1/* 7zCrcOpt.c -- CRC32 calculation
 22013-11-12 : Igor Pavlov : Public domain */
 3
 4#include "Precomp.h"
 5
 6#include "CpuArch.h"
 7
 8#define CRC_UPDATE_BYTE_2(crc, b) (table[((crc) ^ (b)) & 0xFF] ^ ((crc) >> 8))
 9
10#ifndef MY_CPU_BE
11
12UInt32 MY_FAST_CALL CrcUpdateT4(UInt32 v, const void *data, size_t size, const UInt32 *table)
13{
14  const Byte *p = (const Byte *)data;
15  for (; size > 0 && ((unsigned)(ptrdiff_t)p & 3) != 0; size--, p++)
16    v = CRC_UPDATE_BYTE_2(v, *p);
17  for (; size >= 4; size -= 4, p += 4)
18  {
19    v ^= *(const UInt32 *)p;
20    v =
21      table[0x300 + (v & 0xFF)] ^
22      table[0x200 + ((v >> 8) & 0xFF)] ^
23      table[0x100 + ((v >> 16) & 0xFF)] ^
24      table[0x000 + ((v >> 24))];
25  }
26  for (; size > 0; size--, p++)
27    v = CRC_UPDATE_BYTE_2(v, *p);
28  return v;
29}
30
31UInt32 MY_FAST_CALL CrcUpdateT8(UInt32 v, const void *data, size_t size, const UInt32 *table)
32{
33  return CrcUpdateT4(v, data, size, table);
34}
35
36#endif
37
38
39#ifndef MY_CPU_LE
40
41#define CRC_UINT32_SWAP(v) ((v >> 24) | ((v >> 8) & 0xFF00) | ((v << 8) & 0xFF0000) | (v << 24))
42
43UInt32 MY_FAST_CALL CrcUpdateT1_BeT4(UInt32 v, const void *data, size_t size, const UInt32 *table)
44{
45  const Byte *p = (const Byte *)data;
46  for (; size > 0 && ((unsigned)(ptrdiff_t)p & 3) != 0; size--, p++)
47    v = CRC_UPDATE_BYTE_2(v, *p);
48  v = CRC_UINT32_SWAP(v);
49  table += 0x100;
50  for (; size >= 4; size -= 4, p += 4)
51  {
52    v ^= *(const UInt32 *)p;
53    v =
54      table[0x000 + (v & 0xFF)] ^
55      table[0x100 + ((v >> 8) & 0xFF)] ^
56      table[0x200 + ((v >> 16) & 0xFF)] ^
57      table[0x300 + ((v >> 24))];
58  }
59  table -= 0x100;
60  v = CRC_UINT32_SWAP(v);
61  for (; size > 0; size--, p++)
62    v = CRC_UPDATE_BYTE_2(v, *p);
63  return v;
64}
65
66#endif