apps/codecs/libpcm/adpcm_seek.c

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2010 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 "adpcm_seek.h"
  22 #include "codeclib.h"
  23
  24 /*
  25  * The helper functions in order to seek for the adpcm codec
  26  * which does not include the header each the data block.
  27  */
  28
  29 #define MAX_STORE_COUNT 1000
  30
  31 static struct adpcm_data seek_table[MAX_STORE_COUNT];
  32 static int seek_count;
  33 static int cur_count;
  34 static int max_ratio;
  35 static int cur_ratio;
  36
  37 void init_seek_table(uint32_t max_count)
  38 {
  39     int i = 0;
  40
  41     for ( ; i < MAX_STORE_COUNT; i++)
  42     {
  43         seek_table[i].is_valid = false;
  44     }
  45     seek_count = max_count / MAX_STORE_COUNT + 1;
  46     max_ratio  = max_count / seek_count + 1;
  47     cur_count  = 0;
  48     cur_ratio  = -1;
  49 }
  50
  51 void add_adpcm_data(struct adpcm_data *data)
  52 {
  53     if (--cur_count <= 0)
  54     {
  55         cur_count = seek_count;
  56         if (++cur_ratio >= max_ratio)
  57             cur_ratio = max_ratio - 1;
  58
  59         if (!seek_table[cur_ratio].is_valid)
  60         {
  61             seek_table[cur_ratio].pcmdata[0] = data->pcmdata[0];
  62             seek_table[cur_ratio].pcmdata[1] = data->pcmdata[1];
  63             seek_table[cur_ratio].step[0]    = data->step[0];
  64             seek_table[cur_ratio].step[1]    = data->step[1];
  65             seek_table[cur_ratio].is_valid   = true;
  66         }
  67     }
  68 }
  69
  70 uint32_t seek(uint32_t count, struct adpcm_data *seek_data,
  71               uint8_t *(*read_buffer)(size_t *realsize),
  72               int (*decode)(const uint8_t *inbuf, size_t inbufsize))
  73 {
  74     int new_ratio = count / seek_count;
  75
  76     if (new_ratio >= max_ratio)
  77         new_ratio = max_ratio - 1;
  78
  79     if (!seek_table[new_ratio].is_valid)
  80     {
  81         uint8_t *buffer;
  82         size_t n;
  83
  84         do
  85         {
  86             buffer = read_buffer(&n);
  87             if (n == 0)
  88                 break;
  89             decode(buffer, n);
  90         } while (cur_ratio < new_ratio);
  91     }
  92
  93     seek_data->pcmdata[0] = seek_table[new_ratio].pcmdata[0];
  94     seek_data->pcmdata[1] = seek_table[new_ratio].pcmdata[1];
  95     seek_data->step[0]    = seek_table[new_ratio].step[0];
  96     seek_data->step[1]    = seek_table[new_ratio].step[1];
  97
  98     cur_ratio = new_ratio;
  99     cur_count = seek_count;
 100     return cur_ratio * seek_count;
 101 }