1// Protocol Buffers - Google's data interchange format 2// Copyright 2008 Google Inc. All rights reserved. 3// https://developers.google.com/protocol-buffers/ 4// 5// Redistribution and use in source and binary forms, with or without 6// modification, are permitted provided that the following conditions are 7// met: 8// 9// * Redistributions of source code must retain the above copyright 10// notice, this list of conditions and the following disclaimer. 11// * Redistributions in binary form must reproduce the above 12// copyright notice, this list of conditions and the following disclaimer 13// in the documentation and/or other materials provided with the 14// distribution. 15// * Neither the name of Google Inc. nor the names of its 16// contributors may be used to endorse or promote products derived from 17// this software without specific prior written permission. 18// 19// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 20// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 21// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 22// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 23// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 24// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 25// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 26// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 27// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 28// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 29// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 31// All Rights Reserved. 32// 33// Author: Maxim Lifantsev 34// 35 36#include <google/protobuf/stubs/mathlimits.h> 37 38#include <google/protobuf/stubs/common.h> 39 40namespace google { 41namespace protobuf { 42 43// MSVC++ 2005 and older compilers think the header declaration was a 44// definition, and erroneously flag these as a duplicate definition. 45#if defined(COMPILER_MSVC) || __cpluscplus < 201103L 46 47#define DEF_COMMON_LIMITS(Type) 48#define DEF_UNSIGNED_INT_LIMITS(Type) 49#define DEF_SIGNED_INT_LIMITS(Type) 50#define DEF_PRECISION_LIMITS(Type) 51 52#else 53 54#define DEF_COMMON_LIMITS(Type) \ 55const bool MathLimits<Type>::kIsSigned; \ 56const bool MathLimits<Type>::kIsInteger; \ 57const int MathLimits<Type>::kMin10Exp; \ 58const int MathLimits<Type>::kMax10Exp; 59 60#define DEF_UNSIGNED_INT_LIMITS(Type) \ 61DEF_COMMON_LIMITS(Type) \ 62const Type MathLimits<Type>::kPosMin; \ 63const Type MathLimits<Type>::kPosMax; \ 64const Type MathLimits<Type>::kMin; \ 65const Type MathLimits<Type>::kMax; \ 66const Type MathLimits<Type>::kEpsilon; \ 67const Type MathLimits<Type>::kStdError; 68 69#define DEF_SIGNED_INT_LIMITS(Type) \ 70DEF_UNSIGNED_INT_LIMITS(Type) \ 71const Type MathLimits<Type>::kNegMin; \ 72const Type MathLimits<Type>::kNegMax; 73 74#define DEF_PRECISION_LIMITS(Type) \ 75const int MathLimits<Type>::kPrecisionDigits; 76 77#endif // not COMPILER_MSVC 78 79// http://en.wikipedia.org/wiki/Quadruple_precision_floating-point_format#Double-double_arithmetic 80// With some compilers (gcc 4.6.x) on some platforms (powerpc64), 81// "long double" is implemented as a pair of double: "double double" format. 82// This causes a problem with epsilon (eps). 83// eps is the smallest positive number such that 1.0 + eps > 1.0 84// 85// Normal format: 1.0 + e = 1.0...01 // N-1 zeros for N fraction bits 86// D-D format: 1.0 + e = 1.000...0001 // epsilon can be very small 87// 88// In the normal format, 1.0 + e has to fit in one stretch of bits. 89// The maximum rounding error is half of eps. 90// 91// In the double-double format, 1.0 + e splits across two doubles: 92// 1.0 in the high double, e in the low double, and they do not have to 93// be contiguous. The maximum rounding error on a value close to 1.0 is 94// much larger than eps. 95// 96// Some code checks for errors by comparing a computed value to a golden 97// value +/- some multiple of the maximum rounding error. The maximum 98// rounding error is not available so we use eps as an approximation 99// instead. That fails when long double is in the double-double format. 100// Therefore, we define kStdError as a multiple of 101// max(DBL_EPSILON * DBL_EPSILON, kEpsilon) rather than a multiple of kEpsilon. 102 103#define DEF_FP_LIMITS(Type, PREFIX) \ 104DEF_COMMON_LIMITS(Type) \ 105const Type MathLimits<Type>::kPosMin = PREFIX##_MIN; \ 106const Type MathLimits<Type>::kPosMax = PREFIX##_MAX; \ 107const Type MathLimits<Type>::kMin = -MathLimits<Type>::kPosMax; \ 108const Type MathLimits<Type>::kMax = MathLimits<Type>::kPosMax; \ 109const Type MathLimits<Type>::kNegMin = -MathLimits<Type>::kPosMin; \ 110const Type MathLimits<Type>::kNegMax = -MathLimits<Type>::kPosMax; \ 111const Type MathLimits<Type>::kEpsilon = PREFIX##_EPSILON; \ 112/* 32 is 5 bits of mantissa error; should be adequate for common errors */ \ 113const Type MathLimits<Type>::kStdError = \ 114 32 * (DBL_EPSILON * DBL_EPSILON > MathLimits<Type>::kEpsilon \ 115 ? DBL_EPSILON * DBL_EPSILON : MathLimits<Type>::kEpsilon); \ 116DEF_PRECISION_LIMITS(Type) \ 117const Type MathLimits<Type>::kNaN = HUGE_VAL - HUGE_VAL; \ 118const Type MathLimits<Type>::kPosInf = HUGE_VAL; \ 119const Type MathLimits<Type>::kNegInf = -HUGE_VAL; 120 121// The following are *not* casts! 122DEF_SIGNED_INT_LIMITS(int8) 123DEF_SIGNED_INT_LIMITS(int16) // NOLINT(readability/casting) 124DEF_SIGNED_INT_LIMITS(int32) // NOLINT(readability/casting) 125DEF_SIGNED_INT_LIMITS(int64) // NOLINT(readability/casting) 126DEF_UNSIGNED_INT_LIMITS(uint8) 127DEF_UNSIGNED_INT_LIMITS(uint16) // NOLINT(readability/casting) 128DEF_UNSIGNED_INT_LIMITS(uint32) // NOLINT(readability/casting) 129DEF_UNSIGNED_INT_LIMITS(uint64) // NOLINT(readability/casting) 130 131DEF_SIGNED_INT_LIMITS(long int) 132DEF_UNSIGNED_INT_LIMITS(unsigned long int) 133 134DEF_FP_LIMITS(float, FLT) 135DEF_FP_LIMITS(double, DBL) 136DEF_FP_LIMITS(long double, LDBL); 137 138#undef DEF_COMMON_LIMITS 139#undef DEF_SIGNED_INT_LIMITS 140#undef DEF_UNSIGNED_INT_LIMITS 141#undef DEF_FP_LIMITS 142#undef DEF_PRECISION_LIMITS 143} // namespace protobuf 144} // namespace google 145