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//
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// Created by MightyPork on 2018/02/01.
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//
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#include "platform.h"
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#define OW_INTERNAL
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#include "_ow_checksum.h"
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static inline uint8_t crc8_bits(uint8_t data)
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{
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uint8_t crc = 0;
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if(data & 1) crc ^= 0x5e;
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if(data & 2) crc ^= 0xbc;
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if(data & 4) crc ^= 0x61;
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if(data & 8) crc ^= 0xc2;
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if(data & 0x10) crc ^= 0x9d;
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if(data & 0x20) crc ^= 0x23;
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if(data & 0x40) crc ^= 0x46;
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if(data & 0x80) crc ^= 0x8c;
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return crc;
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}
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static uint8_t crc8_add(uint8_t cksum, uint8_t byte)
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{
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return crc8_bits(byte ^ cksum);
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}
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uint8_t ow_checksum(const uint8_t *buff, uint32_t len)
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{
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uint8_t cksum = 0;
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for(uint32_t i = 0; i < len; i++) {
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cksum = crc8_add(cksum, buff[i]);
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}
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return cksum;
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}
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