1 /* 2 * Copyright (C) 2016 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 #include <nanohub/crc.h> 19 20 /* this implements crc32 as crc.h defines it. It is not a normal CRC by any measure, so be careful with it */ 21 22 static const uint32_t crctab[] = 23 { 24 0x00000000, 0x04C11DB7, 0x09823B6E, 0x0D4326D9, 25 0x130476DC ,0x17C56B6B ,0x1A864DB2 ,0x1E475005, 26 0x2608EDB8, 0x22C9F00F, 0x2F8AD6D6, 0x2B4BCB61, 27 0x350C9B64, 0x31CD86D3, 0x3C8EA00A, 0x384FBDBD 28 }; 29 30 static uint32_t crcOneWord(uint32_t crc, uint32_t data, int cnt) 31 { 32 int i; 33 34 crc = crc ^ data; 35 for (i = 0; i < cnt; i++) 36 crc = (crc << 4) ^ crctab[crc >> 28]; 37 38 return crc; 39 } 40 41 uint32_t soft_crc32(const void *buf, size_t size, uint32_t crc) 42 { 43 const uint32_t *data32 = (const uint32_t *)buf; 44 const uint8_t *data8; 45 uint32_t word; 46 size_t i; 47 48 // word by word crc32 49 for (i = 0; i < size / 4; i++) 50 crc = crcOneWord(crc, *data32++, 8); 51 52 data8 = (const uint8_t*)data32; 53 54 // zero pad last word if required 55 if (size & 0x3) { 56 for (i *= 4, word = 0; i < size; i++) 57 word |= (*data8++) << ((i & 0x3) * 8); 58 crc = crcOneWord(crc, word, 8); 59 } 60 61 return crc; 62 } 63
