/*
 * DK3 ADPCM decoder
 *
 * "This format number was used by Duck Corp. but not officially
 * registered with Microsoft"
 *
 * This file is responsible for decoding audio data encoded with
 * Duck Corp's DK3 ADPCM algorithm. Details about the data format
 * can be found here:
 *   http://www.pcisys.net/~melanson/codecs/
 *
 * Copyright (c) 2002 Mike Melanson
 *
 * This file is part of MPlayer.
 *
 * MPlayer 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.
 *
 * MPlayer is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with MPlayer; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#include <libavutil/intreadwrite.h>

#include "config.h"
#include "ad_internal.h"

static const ad_info_t info =
{
	"Duck Corp. DK3 ADPCM decoder",
	"dk3adpcm",
	"Nick Kurshev",
	"Mike Melanson",
	""
};

LIBAD_EXTERN(dk3adpcm)

#define DK3_ADPCM_PREAMBLE_SIZE 16

// useful macros
// clamp a number between 0 and 88
#define CLAMP_0_TO_88(x)  if (x < 0) x = 0; else if (x > 88) x = 88;
// clamp a number within a signed 16-bit range
#define CLAMP_S16(x)  if (x < -32768) x = -32768; \
  else if (x > 32767) x = 32767;
// clamp a number above 16
#define CLAMP_ABOVE_16(x)  if (x < 16) x = 16;
// sign extend a 16-bit value
#define SE_16BIT(x)  if (x & 0x8000) x -= 0x10000;
// sign extend a 4-bit value
#define SE_4BIT(x)  if (x & 0x8) x -= 0x10;

// pertinent tables
static int adpcm_step[89] =
{
  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
};

static int adpcm_index[16] =
{
  -1, -1, -1, -1, 2, 4, 6, 8,
  -1, -1, -1, -1, 2, 4, 6, 8
};

static int preinit(sh_audio_t *sh_audio)
{
  sh_audio->audio_out_minsize = sh_audio->wf->nBlockAlign * 6;
  sh_audio->ds->ss_div =
    (sh_audio->wf->nBlockAlign - DK3_ADPCM_PREAMBLE_SIZE) * 8 / 3;
  sh_audio->audio_in_minsize=
  sh_audio->ds->ss_mul = sh_audio->wf->nBlockAlign;
  return 1;
}

static int init(sh_audio_t *sh_audio)
{
  sh_audio->channels = sh_audio->wf->nChannels;
  sh_audio->samplerate = sh_audio->wf->nSamplesPerSec;
  sh_audio->i_bps =
    (sh_audio->ds->ss_mul * sh_audio->samplerate) / sh_audio->ds->ss_div;
  sh_audio->samplesize=2;
  return 1;
}

static void uninit(sh_audio_t *sh_audio)
{
}

static int control(sh_audio_t *sh_audio,int cmd,void* arg, ...)
{
  if(cmd==ADCTRL_SKIP_FRAME){
    demux_read_data(sh_audio->ds, sh_audio->a_in_buffer,sh_audio->ds->ss_mul);
    return CONTROL_TRUE;
  }
  return CONTROL_UNKNOWN;
}

#define DK3_GET_NEXT_NIBBLE() \
    if (decode_top_nibble_next) \
    { \
      nibble = (last_byte >> 4) & 0x0F; \
      decode_top_nibble_next = 0; \
    } \
    else \
    { \
      last_byte = input[in_ptr++]; \
      nibble = last_byte & 0x0F; \
      decode_top_nibble_next = 1; \
    }

// note: This decoder assumes the format 0x62 data always comes in
// stereo flavor
static int dk3_adpcm_decode_block(unsigned short *output, unsigned char *input,
  int block_size)
{
  int sum_pred;
  int diff_pred;
  int sum_index;
  int diff_index;
  int diff_channel;
  int in_ptr = 0x10;
  int out_ptr = 0;

  unsigned char last_byte = 0;
  unsigned char nibble;
  int decode_top_nibble_next = 0;

  // ADPCM work variables
  int sign;
  int delta;
  int step;
  int diff;

  sum_pred = AV_RL16(&input[10]);
  diff_pred = AV_RL16(&input[12]);
  SE_16BIT(sum_pred);
  SE_16BIT(diff_pred);
  diff_channel = diff_pred;
  sum_index = input[14];
  diff_index = input[15];

  while (in_ptr < block_size - !decode_top_nibble_next)
//  while (in_ptr < 2048)
  {
    // process the first predictor of the sum channel
    DK3_GET_NEXT_NIBBLE();

    step = adpcm_step[sum_index];

    sign = nibble & 8;
    delta = nibble & 7;

    diff = step >> 3;
    if (delta & 4) diff += step;
    if (delta & 2) diff += step >> 1;
    if (delta & 1) diff += step >> 2;

    if (sign)
      sum_pred -= diff;
    else
      sum_pred += diff;

    CLAMP_S16(sum_pred);

    sum_index += adpcm_index[nibble];
    CLAMP_0_TO_88(sum_index);

    // process the diff channel predictor
    DK3_GET_NEXT_NIBBLE();

    step = adpcm_step[diff_index];

    sign = nibble & 8;
    delta = nibble & 7;

    diff = step >> 3;
    if (delta & 4) diff += step;
    if (delta & 2) diff += step >> 1;
    if (delta & 1) diff += step >> 2;

    if (sign)
      diff_pred -= diff;
    else
      diff_pred += diff;

    CLAMP_S16(diff_pred);

    diff_index += adpcm_index[nibble];
    CLAMP_0_TO_88(diff_index);

    // output the first pair of stereo PCM samples
    diff_channel = (diff_channel + diff_pred) / 2;
    output[out_ptr++] = sum_pred + diff_channel;
    output[out_ptr++] = sum_pred - diff_channel;

    // process the second predictor of the sum channel
    DK3_GET_NEXT_NIBBLE();

    step = adpcm_step[sum_index];

    sign = nibble & 8;
    delta = nibble & 7;

    diff = step >> 3;
    if (delta & 4) diff += step;
    if (delta & 2) diff += step >> 1;
    if (delta & 1) diff += step >> 2;

    if (sign)
      sum_pred -= diff;
    else
      sum_pred += diff;

    CLAMP_S16(sum_pred);

    sum_index += adpcm_index[nibble];
    CLAMP_0_TO_88(sum_index);

    // output the second pair of stereo PCM samples
    output[out_ptr++] = sum_pred + diff_channel;
    output[out_ptr++] = sum_pred - diff_channel;
  }

  return out_ptr;
}

static int decode_audio(sh_audio_t *sh_audio,unsigned char *buf,int minlen,int maxlen)
{
  if (demux_read_data(sh_audio->ds, sh_audio->a_in_buffer,
    sh_audio->ds->ss_mul) !=
    sh_audio->ds->ss_mul)
      return -1; /* EOF */

  if (maxlen < 2 * 4 * sh_audio->wf->nBlockAlign * 2 / 3) {
    mp_msg(MSGT_DECAUDIO, MSGL_V, "dk3adpcm: maxlen too small in decode_audio\n");
    return -1;
  }
  return 2 * dk3_adpcm_decode_block(
    (unsigned short*)buf, sh_audio->a_in_buffer,
    sh_audio->ds->ss_mul);
}
