1// © 2018 and later: Unicode, Inc. and others.
2// License & terms of use: http://www.unicode.org/copyright.html
3//
4// From the double-conversion library. Original license:
5//
6// Copyright 2010 the V8 project authors. All rights reserved.
7// Redistribution and use in source and binary forms, with or without
8// modification, are permitted provided that the following conditions are
9// met:
10//
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13// * Redistributions in binary form must reproduce the above
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20//
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31// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32
33// ICU PATCH: ifdef around UCONFIG_NO_FORMATTING
34#include "unicode/utypes.h"
35#if !UCONFIG_NO_FORMATTING
36
37#ifndef DOUBLE_CONVERSION_DIY_FP_H_
38#define DOUBLE_CONVERSION_DIY_FP_H_
39
40// ICU PATCH: Customize header file paths for ICU.
41
42#include "double-conversion-utils.h"
43
44// ICU PATCH: Wrap in ICU namespace
45U_NAMESPACE_BEGIN
46
47namespace double_conversion {
48
49// This "Do It Yourself Floating Point" class implements a floating-point number
50// with a uint64 significand and an int exponent. Normalized DiyFp numbers will
51// have the most significant bit of the significand set.
52// Multiplication and Subtraction do not normalize their results.
53// DiyFp store only non-negative numbers and are not designed to contain special
54// doubles (NaN and Infinity).
55class DiyFp {
56 public:
57 static const int kSignificandSize = 64;
58
59 DiyFp() : f_(0), e_(0) {}
60 DiyFp(const uint64_t significand, const int32_t exponent) : f_(significand), e_(exponent) {}
61
62 // this -= other.
63 // The exponents of both numbers must be the same and the significand of this
64 // must be greater or equal than the significand of other.
65 // The result will not be normalized.
66 void Subtract(const DiyFp& other) {
67 DOUBLE_CONVERSION_ASSERT(e_ == other.e_);
68 DOUBLE_CONVERSION_ASSERT(f_ >= other.f_);
69 f_ -= other.f_;
70 }
71
72 // Returns a - b.
73 // The exponents of both numbers must be the same and a must be greater
74 // or equal than b. The result will not be normalized.
75 static DiyFp Minus(const DiyFp& a, const DiyFp& b) {
76 DiyFp result = a;
77 result.Subtract(b);
78 return result;
79 }
80
81 // this *= other.
82 void Multiply(const DiyFp& other) {
83 // Simply "emulates" a 128 bit multiplication.
84 // However: the resulting number only contains 64 bits. The least
85 // significant 64 bits are only used for rounding the most significant 64
86 // bits.
87 const uint64_t kM32 = 0xFFFFFFFFU;
88 const uint64_t a = f_ >> 32;
89 const uint64_t b = f_ & kM32;
90 const uint64_t c = other.f_ >> 32;
91 const uint64_t d = other.f_ & kM32;
92 const uint64_t ac = a * c;
93 const uint64_t bc = b * c;
94 const uint64_t ad = a * d;
95 const uint64_t bd = b * d;
96 // By adding 1U << 31 to tmp we round the final result.
97 // Halfway cases will be rounded up.
98 const uint64_t tmp = (bd >> 32) + (ad & kM32) + (bc & kM32) + (1U << 31);
99 e_ += other.e_ + 64;
100 f_ = ac + (ad >> 32) + (bc >> 32) + (tmp >> 32);
101 }
102
103 // returns a * b;
104 static DiyFp Times(const DiyFp& a, const DiyFp& b) {
105 DiyFp result = a;
106 result.Multiply(b);
107 return result;
108 }
109
110 void Normalize() {
111 DOUBLE_CONVERSION_ASSERT(f_ != 0);
112 uint64_t significand = f_;
113 int32_t exponent = e_;
114
115 // This method is mainly called for normalizing boundaries. In general,
116 // boundaries need to be shifted by 10 bits, and we optimize for this case.
117 const uint64_t k10MSBits = DOUBLE_CONVERSION_UINT64_2PART_C(0xFFC00000, 00000000);
118 while ((significand & k10MSBits) == 0) {
119 significand <<= 10;
120 exponent -= 10;
121 }
122 while ((significand & kUint64MSB) == 0) {
123 significand <<= 1;
124 exponent--;
125 }
126 f_ = significand;
127 e_ = exponent;
128 }
129
130 static DiyFp Normalize(const DiyFp& a) {
131 DiyFp result = a;
132 result.Normalize();
133 return result;
134 }
135
136 uint64_t f() const { return f_; }
137 int32_t e() const { return e_; }
138
139 void set_f(uint64_t new_value) { f_ = new_value; }
140 void set_e(int32_t new_value) { e_ = new_value; }
141
142 private:
143 static const uint64_t kUint64MSB = DOUBLE_CONVERSION_UINT64_2PART_C(0x80000000, 00000000);
144
145 uint64_t f_;
146 int32_t e_;
147};
148
149} // namespace double_conversion
150
151// ICU PATCH: Close ICU namespace
152U_NAMESPACE_END
153
154#endif // DOUBLE_CONVERSION_DIY_FP_H_
155#endif // ICU PATCH: close #if !UCONFIG_NO_FORMATTING
156