/* 7zCrc.c -- CRC32 init | |
2013-11-12 : Igor Pavlov : Public domain */ | |
#include "Precomp.h" | |
#include "7zCrc.h" | |
#include "CpuArch.h" | |
#define kCrcPoly 0xEDB88320 | |
#ifdef MY_CPU_X86_OR_AMD64 | |
#define CRC_NUM_TABLES 8 | |
UInt32 MY_FAST_CALL CrcUpdateT8(UInt32 v, const void *data, size_t size, const UInt32 *table); | |
#elif defined(MY_CPU_LE) | |
#define CRC_NUM_TABLES 4 | |
#else | |
#define CRC_NUM_TABLES 5 | |
#define CRC_UINT32_SWAP(v) ((v >> 24) | ((v >> 8) & 0xFF00) | ((v << 8) & 0xFF0000) | (v << 24)) | |
UInt32 MY_FAST_CALL CrcUpdateT1_BeT4(UInt32 v, const void *data, size_t size, const UInt32 *table); | |
#endif | |
#ifndef MY_CPU_BE | |
UInt32 MY_FAST_CALL CrcUpdateT4(UInt32 v, const void *data, size_t size, const UInt32 *table); | |
#endif | |
typedef UInt32 (MY_FAST_CALL *CRC_FUNC)(UInt32 v, const void *data, size_t size, const UInt32 *table); | |
CRC_FUNC g_CrcUpdate; | |
UInt32 g_CrcTable[256 * CRC_NUM_TABLES]; | |
UInt32 MY_FAST_CALL CrcUpdate(UInt32 v, const void *data, size_t size) | |
{ | |
return g_CrcUpdate(v, data, size, g_CrcTable); | |
} | |
UInt32 MY_FAST_CALL CrcCalc(const void *data, size_t size) | |
{ | |
return g_CrcUpdate(CRC_INIT_VAL, data, size, g_CrcTable) ^ CRC_INIT_VAL; | |
} | |
void MY_FAST_CALL CrcGenerateTable() | |
{ | |
UInt32 i; | |
for (i = 0; i < 256; i++) | |
{ | |
UInt32 r = i; | |
unsigned j; | |
for (j = 0; j < 8; j++) | |
r = (r >> 1) ^ (kCrcPoly & ~((r & 1) - 1)); | |
g_CrcTable[i] = r; | |
} | |
for (; i < 256 * CRC_NUM_TABLES; i++) | |
{ | |
UInt32 r = g_CrcTable[i - 256]; | |
g_CrcTable[i] = g_CrcTable[r & 0xFF] ^ (r >> 8); | |
} | |
#ifdef MY_CPU_LE | |
g_CrcUpdate = CrcUpdateT4; | |
#if CRC_NUM_TABLES == 8 | |
if (!CPU_Is_InOrder()) | |
g_CrcUpdate = CrcUpdateT8; | |
#endif | |
#else | |
{ | |
#ifndef MY_CPU_BE | |
UInt32 k = 1; | |
if (*(const Byte *)&k == 1) | |
g_CrcUpdate = CrcUpdateT4; | |
else | |
#endif | |
{ | |
for (i = 256 * CRC_NUM_TABLES - 1; i >= 256; i--) | |
{ | |
UInt32 x = g_CrcTable[i - 256]; | |
g_CrcTable[i] = CRC_UINT32_SWAP(x); | |
} | |
g_CrcUpdate = CrcUpdateT1_BeT4; | |
} | |
} | |
#endif | |
} |