source-engine/utils/lzma/C/XzCrc64Opt.c

/* XzCrc64Opt.c -- CRC64 calculation
2011-06-28 : Igor Pavlov : Public domain */

#include "Precomp.h"

#include "CpuArch.h"

#define CRC_UPDATE_BYTE_2(crc, b) (table[((crc) ^ (b)) & 0xFF] ^ ((crc) >> 8))

#ifndef MY_CPU_BE

UInt64 MY_FAST_CALL XzCrc64UpdateT4(UInt64 v, const void *data, size_t size, const UInt64 *table)
{
  const Byte *p = (const Byte *)data;
  for (; size > 0 && ((unsigned)(ptrdiff_t)p & 3) != 0; size--, p++)
    v = CRC_UPDATE_BYTE_2(v, *p);
  for (; size >= 4; size -= 4, p += 4)
  {
    UInt32 d = (UInt32)v ^ *(const UInt32 *)p;
    v = (v >> 32) ^
      table[0x300 + ((d      ) & 0xFF)] ^
      table[0x200 + ((d >>  8) & 0xFF)] ^
      table[0x100 + ((d >> 16) & 0xFF)] ^
      table[0x000 + ((d >> 24))];
  }
  for (; size > 0; size--, p++)
    v = CRC_UPDATE_BYTE_2(v, *p);
  return v;
}

#endif


#ifndef MY_CPU_LE

#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)
{
  const Byte *p = (const Byte *)data;
  for (; size > 0 && ((unsigned)(ptrdiff_t)p & 3) != 0; size--, p++)
    v = CRC_UPDATE_BYTE_2(v, *p);
  v = CRC_UINT64_SWAP(v);
  table += 0x100;
  for (; size >= 4; size -= 4, p += 4)
  {
    UInt32 d = (UInt32)(v >> 32) ^ *(const UInt32 *)p;
    v = (v << 32) ^
      table[0x000 + ((d      ) & 0xFF)] ^
      table[0x100 + ((d >>  8) & 0xFF)] ^
      table[0x200 + ((d >> 16) & 0xFF)] ^
      table[0x300 + ((d >> 24))];
  }
  table -= 0x100;
  v = CRC_UINT64_SWAP(v);
  for (; size > 0; size--, p++)
    v = CRC_UPDATE_BYTE_2(v, *p);
  return v;
}

#endif