1/* 7zCrc.c -- CRC32 init
22010-12-01 : Igor Pavlov : Public domain */
3
4#include "7zCrc.h"
5#include "CpuArch.h"
6
7#define kCrcPoly 0xEDB88320
8
9#ifdef MY_CPU_X86_OR_AMD64
10 #define CRC_NUM_TABLES 8
11 UInt32 MY_FAST_CALL CrcUpdateT8(UInt32 v, const void *data, size_t size, const UInt32 *table);
12#elif defined(MY_CPU_LE)
13 #define CRC_NUM_TABLES 4
14#else
15 #define CRC_NUM_TABLES 5
16 #define CRC_UINT32_SWAP(v) ((v >> 24) | ((v >> 8) & 0xFF00) | ((v << 8) & 0xFF0000) | (v << 24))
17 UInt32 MY_FAST_CALL CrcUpdateT1_BeT4(UInt32 v, const void *data, size_t size, const UInt32 *table);
18#endif
19
20#ifndef MY_CPU_BE
21 UInt32 MY_FAST_CALL CrcUpdateT4(UInt32 v, const void *data, size_t size, const UInt32 *table);
22#endif
23
24typedef UInt32 (MY_FAST_CALL *CRC_FUNC)(UInt32 v, const void *data, size_t size, const UInt32 *table);
25
26static CRC_FUNC g_CrcUpdate;
27UInt32 g_CrcTable[256 * CRC_NUM_TABLES];
28
29UInt32 MY_FAST_CALL CrcUpdate(UInt32 v, const void *data, size_t size)
30{
31 return g_CrcUpdate(v, data, size, g_CrcTable);
32}
33
34UInt32 MY_FAST_CALL CrcCalc(const void *data, size_t size)
35{
36 return g_CrcUpdate(CRC_INIT_VAL, data, size, g_CrcTable) ^ CRC_INIT_VAL;
37}
38
39void MY_FAST_CALL CrcGenerateTable()
40{
41 UInt32 i;
42 for (i = 0; i < 256; i++)
43 {
44 UInt32 r = i;
45 unsigned j;
46 for (j = 0; j < 8; j++)
47 r = (r >> 1) ^ (kCrcPoly & ~((r & 1) - 1));
48 g_CrcTable[i] = r;
49 }
50 for (; i < 256 * CRC_NUM_TABLES; i++)
51 {
52 UInt32 r = g_CrcTable[i - 256];
53 g_CrcTable[i] = g_CrcTable[r & 0xFF] ^ (r >> 8);
54 }
55
56 #ifdef MY_CPU_LE
57
58 g_CrcUpdate = CrcUpdateT4;
59
60 #if CRC_NUM_TABLES == 8
61 if (!CPU_Is_InOrder())
62 g_CrcUpdate = CrcUpdateT8;
63 #endif
64
65 #else
66 {
67 #ifndef MY_CPU_BE
68 UInt32 k = 1;
69 if (*(const Byte *)&k == 1)
70 g_CrcUpdate = CrcUpdateT4;
71 else
72 #endif
73 {
74 for (i = 256 * CRC_NUM_TABLES - 1; i >= 256; i--)
75 {
76 UInt32 x = g_CrcTable[i - 256];
77 g_CrcTable[i] = CRC_UINT32_SWAP(x);
78 }
79 g_CrcUpdate = CrcUpdateT1_BeT4;
80 }
81 }
82 #endif
83}
84