text: /**
  * Copyright © 2021 Dalelven Produktutveckling AB
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the “Software”), to deal
  * in the Software without restriction, including without limitation the rights
  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  * copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
  * IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  */
  
  #pragma once
  
  #include "etl/span.h"
  
  #include <cstdint>
  
  namespace poly::crc
  {
  struct crc16_ccitt
  {
      uint16_t state_ = 0xFFFF;
      crc16_ccitt() = default;
      crc16_ccitt(uint16_t start_state): state_(start_state) {}
      crc16_ccitt operator()(uint8_t data) const
      {
          data ^= state_ & 0xFF;
          data ^= data << 4;
  
          uint32_t retval = ((((uint32_t)data << 8) | ((state_ & 0xFF00) >> 8))
                               ^ (unsigned char)(data >> 4)
                               ^ ((uint32_t)data << 3));
          return retval & 0x0000'FFFFu;
      }
  
      uint16_t crc() const {
          return state_;
      }
  };
  template<class Algorithm>
  Algorithm calculate(etl::span<const uint8_t> data, Algorithm crc = Algorithm{})
  {
      for(auto b: data) {
          crc = crc(b);
      }
      return crc;
  }
  }
  