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1 // Copyright 2011 the V8 project authors. All rights reserved. | 1 // Copyright 2011 the V8 project authors. All rights reserved. |
2 // Redistribution and use in source and binary forms, with or without | 2 // Redistribution and use in source and binary forms, with or without |
3 // modification, are permitted provided that the following conditions are | 3 // modification, are permitted provided that the following conditions are |
4 // met: | 4 // met: |
5 // | 5 // |
6 // * Redistributions of source code must retain the above copyright | 6 // * Redistributions of source code must retain the above copyright |
7 // notice, this list of conditions and the following disclaimer. | 7 // notice, this list of conditions and the following disclaimer. |
8 // * Redistributions in binary form must reproduce the above | 8 // * Redistributions in binary form must reproduce the above |
9 // copyright notice, this list of conditions and the following | 9 // copyright notice, this list of conditions and the following |
10 // disclaimer in the documentation and/or other materials provided | 10 // disclaimer in the documentation and/or other materials provided |
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38 // Maximum number of significant digits in decimal representation. | 38 // Maximum number of significant digits in decimal representation. |
39 // The longest possible double in decimal representation is | 39 // The longest possible double in decimal representation is |
40 // (2^53 - 1) * 2 ^ -1074 that is (2 ^ 53 - 1) * 5 ^ 1074 / 10 ^ 1074 | 40 // (2^53 - 1) * 2 ^ -1074 that is (2 ^ 53 - 1) * 5 ^ 1074 / 10 ^ 1074 |
41 // (768 digits). If we parse a number whose first digits are equal to a | 41 // (768 digits). If we parse a number whose first digits are equal to a |
42 // mean of 2 adjacent doubles (that could have up to 769 digits) the result | 42 // mean of 2 adjacent doubles (that could have up to 769 digits) the result |
43 // must be rounded to the bigger one unless the tail consists of zeros, so | 43 // must be rounded to the bigger one unless the tail consists of zeros, so |
44 // we don't need to preserve all the digits. | 44 // we don't need to preserve all the digits. |
45 const int kMaxSignificantDigits = 772; | 45 const int kMaxSignificantDigits = 772; |
46 | 46 |
47 | 47 |
48 static inline bool isDigit(int x, int radix) { | 48 inline bool isDigit(int x, int radix) { |
49 return (x >= '0' && x <= '9' && x < '0' + radix) | 49 return (x >= '0' && x <= '9' && x < '0' + radix) |
50 || (radix > 10 && x >= 'a' && x < 'a' + radix - 10) | 50 || (radix > 10 && x >= 'a' && x < 'a' + radix - 10) |
51 || (radix > 10 && x >= 'A' && x < 'A' + radix - 10); | 51 || (radix > 10 && x >= 'A' && x < 'A' + radix - 10); |
52 } | 52 } |
53 | 53 |
54 | 54 |
55 static inline double SignedZero(bool negative) { | 55 inline double SignedZero(bool negative) { |
56 return negative ? -0.0 : 0.0; | 56 return negative ? -0.0 : 0.0; |
57 } | 57 } |
58 | 58 |
59 | 59 |
60 // The fast double-to-(unsigned-)int conversion routine does not guarantee | 60 // The fast double-to-(unsigned-)int conversion routine does not guarantee |
61 // rounding towards zero. | 61 // rounding towards zero. |
62 // The result is unspecified if x is infinite or NaN, or if the rounded | 62 // The result is unspecified if x is infinite or NaN, or if the rounded |
63 // integer value is outside the range of type int. | 63 // integer value is outside the range of type int. |
64 static inline int FastD2I(double x) { | 64 inline int FastD2I(double x) { |
65 // The static_cast convertion from double to int used to be slow, but | 65 // The static_cast convertion from double to int used to be slow, but |
66 // as new benchmarks show, now it is much faster than lrint(). | 66 // as new benchmarks show, now it is much faster than lrint(). |
67 return static_cast<int>(x); | 67 return static_cast<int>(x); |
68 } | 68 } |
69 | 69 |
70 static inline unsigned int FastD2UI(double x); | 70 inline unsigned int FastD2UI(double x); |
71 | 71 |
72 | 72 |
73 static inline double FastI2D(int x) { | 73 inline double FastI2D(int x) { |
74 // There is no rounding involved in converting an integer to a | 74 // There is no rounding involved in converting an integer to a |
75 // double, so this code should compile to a few instructions without | 75 // double, so this code should compile to a few instructions without |
76 // any FPU pipeline stalls. | 76 // any FPU pipeline stalls. |
77 return static_cast<double>(x); | 77 return static_cast<double>(x); |
78 } | 78 } |
79 | 79 |
80 | 80 |
81 static inline double FastUI2D(unsigned x) { | 81 inline double FastUI2D(unsigned x) { |
82 // There is no rounding involved in converting an unsigned integer to a | 82 // There is no rounding involved in converting an unsigned integer to a |
83 // double, so this code should compile to a few instructions without | 83 // double, so this code should compile to a few instructions without |
84 // any FPU pipeline stalls. | 84 // any FPU pipeline stalls. |
85 return static_cast<double>(x); | 85 return static_cast<double>(x); |
86 } | 86 } |
87 | 87 |
88 | 88 |
89 // This function should match the exact semantics of ECMA-262 9.4. | 89 // This function should match the exact semantics of ECMA-262 9.4. |
90 static inline double DoubleToInteger(double x); | 90 inline double DoubleToInteger(double x); |
91 | 91 |
92 | 92 |
93 // This function should match the exact semantics of ECMA-262 9.5. | 93 // This function should match the exact semantics of ECMA-262 9.5. |
94 static inline int32_t DoubleToInt32(double x); | 94 inline int32_t DoubleToInt32(double x); |
95 | 95 |
96 | 96 |
97 // This function should match the exact semantics of ECMA-262 9.6. | 97 // This function should match the exact semantics of ECMA-262 9.6. |
98 static inline uint32_t DoubleToUint32(double x) { | 98 inline uint32_t DoubleToUint32(double x) { |
99 return static_cast<uint32_t>(DoubleToInt32(x)); | 99 return static_cast<uint32_t>(DoubleToInt32(x)); |
100 } | 100 } |
101 | 101 |
102 | 102 |
103 // Enumeration for allowing octals and ignoring junk when converting | 103 // Enumeration for allowing octals and ignoring junk when converting |
104 // strings to numbers. | 104 // strings to numbers. |
105 enum ConversionFlags { | 105 enum ConversionFlags { |
106 NO_FLAGS = 0, | 106 NO_FLAGS = 0, |
107 ALLOW_HEX = 1, | 107 ALLOW_HEX = 1, |
108 ALLOW_OCTALS = 2, | 108 ALLOW_OCTALS = 2, |
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139 // Additional number to string conversions for the number type. | 139 // Additional number to string conversions for the number type. |
140 // The caller is responsible for calling free on the returned pointer. | 140 // The caller is responsible for calling free on the returned pointer. |
141 char* DoubleToFixedCString(double value, int f); | 141 char* DoubleToFixedCString(double value, int f); |
142 char* DoubleToExponentialCString(double value, int f); | 142 char* DoubleToExponentialCString(double value, int f); |
143 char* DoubleToPrecisionCString(double value, int f); | 143 char* DoubleToPrecisionCString(double value, int f); |
144 char* DoubleToRadixCString(double value, int radix); | 144 char* DoubleToRadixCString(double value, int radix); |
145 | 145 |
146 } } // namespace v8::internal | 146 } } // namespace v8::internal |
147 | 147 |
148 #endif // V8_CONVERSIONS_H_ | 148 #endif // V8_CONVERSIONS_H_ |
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