1/* 2 * Copyright (c) 2012 Apple, Inc. All Rights Reserved. 3 * 4 * @APPLE_LICENSE_HEADER_START@ 5 * 6 * This file contains Original Code and/or Modifications of Original Code 7 * as defined in and that are subject to the Apple Public Source License 8 * Version 2.0 (the 'License'). You may not use this file except in 9 * compliance with the License. Please obtain a copy of the License at 10 * http://www.opensource.apple.com/apsl/ and read it before using this 11 * file. 12 * 13 * The Original Code and all software distributed under the License are 14 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER 15 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, 16 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, 17 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. 18 * Please see the License for the specific language governing rights and 19 * limitations under the License. 20 * 21 * @APPLE_LICENSE_HEADER_END@ 22 */ 23 24#include "crc.h" 25 26static const int adler_mod_value = 65521; 27 28static uint64_t 29adler32_setup() { return 0; } 30 31static uint64_t 32adler32_implementation(size_t len, const void *in, uint64_t crc) 33{ 34 uint32_t a = 1, b = 0; 35 uint8_t *bytes = (uint8_t *) in; 36 37 for (size_t i = 0; i < len; i++) { 38 a = (a + bytes[i]) % adler_mod_value; 39 b = (b + a) % adler_mod_value; 40 } 41 return (b << 16) | a; 42} 43 44static uint64_t 45adler32_final(size_t length, uint64_t crc) { return crc; } 46 47 48static uint64_t 49adler32_oneshot(size_t len, const void *in) 50{ 51 return adler32_implementation(len, in, 0); 52} 53 54 55 56const crcDescriptor adler32 = { 57 .name = "adler-32", 58 .defType = functions, 59 .def.funcs.setup = adler32_setup, 60 .def.funcs.update = adler32_implementation, 61 .def.funcs.final = adler32_final, 62 .def.funcs.oneshot = adler32_oneshot 63}; 64