1// Protocol Buffers - Google's data interchange format
2// Copyright 2008 Google Inc.  All rights reserved.
3// https://developers.google.com/protocol-buffers/
4//
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6// modification, are permitted provided that the following conditions are
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8//
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13// in the documentation and/or other materials provided with the
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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
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22// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
23// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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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