Tektronix DPO/MSO2000 calibration data checksum calculation

                    // read first two byte -> stored checksum
    fread(u16ChecksumStored,2,1,calFileHandler);
    u32Mod7Counter = 0;
                    // read until the end of file
    while (sVar2 = fread(u8ReadBuffer,1,1,calFileHandler), sVar2 == 1) {
      u32Mod7 = u32Mod7Counter & 0b00000111;
      u32Mod7Counter = u32Mod7Counter + 1;
      u32SumAccumulator =
           u32SumAccumulator +
           (u8ReadBuffer[0] << u32Mod7) + (u8ReadBuffer[0] >> (7 - u32Mod7 & 0b00111111));
    }
                    // cast to uint16_t
    *u16ChecksumCalculated = u32SumAccumulator._2_2_;
    if (*u16ChecksumCalculated == *u16ChecksumStored) {
      isChecksumMatch = 1;
    }
    else {
      isChecksumMatch = 0;
    }
  }
  return isChecksumMatch;