Subversion Repositories HomeAutomation

Rev

Blame | Last modification | View Log | SVN | RSS feed

  1. /* please read copyright-notice at EOF */
  2.  
  3. #include <inttypes.h>
  4. #include "eeprom_crc8.h"
  5. #define CRC8INIT    0x00
  6. #define CRC8POLY    0x18              //0X18 = X^8+X^5+X^4+X^0
  7.  
  8. uint8_t eeprom_crc8 ( uint8_t *data_in, uint16_t number_of_bytes_to_read )
  9. {
  10.     uint8_t  crc;
  11.     uint16_t loop_count;
  12.     uint8_t  bit_counter;
  13.     uint8_t  data;
  14.     uint8_t  feedback_bit;
  15.    
  16.     crc = CRC8INIT;
  17.  
  18.     for (loop_count = 0; loop_count != number_of_bytes_to_read; loop_count++)
  19.     {
  20.         data = eeprom_read_byte(&data_in[loop_count]);
  21.        
  22.         bit_counter = 8;
  23.         do {
  24.             feedback_bit = (crc ^ data) & 0x01;
  25.    
  26.             if ( feedback_bit == 0x01 ) {
  27.                 crc = crc ^ CRC8POLY;
  28.             }
  29.             crc = (crc >> 1) & 0x7F;
  30.             if ( feedback_bit == 0x01 ) {
  31.                 crc = crc | 0x80;
  32.             }
  33.        
  34.             data = data >> 1;
  35.             bit_counter--;
  36.        
  37.         } while (bit_counter > 0);
  38.     }
  39.    
  40.     return crc;
  41. }
  42.  
  43. /*
  44. This code is from Colin O'Flynn - Copyright (c) 2002
  45. only minor changes by M.Thomas 9/2004
  46.  
  47. Permission is hereby granted, free of charge, to any person obtaining a copy of
  48. this software and associated documentation files (the "Software"), to deal in
  49. the Software without restriction, including without limitation the rights to
  50. use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
  51. the Software, and to permit persons to whom the Software is furnished to do so,
  52. subject to the following conditions:
  53.  
  54. The above copyright notice and this permission notice shall be included in all
  55. copies or substantial portions of the Software.
  56.  
  57. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  58. IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
  59. FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
  60. COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
  61. IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  62. CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  63. */
  64.