1 /* crc.h -- cyclic redundancy checks 2 Copyright (C) 2005, 2009-2021 Free Software Foundation, Inc. 3 4 This file is free software: you can redistribute it and/or modify 5 it under the terms of the GNU Lesser General Public License as 6 published by the Free Software Foundation; either version 3 of the 7 License, or (at your option) any later version. 8 9 This file is distributed in the hope that it will be useful, 10 but WITHOUT ANY WARRANTY; without even the implied warranty of 11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 GNU Lesser General Public License for more details. 13 14 You should have received a copy of the GNU Lesser General Public License 15 along with this program. If not, see <https://www.gnu.org/licenses/>. */ 16 17 /* Written by Simon Josefsson. */ 18 19 #ifndef CRC_H 20 # define CRC_H 1 21 22 #include <stddef.h> 23 #include <stdint.h> 24 25 /* Compute CRC-32 value of LEN bytes long BUF, and return it. */ 26 extern uint32_t crc32 (const char *buf, size_t len); 27 28 /* Incrementally update CRC-32 value CRC using LEN bytes long BUF. In 29 the first call, use 0 as the value for CRC. Return the updated 30 CRC-32 value. */ 31 extern uint32_t crc32_update (uint32_t crc, const char *buf, size_t len); 32 33 /* Compute modified-CRC-32 value of LEN bytes long BUF, and return it. 34 The "modification" is to avoid the initial and final XOR operation. 35 Due to historic implementation errors, this variant is sometimes 36 used (i.e., in RFC 3961). */ 37 extern uint32_t crc32_no_xor (const char *buf, size_t len); 38 39 /* Incrementally update modified-CRC-32 value CRC using LEN bytes long 40 BUF. In the first call, use 0 as the value for CRC. Return the 41 updated modified-CRC-32 value. The "modification" is to avoid the 42 initial and final XOR operation. Due to historic implementation 43 errors, this variant is sometimes used (i.e., in RFC 3961). */ 44 extern uint32_t 45 crc32_update_no_xor (uint32_t crc, const char *buf, size_t len); 46 47 #endif /* CRC_H */