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/******************************** MPEG Audio Encoder **************************
(C) copyright Fraunhofer-IIS (1999)
All Rights Reserved
Please be advised that this software and/or program delivery is
Confidential Information of Fraunhofer and subject to and covered by the
Fraunhofer IIS Software Evaluation Agreement
between Google Inc. and Fraunhofer
effective and in full force since March 1, 2012.
You may use this software and/or program only under the terms and
conditions described in the above mentioned Fraunhofer IIS Software
Evaluation Agreement. Any other and/or further use requires a separate agreement.
This software and/or program is protected by copyright law and international
treaties. Any reproduction or distribution of this software and/or program,
or any portion of it, may result in severe civil and criminal penalties, and
will be prosecuted to the maximum extent possible under law.
$Id$
Initial author:
contents/description: CRC calculation
******************************************************************************/
#ifndef FDK_CRC_H
#define FDK_CRC_H
#include "FDK_bitstream.h"
#define MAX_CRC_REGS 3 /*!< Maximal number of overlapping crc region in ADTS channel pair element is two.
Select three independent regions preventively. */
/**
* This structure describes single crc region used for crc calculation.
*/
typedef struct
{
UCHAR isActive;
INT maxBits;
UINT bitBufCntBits;
UINT validBits;
} CCrcRegData;
/**
* CRC info structure.
*/
typedef struct
{
CCrcRegData crcRegData[MAX_CRC_REGS]; /*!< Multiple crc region description. */
const USHORT *pCrcLookup; /*!< Pointer to lookup table filled in FDK_crcInit(). */
USHORT crcPoly; /*!< CRC generator polynom. */
USHORT crcMask; /*!< CRC mask. */
USHORT startValue; /*!< CRC start value. */
UCHAR crcLen; /*!< CRC length. */
UINT regStart; /*!< Start region marker for synchronization. */
UINT regStop; /*!< Stop region marker for synchronization. */
USHORT crcValue; /*!< Crc value to be calculated. */
} FDK_CRCINFO;
/**
* CRC info handle.
*/
typedef FDK_CRCINFO* HANDLE_FDK_CRCINFO;
/**
* \brief Initialize CRC structure.
*
* The function initializes existing crc info structure with denoted configuration.
*
* \param hCrcInfo Pointer to an outlying allocated crc info structure.
* \param crcPoly Configure crc polynom.
* \param crcStartValue Configure crc start value.
* \param crcLen Configure crc length.
*
* \return none
*/
void FDKcrcInit(
HANDLE_FDK_CRCINFO hCrcInfo,
const UINT crcPoly,
const UINT crcStartValue,
const UINT crcLen
);
/**
* \brief Reset CRC info structure.
*
* This function clears all intern states of the crc structure.
*
* \param hCrcInfo Pointer to crc info stucture.
*
* \return none
*/
void FDKcrcReset(
HANDLE_FDK_CRCINFO hCrcInfo
);
/**
* \brief Start CRC region with maximum number of bits.
*
* This function marks position in bitstream to be used as start point for crc calculation.
* Bitstream range for crc calculation can be limited or kept dynamic depending on mBits parameter.
* The crc region has to be terminated with FDKcrcEndReg() in each case.
*
* \param hCrcInfo Pointer to crc info stucture.
* \param hBs Pointer to current bit buffer structure.
* \param mBits Number of bits in crc region to be calculated.
* - mBits > 0: Zero padding will be used for CRC calculation, if there
* are less than mBits bits available.
* - mBits < 0: No zero padding is done.
* - mBits = 0: The number of bits used in crc calculation is dynamically,
* depending on bitstream position between FDKcrcStartReg() and
* FDKcrcEndReg() call.
*
* \return ID for the created region, -1 in case of an error
*/
INT FDKcrcStartReg(
HANDLE_FDK_CRCINFO hCrcInfo,
const HANDLE_FDK_BITSTREAM hBs,
const INT mBits
);
/**
* \brief Ends CRC region.
*
* This function terminates crc region specified with FDKcrcStartReg(). The number of bits in crc region depends
* on mBits parameter of FDKcrcStartReg().
* This function calculates and updates crc in info structure.
*
* \param hCrcInfo Pointer to crc info stucture.
* \param hBs Pointer to current bit buffer structure.
* \param reg Crc region ID created in FDKcrcStartReg().
*
* \return 0 on success
*/
INT FDKcrcEndReg(
HANDLE_FDK_CRCINFO hCrcInfo,
const HANDLE_FDK_BITSTREAM hBs,
const INT reg
);
/**
* \brief This function returns crc value from info struct.
*
* \param hCrcInfo Pointer to crc info stucture.
*
* \return CRC value masked with crc length.
*/
USHORT FDKcrcGetCRC(
const HANDLE_FDK_CRCINFO hCrcInfo
);
#endif /* FDK_CRC_H */
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