rlm@1
|
1 /* 7zCrc.c -- CRC32 calculation
|
rlm@1
|
2 2008-08-05
|
rlm@1
|
3 Igor Pavlov
|
rlm@1
|
4 Public domain */
|
rlm@1
|
5
|
rlm@1
|
6 #include "7zCrc.h"
|
rlm@1
|
7
|
rlm@1
|
8 #define kCrcPoly 0xEDB88320
|
rlm@1
|
9 UInt32 g_CrcTable[256];
|
rlm@1
|
10
|
rlm@1
|
11 void MY_FAST_CALL CrcGenerateTable(void)
|
rlm@1
|
12 {
|
rlm@1
|
13 UInt32 i;
|
rlm@1
|
14 for (i = 0; i < 256; i++)
|
rlm@1
|
15 {
|
rlm@1
|
16 UInt32 r = i;
|
rlm@1
|
17 int j;
|
rlm@1
|
18 for (j = 0; j < 8; j++)
|
rlm@1
|
19 r = (r >> 1) ^ (kCrcPoly & ~((r & 1) - 1));
|
rlm@1
|
20 g_CrcTable[i] = r;
|
rlm@1
|
21 }
|
rlm@1
|
22 }
|
rlm@1
|
23
|
rlm@1
|
24 UInt32 MY_FAST_CALL CrcUpdate(UInt32 v, const void *data, size_t size)
|
rlm@1
|
25 {
|
rlm@1
|
26 const Byte *p = (const Byte *)data;
|
rlm@1
|
27 for (; size > 0 ; size--, p++)
|
rlm@1
|
28 v = CRC_UPDATE_BYTE(v, *p);
|
rlm@1
|
29 return v;
|
rlm@1
|
30 }
|
rlm@1
|
31
|
rlm@1
|
32 UInt32 MY_FAST_CALL CrcCalc(const void *data, size_t size)
|
rlm@1
|
33 {
|
rlm@1
|
34 return CrcUpdate(CRC_INIT_VAL, data, size) ^ 0xFFFFFFFF;
|
rlm@1
|
35 }
|