1 /* 2 * Copyright (c) 2022, The OpenThread Authors. 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 3. Neither the name of the copyright holder nor the 13 * names of its contributors may be used to endorse or promote products 14 * derived from this software without specific prior written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 17 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE 20 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 26 * POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 /** 30 * @file 31 * This file includes definitions for serial number comparison similar to RFC-1982. 32 */ 33 34 #ifndef SERIAL_NUMBER_HPP_ 35 #define SERIAL_NUMBER_HPP_ 36 37 #include "openthread-core-config.h" 38 39 #include <stdint.h> 40 41 #include "common/numeric_limits.hpp" 42 #include "common/type_traits.hpp" 43 44 namespace ot { 45 46 class SerialNumber 47 { 48 public: 49 /** 50 * Indicates whether or not a first serial number is strictly less than a second serial number. 51 * 52 * The comparison takes into account the wrapping of serial number values (similar to RFC-1982). It is semantically 53 * equivalent to `aFirst < aSecond`. 54 * 55 * @tparam UintType The unsigned integer type. 56 * 57 * @param[in] aFirst The first serial number. 58 * @param[in] aSecond The second serial number. 59 * 60 * @retval TRUE If @p aFirst is less than @p aSecond. 61 * @retval FALSE If @p aFirst is not less than @p aSecond. 62 * 63 */ IsLess(UintType aFirst,UintType aSecond)64 template <typename UintType> static bool IsLess(UintType aFirst, UintType aSecond) 65 { 66 static_assert(TypeTraits::IsSame<UintType, uint8_t>::kValue || TypeTraits::IsSame<UintType, uint16_t>::kValue || 67 TypeTraits::IsSame<UintType, uint32_t>::kValue || 68 TypeTraits::IsSame<UintType, uint64_t>::kValue, 69 "UintType MUST be an 8, 16, 32, or 64 bit `uint` type"); 70 71 static constexpr UintType kNegativeMask = (NumericLimits<UintType>::kMax >> 1) + 1; 72 73 return ((aFirst - aSecond) & kNegativeMask) != 0; 74 } 75 76 /** 77 * Indicates whether or not a first serial number is strictly greater than a second serial 78 * number. 79 * 80 * The comparison takes into account the wrapping of serial number values (similar to RFC-1982). It is semantically 81 * equivalent to `aFirst > aSecond`. 82 * 83 * @tparam UintType The unsigned integer type. 84 * 85 * @param[in] aFirst The first serial number. 86 * @param[in] aSecond The second serial number. 87 * 88 * @retval TRUE If @p aFirst is greater than @p aSecond. 89 * @retval FALSE If @p aFirst is not greater than @p aSecond. 90 * 91 */ IsGreater(UintType aFirst,UintType aSecond)92 template <typename UintType> static bool IsGreater(UintType aFirst, UintType aSecond) 93 { 94 return IsLess(aSecond, aFirst); 95 } 96 }; 97 98 } // namespace ot 99 100 #endif // SERIAL_NUMBER_HPP_ 101
