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![Sergey Lipskiy](/assets/img/avatar_default.png)
* type cast fixes * signed/unsigned fixes * code formatting fixes * class members initialization fixes
67 lines
1.3 KiB
C++
67 lines
1.3 KiB
C++
#include "CRC.h"
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#define CRC32_POLYNOMIAL 0x04C11DB7U
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static unsigned int CRCTable[ 256 ];
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static
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u32 Reflect( u32 ref, u32 ch )
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{
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u32 value = 0;
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// Swap bit 0 for bit 7
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// bit 1 for bit 6, etc.
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for (u32 i = 1; i < (ch + 1); ++i) {
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if(ref & 1)
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value |= 1 << (ch - i);
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ref >>= 1;
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}
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return value;
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}
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void CRC_Init()
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{
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u32 crc;
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for (u32 i = 0; i < 256; ++i) {
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crc = Reflect( i, 8U ) << 24U;
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for (int j = 0; j < 8; ++j)
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crc = (crc << 1U) ^ (crc & (1U << 31U) ? CRC32_POLYNOMIAL : 0U);
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CRCTable[i] = Reflect( crc, 32U );
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}
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}
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u64 CRC_Calculate( u64 crc, const void * buffer, u32 count )
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{
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u32 crc32 = static_cast<u32>(crc);
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u32 orig = crc32;
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const u8 *p = reinterpret_cast<const u8*>(buffer);
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while (count--)
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crc32 = (crc32 >> 8) ^ CRCTable[(crc32 & 0xFF) ^ *p++];
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return crc32 ^ orig;
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}
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u32 CRC_Calculate_Strict( u32 crc, const void * buffer, u32 count )
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{
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return static_cast<u32>(CRC_Calculate(crc, buffer, count));
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}
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u64 CRC_CalculatePalette(u64 crc, const void * buffer, u32 count )
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{
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u32 crc32 = static_cast<u32>(crc);
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u32 orig = crc32;
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const u8 *p = reinterpret_cast<const u8*>(buffer);
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while (count--) {
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crc32 = (crc32 >> 8) ^ CRCTable[(crc32 & 0xFF) ^ *p++];
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crc32 = (crc32 >> 8) ^ CRCTable[(crc32 & 0xFF) ^ *p++];
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p += 6;
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}
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return crc32 ^ orig;
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}
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