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https://github.com/dborth/vbagx.git
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77 lines
1.5 KiB
C
77 lines
1.5 KiB
C
/* 7zCrc.c */
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#include "7zCrc.h"
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#define kCrcPoly 0xEDB88320
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UInt32 g_CrcTable[256];
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void InitCrcTable()
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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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UInt32 r = i;
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int j;
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for (j = 0; j < 8; j++)
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if (r & 1)
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r = (r >> 1) ^ kCrcPoly;
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else
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r >>= 1;
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g_CrcTable[i] = r;
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}
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}
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void CrcInit(UInt32 *crc) { *crc = 0xFFFFFFFF; }
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UInt32 CrcGetDigest(UInt32 *crc) { return *crc ^ 0xFFFFFFFF; }
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void CrcUpdateByte(UInt32 *crc, Byte b)
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{
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*crc = g_CrcTable[((Byte)(*crc)) ^ b] ^ (*crc >> 8);
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}
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void CrcUpdateUInt16(UInt32 *crc, UInt16 v)
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{
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CrcUpdateByte(crc, (Byte)v);
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CrcUpdateByte(crc, (Byte)(v >> 8));
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}
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void CrcUpdateUInt32(UInt32 *crc, UInt32 v)
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{
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int i;
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for (i = 0; i < 4; i++)
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CrcUpdateByte(crc, (Byte)(v >> (8 * i)));
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}
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void CrcUpdateUInt64(UInt32 *crc, UInt64 v)
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{
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int i;
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for (i = 0; i < 8; i++)
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{
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CrcUpdateByte(crc, (Byte)(v));
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v >>= 8;
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}
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}
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void CrcUpdate(UInt32 *crc, const void *data, size_t size)
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{
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UInt32 v = *crc;
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const Byte *p = (const Byte *)data;
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for (; size > 0 ; size--, p++)
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v = g_CrcTable[((Byte)(v)) ^ *p] ^ (v >> 8);
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*crc = v;
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}
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UInt32 CrcCalculateDigest(const void *data, size_t size)
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{
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UInt32 crc;
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CrcInit(&crc);
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CrcUpdate(&crc, data, size);
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return CrcGetDigest(&crc);
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}
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int CrcVerifyDigest(UInt32 digest, const void *data, size_t size)
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{
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return (CrcCalculateDigest(data, size) == digest);
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}
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