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41 lines
722 B
C
41 lines
722 B
C
unsigned short crc16(unsigned char *buf, unsigned char len)
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{
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register unsigned char crc_lo, crc_hi, byte;
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crc_lo = 0xFF;
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crc_hi = 0xFF;
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while (len--)
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{
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byte = *(buf++);
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byte ^= crc_hi;
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crc_hi = ( byte & 0x02 ) ? (crc_lo - 0x80) : crc_lo;
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if ( byte & 0x01 )
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crc_hi ^= 0xC0;
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crc_lo = byte;
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crc_lo >>= 1;
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crc_lo ^= byte;
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crc_lo >>= 1;
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byte ^= crc_lo;
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if ( byte & 0x08 )
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--byte;
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if ( byte & 0x40 )
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--byte;
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byte &= 0x01;
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if ( byte )
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crc_lo ^= 0xC0;
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crc_hi ^= byte;
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}
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return (unsigned short)(((unsigned short)crc_hi << 8) | crc_lo);
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}
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