release/src-rt-6.x/linux/linux-2.6/scripts/squashfs/lzma/C/7zip/Archive/7z_C/7zCrc.c

   1 /* 7zCrc.c */
   2
   3 #include "7zCrc.h"
   4
   5 #define kCrcPoly 0xEDB88320
   6
   7 UInt32 g_CrcTable[256];
   8
   9 void InitCrcTable()
  10 {
  11   UInt32 i;
  12   for (i = 0; i < 256; i++)
  13   {
  14     UInt32 r = i;
  15     int j;
  16     for (j = 0; j < 8; j++)
  17       if (r & 1)
  18         r = (r >> 1) ^ kCrcPoly;
  19       else
  20         r >>= 1;
  21     g_CrcTable[i] = r;
  22   }
  23 }
  24
  25 void CrcInit(UInt32 *crc) { *crc = 0xFFFFFFFF; }
  26 UInt32 CrcGetDigest(UInt32 *crc) { return *crc ^ 0xFFFFFFFF; }
  27
  28 void CrcUpdateByte(UInt32 *crc, Byte b)
  29 {
  30   *crc = g_CrcTable[((Byte)(*crc)) ^ b] ^ (*crc >> 8);
  31 }
  32
  33 void CrcUpdateUInt16(UInt32 *crc, UInt16 v)
  34 {
  35   CrcUpdateByte(crc, (Byte)v);
  36   CrcUpdateByte(crc, (Byte)(v >> 8));
  37 }
  38
  39 void CrcUpdateUInt32(UInt32 *crc, UInt32 v)
  40 {
  41   int i;
  42   for (i = 0; i < 4; i++)
  43     CrcUpdateByte(crc, (Byte)(v >> (8 * i)));
  44 }
  45
  46 void CrcUpdateUInt64(UInt32 *crc, UInt64 v)
  47 {
  48   int i;
  49   for (i = 0; i < 8; i++)
  50   {
  51     CrcUpdateByte(crc, (Byte)(v));
  52     v >>= 8;
  53   }
  54 }
  55
  56 void CrcUpdate(UInt32 *crc, const void *data, size_t size)
  57 {
  58   UInt32 v = *crc;
  59   const Byte *p = (const Byte *)data;
  60   for (; size > 0 ; size--, p++)
  61     v = g_CrcTable[((Byte)(v)) ^ *p] ^ (v >> 8);
  62   *crc = v;
  63 }
  64
  65 UInt32 CrcCalculateDigest(const void *data, size_t size)
  66 {
  67   UInt32 crc;
  68   CrcInit(&crc);
  69   CrcUpdate(&crc, data, size);
  70   return CrcGetDigest(&crc);
  71 }
  72
  73 int CrcVerifyDigest(UInt32 digest, const void *data, size_t size)
  74 {
  75   return (CrcCalculateDigest(data, size) == digest);
  76 }