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/* seek the source pointer to the next
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channel */
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++src;
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}
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/* skip the second byte of each channel, because we
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have already copied it */
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src += channels;
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}
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return dest0;
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}
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