src/pcm_pack.c

   1 /*
   2  * Copyright (C) 2003-2010 The Music Player Daemon Project
   3  * http://www.musicpd.org
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18  */
  19
  20 #include "pcm_pack.h"
  21
  22 #include <glib.h>
  23
  24 static void
  25 pack_sample(uint8_t *dest, const int32_t *src0, bool reverse_endian)
  26 {
  27         const uint8_t *src = (const uint8_t *)src0;
  28
  29         if ((G_BYTE_ORDER == G_BIG_ENDIAN) != reverse_endian)
  30                 ++src;
  31
  32         *dest++ = *src++;
  33         *dest++ = *src++;
  34         *dest++ = *src++;
  35 }
  36
  37 void
  38 pcm_pack_24(uint8_t *dest, const int32_t *src, unsigned num_samples,
  39             bool reverse_endian)
  40 {
  41         /* duplicate loop to help the compiler's optimizer (constant
  42            parameter to the pack_sample() inline function) */
  43
  44         if (G_LIKELY(!reverse_endian)) {
  45                 while (num_samples-- > 0) {
  46                         pack_sample(dest, src++, false);
  47                         dest += 3;
  48                 }
  49         } else {
  50                 while (num_samples-- > 0) {
  51                         pack_sample(dest, src++, true);
  52                         dest += 3;
  53                 }
  54         }
  55 }
  56
  57 static void
  58 unpack_sample(int32_t *dest0, const uint8_t *src, bool reverse_endian)
  59 {
  60         uint8_t *dest = (uint8_t *)dest0;
  61
  62         if ((G_BYTE_ORDER == G_BIG_ENDIAN) != reverse_endian)
  63                 /* extend the sign bit to the most fourth byte */
  64                 *dest++ = *src & 0x80 ? 0xff : 0x00;
  65
  66         *dest++ = *src++;
  67         *dest++ = *src++;
  68         *dest++ = *src;
  69
  70         if ((G_BYTE_ORDER == G_LITTLE_ENDIAN) != reverse_endian)
  71                 /* extend the sign bit to the most fourth byte */
  72                 *dest++ = *src & 0x80 ? 0xff : 0x00;
  73 }
  74
  75 void
  76 pcm_unpack_24(int32_t *dest, const uint8_t *src, unsigned num_samples,
  77               bool reverse_endian)
  78 {
  79         /* duplicate loop to help the compiler's optimizer (constant
  80            parameter to the unpack_sample() inline function) */
  81
  82         if (G_LIKELY(!reverse_endian)) {
  83                 while (num_samples-- > 0) {
  84                         unpack_sample(dest++, src, false);
  85                         src += 3;
  86                 }
  87         } else {
  88                 while (num_samples-- > 0) {
  89                         unpack_sample(dest++, src, true);
  90                         src += 3;
  91                 }
  92         }
  93 }