path: root/libFDK/src/FDK_crc.cpp

/******************************** MPEG Audio Encoder **************************

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    effective and in full force since March 1, 2012.

    You may use this software and/or program only under the terms and
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    Evaluation Agreement. Any other and/or further use requires a separate agreement.


   This software and/or program is protected by copyright law and international
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   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

******************************************************************************/

#include "FDK_crc.h"



/*---------------- constants -----------------------*/

/**
 * \brief  This table defines precalculated lookup tables for crc polynom  x^16 + x^15 + x^2 + x^0.
 */
static const USHORT crcLookup_16_15_2_0[256] =
{
  0x0000, 0x8005, 0x800f, 0x000a, 0x801b, 0x001e, 0x0014, 0x8011,
  0x8033, 0x0036, 0x003c, 0x8039, 0x0028, 0x802d, 0x8027, 0x0022,
  0x8063, 0x0066, 0x006c, 0x8069, 0x0078, 0x807d, 0x8077, 0x0072,
  0x0050, 0x8055, 0x805f, 0x005a, 0x804b, 0x004e, 0x0044, 0x8041,
  0x80c3, 0x00c6, 0x00cc, 0x80c9, 0x00d8, 0x80dd, 0x80d7, 0x00d2,
  0x00f0, 0x80f5, 0x80ff, 0x00fa, 0x80eb, 0x00ee, 0x00e4, 0x80e1,
  0x00a0, 0x80a5, 0x80af, 0x00aa, 0x80bb, 0x00be, 0x00b4, 0x80b1,
  0x8093, 0x0096, 0x009c, 0x8099, 0x0088, 0x808d, 0x8087, 0x0082,
  0x8183, 0x0186, 0x018c, 0x8189, 0x0198, 0x819d, 0x8197, 0x0192,
  0x01b0, 0x81b5, 0x81bf, 0x01ba, 0x81ab, 0x01ae, 0x01a4, 0x81a1,
  0x01e0, 0x81e5, 0x81ef, 0x01ea, 0x81fb, 0x01fe, 0x01f4, 0x81f1,
  0x81d3, 0x01d6, 0x01dc, 0x81d9, 0x01c8, 0x81cd, 0x81c7, 0x01c2,
  0x0140, 0x8145, 0x814f, 0x014a, 0x815b, 0x015e, 0x0154, 0x8151,
  0x8173, 0x0176, 0x017c, 0x8179, 0x0168, 0x816d, 0x8167, 0x0162,
  0x8123, 0x0126, 0x012c, 0x8129, 0x0138, 0x813d, 0x8137, 0x0132,
  0x0110, 0x8115, 0x811f, 0x011a, 0x810b, 0x010e, 0x0104, 0x8101,
  0x8303, 0x0306, 0x030c, 0x8309, 0x0318, 0x831d, 0x8317, 0x0312,
  0x0330, 0x8335, 0x833f, 0x033a, 0x832b, 0x032e, 0x0324, 0x8321,
  0x0360, 0x8365, 0x836f, 0x036a, 0x837b, 0x037e, 0x0374, 0x8371,
  0x8353, 0x0356, 0x035c, 0x8359, 0x0348, 0x834d, 0x8347, 0x0342,
  0x03c0, 0x83c5, 0x83cf, 0x03ca, 0x83db, 0x03de, 0x03d4, 0x83d1,
  0x83f3, 0x03f6, 0x03fc, 0x83f9, 0x03e8, 0x83ed, 0x83e7, 0x03e2,
  0x83a3, 0x03a6, 0x03ac, 0x83a9, 0x03b8, 0x83bd, 0x83b7, 0x03b2,
  0x0390, 0x8395, 0x839f, 0x039a, 0x838b, 0x038e, 0x0384, 0x8381,
  0x0280, 0x8285, 0x828f, 0x028a, 0x829b, 0x029e, 0x0294, 0x8291,
  0x82b3, 0x02b6, 0x02bc, 0x82b9, 0x02a8, 0x82ad, 0x82a7, 0x02a2,
  0x82e3, 0x02e6, 0x02ec, 0x82e9, 0x02f8, 0x82fd, 0x82f7, 0x02f2,
  0x02d0, 0x82d5, 0x82df, 0x02da, 0x82cb, 0x02ce, 0x02c4, 0x82c1,
  0x8243, 0x0246, 0x024c, 0x8249, 0x0258, 0x825d, 0x8257, 0x0252,
  0x0270, 0x8275, 0x827f, 0x027a, 0x826b, 0x026e, 0x0264, 0x8261,
  0x0220, 0x8225, 0x822f, 0x022a, 0x823b, 0x023e, 0x0234, 0x8231,
  0x8213, 0x0216, 0x021c, 0x8219, 0x0208, 0x820d, 0x8207, 0x0202
};

/**
 * \brief  This table defines precalculated lookup tables for crc polynom  x^16 + x^12 + x^5 + x^0.
 */
static const USHORT crcLookup_16_12_5_0[256] =
{
  0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
  0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,
  0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6,
  0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de,
  0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485,
  0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d,
  0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4,
  0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc,
  0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823,
  0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b,
  0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12,
  0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a,
  0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41,
  0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49,
  0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70,
  0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78,
  0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f,
  0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,
  0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e,
  0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256,
  0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d,
  0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
  0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c,
  0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634,
  0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab,
  0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3,
  0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,
  0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92,
  0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9,
  0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1,
  0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8,
  0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0
};


/*--------------- function declarations --------------------*/

static inline INT calcCrc_Bits(
        USHORT * const                  pCrc,
        USHORT                          crcMask,
        USHORT                          crcPoly,
        HANDLE_FDK_BITSTREAM            hBs,
        INT                             nBits
        );

static inline INT calcCrc_Bytes(
        USHORT * const                  pCrc,
        const USHORT *                  pCrcLookup,
        HANDLE_FDK_BITSTREAM            hBs,
        INT                             nBytes
        );

static void crcCalc(
        HANDLE_FDK_CRCINFO              hCrcInfo,
        HANDLE_FDK_BITSTREAM            hBs,
        const INT                       reg
        );


/*------------- function definitions ----------------*/

void FDKcrcInit(
        HANDLE_FDK_CRCINFO              hCrcInfo,
        const UINT                      crcPoly,
        const UINT                      crcStartValue,
        const UINT                      crcLen
        )
{
  /* crc polynom example:
  x^16 + x^15 + x^2 + x^0        (1) 1000 0000 0000 0101 -> 0x8005
  x^16 + x^12 + x^5 + x^0        (1) 0001 0000 0010 0001 -> 0x1021
  x^8 + x^4 + x^3 + x^2 + x^0              (1) 0001 1101 -> 0x001d */

  hCrcInfo->crcLen     = crcLen;
  hCrcInfo->crcPoly    = crcPoly;
  hCrcInfo->startValue = crcStartValue;
  hCrcInfo->crcMask    = (crcLen) ? (1<<(crcLen-1)) : 0;

  FDKcrcReset(hCrcInfo);

  hCrcInfo->pCrcLookup = 0;

  if (hCrcInfo->crcLen==16) {
    switch ( crcPoly ) {
      case 0x8005:
        hCrcInfo->pCrcLookup = crcLookup_16_15_2_0;
        break;
      case 0x1021:
        hCrcInfo->pCrcLookup = crcLookup_16_12_5_0;
        break;
      case 0x001d:
      default:
        /* no lookup table */
        hCrcInfo->pCrcLookup = 0;
    }
  }


}

void FDKcrcReset(HANDLE_FDK_CRCINFO hCrcInfo)
{
  int i;

  hCrcInfo->crcValue = hCrcInfo->startValue;

  for(i=0;i<MAX_CRC_REGS;i++) {
    hCrcInfo->crcRegData[i].isActive = 0;
  }
  hCrcInfo->regStart = 0;
  hCrcInfo->regStop  = 0;
}

INT FDKcrcStartReg(
        HANDLE_FDK_CRCINFO              hCrcInfo,
        const HANDLE_FDK_BITSTREAM      hBs,
        const INT                       mBits
        )
{
  int reg = hCrcInfo->regStart;

  FDK_ASSERT(hCrcInfo->crcRegData[reg].isActive==0);
  hCrcInfo->crcRegData[reg].isActive      = 1;
  hCrcInfo->crcRegData[reg].maxBits       = mBits;
  hCrcInfo->crcRegData[reg].validBits     = FDKgetValidBits(hBs) ;
  hCrcInfo->crcRegData[reg].bitBufCntBits = 0;

  hCrcInfo->regStart = (hCrcInfo->regStart+1)%MAX_CRC_REGS;

  return (reg);
}

INT FDKcrcEndReg(
        HANDLE_FDK_CRCINFO              hCrcInfo,
        const HANDLE_FDK_BITSTREAM      hBs,
        const INT                       reg
        )
{
  FDK_ASSERT((reg==(INT)hCrcInfo->regStop)&&(hCrcInfo->crcRegData[reg].isActive==1));

  if (hBs->ConfigCache==BS_WRITER) {
    hCrcInfo->crcRegData[reg].bitBufCntBits = FDKgetValidBits(hBs) - hCrcInfo->crcRegData[reg].validBits;
  }
  else {
    hCrcInfo->crcRegData[reg].bitBufCntBits = hCrcInfo->crcRegData[reg].validBits - FDKgetValidBits(hBs);
  }

  if (hCrcInfo->crcRegData[reg].maxBits == 0) {
    hCrcInfo->crcRegData[reg].maxBits = hCrcInfo->crcRegData[reg].bitBufCntBits;
  }

  crcCalc( hCrcInfo, hBs, reg);

  hCrcInfo->crcRegData[reg].isActive = 0;
  hCrcInfo->regStop = (hCrcInfo->regStop+1)%MAX_CRC_REGS;

  return 0;
}

USHORT FDKcrcGetCRC(
        const HANDLE_FDK_CRCINFO        hCrcInfo
        )
{
  return ( hCrcInfo->crcValue & (((hCrcInfo->crcMask-1)<<1)+1) );
}

/**
 * \brief  Calculate crc bits.
 *
 * Calculate crc starting at current bitstream postion over nBits.
 *
 * \param pCrc                  Pointer to an outlying allocated crc info structure.
 * \param crcMask               CrcMask in use.
 * \param crcPoly               Crc polynom in use.
 * \param hBs                   Handle to current bit buffer structure.
 * \param nBits                 Number of processing bits.
 *
 * \return  Number of processed bits.
 */
static inline INT calcCrc_Bits(
        USHORT * const                  pCrc,
        USHORT                          crcMask,
        USHORT                          crcPoly,
        HANDLE_FDK_BITSTREAM            hBs,
        INT                             nBits
        )
{
  int i;
  USHORT crc = *pCrc; /* get crc value */

  if (hBs!=NULL) {
    for (i = 0; (i < nBits); i++) {
      USHORT tmp = FDKreadBits(hBs,1);     // process single bit
      tmp ^= ( (crc & crcMask) ? 1 : 0 );
      tmp *= crcPoly;
      crc <<= 1;
      crc ^= tmp;
    }
  }
  else {
    for (i = 0; (i < nBits); i++) {
      USHORT tmp = 0;     // process single bit
      tmp ^= ( (crc & crcMask) ? 1 : 0 );
      tmp *= crcPoly;
      crc <<= 1;
      crc ^= tmp;
    }
  }
  *pCrc = crc; /* update crc value */

  return nBits;
}

/**
 * \brief  Calculate crc bytes.
 *
 * Calculate crc starting at current bitstream postion over nBytes.
 *
 * \param pCrc                  Pointer to an outlying allocated crc info structure.
 * \param pCrcLookup            Pointer to lookup table used for fast crc calculation.
 * \param hBs                   Handle to current bit buffer structure.
 * \param nBits                 Number of processing bytes.
 *
 * \return  Number of processed bits.
 */
static inline INT calcCrc_Bytes(
        USHORT * const                  pCrc,
        const USHORT *                  pCrcLookup,
        HANDLE_FDK_BITSTREAM            hBs,
        INT                             nBytes
        )
{
  int i;
  USHORT crc = *pCrc; /* get crc value */

  if (hBs!=NULL) {
    for (i=0; i<nBytes; i++) {
      crc = (crc<<8)^pCrcLookup[((crc>>8)^((UCHAR)FDKreadBits(hBs,8)))&0xFF];
    }
  }
  else {
    for (i=0; i<nBytes; i++) {
      crc = (crc<<8)^pCrcLookup[((crc>>8)^((UCHAR)0))&0xFF];
    }
  }

  *pCrc = crc; /* update crc value */

  return (i);
}

/**
 * \brief  Calculate crc.
 *
 * Calculate crc. Lenght depends on mBits parameter in FDKcrcStartReg() configuration.
 *
 * \param hCrcInfo              Pointer to an outlying allocated crc info structure.
 * \param hBs                   Pointer to current bit buffer structure.
 * \param reg                   Crc region ID.
 *
 * \return  Number of processed bits.
 */
static void crcCalc(
        HANDLE_FDK_CRCINFO              hCrcInfo,
        HANDLE_FDK_BITSTREAM            hBs,
        const INT                       reg
        )
{
  USHORT crc = hCrcInfo->crcValue;
  CCrcRegData *rD = &hCrcInfo->crcRegData[reg];
  FDK_BITSTREAM bsReader;

  if (hBs->ConfigCache==BS_READER) {
    bsReader = *hBs;
    FDKpushBiDirectional(&bsReader, -(INT)(rD->validBits-FDKgetValidBits(&bsReader)));
  }
  else {
    FDKinitBitStream(&bsReader, hBs->hBitBuf.Buffer, hBs->hBitBuf.bufSize, hBs->hBitBuf.ValidBits, BS_READER);
    FDKpushBiDirectional(&bsReader, rD->validBits);
  }

  int bits, rBits;
  rBits = (rD->maxBits>=0) ? rD->maxBits : -rD->maxBits; /* ramaining bits */
  if ((rD->maxBits>0) && (((INT)rD->bitBufCntBits>>3<<3)<rBits) ) {
    bits = rD->bitBufCntBits;
  }
  else {
    bits = rBits;
  }

  int words = bits >> 3;  /* processing bytes */
  int mBits = bits & 0x7; /* modulo bits */

  if(hCrcInfo->pCrcLookup) {
    rBits -= (calcCrc_Bytes(&crc, hCrcInfo->pCrcLookup, &bsReader, words)<<3);
  }
  else {
    rBits -= calcCrc_Bits(&crc, hCrcInfo->crcMask, hCrcInfo->crcPoly, &bsReader, words<<3 );
  }

  /* remaining valid bits*/
  if(mBits!=0) {
    rBits -= calcCrc_Bits(&crc, hCrcInfo->crcMask, hCrcInfo->crcPoly, &bsReader, mBits );
  }

  if (rBits!=0) {
    /* zero bytes */
    if ( (hCrcInfo->pCrcLookup) && (rBits>8) ) {
      rBits -= (calcCrc_Bytes(&crc, hCrcInfo->pCrcLookup, NULL, rBits>>3)<<3);
    }
    /* remaining zero bits */
    if (rBits!=0) {
      rBits -= calcCrc_Bits(&crc, hCrcInfo->crcMask, hCrcInfo->crcPoly, NULL, rBits );
    }
  }

  hCrcInfo->crcValue = crc;
}