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_t 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__