/* XzCrc64.c -- CRC64 calculation

2017-05-23 : Igor Pavlov : Public domain */

#include "Precomp.h"

#include "XzCrc64.h"

#include "CpuArch.h"

#define kCrc64Poly UINT64_CONST(0xC96C5795D7870F42)

#ifdef MY_CPU_LE

  #define CRC64_NUM_TABLES 4

#else

  #define CRC64_NUM_TABLES 5

  #define CRC_UINT64_SWAP(v) \

      ((v >> 56) \

    | ((v >> 40) & ((UInt64)0xFF <<  8)) \

    | ((v >> 24) & ((UInt64)0xFF << 16)) \

    | ((v >>  8) & ((UInt64)0xFF << 24)) \

    | ((v <<  8) & ((UInt64)0xFF << 32)) \

    | ((v << 24) & ((UInt64)0xFF << 40)) \

    | ((v << 40) & ((UInt64)0xFF << 48)) \

    | ((v << 56)))

  UInt64 MY_FAST_CALL XzCrc64UpdateT1_BeT4(UInt64 v, const void *data, size_t size, const UInt64 *table);

#endif

#ifndef MY_CPU_BE

  UInt64 MY_FAST_CALL XzCrc64UpdateT4(UInt64 v, const void *data, size_t size, const UInt64 *table);

#endif

typedef UInt64 (MY_FAST_CALL *CRC64_FUNC)(UInt64 v, const void *data, size_t size, const UInt64 *table);

static CRC64_FUNC g_Crc64Update;

UInt64 g_Crc64Table[256 * CRC64_NUM_TABLES];

UInt64 MY_FAST_CALL Crc64Update(UInt64 v, const void *data, size_t size)

{

  return g_Crc64Update(v, data, size, g_Crc64Table);

}

UInt64 MY_FAST_CALL Crc64Calc(const void *data, size_t size)

{

  return g_Crc64Update(CRC64_INIT_VAL, data, size, g_Crc64Table) ^ CRC64_INIT_VAL;

}

void MY_FAST_CALL Crc64GenerateTable()

{

  UInt32 i;

  for (i = 0; i < 256; i++)

  {

    UInt64 r = i;

    unsigned j;

    for (j = 0; j < 8; j++)

      r = (r >> 1) ^ (kCrc64Poly & ((UInt64)0 - (r & 1)));

    g_Crc64Table[i] = r;

  }

  for (i = 256; i < 256 * CRC64_NUM_TABLES; i++)

  {

    UInt64 r = g_Crc64Table[(size_t)i - 256];

    g_Crc64Table[i] = g_Crc64Table[r & 0xFF] ^ (r >> 8);

  }

  #ifdef MY_CPU_LE

  g_Crc64Update = XzCrc64UpdateT4;

  #else

  {

    #ifndef MY_CPU_BE

    UInt32 k = 1;

    if (*(const Byte *)&k == 1)

      g_Crc64Update = XzCrc64UpdateT4;

    else

    #endif

    {

      for (i = 256 * CRC64_NUM_TABLES - 1; i >= 256; i--)

      {

        UInt64 x = g_Crc64Table[(size_t)i - 256];

        g_Crc64Table[i] = CRC_UINT64_SWAP(x);

      }

      g_Crc64Update = XzCrc64UpdateT1_BeT4;

    }

  }

  #endif

}