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## Elixir Cross Referencer

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122``` ```/* * Copyright (c) 2017 Intel Corporation. * * SPDX-License-Identifier: Apache-2.0 */ /** @file * @brief CRC 16 computation function */ #ifndef __CRC16_H #define __CRC16_H #include #include #include #ifdef __cplusplus extern "C" { #endif /** * @defgroup checksum Checksum */ /** * @defgroup crc16 CRC 16 * @ingroup checksum * @{ */ /** * @brief Generic function for computing CRC 16 * * Compute CRC 16 by passing in the address of the input, the input length * and polynomial used in addition to the initial value. * * @param src Input bytes for the computation * @param len Length of the input in bytes * @param polynomial The polynomial to use omitting the leading x^16 * coefficient * @param initial_value Initial value for the CRC computation * @param pad Adds padding with zeros at the end of input bytes * * @return The computed CRC16 value */ u16_t crc16(const u8_t *src, size_t len, u16_t polynomial, u16_t initial_value, bool pad); /** * @brief Compute the CRC-16/CCITT checksum of a buffer. * * See ITU-T Recommendation V.41 (November 1988). Uses 0x1021 as the * polynomial, reflects the input, and reflects the output. * * To calculate the CRC across non-contiguous blocks use the return * value from block N-1 as the seed for block N. * * For CRC-16/CCITT, use 0 as the initial seed. Other checksums in * the same family can be calculated by changing the seed and/or * XORing the final value. Examples include: * * - X-25 (used in PPP): seed=0xffff, xor=0xffff, residual=0xf0b8 * * @note API changed in Zephyr 1.11. * * @param seed Value to seed the CRC with * @param src Input bytes for the computation * @param len Length of the input in bytes * * @return The computed CRC16 value */ u16_t crc16_ccitt(u16_t seed, const u8_t *src, size_t len); /** * @brief Compute the CRC-16/XMODEM checksum of a buffer. * * The MSB first version of ITU-T Recommendation V.41 (November 1988). * Uses 0x1021 as the polynomial with no reflection. * * To calculate the CRC across non-contiguous blocks use the return * value from block N-1 as the seed for block N. * * For CRC-16/XMODEM, use 0 as the initial seed. Other checksums in * the same family can be calculated by changing the seed and/or * XORing the final value. Examples include: * * - CCIITT-FALSE: seed=0xffff * - GSM: seed=0, xorout=0xffff, residue=0x1d0f * * @param seed Value to seed the CRC with * @param src Input bytes for the computation * @param len Length of the input in bytes * * @return The computed CRC16 value */ u16_t crc16_itu_t(u16_t seed, const u8_t *src, size_t len); /** * @brief Compute ANSI variant of CRC 16 * * ANSI variant of CRC 16 is using 0x8005 as its polynomial with the initial * value set to 0xffff. * * @param src Input bytes for the computation * @param len Length of the input in bytes * * @return The computed CRC16 value */ static inline u16_t crc16_ansi(const u8_t *src, size_t len) { return crc16(src, len, 0x8005, 0xffff, true); } /** * @} */ #ifdef __cplusplus } #endif #endif ```