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/* ------------------------------------------------------------------
* Copyright (C) 1998-2009 PacketVideo
*
* 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.
* -------------------------------------------------------------------
*/
#include "mp4dec_lib.h"
#include "vlc_decode.h"
#include "bitstream.h"
#include "zigzag.h"
PV_STATUS PV_DecodePredictedIntraDC(
int compnum,
BitstreamDecVideo *stream,
int16 *INTRADC_delta)
{
/*----------------------------------------------------------------------------
; Define all local variables
----------------------------------------------------------------------------*/
PV_STATUS status = PV_SUCCESS;
uint DC_size;
uint code;
int first_bit;
/*----------------------------------------------------------------------------
; Function body here
----------------------------------------------------------------------------*/
/* read DC size 2 - 8 bits */
status = PV_VlcDecIntraDCPredSize(stream, compnum, &DC_size);
if (status == PV_SUCCESS)
{
if (DC_size == 0)
{
*INTRADC_delta = 0;
}
else
{
/* read delta DC 0 - 8 bits */
code = (int) BitstreamReadBits16_INLINE(stream, DC_size);
first_bit = code >> (DC_size - 1);
if (first_bit == 0)
{
/* negative delta INTRA DC */
*INTRADC_delta = code ^((1 << DC_size) - 1);
*INTRADC_delta = -(*INTRADC_delta);
}
else
{ /* positive delta INTRA DC */
*INTRADC_delta = code;
}
if (DC_size > 8) BitstreamRead1Bits_INLINE(stream);
}
}
/*----------------------------------------------------------------------------
; Return nothing or data or data pointer
----------------------------------------------------------------------------*/
return status;
}
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