decoder/srce/decoder-private.c

/******************************************************************************
 *
 *  Copyright 2014 The Android Open Source Project
 *  Copyright 2003 - 2004 Open Interface North America, Inc. All rights
 *                        reserved.
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at:
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 ******************************************************************************/

/*******************************************************************************
  $Revision: #1 $
 ******************************************************************************/

/**
@file
This file drives SBC decoding.

@ingroup codec_internal
*/

/**
@addtogroup codec_internal
@{
*/

#include <stdio.h>
#include "oi_bitstream.h"
#include "oi_codec_sbc_private.h"

OI_CHAR* const OI_Codec_Copyright =
    "Copyright 2002-2007 Open Interface North America, Inc. All rights "
    "reserved";

INLINE OI_STATUS internal_DecoderReset(OI_CODEC_SBC_DECODER_CONTEXT* context,
                                       uint32_t* decoderData,
                                       uint32_t decoderDataBytes,
                                       OI_BYTE maxChannels, OI_BYTE pcmStride,
                                       OI_BOOL enhanced) {
  OI_UINT i;
  OI_STATUS status;

  for (i = 0; i < sizeof(*context); i++) {
    ((char*)context)[i] = 0;
  }

#ifdef SBC_ENHANCED
  context->enhancedEnabled = enhanced ? TRUE : FALSE;
#else
  context->enhancedEnabled = FALSE;
  if (enhanced) {
    return OI_STATUS_INVALID_PARAMETERS;
  }
#endif

  status = OI_CODEC_SBC_Alloc(&context->common, decoderData, decoderDataBytes,
                              maxChannels, pcmStride);

  if (!OI_SUCCESS(status)) {
    return status;
  }

  context->common.codecInfo = OI_Codec_Copyright;
  context->common.maxBitneed = 0;
  context->limitFrameFormat = FALSE;
  OI_SBC_ExpandFrameFields(&context->common.frameInfo);

  /*PLATFORM_DECODER_RESET(context);*/

  return OI_OK;
}

/**
 * Read the SBC header up to but not including the joint stereo mask. The
 * syncword has already been examined, and the enhanced mode flag set, by
 * FindSyncword.
 */
INLINE void OI_SBC_ReadHeader(OI_CODEC_SBC_COMMON_CONTEXT* common,
                              const OI_BYTE* data) {
  OI_CODEC_SBC_FRAME_INFO* frame = &common->frameInfo;
  uint8_t d1;

  OI_ASSERT(data[0] == OI_SBC_SYNCWORD || data[0] == OI_SBC_ENHANCED_SYNCWORD);

  /* Avoid filling out all these strucutures if we already remember the values
   * from last time. Just in case we get a stream corresponding to data[1] ==
   * 0, DecoderReset is responsible for ensuring the lookup table entries have
   * already been populated
   */
  d1 = data[1];
  if (d1 != frame->cachedInfo) {
    frame->freqIndex = (d1 & (BIT7 | BIT6)) >> 6;
    frame->frequency = freq_values[frame->freqIndex];

    frame->blocks = (d1 & (BIT5 | BIT4)) >> 4;
    frame->nrof_blocks = block_values[frame->blocks];

    frame->mode = (d1 & (BIT3 | BIT2)) >> 2;
    frame->nrof_channels = channel_values[frame->mode];

    frame->alloc = (d1 & BIT1) >> 1;

    frame->subbands = (d1 & BIT0);
    frame->nrof_subbands = band_values[frame->subbands];

    frame->cachedInfo = d1;
  }
  /*
   * For decode, the bit allocator needs to know the bitpool value
   */
  frame->bitpool = data[2];
  frame->crc = data[3];
}

#define LOW(x) ((x)&0xf)
#define HIGH(x) ((x) >> 4)

/*
 * Read scalefactor values and prepare the bitstream for OI_SBC_ReadSamples
 */
PRIVATE void OI_SBC_ReadScalefactors(OI_CODEC_SBC_COMMON_CONTEXT* common,
                                     const OI_BYTE* b, OI_BITSTREAM* bs) {
  OI_UINT i = common->frameInfo.nrof_subbands * common->frameInfo.nrof_channels;
  int8_t* scale_factor = common->scale_factor;
  OI_UINT f;

  if (common->frameInfo.nrof_subbands == 8 ||
      common->frameInfo.mode != SBC_JOINT_STEREO) {
    if (common->frameInfo.mode == SBC_JOINT_STEREO) {
      common->frameInfo.join = *b++;
    } else {
      common->frameInfo.join = 0;
    }
    i /= 2;
    do {
      *scale_factor++ = HIGH(f = *b++);
      *scale_factor++ = LOW(f);
    } while (--i);
    /*
     * In this case we know that the scale factors end on a byte boundary so all
     * we need to do
     * is initialize the bitstream.
     */
    OI_BITSTREAM_ReadInit(bs, b);
  } else {
    OI_ASSERT(common->frameInfo.nrof_subbands == 4 &&
              common->frameInfo.mode == SBC_JOINT_STEREO);
    common->frameInfo.join = HIGH(f = *b++);
    i = (i - 1) / 2;
    do {
      *scale_factor++ = LOW(f);
      *scale_factor++ = HIGH(f = *b++);
    } while (--i);
    *scale_factor++ = LOW(f);
    /*
     * In 4-subband joint stereo mode, the joint stereo information ends on a
     * half-byte
     * boundary, so it's necessary to use the bitstream abstraction to read it,
     * since
     * OI_SBC_ReadSamples will need to pick up in mid-byte.
     */
    OI_BITSTREAM_ReadInit(bs, b);
    *scale_factor++ = OI_BITSTREAM_ReadUINT4Aligned(bs);
  }
}

/** Read quantized subband samples from the input bitstream and expand them. */
PRIVATE void OI_SBC_ReadSamples(OI_CODEC_SBC_DECODER_CONTEXT* context,
                                OI_BITSTREAM* global_bs) {
  OI_CODEC_SBC_COMMON_CONTEXT* common = &context->common;
  OI_UINT nrof_blocks = common->frameInfo.nrof_blocks;
  int32_t* RESTRICT s = common->subdata;
  uint8_t* ptr = global_bs->ptr.w;
  uint32_t value = global_bs->value;
  OI_UINT bitPtr = global_bs->bitPtr;

  const OI_UINT iter_count =
      common->frameInfo.nrof_channels * common->frameInfo.nrof_subbands / 4;
  do {
    OI_UINT i;
    for (i = 0; i < iter_count; ++i) {
      uint32_t sf_by4 = ((uint32_t*)common->scale_factor)[i];
      uint32_t bits_by4 = common->bits.uint32[i];
      OI_UINT n;
      for (n = 0; n < 4; ++n) {
        int32_t dequant;
        OI_UINT bits;
        OI_INT sf;

        if (OI_CPU_BYTE_ORDER == OI_LITTLE_ENDIAN_BYTE_ORDER) {
          bits = bits_by4 & 0xFF;
          bits_by4 >>= 8;
          sf = sf_by4 & 0xFF;
          sf_by4 >>= 8;
        } else {
          bits = (bits_by4 >> 24) & 0xFF;
          bits_by4 <<= 8;
          sf = (sf_by4 >> 24) & 0xFF;
          sf_by4 <<= 8;
        }
        if (bits) {
          uint32_t raw;
          OI_BITSTREAM_READUINT(raw, bits, ptr, value, bitPtr);
          dequant = OI_SBC_Dequant(raw, sf, bits);
        } else {
          dequant = 0;
        }
        *s++ = dequant;
      }
    }
  } while (--nrof_blocks);
}

/**
@}
*/