aboutsummaryrefslogtreecommitdiffhomepage
path: root/src/google/protobuf/stubs/mathlimits.cc
blob: 0373b2bb97137b438f4635556984b99f23c0b0f8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc.  All rights reserved.
// https://developers.google.com/protocol-buffers/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
//     * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//     * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
//     * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

// All Rights Reserved.
//
// Author: Maxim Lifantsev
//

#include <google/protobuf/stubs/mathlimits.h>

#include <google/protobuf/stubs/common.h>

namespace google {
namespace protobuf {

// MSVC++ 2005 and older compilers think the header declaration was a
// definition, and erroneously flag these as a duplicate definition.
#if defined(COMPILER_MSVC) || __cpluscplus < 201103L

#define DEF_COMMON_LIMITS(Type)
#define DEF_UNSIGNED_INT_LIMITS(Type)
#define DEF_SIGNED_INT_LIMITS(Type)
#define DEF_PRECISION_LIMITS(Type)

#else

#define DEF_COMMON_LIMITS(Type) \
const bool MathLimits<Type>::kIsSigned; \
const bool MathLimits<Type>::kIsInteger; \
const int MathLimits<Type>::kMin10Exp; \
const int MathLimits<Type>::kMax10Exp;

#define DEF_UNSIGNED_INT_LIMITS(Type) \
DEF_COMMON_LIMITS(Type) \
const Type MathLimits<Type>::kPosMin; \
const Type MathLimits<Type>::kPosMax; \
const Type MathLimits<Type>::kMin; \
const Type MathLimits<Type>::kMax; \
const Type MathLimits<Type>::kEpsilon; \
const Type MathLimits<Type>::kStdError;

#define DEF_SIGNED_INT_LIMITS(Type) \
DEF_UNSIGNED_INT_LIMITS(Type) \
const Type MathLimits<Type>::kNegMin; \
const Type MathLimits<Type>::kNegMax;

#define DEF_PRECISION_LIMITS(Type) \
const int MathLimits<Type>::kPrecisionDigits;

#endif  // not COMPILER_MSVC

// http://en.wikipedia.org/wiki/Quadruple_precision_floating-point_format#Double-double_arithmetic
// With some compilers (gcc 4.6.x) on some platforms (powerpc64),
// "long double" is implemented as a pair of double: "double double" format.
// This causes a problem with epsilon (eps).
// eps is the smallest positive number such that 1.0 + eps > 1.0
//
// Normal format:  1.0 + e = 1.0...01      // N-1 zeros for N fraction bits
// D-D format:     1.0 + e = 1.000...0001  // epsilon can be very small
//
// In the normal format, 1.0 + e has to fit in one stretch of bits.
// The maximum rounding error is half of eps.
//
// In the double-double format, 1.0 + e splits across two doubles:
// 1.0 in the high double, e in the low double, and they do not have to
// be contiguous.  The maximum rounding error on a value close to 1.0 is
// much larger than eps.
//
// Some code checks for errors by comparing a computed value to a golden
// value +/- some multiple of the maximum rounding error.  The maximum
// rounding error is not available so we use eps as an approximation
// instead.  That fails when long double is in the double-double format.
// Therefore, we define kStdError as a multiple of
// max(DBL_EPSILON * DBL_EPSILON, kEpsilon) rather than a multiple of kEpsilon.

#define DEF_FP_LIMITS(Type, PREFIX) \
DEF_COMMON_LIMITS(Type) \
const Type MathLimits<Type>::kPosMin = PREFIX##_MIN; \
const Type MathLimits<Type>::kPosMax = PREFIX##_MAX; \
const Type MathLimits<Type>::kMin = -MathLimits<Type>::kPosMax; \
const Type MathLimits<Type>::kMax = MathLimits<Type>::kPosMax; \
const Type MathLimits<Type>::kNegMin = -MathLimits<Type>::kPosMin; \
const Type MathLimits<Type>::kNegMax = -MathLimits<Type>::kPosMax; \
const Type MathLimits<Type>::kEpsilon = PREFIX##_EPSILON; \
/* 32 is 5 bits of mantissa error; should be adequate for common errors */ \
const Type MathLimits<Type>::kStdError = \
  32 * (DBL_EPSILON * DBL_EPSILON > MathLimits<Type>::kEpsilon \
      ? DBL_EPSILON * DBL_EPSILON : MathLimits<Type>::kEpsilon); \
DEF_PRECISION_LIMITS(Type) \
const Type MathLimits<Type>::kNaN = HUGE_VAL - HUGE_VAL; \
const Type MathLimits<Type>::kPosInf = HUGE_VAL; \
const Type MathLimits<Type>::kNegInf = -HUGE_VAL;

// The following are *not* casts!
DEF_SIGNED_INT_LIMITS(int8)
DEF_SIGNED_INT_LIMITS(int16)  // NOLINT(readability/casting)
DEF_SIGNED_INT_LIMITS(int32)  // NOLINT(readability/casting)
DEF_SIGNED_INT_LIMITS(int64)  // NOLINT(readability/casting)
DEF_UNSIGNED_INT_LIMITS(uint8)
DEF_UNSIGNED_INT_LIMITS(uint16)  // NOLINT(readability/casting)
DEF_UNSIGNED_INT_LIMITS(uint32)  // NOLINT(readability/casting)
DEF_UNSIGNED_INT_LIMITS(uint64)  // NOLINT(readability/casting)

DEF_SIGNED_INT_LIMITS(long int)
DEF_UNSIGNED_INT_LIMITS(unsigned long int)

DEF_FP_LIMITS(float, FLT)
DEF_FP_LIMITS(double, DBL)
DEF_FP_LIMITS(long double, LDBL);

#undef DEF_COMMON_LIMITS
#undef DEF_SIGNED_INT_LIMITS
#undef DEF_UNSIGNED_INT_LIMITS
#undef DEF_FP_LIMITS
#undef DEF_PRECISION_LIMITS
}  // namespace protobuf
}  // namespace google