Victor Chang | 7322950 | 2020-09-17 13:39:19 +0100 | [diff] [blame] | 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 | // |
| 11 | // * Redistributions of source code must retain the above copyright |
| 12 | // notice, this list of conditions and the following disclaimer. |
| 13 | // * Redistributions in binary form must reproduce the above |
| 14 | // copyright notice, this list of conditions and the following |
| 15 | // disclaimer in the documentation and/or other materials provided |
| 16 | // with the distribution. |
| 17 | // * Neither the name of Google Inc. nor the names of its |
| 18 | // contributors may be used to endorse or promote products derived |
| 19 | // from this software without specific prior written permission. |
| 20 | // |
| 21 | // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 22 | // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 23 | // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| 24 | // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| 25 | // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| 26 | // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| 27 | // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 28 | // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 29 | // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 30 | // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| 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 |
| 45 | U_NAMESPACE_BEGIN |
| 46 | |
| 47 | namespace 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). |
| 55 | class 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 |
| 152 | U_NAMESPACE_END |
| 153 | |
| 154 | #endif // DOUBLE_CONVERSION_DIY_FP_H_ |
| 155 | #endif // ICU PATCH: close #if !UCONFIG_NO_FORMATTING |