ref: bb4b01a1f96ee6576fb0ccc8237cf635e89a01ec
dir: h264bsd/src/h264bsd_stream.c
/*
* Copyright (C) 2009 The Android Open Source Project
* Modified for use by h264bsd standalone library
*
* 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.
*/
/*------------------------------------------------------------------------------
Table of contents
1. Include headers
2. External compiler flags
3. Module defines
4. Local function prototypes
5. Functions
h264bsdGetBits
h264bsdShowBits32
h264bsdFlushBits
h264bsdIsByteAligned
------------------------------------------------------------------------------*/
/*------------------------------------------------------------------------------
1. Include headers
------------------------------------------------------------------------------*/
#include "h264bsd_util.h"
#include "h264bsd_stream.h"
/*------------------------------------------------------------------------------
2. External compiler flags
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
3. Module defines
------------------------------------------------------------------------------*/
/*------------------------------------------------------------------------------
4. Local function prototypes
------------------------------------------------------------------------------*/
/*------------------------------------------------------------------------------
Function: h264bsdGetBits
Functional description:
Read and remove bits from the stream buffer.
Input:
pStrmData pointer to stream data structure
numBits number of bits to read
Output:
none
Returns:
bits read from stream
END_OF_STREAM if not enough bits left
------------------------------------------------------------------------------*/
u32 h264bsdGetBits(strmData_t *pStrmData, u32 numBits)
{
u32 out;
ASSERT(pStrmData);
ASSERT(numBits < 32);
out = h264bsdShowBits32(pStrmData) >> (32 - numBits);
if (h264bsdFlushBits(pStrmData, numBits) == HANTRO_OK)
{
return(out);
}
else
{
return(END_OF_STREAM);
}
}
/*------------------------------------------------------------------------------
Function: h264bsdShowBits32
Functional description:
Read 32 bits from the stream buffer. Buffer is left as it is, i.e.
no bits are removed. First bit read from the stream is the MSB of
the return value. If there is not enough bits in the buffer ->
bits beyong the end of the stream are set to '0' in the return
value.
Input:
pStrmData pointer to stream data structure
Output:
none
Returns:
bits read from stream
------------------------------------------------------------------------------*/
u32 h264bsdShowBits32(strmData_t *pStrmData)
{
i32 bits, shift;
u32 out;
u8 *pStrm;
ASSERT(pStrmData);
ASSERT(pStrmData->pStrmCurrPos);
ASSERT(pStrmData->bitPosInWord < 8);
ASSERT(pStrmData->bitPosInWord ==
(pStrmData->strmBuffReadBits & 0x7));
pStrm = pStrmData->pStrmCurrPos;
/* number of bits left in the buffer */
bits = (i32)pStrmData->strmBuffSize*8 - (i32)pStrmData->strmBuffReadBits;
/* at least 32-bits in the buffer */
if (bits >= 32)
{
u32 bitPosInWord = pStrmData->bitPosInWord;
out = ((u32)pStrm[0] << 24) | ((u32)pStrm[1] << 16) |
((u32)pStrm[2] << 8) | ((u32)pStrm[3]);
if (bitPosInWord)
{
u32 byte = (u32)pStrm[4];
u32 tmp = (8-bitPosInWord);
out <<= bitPosInWord;
out |= byte>>tmp;
}
return (out);
}
/* at least one bit in the buffer */
else if (bits > 0)
{
shift = (i32)(24 + pStrmData->bitPosInWord);
out = (u32)(*pStrm++) << shift;
bits -= (i32)(8 - pStrmData->bitPosInWord);
while (bits > 0)
{
shift -= 8;
out |= (u32)(*pStrm++) << shift;
bits -= 8;
}
return (out);
}
else
return (0);
}
/*------------------------------------------------------------------------------
Function: h264bsdFlushBits
Functional description:
Remove bits from the stream buffer
Input:
pStrmData pointer to stream data structure
numBits number of bits to remove
Output:
none
Returns:
HANTRO_OK success
END_OF_STREAM not enough bits left
------------------------------------------------------------------------------*/
#ifndef H264DEC_NEON
u32 h264bsdFlushBits(strmData_t *pStrmData, u32 numBits)
{
ASSERT(pStrmData);
ASSERT(pStrmData->pStrmBuffStart);
ASSERT(pStrmData->pStrmCurrPos);
ASSERT(pStrmData->bitPosInWord < 8);
ASSERT(pStrmData->bitPosInWord == (pStrmData->strmBuffReadBits & 0x7));
pStrmData->strmBuffReadBits += numBits;
pStrmData->bitPosInWord = pStrmData->strmBuffReadBits & 0x7;
if ( (pStrmData->strmBuffReadBits ) <= (8*pStrmData->strmBuffSize) )
{
pStrmData->pStrmCurrPos = pStrmData->pStrmBuffStart +
(pStrmData->strmBuffReadBits >> 3);
return(HANTRO_OK);
}
else
return(END_OF_STREAM);
}
#endif
/*------------------------------------------------------------------------------
Function: h264bsdIsByteAligned
Functional description:
Check if current stream position is byte aligned.
Inputs:
pStrmData pointer to stream data structure
Outputs:
none
Returns:
TRUE stream is byte aligned
FALSE stream is not byte aligned
------------------------------------------------------------------------------*/
u32 h264bsdIsByteAligned(strmData_t *pStrmData)
{
/* Variables */
/* Code */
if (!pStrmData->bitPosInWord)
return(HANTRO_TRUE);
else
return(HANTRO_FALSE);
}