chromium/third_party/lzma_sdk/C/7zCrcOpt.c

/* 7zCrcOpt.c -- CRC32 calculation
2021-02-09 : Igor Pavlov : Public domain */

#include "Precomp.h"

#include "CpuArch.h"

#ifndef MY_CPU_BE

#define CRC_UPDATE_BYTE_2(crc, b) …

UInt32 MY_FAST_CALL CrcUpdateT4(UInt32 v, const void *data, size_t size, const UInt32 *table);
UInt32 MY_FAST_CALL CrcUpdateT4(UInt32 v, const void *data, size_t size, const UInt32 *table)
{ … }

UInt32 MY_FAST_CALL CrcUpdateT8(UInt32 v, const void *data, size_t size, const UInt32 *table);
UInt32 MY_FAST_CALL CrcUpdateT8(UInt32 v, const void *data, size_t size, const UInt32 *table)
{ … }

#endif


#ifndef MY_CPU_LE

#define CRC_UINT32_SWAP …

#define CRC_UPDATE_BYTE_2_BE …

UInt32 MY_FAST_CALL CrcUpdateT1_BeT4(UInt32 v, const void *data, size_t size, const UInt32 *table)
{
  const Byte *p = (const Byte *)data;
  table += 0x100;
  v = CRC_UINT32_SWAP(v);
  for (; size > 0 && ((unsigned)(ptrdiff_t)p & 3) != 0; size--, p++)
    v = CRC_UPDATE_BYTE_2_BE(v, *p);
  for (; size >= 4; size -= 4, p += 4)
  {
    v ^= *(const UInt32 *)(const void *)p;
    v =
          (table + 0x000)[((v      ) & 0xFF)]
        ^ (table + 0x100)[((v >>  8) & 0xFF)]
        ^ (table + 0x200)[((v >> 16) & 0xFF)]
        ^ (table + 0x300)[((v >> 24))];
  }
  for (; size > 0; size--, p++)
    v = CRC_UPDATE_BYTE_2_BE(v, *p);
  return CRC_UINT32_SWAP(v);
}

UInt32 MY_FAST_CALL CrcUpdateT1_BeT8(UInt32 v, const void *data, size_t size, const UInt32 *table)
{
  const Byte *p = (const Byte *)data;
  table += 0x100;
  v = CRC_UINT32_SWAP(v);
  for (; size > 0 && ((unsigned)(ptrdiff_t)p & 7) != 0; size--, p++)
    v = CRC_UPDATE_BYTE_2_BE(v, *p);
  for (; size >= 8; size -= 8, p += 8)
  {
    UInt32 d;
    v ^= *(const UInt32 *)(const void *)p;
    v =
          (table + 0x400)[((v      ) & 0xFF)]
        ^ (table + 0x500)[((v >>  8) & 0xFF)]
        ^ (table + 0x600)[((v >> 16) & 0xFF)]
        ^ (table + 0x700)[((v >> 24))];
    d = *((const UInt32 *)(const void *)p + 1);
    v ^=
          (table + 0x000)[((d      ) & 0xFF)]
        ^ (table + 0x100)[((d >>  8) & 0xFF)]
        ^ (table + 0x200)[((d >> 16) & 0xFF)]
        ^ (table + 0x300)[((d >> 24))];
  }
  for (; size > 0; size--, p++)
    v = CRC_UPDATE_BYTE_2_BE(v, *p);
  return CRC_UINT32_SWAP(v);
}

#endif