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https://github.com/ZDoom/gzdoom.git
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80 lines
1.8 KiB
C
80 lines
1.8 KiB
C
/* XzCrc64.c -- CRC64 calculation
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2023-04-02 : Igor Pavlov : Public domain */
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#include "Precomp.h"
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#include "XzCrc64.h"
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#include "CpuArch.h"
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#define kCrc64Poly UINT64_CONST(0xC96C5795D7870F42)
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#ifdef MY_CPU_LE
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#define CRC64_NUM_TABLES 4
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#else
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#define CRC64_NUM_TABLES 5
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UInt64 Z7_FASTCALL XzCrc64UpdateT1_BeT4(UInt64 v, const void *data, size_t size, const UInt64 *table);
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#endif
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#ifndef MY_CPU_BE
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UInt64 Z7_FASTCALL XzCrc64UpdateT4(UInt64 v, const void *data, size_t size, const UInt64 *table);
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#endif
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typedef UInt64 (Z7_FASTCALL *CRC64_FUNC)(UInt64 v, const void *data, size_t size, const UInt64 *table);
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static CRC64_FUNC g_Crc64Update;
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UInt64 g_Crc64Table[256 * CRC64_NUM_TABLES];
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UInt64 Z7_FASTCALL Crc64Update(UInt64 v, const void *data, size_t size)
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{
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return g_Crc64Update(v, data, size, g_Crc64Table);
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}
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UInt64 Z7_FASTCALL Crc64Calc(const void *data, size_t size)
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{
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return g_Crc64Update(CRC64_INIT_VAL, data, size, g_Crc64Table) ^ CRC64_INIT_VAL;
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}
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void Z7_FASTCALL Crc64GenerateTable(void)
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{
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UInt32 i;
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for (i = 0; i < 256; i++)
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{
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UInt64 r = i;
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unsigned j;
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for (j = 0; j < 8; j++)
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r = (r >> 1) ^ (kCrc64Poly & ((UInt64)0 - (r & 1)));
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g_Crc64Table[i] = r;
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}
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for (i = 256; i < 256 * CRC64_NUM_TABLES; i++)
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{
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const UInt64 r = g_Crc64Table[(size_t)i - 256];
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g_Crc64Table[i] = g_Crc64Table[r & 0xFF] ^ (r >> 8);
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}
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#ifdef MY_CPU_LE
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g_Crc64Update = XzCrc64UpdateT4;
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#else
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{
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#ifndef MY_CPU_BE
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UInt32 k = 1;
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if (*(const Byte *)&k == 1)
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g_Crc64Update = XzCrc64UpdateT4;
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else
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#endif
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{
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for (i = 256 * CRC64_NUM_TABLES - 1; i >= 256; i--)
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{
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const UInt64 x = g_Crc64Table[(size_t)i - 256];
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g_Crc64Table[i] = Z7_BSWAP64(x);
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}
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g_Crc64Update = XzCrc64UpdateT1_BeT4;
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}
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}
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#endif
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}
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#undef kCrc64Poly
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#undef CRC64_NUM_TABLES
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