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/*******************************************************************************
* Copyright (C) Maxim Integrated Products, Inc., All Rights Reserved.
*
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* copy of this software and associated documentation files (the "Software"),
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* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
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* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* OTHER DEALINGS IN THE SOFTWARE.
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* Products, Inc. Branding Policy.
*
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*******************************************************************************/

#include "Crc.hpp"

namespace MaximInterfaceCore {

uint_fast8_t calculateCrc8(uint_fast8_t crc, uint_fast8_t data) {
  // See Application Note 27
  crc = (crc ^ data) & 0xFF;
  for (int i = 0; i < 8; ++i) {
    if (crc & 1) {
      crc = (crc >> 1) ^ 0x8C;
    } else {
      crc = (crc >> 1);
    }
  }
  return crc;
}

uint_fast8_t calculateCrc8(uint_fast8_t crc, span<const uint_least8_t> data) {
  for (span<const uint_least8_t>::index_type i = 0; i < data.size(); ++i) {
    crc = calculateCrc8(crc, data[i]);
  }
  return crc;
}

uint_fast16_t calculateCrc16(uint_fast16_t crc, uint_fast8_t data) {
  static const uint_least8_t oddparity[] = {0, 1, 1, 0, 1, 0, 0, 1,
                                            1, 0, 0, 1, 0, 1, 1, 0};

  uint_fast16_t data16 = (data ^ crc) & 0xFF;
  crc = (crc >> 8) & 0xFF;
  if (oddparity[data16 & 0xF] ^ oddparity[data16 >> 4]) {
    crc ^= 0xC001u;
  }
  data16 <<= 6;
  crc ^= data16;
  data16 <<= 1;
  crc ^= data16;
  return crc;
}

uint_fast16_t calculateCrc16(uint_fast16_t crc,
                             span<const uint_least8_t> data) {
  for (span<const uint_least8_t>::index_type i = 0; i < data.size(); ++i) {
    crc = calculateCrc16(crc, data[i]);
  }
  return crc;
}

} // namespace MaximInterfaceCore