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/***************************************************************************
* __________ __ ___.
* Open \______ \ ____ ____ | | _\_ |__ _______ ___
* Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
* Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
* Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
* \/ \/ \/ \/ \/
* $Id$
*
* Copyright (C) 2010 Yoshihisa Uchida
*
* 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 software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
****************************************************************************/
#include "codeclib.h"
#include "pcm_common.h"
#include "ima_adpcm_common.h"
/*
* Functions for IMA ADPCM and IMA ADPCM series format
*
* References
* [1] The IMA Digital Audio Focus and Technical Working Groups,
* Recommended Practices for Enhancing Digital Audio Compatibility
* in Multimedia Systems Revision 3.00, 1992
* [2] Microsoft Corporation, New Multimedia Data Types and Data Techniques,
* Revision:3.0, 1994
* [3] ffmpeg source code, libavcodec/adpcm.c
*/
/* step table */
static const uint16_t step_table[89] ICONST_ATTR = {
7, 8, 9, 10, 11, 12, 13, 14,
16, 17, 19, 21, 23, 25, 28, 31,
34, 37, 41, 45, 50, 55, 60, 66,
73, 80, 88, 97, 107, 118, 130, 143,
157, 173, 190, 209, 230, 253, 279, 307,
337, 371, 408, 449, 494, 544, 598, 658,
724, 796, 876, 963, 1060, 1166, 1282, 1411,
1552, 1707, 1878, 2066, 2272, 2499, 2749, 3024,
3327, 3660, 4026, 4428, 4871, 5358, 5894, 6484,
7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899,
15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794,
32767
};
/* step index tables */
static const int index_tables[4][16] ICONST_ATTR = {
/* adpcm data size is 2 */
{ -1, 2 },
/* adpcm data size is 3 */
{ -1, -1, 1, 2 },
/* adpcm data size is 4 */
{ -1, -1, -1, -1, 2, 4, 6, 8 },
/* adpcm data size is 5 */
{ -1, -1, -1, -1, -1, -1, -1, -1, 1, 2, 4, 6, 8, 10, 13, 16 },
};
static int32_t pcmdata[2];
static int8_t indices[2];
static int adpcm_data_size;
static uint8_t step_mask;
static uint8_t step_sign_mask;
static int8_t step_shift;
static const int *use_index_table;
/*
* Before first decoding, this function must be executed.
*
* params
* bit: adpcm data size (2 <= bit <= 5).
* index_table: step index table
* if index_table is null, then step index table
* is used index_tables[bit-2].
*/
void init_ima_adpcm_decoder(int bit, const int *index_table)
{
adpcm_data_size = bit;
step_sign_mask = 1 << (adpcm_data_size - 1);
step_mask = step_sign_mask - 1;
step_shift = adpcm_data_size - 2;
if (index_table)
use_index_table = index_table;
else
use_index_table = index_tables[adpcm_data_size - 2];
}
/*
* When starting decoding for each block, this function must be executed.
*
* params
* channels: channel count
* init_pcmdata: array of init pcmdata
* init_index: array of init step indexes
*/
void set_decode_parameters(int channels, int32_t *init_pcmdata, int8_t *init_index)
{
int ch;
for (ch = 0; ch < channels; ch++)
{
pcmdata[ch] = init_pcmdata[ch];
indices[ch] = init_index[ch];
}
}
/*
* convert ADPCM to PCM for any adpcm data size.
*
* If adpcm_data_size is 4, then you use create_pcmdata_size4()
* in place of this functon.
*/
int16_t create_pcmdata(int ch, uint8_t nibble)
{
int check_bit = 1 << step_shift;
int32_t delta = 0;
int16_t step = step_table[indices[ch]];
do {
if (nibble & check_bit)
delta += step;
step >>= 1;
check_bit >>= 1;
} while (check_bit);
delta += step;
if (nibble & step_sign_mask)
pcmdata[ch] -= delta;
else
pcmdata[ch] += delta;
indices[ch] += use_index_table[nibble & step_mask];
CLIP(indices[ch], 0, 88);
CLIP(pcmdata[ch], -32768, 32767);
return (int16_t)pcmdata[ch];
}
/*
* convert ADPCM to PCM when adpcm data size is 4.
*/
int16_t create_pcmdata_size4(int ch, uint8_t nibble)
{
int32_t delta;
int16_t step = step_table[indices[ch]];
delta = (step >> 3);
if (nibble & 4) delta += step;
if (nibble & 2) delta += (step >> 1);
if (nibble & 1) delta += (step >> 2);
if (nibble & 0x08)
pcmdata[ch] -= delta;
else
pcmdata[ch] += delta;
indices[ch] += use_index_table[nibble & 0x07];
CLIP(indices[ch], 0, 88);
CLIP(pcmdata[ch], -32768, 32767);
return (int16_t)pcmdata[ch];
}
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