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/*
** Copyright 2003-2010, VisualOn, Inc.
**
** 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.
*/
/*******************************************************************************
File: bitbuffer.c
Content: Bit Buffer Management functions
*******************************************************************************/
#include "bitbuffer.h"
/*****************************************************************************
*
* function name: CreateBitBuffer
* description: create and init Bit Buffer Management
*
*****************************************************************************/
HANDLE_BIT_BUF CreateBitBuffer(HANDLE_BIT_BUF hBitBuf,
UWord8 *pBitBufBase,
Word16 bitBufSize)
{
assert(bitBufSize*8 <= 32768);
hBitBuf->pBitBufBase = pBitBufBase;
hBitBuf->pBitBufEnd = pBitBufBase + bitBufSize - 1;
hBitBuf->pWriteNext = pBitBufBase;
hBitBuf->cache = 0;
hBitBuf->wBitPos = 0;
hBitBuf->cntBits = 0;
hBitBuf->size = (bitBufSize << 3);
hBitBuf->isValid = 1;
return hBitBuf;
}
/*****************************************************************************
*
* function name: DeleteBitBuffer
* description: uninit Bit Buffer Management
*
*****************************************************************************/
void DeleteBitBuffer(HANDLE_BIT_BUF *hBitBuf)
{
if(*hBitBuf)
(*hBitBuf)->isValid = 0;
*hBitBuf = NULL;
}
/*****************************************************************************
*
* function name: ResetBitBuf
* description: reset Bit Buffer Management
*
*****************************************************************************/
void ResetBitBuf(HANDLE_BIT_BUF hBitBuf,
UWord8 *pBitBufBase,
Word16 bitBufSize)
{
hBitBuf->pBitBufBase = pBitBufBase;
hBitBuf->pBitBufEnd = pBitBufBase + bitBufSize - 1;
hBitBuf->pWriteNext = pBitBufBase;
hBitBuf->wBitPos = 0;
hBitBuf->cntBits = 0;
hBitBuf->cache = 0;
}
/*****************************************************************************
*
* function name: CopyBitBuf
* description: copy Bit Buffer Management
*
*****************************************************************************/
void CopyBitBuf(HANDLE_BIT_BUF hBitBufSrc,
HANDLE_BIT_BUF hBitBufDst)
{
*hBitBufDst = *hBitBufSrc;
}
/*****************************************************************************
*
* function name: GetBitsAvail
* description: get available bits
*
*****************************************************************************/
Word16 GetBitsAvail(HANDLE_BIT_BUF hBitBuf)
{
return hBitBuf->cntBits;
}
/*****************************************************************************
*
* function name: WriteBits
* description: write bits to the buffer
*
*****************************************************************************/
Word16 WriteBits(HANDLE_BIT_BUF hBitBuf,
UWord32 writeValue,
Word16 noBitsToWrite)
{
Word16 wBitPos;
assert(noBitsToWrite <= (Word16)sizeof(Word32)*8);
if(noBitsToWrite == 0)
return noBitsToWrite;
hBitBuf->cntBits += noBitsToWrite;
wBitPos = hBitBuf->wBitPos;
wBitPos += noBitsToWrite;
writeValue &= ~(0xffffffff << noBitsToWrite); // Mask out everything except the lowest noBitsToWrite bits
writeValue <<= 32 - wBitPos;
writeValue |= hBitBuf->cache;
while (wBitPos >= 8)
{
UWord8 tmp;
tmp = (UWord8)((writeValue >> 24) & 0xFF);
*hBitBuf->pWriteNext++ = tmp;
writeValue <<= 8;
wBitPos -= 8;
}
hBitBuf->wBitPos = wBitPos;
hBitBuf->cache = writeValue;
return noBitsToWrite;
}
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