ref: 3e13874a77196c53d561e4901b14025f30b1195d
dir: /codec/decoder/core/inc/dec_golomb.h/
/*!
* \copy
* Copyright (c) 2009-2013, Cisco Systems
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
*
* \file golomb.h
*
* \brief Exponential Golomb entropy coding/decoding routine
*
* \date 03/13/2009 Created
*
*************************************************************************************
*/
#ifndef WELS_EXPONENTIAL_GOLOMB_ENTROPY_CODING_H__
#define WELS_EXPONENTIAL_GOLOMB_ENTROPY_CODING_H__
#include "typedefs.h"
#include "bit_stream.h"
#include "macros.h"
//#include <assert.h>
#include "ls_defines.h"
namespace WelsDec {
#define GET_WORD(iCurBits, pBufPtr, iLeftBits) { \
iCurBits |= ((pBufPtr[0] << 8) | pBufPtr[1]) << (iLeftBits); \
iLeftBits -= 16; \
pBufPtr +=2; \
}
#define NEED_BITS(iCurBits, pBufPtr, iLeftBits) { \
if( iLeftBits > 0 ) { \
GET_WORD(iCurBits, pBufPtr, iLeftBits); \
} \
}
#define UBITS(iCurBits, iNumBits) (iCurBits>>(32-(iNumBits)))
#define DUMP_BITS(iCurBits, pBufPtr, iLeftBits, iNumBits) { \
iCurBits <<= (iNumBits); \
iLeftBits += (iNumBits); \
NEED_BITS(iCurBits, pBufPtr, iLeftBits); \
}
static inline int32_t ShowBits (PBitStringAux pBs, int32_t iNumBits) {
return UBITS (pBs->uiCurBits, iNumBits);
}
static inline void FlushBits (PBitStringAux pBs, int32_t iNumBits) {
DUMP_BITS (pBs->uiCurBits, pBs->pCurBuf, pBs->iLeftBits, iNumBits);
}
static inline int32_t BsGetBits (PBitStringAux pBs, int32_t iNumBits) {
int32_t iRc = UBITS (pBs->uiCurBits, iNumBits);
DUMP_BITS (pBs->uiCurBits, pBs->pCurBuf, pBs->iLeftBits, iNumBits);
return iRc;
}
/*
* Exponential Golomb codes decoding routines
*/
// for data sharing cross modules and try to reduce size of binary generated, 12/10/2009
extern const uint8_t g_kuiIntra4x4CbpTable[48];
extern const uint8_t g_kuiInterCbpTable[48];
extern const uint8_t g_kuiLeadingZeroTable[256];
static const uint32_t g_kuiPrefix8BitsTable[16] = {
0, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3
};
static inline uint32_t GetPrefixBits (uint32_t uiValue) {
uint32_t iNumBit = 0;
if (uiValue & 0xffff0000) {
uiValue >>= 16;
iNumBit += 16;
}
if (uiValue & 0xff00) {
uiValue >>= 8;
iNumBit += 8;
}
if (uiValue & 0xf0) {
uiValue >>= 4;
iNumBit += 4;
}
iNumBit += g_kuiPrefix8BitsTable[uiValue];
return (32 - iNumBit);
}
/*
* Read one bit from bit stream followed
*/
static inline uint32_t BsGetOneBit (PBitStringAux pBs) {
return (BsGetBits (pBs, 1));
}
static inline int32_t GetLeadingZeroBits (uint32_t iCurBits) { //<=16 bits
int32_t iValue;
iValue = UBITS (iCurBits, 8); //ShowBits( bs, 8 );
if (iValue) {
return g_kuiLeadingZeroTable[iValue];
}
iValue = UBITS (iCurBits, 16); //ShowBits( bs, 16 );
if (iValue) {
return (g_kuiLeadingZeroTable[iValue] + 8);
}
//ASSERT(false); // should not go here
return -1;
}
static inline uint32_t BsGetUe (PBitStringAux pBs) {
uint32_t iValue = 0;
int32_t iLeadingZeroBits = GetLeadingZeroBits (pBs->uiCurBits);
if (iLeadingZeroBits == -1) { //bistream error
return 0xffffffff;//-1
}
DUMP_BITS (pBs->uiCurBits, pBs->pCurBuf, pBs->iLeftBits, iLeadingZeroBits + 1);
if (iLeadingZeroBits) {
iValue = UBITS (pBs->uiCurBits, iLeadingZeroBits);
DUMP_BITS (pBs->uiCurBits, pBs->pCurBuf, pBs->iLeftBits, iLeadingZeroBits);
}
return ((1 << iLeadingZeroBits) - 1 + iValue);
}
/*
* Read signed exp golomb codes
*/
static inline int32_t BsGetSe (PBitStringAux pBs) {
uint32_t uiCodeNum;
uiCodeNum = BsGetUe (pBs);
if (uiCodeNum & 0x01) {
return (int32_t) ((uiCodeNum + 1) >> 1);
} else {
return NEG_NUM ((int32_t) (uiCodeNum >> 1));
}
}
/*
* Read truncated exp golomb codes
*/
static inline uint32_t BsGetTe (PBitStringAux pBs, uint8_t uiRange) {
if (1 == uiRange) {
return BsGetOneBit (pBs) ^ 1;
} else {
return BsGetUe (pBs);
}
}
/*
* Get unsigned truncated exp golomb code.
*/
static inline int32_t BsGetTe0 (PBitStringAux pBs, int32_t iRange) {
if (iRange == 1)
return 0;
else if (iRange == 2)
return BsGetOneBit (pBs) ^ 1;
else
return BsGetUe (pBs);
}
/*
* Get number of trailing bits
*/
static inline int32_t BsGetTrailingBits (uint8_t* pBuf) {
// TODO
uint32_t uiValue = *pBuf;
int32_t iRetNum = 1;
do {
if (uiValue & 1)
return iRetNum;
uiValue >>= 1;
++ iRetNum;
} while (iRetNum < 9);
return 0;
}
} // namespace WelsDec
#endif//WELS_EXPONENTIAL_GOLOMB_ENTROPY_CODING_H__