1 /* 7zCrc.c -- CRC32 init
2 2013-11-12 : 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_X86_OR_AMD64
12 #define CRC_NUM_TABLES 8
13 UInt32 MY_FAST_CALL CrcUpdateT8(UInt32 v, const void *data, size_t size, const UInt32 *table);
14 #elif defined(MY_CPU_LE)
15 #define CRC_NUM_TABLES 4
16 #else
17 #define CRC_NUM_TABLES 5
18 #define CRC_UINT32_SWAP(v) ((v >> 24) | ((v >> 8) & 0xFF00) | ((v << 8) & 0xFF0000) | (v << 24))
19 UInt32 MY_FAST_CALL CrcUpdateT1_BeT4(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 #endif
25
26 typedef UInt32 (MY_FAST_CALL *CRC_FUNC)(UInt32 v, const void *data, size_t size, const UInt32 *table);
27
28 CRC_FUNC g_CrcUpdate;
29 UInt32 g_CrcTable[256 * CRC_NUM_TABLES];
30
CrcUpdate(UInt32 v,const void * data,size_t size)31 UInt32 MY_FAST_CALL CrcUpdate(UInt32 v, const void *data, size_t size)
32 {
33 return g_CrcUpdate(v, data, size, g_CrcTable);
34 }
35
CrcCalc(const void * data,size_t size)36 UInt32 MY_FAST_CALL CrcCalc(const void *data, size_t size)
37 {
38 return g_CrcUpdate(CRC_INIT_VAL, data, size, g_CrcTable) ^ CRC_INIT_VAL;
39 }
40
CrcGenerateTable()41 void MY_FAST_CALL CrcGenerateTable()
42 {
43 UInt32 i;
44 for (i = 0; i < 256; i++)
45 {
46 UInt32 r = i;
47 unsigned j;
48 for (j = 0; j < 8; j++)
49 r = (r >> 1) ^ (kCrcPoly & ~((r & 1) - 1));
50 g_CrcTable[i] = r;
51 }
52 for (; i < 256 * CRC_NUM_TABLES; i++)
53 {
54 UInt32 r = g_CrcTable[i - 256];
55 g_CrcTable[i] = g_CrcTable[r & 0xFF] ^ (r >> 8);
56 }
57
58 #ifdef MY_CPU_LE
59
60 g_CrcUpdate = CrcUpdateT4;
61
62 #if CRC_NUM_TABLES == 8
63 if (!CPU_Is_InOrder())
64 g_CrcUpdate = CrcUpdateT8;
65 #endif
66
67 #else
68 {
69 #ifndef MY_CPU_BE
70 UInt32 k = 1;
71 if (*(const Byte *)&k == 1)
72 g_CrcUpdate = CrcUpdateT4;
73 else
74 #endif
75 {
76 for (i = 256 * CRC_NUM_TABLES - 1; i >= 256; i--)
77 {
78 UInt32 x = g_CrcTable[i - 256];
79 g_CrcTable[i] = CRC_UINT32_SWAP(x);
80 }
81 g_CrcUpdate = CrcUpdateT1_BeT4;
82 }
83 }
84 #endif
85 }
86