crc.cpp

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00032 
00033 #include "crc.hpp"
00034 
00035 namespace MaximInterface {
00036 
00037 uint_fast8_t calculateCrc8(uint_fast8_t data, uint_fast8_t crc) {
00038   // See Application Note 27
00039   crc ^= data;
00040   crc &= 0xff;
00041   for (int i = 0; i < 8; i++) {
00042     if (crc & 1) {
00043       crc = (crc >> 1) ^ 0x8c;
00044     } else {
00045       crc = (crc >> 1);
00046     }
00047   }
00048   return crc;
00049 }
00050 
00051 uint_fast8_t calculateCrc8(span<const uint_least8_t> data, uint_fast8_t crc) {
00052   for (span<const uint_least8_t>::index_type i = 0; i < data.size(); ++i) {
00053     crc = calculateCrc8(data[i], crc);
00054   }
00055   return crc;
00056 }
00057 
00058 uint_fast16_t calculateCrc16(uint_fast8_t data, uint_fast16_t crc) {
00059   const uint_least8_t oddparity[] = {0, 1, 1, 0, 1, 0, 0, 1,
00060                                      1, 0, 0, 1, 0, 1, 1, 0};
00061 
00062   uint_fast16_t data16 = (data ^ crc) & 0xff;
00063   crc = (crc >> 8) & 0xff;
00064 
00065   if (oddparity[data16 & 0xf] ^ oddparity[data16 >> 4]) {
00066     crc ^= 0xc001;
00067   }
00068 
00069   data16 <<= 6;
00070   crc ^= data16;
00071   data16 <<= 1;
00072   crc ^= data16;
00073 
00074   return crc;
00075 }
00076 
00077 uint_fast16_t calculateCrc16(span<const uint_least8_t> data,
00078                              uint_fast16_t crc) {
00079   for (span<const uint_least8_t>::index_type i = 0; i < data.size(); ++i) {
00080     crc = calculateCrc16(data[i], crc);
00081   }
00082   return crc;
00083 }
00084 
00085 } // namespace MaximInterface