openh264/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__