Arun Raj / Mbed OS MAXREFDES101_SOURCE

TEST

Dependencies:   max32630fthr Adafruit_FeatherOLED USBDevice

Utilities/CRC8.cpp@4:291477e8690d, 2020-04-19 (annotated)

Committer:
wwwarunraj
Date:
Sun Apr 19 11:19:57 2020 +0000
Revision:
4:291477e8690d
Parent:
1:f60eafbf009a 
19/04

Who changed what in which revision?

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gmehmet 1:f60eafbf009a 1 /***************************************************************************
gmehmet 1:f60eafbf009a 2 * Copyright (C) 2017 Maxim Integrated Products, Inc., All Rights Reserved.
gmehmet 1:f60eafbf009a 3 *
gmehmet 1:f60eafbf009a 4 * Permission is hereby granted, free of charge, to any person obtaining a
gmehmet 1:f60eafbf009a 5 * copy of this software and associated documentation files (the "Software"),
gmehmet 1:f60eafbf009a 6 * to deal in the Software without restriction, including without limitation
gmehmet 1:f60eafbf009a 7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
gmehmet 1:f60eafbf009a 8 * and/or sell copies of the Software, and to permit persons to whom the
gmehmet 1:f60eafbf009a 9 * Software is furnished to do so, subject to the following conditions:
gmehmet 1:f60eafbf009a 10 *
gmehmet 1:f60eafbf009a 11 * The above copyright notice and this permission notice shall be included
gmehmet 1:f60eafbf009a 12 * in all copies or substantial portions of the Software.
gmehmet 1:f60eafbf009a 13 *
gmehmet 1:f60eafbf009a 14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
gmehmet 1:f60eafbf009a 15 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
gmehmet 1:f60eafbf009a 16 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
gmehmet 1:f60eafbf009a 17 * IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES
gmehmet 1:f60eafbf009a 18 * OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
gmehmet 1:f60eafbf009a 19 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
gmehmet 1:f60eafbf009a 20 * OTHER DEALINGS IN THE SOFTWARE.
gmehmet 1:f60eafbf009a 21 *
gmehmet 1:f60eafbf009a 22 * Except as contained in this notice, the name of Maxim Integrated
gmehmet 1:f60eafbf009a 23 * Products, Inc. shall not be used except as stated in the Maxim Integrated
gmehmet 1:f60eafbf009a 24 * Products, Inc. Branding Policy.
gmehmet 1:f60eafbf009a 25 *
gmehmet 1:f60eafbf009a 26 * The mere transfer of this software does not imply any licenses
gmehmet 1:f60eafbf009a 27 * of trade secrets, proprietary technology, copyrights, patents,
gmehmet 1:f60eafbf009a 28 * trademarks, maskwork rights, or any other form of intellectual
gmehmet 1:f60eafbf009a 29 * property whatsoever. Maxim Integrated Products, Inc. retains all
gmehmet 1:f60eafbf009a 30 * ownership rights.
gmehmet 1:f60eafbf009a 31 ****************************************************************************
gmehmet 1:f60eafbf009a 32 */
gmehmet 1:f60eafbf009a 33 #include <stdint.h>
gmehmet 1:f60eafbf009a 34
gmehmet 1:f60eafbf009a 35 /*
gmehmet 1:f60eafbf009a 36 * CRC-8:
gmehmet 1:f60eafbf009a 37 *
gmehmet 1:f60eafbf009a 38 * Width: 8
gmehmet 1:f60eafbf009a 39 * Poly: 0x07
gmehmet 1:f60eafbf009a 40 * Init: 0x00
gmehmet 1:f60eafbf009a 41 * RefIn: False
gmehmet 1:f60eafbf009a 42 * RefOut: False
gmehmet 1:f60eafbf009a 43 * XOROur: 0x00
gmehmet 1:f60eafbf009a 44 * Check: 0xF4
gmehmet 1:f60eafbf009a 45 */
gmehmet 1:f60eafbf009a 46
gmehmet 1:f60eafbf009a 47 static const uint8_t CRC8_POLY = 0x07;
gmehmet 1:f60eafbf009a 48 static bool crc8_initialized = false;
gmehmet 1:f60eafbf009a 49
gmehmet 1:f60eafbf009a 50 static uint8_t crc8_table[256];
gmehmet 1:f60eafbf009a 51
gmehmet 1:f60eafbf009a 52
gmehmet 1:f60eafbf009a 53 static void init_crc8()
gmehmet 1:f60eafbf009a 54 {
gmehmet 1:f60eafbf009a 55 uint8_t msb = 1 << 7;
gmehmet 1:f60eafbf009a 56 uint8_t bit;
gmehmet 1:f60eafbf009a 57 uint8_t rem;
gmehmet 1:f60eafbf009a 58 uint32_t byte = 0;
gmehmet 1:f60eafbf009a 59
gmehmet 1:f60eafbf009a 60 if (crc8_initialized)
gmehmet 1:f60eafbf009a 61 return;
gmehmet 1:f60eafbf009a 62
gmehmet 1:f60eafbf009a 63 while (byte < 256) {
gmehmet 1:f60eafbf009a 64 rem = byte;
gmehmet 1:f60eafbf009a 65 for (bit = 0; bit < 8; bit++) {
gmehmet 1:f60eafbf009a 66 if (rem & msb)
gmehmet 1:f60eafbf009a 67 rem = (rem << 1) ^ CRC8_POLY;
gmehmet 1:f60eafbf009a 68 else
gmehmet 1:f60eafbf009a 69 rem <<= 1;
gmehmet 1:f60eafbf009a 70 }
gmehmet 1:f60eafbf009a 71
gmehmet 1:f60eafbf009a 72 crc8_table[byte++] = rem;
gmehmet 1:f60eafbf009a 73 }
gmehmet 1:f60eafbf009a 74
gmehmet 1:f60eafbf009a 75 crc8_initialized = true;
gmehmet 1:f60eafbf009a 76 }
gmehmet 1:f60eafbf009a 77
gmehmet 1:f60eafbf009a 78 uint8_t crc8(uint8_t *data, uint32_t length)
gmehmet 1:f60eafbf009a 79 {
gmehmet 1:f60eafbf009a 80 uint8_t crc = 0x00;
gmehmet 1:f60eafbf009a 81 uint32_t msg_idx = 0;
gmehmet 1:f60eafbf009a 82
gmehmet 1:f60eafbf009a 83 if (length == 0xFFFFFFFF)
gmehmet 1:f60eafbf009a 84 return 0;
gmehmet 1:f60eafbf009a 85
gmehmet 1:f60eafbf009a 86 init_crc8();
gmehmet 1:f60eafbf009a 87
gmehmet 1:f60eafbf009a 88 while (msg_idx < length) {
gmehmet 1:f60eafbf009a 89 crc = crc8_table[crc ^ data[msg_idx++]];
gmehmet 1:f60eafbf009a 90 }
gmehmet 1:f60eafbf009a 91
gmehmet 1:f60eafbf009a 92 return crc;
gmehmet 1:f60eafbf009a 93 }