Analog Devices / platform_drivers

Platform drivers for Mbed.

Dependents:   EVAL-CN0535-FMCZ EVAL-CN0535-FMCZ EVAL-AD568x-AD569x EVAL-AD7606 ... more

src/crc16.c@16:61ad39564f45, 2021-03-19 (annotated)

Committer:
mahphalke
Date:
Fri Mar 19 12:10:16 2021 +0530
Revision:
16:61ad39564f45
Parent:
11:a2dcf0ebb5b5 
Added uart changes

Who changed what in which revision?

UserRevisionLine numberNew contents of line
Mahesh Phalke 11:a2dcf0ebb5b5 1 /***************************************************************************//**
Mahesh Phalke 11:a2dcf0ebb5b5 2 * @file crc16.c
Mahesh Phalke 11:a2dcf0ebb5b5 3 * @brief Source file of CRC-16 computation.
Mahesh Phalke 11:a2dcf0ebb5b5 4 * @author Darius Berghe (darius.berghe@analog.com)
Mahesh Phalke 11:a2dcf0ebb5b5 5 ********************************************************************************
Mahesh Phalke 11:a2dcf0ebb5b5 6 * Copyright 2020(c) Analog Devices, Inc.
Mahesh Phalke 11:a2dcf0ebb5b5 7 *
Mahesh Phalke 11:a2dcf0ebb5b5 8 * All rights reserved.
Mahesh Phalke 11:a2dcf0ebb5b5 9 *
Mahesh Phalke 11:a2dcf0ebb5b5 10 * Redistribution and use in source and binary forms, with or without
Mahesh Phalke 11:a2dcf0ebb5b5 11 * modification, are permitted provided that the following conditions are met:
Mahesh Phalke 11:a2dcf0ebb5b5 12 * - Redistributions of source code must retain the above copyright
Mahesh Phalke 11:a2dcf0ebb5b5 13 * notice, this list of conditions and the following disclaimer.
Mahesh Phalke 11:a2dcf0ebb5b5 14 * - Redistributions in binary form must reproduce the above copyright
Mahesh Phalke 11:a2dcf0ebb5b5 15 * notice, this list of conditions and the following disclaimer in
Mahesh Phalke 11:a2dcf0ebb5b5 16 * the documentation and/or other materials provided with the
Mahesh Phalke 11:a2dcf0ebb5b5 17 * distribution.
Mahesh Phalke 11:a2dcf0ebb5b5 18 * - Neither the name of Analog Devices, Inc. nor the names of its
Mahesh Phalke 11:a2dcf0ebb5b5 19 * contributors may be used to endorse or promote products derived
Mahesh Phalke 11:a2dcf0ebb5b5 20 * from this software without specific prior written permission.
Mahesh Phalke 11:a2dcf0ebb5b5 21 * - The use of this software may or may not infringe the patent rights
Mahesh Phalke 11:a2dcf0ebb5b5 22 * of one or more patent holders. This license does not release you
Mahesh Phalke 11:a2dcf0ebb5b5 23 * from the requirement that you obtain separate licenses from these
Mahesh Phalke 11:a2dcf0ebb5b5 24 * patent holders to use this software.
Mahesh Phalke 11:a2dcf0ebb5b5 25 * - Use of the software either in source or binary form, must be run
Mahesh Phalke 11:a2dcf0ebb5b5 26 * on or directly connected to an Analog Devices Inc. component.
Mahesh Phalke 11:a2dcf0ebb5b5 27 *
Mahesh Phalke 11:a2dcf0ebb5b5 28 * THIS SOFTWARE IS PROVIDED BY ANALOG DEVICES "AS IS" AND ANY EXPRESS OR
Mahesh Phalke 11:a2dcf0ebb5b5 29 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, NON-INFRINGEMENT,
Mahesh Phalke 11:a2dcf0ebb5b5 30 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
Mahesh Phalke 11:a2dcf0ebb5b5 31 * IN NO EVENT SHALL ANALOG DEVICES BE LIABLE FOR ANY DIRECT, INDIRECT,
Mahesh Phalke 11:a2dcf0ebb5b5 32 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
Mahesh Phalke 11:a2dcf0ebb5b5 33 * LIMITED TO, INTELLECTUAL PROPERTY RIGHTS, PROCUREMENT OF SUBSTITUTE GOODS OR
Mahesh Phalke 11:a2dcf0ebb5b5 34 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
Mahesh Phalke 11:a2dcf0ebb5b5 35 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
Mahesh Phalke 11:a2dcf0ebb5b5 36 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
Mahesh Phalke 11:a2dcf0ebb5b5 37 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Mahesh Phalke 11:a2dcf0ebb5b5 38 *******************************************************************************/
Mahesh Phalke 11:a2dcf0ebb5b5 39 #include "crc16.h"
Mahesh Phalke 11:a2dcf0ebb5b5 40
Mahesh Phalke 11:a2dcf0ebb5b5 41 /***************************************************************************//**
Mahesh Phalke 11:a2dcf0ebb5b5 42 * @brief Creates the CRC-16 lookup table for a given polynomial.
Mahesh Phalke 11:a2dcf0ebb5b5 43 *
Mahesh Phalke 11:a2dcf0ebb5b5 44 * @param table - Pointer to a CRC-16 lookup table to write to.
Mahesh Phalke 11:a2dcf0ebb5b5 45 * @param polynomial - msb-first representation of desired polynomial.
Mahesh Phalke 11:a2dcf0ebb5b5 46 *
Mahesh Phalke 11:a2dcf0ebb5b5 47 * Polynomials in CRC algorithms are typically represented as shown below.
Mahesh Phalke 11:a2dcf0ebb5b5 48 *
Mahesh Phalke 11:a2dcf0ebb5b5 49 * poly = x^16 + x^14 + x^13 + x^12 + x^10 + x^8 + x^6 + x^4 + x^3 +
Mahesh Phalke 11:a2dcf0ebb5b5 50 * x^1 + 1
Mahesh Phalke 11:a2dcf0ebb5b5 51 *
Mahesh Phalke 11:a2dcf0ebb5b5 52 * Using msb-first direction, x^15 maps to the msb.
Mahesh Phalke 11:a2dcf0ebb5b5 53 *
Mahesh Phalke 11:a2dcf0ebb5b5 54 * msb first: poly = (1)0111010101011011 = 0xBAAD
Mahesh Phalke 11:a2dcf0ebb5b5 55 * ^
Mahesh Phalke 11:a2dcf0ebb5b5 56 *
Mahesh Phalke 11:a2dcf0ebb5b5 57 * @return None.
Mahesh Phalke 11:a2dcf0ebb5b5 58 *******************************************************************************/
Mahesh Phalke 11:a2dcf0ebb5b5 59 void crc16_populate_msb(uint16_t * table, const uint16_t polynomial)
Mahesh Phalke 11:a2dcf0ebb5b5 60 {
Mahesh Phalke 11:a2dcf0ebb5b5 61 if (!table)
Mahesh Phalke 11:a2dcf0ebb5b5 62 return;
Mahesh Phalke 11:a2dcf0ebb5b5 63
Mahesh Phalke 11:a2dcf0ebb5b5 64 for (int16_t n = 0; n < CRC16_TABLE_SIZE; n++) {
Mahesh Phalke 11:a2dcf0ebb5b5 65 uint16_t currByte = (uint16_t)(n << 8);
Mahesh Phalke 11:a2dcf0ebb5b5 66 for (uint8_t bit = 0; bit < 8; bit++) {
Mahesh Phalke 11:a2dcf0ebb5b5 67 if ((currByte & 0x8000) != 0) {
Mahesh Phalke 11:a2dcf0ebb5b5 68 currByte <<= 1;
Mahesh Phalke 11:a2dcf0ebb5b5 69 currByte ^= polynomial;
Mahesh Phalke 11:a2dcf0ebb5b5 70 } else {
Mahesh Phalke 11:a2dcf0ebb5b5 71 currByte <<= 1;
Mahesh Phalke 11:a2dcf0ebb5b5 72 }
Mahesh Phalke 11:a2dcf0ebb5b5 73 }
Mahesh Phalke 11:a2dcf0ebb5b5 74 table[n] = currByte;
Mahesh Phalke 11:a2dcf0ebb5b5 75 }
Mahesh Phalke 11:a2dcf0ebb5b5 76 }
Mahesh Phalke 11:a2dcf0ebb5b5 77
Mahesh Phalke 11:a2dcf0ebb5b5 78 /***************************************************************************//**
Mahesh Phalke 11:a2dcf0ebb5b5 79 * @brief Computes the CRC-16 over a buffer of data.
Mahesh Phalke 11:a2dcf0ebb5b5 80 *
Mahesh Phalke 11:a2dcf0ebb5b5 81 * @param table - Pointer to a CRC-16 lookup table for the desired polynomial.
Mahesh Phalke 11:a2dcf0ebb5b5 82 * @param pdata - Pointer to data buffer.
Mahesh Phalke 11:a2dcf0ebb5b5 83 * @param nbytes - Number of bytes to compute the CRC-16 over.
Mahesh Phalke 11:a2dcf0ebb5b5 84 * @param crc - Initial value for the CRC-16 computation. Can be used to
Mahesh Phalke 11:a2dcf0ebb5b5 85 * cascade calls to this function by providing a previous
Mahesh Phalke 11:a2dcf0ebb5b5 86 * output of this function as the crc parameter.
Mahesh Phalke 11:a2dcf0ebb5b5 87 *
Mahesh Phalke 11:a2dcf0ebb5b5 88 * @return crc - Computed CRC-16 value.
Mahesh Phalke 11:a2dcf0ebb5b5 89 *******************************************************************************/
Mahesh Phalke 11:a2dcf0ebb5b5 90 uint16_t crc16(const uint16_t * table,
Mahesh Phalke 11:a2dcf0ebb5b5 91 const uint8_t *pdata,
Mahesh Phalke 11:a2dcf0ebb5b5 92 size_t nbytes,
Mahesh Phalke 11:a2dcf0ebb5b5 93 uint16_t crc)
Mahesh Phalke 11:a2dcf0ebb5b5 94 {
Mahesh Phalke 11:a2dcf0ebb5b5 95 unsigned int idx;
Mahesh Phalke 11:a2dcf0ebb5b5 96
Mahesh Phalke 11:a2dcf0ebb5b5 97 while (nbytes--) {
Mahesh Phalke 11:a2dcf0ebb5b5 98 idx = ((crc >> 8) ^ *pdata) & 0xff;
Mahesh Phalke 11:a2dcf0ebb5b5 99 crc = (table[idx] ^ (crc << 8)) & 0xffff;
Mahesh Phalke 11:a2dcf0ebb5b5 100 pdata++;
Mahesh Phalke 11:a2dcf0ebb5b5 101 }
Mahesh Phalke 11:a2dcf0ebb5b5 102
Mahesh Phalke 11:a2dcf0ebb5b5 103 return crc;
Mahesh Phalke 11:a2dcf0ebb5b5 104 }