RFAL library for the STMicroelectronics X-NUCLEO-NFC05A1
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rfal_crc.cpp
00001 00002 /****************************************************************************** 00003 * @attention 00004 * 00005 * <h2><center>© COPYRIGHT 2016 STMicroelectronics</center></h2> 00006 * 00007 * Licensed under ST MYLIBERTY SOFTWARE LICENSE AGREEMENT (the "License"); 00008 * You may not use this file except in compliance with the License. 00009 * You may obtain a copy of the License at: 00010 * 00011 * http://www.st.com/myliberty 00012 * 00013 * Unless required by applicable law or agreed to in writing, software 00014 * distributed under the License is distributed on an "AS IS" BASIS, 00015 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied, 00016 * AND SPECIFICALLY DISCLAIMING THE IMPLIED WARRANTIES OF MERCHANTABILITY, 00017 * FITNESS FOR A PARTICULAR PURPOSE, AND NON-INFRINGEMENT. 00018 * See the License for the specific language governing permissions and 00019 * limitations under the License. 00020 * 00021 ******************************************************************************/ 00022 00023 /* 00024 * PROJECT: ST25R391x firmware 00025 * $Revision: $ 00026 * LANGUAGE: ISO C99 00027 */ 00028 00029 /*! \file rfal_crc.c 00030 * 00031 * \author Oliver Regenfelder 00032 * 00033 * \brief CRC calculation implementation 00034 * 00035 */ 00036 00037 /* 00038 ****************************************************************************** 00039 * INCLUDES 00040 ****************************************************************************** 00041 */ 00042 #include "rfal_crc.h" 00043 00044 /* 00045 ****************************************************************************** 00046 * LOCAL FUNCTION PROTOTYPES 00047 ****************************************************************************** 00048 */ 00049 static uint16_t rfalCrcUpdateCcitt(uint16_t crc, uint8_t dat); 00050 00051 /* 00052 ****************************************************************************** 00053 * GLOBAL FUNCTIONS 00054 ****************************************************************************** 00055 */ 00056 uint16_t rfalCrcCalculateCcitt(uint16_t preloadValue, const uint8_t* buf, uint16_t length) 00057 { 00058 uint16_t crc = preloadValue; 00059 uint16_t index; 00060 00061 for (index = 0; index < length; index++) 00062 { 00063 crc = rfalCrcUpdateCcitt(crc, buf[index]); 00064 } 00065 00066 return crc; 00067 } 00068 00069 /* 00070 ****************************************************************************** 00071 * LOCAL FUNCTIONS 00072 ****************************************************************************** 00073 */ 00074 static uint16_t rfalCrcUpdateCcitt(uint16_t crc, uint8_t dat) 00075 { 00076 dat ^= ((uint8_t)crc) & 0xFF; 00077 dat ^= dat << 4; 00078 00079 crc = (crc >> 8)^(((uint16_t) dat) << 8)^(((uint16_t) dat) << 3)^(((uint16_t) dat) >> 4); 00080 00081 return crc; 00082 } 00083
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