nel/3rdparty/seven_zip/7zCrc.c

   1 /* 7zCrc.c -- CRC32 init
   2 2017-06-06 : 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
  27 typedef UInt32 (MY_FAST_CALL *CRC_FUNC)(UInt32 v, const void *data, size_t size, const UInt32 *table);
  28
  29 CRC_FUNC g_CrcUpdateT4;
  30 CRC_FUNC g_CrcUpdateT8;
  31 CRC_FUNC g_CrcUpdate;
  32
  33 UInt32 g_CrcTable[256 * CRC_NUM_TABLES];
  34
  35 UInt32 MY_FAST_CALL CrcUpdate(UInt32 v, const void *data, size_t size)
  36 {
  37   return g_CrcUpdate(v, data, size, g_CrcTable);
  38 }
  39
  40 UInt32 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
  47 UInt32 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
  56 void 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 & ((UInt32)0 - (r & 1)));
  65     g_CrcTable[i] = r;
  66   }
  67   for (i = 256; i < 256 * CRC_NUM_TABLES; i++)
  68   {
  69     UInt32 r = g_CrcTable[(size_t)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       #endif
  90         g_CrcUpdate = CrcUpdateT8;
  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[(size_t)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 }