apps/codecs/libpcm/ieee_float.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2009 Yoshihisa Uchida
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version 2
  15  * of the License, or (at your option) any later version.
  16  *
  17  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  18  * KIND, either express or implied.
  19  *
  20  ****************************************************************************/
  21 #include "codeclib.h"
  22 #include "pcm_common.h"
  23 #include "support_formats.h"
  24
  25 /*
  26  * IEEE float
  27  */
  28
  29 static struct pcm_format *fmt;
  30
  31 static bool set_format(struct pcm_format *format)
  32 {
  33     fmt = format;
  34
  35     if (fmt->bitspersample != 32 && fmt->bitspersample != 64)
  36     {
  37         DEBUGF("CODEC_ERROR: ieee float must be 32 or 64 bitspersample: %d\n",
  38                              fmt->bitspersample);
  39         return false;
  40     }
  41
  42     fmt->bytespersample = fmt->bitspersample >> 3;
  43     fmt->samplesperblock = fmt->blockalign / (fmt->bytespersample * fmt->channels);
  44
  45     /* chunksize = about 1/50[sec] data */
  46     fmt->chunksize = (ci->id3->frequency / (50 * fmt->samplesperblock))
  47                                          * fmt->blockalign;
  48
  49     return true;
  50 }
  51
  52 static struct pcm_pos *get_seek_pos(long seek_time,
  53                                     uint8_t *(*read_buffer)(size_t *realsize))
  54 {
  55     static struct pcm_pos newpos;
  56     uint32_t newblock = ((uint64_t)seek_time * ci->id3->frequency)
  57                                              / (1000LL * fmt->samplesperblock);
  58
  59     (void)read_buffer;
  60     newpos.pos     = newblock * fmt->blockalign;
  61     newpos.samples = newblock * fmt->samplesperblock;
  62     return &newpos;
  63 }
  64
  65 static int decode(const uint8_t *inbuf, size_t inbufsize,
  66                   int32_t *outbuf, int *outbufsize)
  67 {
  68     uint32_t i;
  69     int32_t pcm;
  70     int16_t exp;
  71     int sgn;
  72
  73     if (fmt->bitspersample == 32)
  74     {
  75         for (i = 0; i < inbufsize; i += 4)
  76         {
  77             if (fmt->is_little_endian)
  78             {
  79                 pcm = (inbuf[0]<<5)|(inbuf[1]<<13)|((inbuf[2]|0x80)<<21);
  80                 exp = ((inbuf[2]>>7)|((inbuf[3]&0x7f)<<1)) - 127;
  81                 sgn = inbuf[3] & 0x80;
  82             }
  83             else
  84             {
  85                 pcm = (inbuf[3]<<5)|(inbuf[2]<<13)|((inbuf[1]|0x80)<<21);
  86                 exp = ((inbuf[1]>>7)|((inbuf[0]&0x7f)<<1)) - 127;
  87                 sgn = inbuf[0] & 0x80;
  88             }
  89             if (exp > -29 && exp < 0)
  90             {
  91                 pcm >>= -exp;
  92                 if (sgn)
  93                     pcm = -pcm;
  94             }
  95             else if (exp < -28)
  96                 pcm = 0;
  97             else
  98                 pcm = (sgn)?-(1<<28):(1<<28)-1;
  99
 100             outbuf[i/4] = pcm;
 101             inbuf += 4;
 102         }
 103         *outbufsize = inbufsize >> 2;
 104     }
 105     else
 106     {
 107         for (i = 0; i < inbufsize; i += 8)
 108         {
 109             if (fmt->is_little_endian)
 110             {
 111                 pcm = inbuf[3]|(inbuf[4]<<8)|(inbuf[5]<<16)|(((inbuf[6]&0x0f)|0x10)<<24);
 112                 exp = (((inbuf[6]&0xf0)>>4)|((inbuf[7]&0x7f)<<4)) - 1023;
 113                 sgn = inbuf[7] & 0x80;
 114             }
 115             else
 116             {
 117                 pcm = inbuf[4]|(inbuf[3]<<8)|(inbuf[2]<<16)|(((inbuf[1]&0x0f)|0x10)<<24);
 118                 exp = (((inbuf[1]&0xf0)>>4)|((inbuf[0]&0x7f)<<4)) - 1023;
 119                 sgn = inbuf[0] & 0x80;
 120             }
 121             if (exp > -29 && exp < 0)
 122             {
 123                 pcm >>= -exp;
 124                 if (sgn)
 125                     pcm = -pcm;
 126             }
 127             else if (exp < -28)
 128                 pcm = 0;
 129             else
 130                 pcm = (sgn)?-(1<<28):(1<<28)-1;
 131
 132             outbuf[i/8] = pcm;
 133             inbuf += 8;
 134         }
 135         *outbufsize = inbufsize >> 3;
 136     }
 137
 138     if (fmt->channels == 2)
 139         *outbufsize >>= 1;
 140
 141     return CODEC_OK;
 142 }
 143
 144 static const struct pcm_codec codec = {
 145                                           set_format,
 146                                           get_seek_pos,
 147                                           decode,
 148                                       };
 149
 150 const struct pcm_codec *get_ieee_float_codec(void)
 151 {
 152     return &codec;
 153 }