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1 /* please read copyright-notice at EOF */ |
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2 |
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3 #include <stdint.h> |
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4 |
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5 #define CRC8INIT 0x00 |
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6 #define CRC8POLY 0x18 //0X18 = X^8+X^5+X^4+X^0 |
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7 |
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8 uint8_t crc8( uint8_t *data, uint16_t number_of_bytes_in_data ) |
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9 { |
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10 uint8_t crc; |
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11 uint16_t loop_count; |
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12 uint8_t bit_counter; |
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13 uint8_t b; |
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14 uint8_t feedback_bit; |
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15 |
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16 crc = CRC8INIT; |
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17 |
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18 for (loop_count = 0; loop_count != number_of_bytes_in_data; loop_count++) |
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19 { |
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20 b = data[loop_count]; |
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21 |
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22 bit_counter = 8; |
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23 do { |
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24 feedback_bit = (crc ^ b) & 0x01; |
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25 |
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26 if ( feedback_bit == 0x01 ) { |
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27 crc = crc ^ CRC8POLY; |
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28 } |
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29 crc = (crc >> 1) & 0x7F; |
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30 if ( feedback_bit == 0x01 ) { |
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31 crc = crc | 0x80; |
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32 } |
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33 |
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34 b = b >> 1; |
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35 bit_counter--; |
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36 |
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37 } while (bit_counter > 0); |
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38 } |
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39 |
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40 return crc; |
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41 } |
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42 |
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43 /* |
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44 This code is from Colin O'Flynn - Copyright (c) 2002 |
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45 only minor changes by M.Thomas 9/2004 |
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46 |
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47 Permission is hereby granted, free of charge, to any person obtaining a copy of |
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48 this software and associated documentation files (the "Software"), to deal in |
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49 the Software without restriction, including without limitation the rights to |
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50 use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of |
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51 the Software, and to permit persons to whom the Software is furnished to do so, |
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52 subject to the following conditions: |
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53 |
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54 The above copyright notice and this permission notice shall be included in all |
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55 copies or substantial portions of the Software. |
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56 |
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57 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
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58 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS |
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59 FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR |
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60 COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER |
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61 IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN |
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62 CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
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63 */ |
