CRC-16 / TELEDISK

/* 
 * Model: CRC-16 / TELEDISK (16-bit)
 * Poly: 0xA097, Init: 0x0000, XorOut: 0x0000
 * CRC Table C Source Code & Lookup Table Generator
 */
#include <stdint.h>
#include <stddef.h>

const uint16_t crc_table[256] = {
  0x0000, 0xA097, 0xE1B9, 0x412E, 0x63E5, 0xC372, 0x825C, 0x22CB, 
  0xC7CA, 0x675D, 0x2673, 0x86E4, 0xA42F, 0x04B8, 0x4596, 0xE501, 
  0x2F03, 0x8F94, 0xCEBA, 0x6E2D, 0x4CE6, 0xEC71, 0xAD5F, 0x0DC8, 
  0xE8C9, 0x485E, 0x0970, 0xA9E7, 0x8B2C, 0x2BBB, 0x6A95, 0xCA02, 
  0x5E06, 0xFE91, 0xBFBF, 0x1F28, 0x3DE3, 0x9D74, 0xDC5A, 0x7CCD, 
  0x99CC, 0x395B, 0x7875, 0xD8E2, 0xFA29, 0x5ABE, 0x1B90, 0xBB07, 
  0x7105, 0xD192, 0x90BC, 0x302B, 0x12E0, 0xB277, 0xF359, 0x53CE, 
  0xB6CF, 0x1658, 0x5776, 0xF7E1, 0xD52A, 0x75BD, 0x3493, 0x9404, 
  0xBC0C, 0x1C9B, 0x5DB5, 0xFD22, 0xDFE9, 0x7F7E, 0x3E50, 0x9EC7, 
  0x7BC6, 0xDB51, 0x9A7F, 0x3AE8, 0x1823, 0xB8B4, 0xF99A, 0x590D, 
  0x930F, 0x3398, 0x72B6, 0xD221, 0xF0EA, 0x507D, 0x1153, 0xB1C4, 
  0x54C5, 0xF452, 0xB57C, 0x15EB, 0x3720, 0x97B7, 0xD699, 0x760E, 
  0xE20A, 0x429D, 0x03B3, 0xA324, 0x81EF, 0x2178, 0x6056, 0xC0C1, 
  0x25C0, 0x8557, 0xC479, 0x64EE, 0x4625, 0xE6B2, 0xA79C, 0x070B, 
  0xCD09, 0x6D9E, 0x2CB0, 0x8C27, 0xAEEC, 0x0E7B, 0x4F55, 0xEFC2, 
  0x0AC3, 0xAA54, 0xEB7A, 0x4BED, 0x6926, 0xC9B1, 0x889F, 0x2808, 
  0xD88F, 0x7818, 0x3936, 0x99A1, 0xBB6A, 0x1BFD, 0x5AD3, 0xFA44, 
  0x1F45, 0xBFD2, 0xFEFC, 0x5E6B, 0x7CA0, 0xDC37, 0x9D19, 0x3D8E, 
  0xF78C, 0x571B, 0x1635, 0xB6A2, 0x9469, 0x34FE, 0x75D0, 0xD547, 
  0x3046, 0x90D1, 0xD1FF, 0x7168, 0x53A3, 0xF334, 0xB21A, 0x128D, 
  0x8689, 0x261E, 0x6730, 0xC7A7, 0xE56C, 0x45FB, 0x04D5, 0xA442, 
  0x4143, 0xE1D4, 0xA0FA, 0x006D, 0x22A6, 0x8231, 0xC31F, 0x6388, 
  0xA98A, 0x091D, 0x4833, 0xE8A4, 0xCA6F, 0x6AF8, 0x2BD6, 0x8B41, 
  0x6E40, 0xCED7, 0x8FF9, 0x2F6E, 0x0DA5, 0xAD32, 0xEC1C, 0x4C8B, 
  0x6483, 0xC414, 0x853A, 0x25AD, 0x0766, 0xA7F1, 0xE6DF, 0x4648, 
  0xA349, 0x03DE, 0x42F0, 0xE267, 0xC0AC, 0x603B, 0x2115, 0x8182, 
  0x4B80, 0xEB17, 0xAA39, 0x0AAE, 0x2865, 0x88F2, 0xC9DC, 0x694B, 
  0x8C4A, 0x2CDD, 0x6DF3, 0xCD64, 0xEFAF, 0x4F38, 0x0E16, 0xAE81, 
  0x3A85, 0x9A12, 0xDB3C, 0x7BAB, 0x5960, 0xF9F7, 0xB8D9, 0x184E, 
  0xFD4F, 0x5DD8, 0x1CF6, 0xBC61, 0x9EAA, 0x3E3D, 0x7F13, 0xDF84, 
  0x1586, 0xB511, 0xF43F, 0x54A8, 0x7663, 0xD6F4, 0x97DA, 0x374D, 
  0xD24C, 0x72DB, 0x33F5, 0x9362, 0xB1A9, 0x113E, 0x5010, 0xF087
};

uint16_t calculate_crc(const uint8_t *data, size_t length) {
    uint16_t crc = 0x0000;
    for (size_t i = 0; i < length; i++) {
        #if 0
        uint8_t idx = (uint8_t)(crc ^ data[i]);
        crc = (crc >> 8) ^ crc_table[idx];
        #else
        uint8_t idx = (uint8_t)((crc >> 8) ^ data[i]);
        crc = (crc << 8) ^ crc_table[idx];
        #endif
    }
    return crc ^ 0x0000;
}