1/* 7zCrc.c -- CRC32 init
  22015-03-10 : Igor Pavlov : Public domain */
  3
  4#include "Precomp.h"
  5
  6#include "7zCrc.h"
  7#include "CpuArch.h"
  8
  9#define kCrcPoly 0xEDB88320
 10
 11#ifdef MY_CPU_LE
 12  #define CRC_NUM_TABLES 8
 13#else
 14  #define CRC_NUM_TABLES 9
 15
 16  #define CRC_UINT32_SWAP(v) ((v >> 24) | ((v >> 8) & 0xFF00) | ((v << 8) & 0xFF0000) | (v << 24))
 17
 18  UInt32 MY_FAST_CALL CrcUpdateT1_BeT4(UInt32 v, const void *data, size_t size, const UInt32 *table);
 19  UInt32 MY_FAST_CALL CrcUpdateT1_BeT8(UInt32 v, const void *data, size_t size, const UInt32 *table);
 20#endif
 21
 22#ifndef MY_CPU_BE
 23  UInt32 MY_FAST_CALL CrcUpdateT4(UInt32 v, const void *data, size_t size, const UInt32 *table);
 24  UInt32 MY_FAST_CALL CrcUpdateT8(UInt32 v, const void *data, size_t size, const UInt32 *table);
 25#endif
 26
 27typedef UInt32 (MY_FAST_CALL *CRC_FUNC)(UInt32 v, const void *data, size_t size, const UInt32 *table);
 28
 29CRC_FUNC g_CrcUpdateT4;
 30CRC_FUNC g_CrcUpdateT8;
 31CRC_FUNC g_CrcUpdate;
 32
 33UInt32 g_CrcTable[256 * CRC_NUM_TABLES];
 34
 35UInt32 MY_FAST_CALL CrcUpdate(UInt32 v, const void *data, size_t size)
 36{
 37  return g_CrcUpdate(v, data, size, g_CrcTable);
 38}
 39
 40UInt32 MY_FAST_CALL CrcCalc(const void *data, size_t size)
 41{
 42  return g_CrcUpdate(CRC_INIT_VAL, data, size, g_CrcTable) ^ CRC_INIT_VAL;
 43}
 44
 45#define CRC_UPDATE_BYTE_2(crc, b) (table[((crc) ^ (b)) & 0xFF] ^ ((crc) >> 8))
 46
 47UInt32 MY_FAST_CALL CrcUpdateT1(UInt32 v, const void *data, size_t size, const UInt32 *table)
 48{
 49  const Byte *p = (const Byte *)data;
 50  const Byte *pEnd = p + size;
 51  for (; p != pEnd; p++)
 52    v = CRC_UPDATE_BYTE_2(v, *p);
 53  return v;
 54}
 55
 56void MY_FAST_CALL CrcGenerateTable()
 57{
 58  UInt32 i;
 59  for (i = 0; i < 256; i++)
 60  {
 61    UInt32 r = i;
 62    unsigned j;
 63    for (j = 0; j < 8; j++)
 64      r = (r >> 1) ^ (kCrcPoly & ~((r & 1) - 1));
 65    g_CrcTable[i] = r;
 66  }
 67  for (; i < 256 * CRC_NUM_TABLES; i++)
 68  {
 69    UInt32 r = g_CrcTable[i - 256];
 70    g_CrcTable[i] = g_CrcTable[r & 0xFF] ^ (r >> 8);
 71  }
 72
 73  #if CRC_NUM_TABLES < 4
 74  
 75  g_CrcUpdate = CrcUpdateT1;
 76  
 77  #else
 78 
 79  #ifdef MY_CPU_LE
 80
 81    g_CrcUpdateT4 = CrcUpdateT4;
 82    g_CrcUpdate = CrcUpdateT4;
 83
 84    #if CRC_NUM_TABLES >= 8
 85      g_CrcUpdateT8 = CrcUpdateT8;
 86  
 87      #ifdef MY_CPU_X86_OR_AMD64
 88      if (!CPU_Is_InOrder())
 89        g_CrcUpdate = CrcUpdateT8;
 90      #endif
 91    #endif
 92
 93  #else
 94  {
 95    #ifndef MY_CPU_BE
 96    UInt32 k = 0x01020304;
 97    const Byte *p = (const Byte *)&k;
 98    if (p[0] == 4 && p[1] == 3)
 99    {
100      g_CrcUpdateT4 = CrcUpdateT4;
101      g_CrcUpdate = CrcUpdateT4;
102      #if CRC_NUM_TABLES >= 8
103      g_CrcUpdateT8 = CrcUpdateT8;
104      // g_CrcUpdate = CrcUpdateT8;
105      #endif
106    }
107    else if (p[0] != 1 || p[1] != 2)
108      g_CrcUpdate = CrcUpdateT1;
109    else
110    #endif
111    {
112      for (i = 256 * CRC_NUM_TABLES - 1; i >= 256; i--)
113      {
114        UInt32 x = g_CrcTable[i - 256];
115        g_CrcTable[i] = CRC_UINT32_SWAP(x);
116      }
117      g_CrcUpdateT4 = CrcUpdateT1_BeT4;
118      g_CrcUpdate = CrcUpdateT1_BeT4;
119      #if CRC_NUM_TABLES >= 8
120      g_CrcUpdateT8 = CrcUpdateT1_BeT8;
121      // g_CrcUpdate = CrcUpdateT1_BeT8;
122      #endif
123    }
124  }
125  #endif
126
127  #endif
128}