1 /* 2 * Copyright (C) 2015 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #include <stdint.h> 18 19 /* Calculate CRC32 how the STM32F4xx family does */ 20 21 static unsigned int crc_table[] = 22 { 23 0x00000000, 0x04C11DB7, 0x09823B6E, 0x0D4326D9, 24 0x130476DC ,0x17C56B6B ,0x1A864DB2 ,0x1E475005, 25 0x2608EDB8, 0x22C9F00F, 0x2F8AD6D6, 0x2B4BCB61, 26 0x350C9B64, 0x31CD86D3, 0x3C8EA00A, 0x384FBDBD 27 }; 28 29 static uint32_t crc32_word(uint32_t crc, uint32_t data) 30 { 31 crc = crc ^ data; 32 33 crc = (crc << 4) ^ crc_table[crc >> 28]; 34 crc = (crc << 4) ^ crc_table[crc >> 28]; 35 crc = (crc << 4) ^ crc_table[crc >> 28]; 36 crc = (crc << 4) ^ crc_table[crc >> 28]; 37 crc = (crc << 4) ^ crc_table[crc >> 28]; 38 crc = (crc << 4) ^ crc_table[crc >> 28]; 39 crc = (crc << 4) ^ crc_table[crc >> 28]; 40 crc = (crc << 4) ^ crc_table[crc >> 28]; 41 42 return crc; 43 } 44 45 uint32_t stm32f4_crc32(uint8_t *buffer, int length) 46 { 47 uint32_t *data = (uint32_t *)buffer; 48 uint32_t word; 49 uint32_t crc = ~0; 50 int i; 51 52 /* word by word crc32 */ 53 for (i=0; i<(length>>2); i++) { 54 crc = crc32_word(crc, data[i]); 55 } 56 57 /* zero pad last word if required */ 58 if (length & 0x3) { 59 for (i*=4, word=0; i<length; i++) 60 word |= buffer[i] << ((i & 0x3) * 8); 61 crc = crc32_word(crc, word); 62 } 63 64 return crc; 65 } 66
