1 // Copyright 2011 the V8 project authors. All rights reserved.
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3 // modification, are permitted provided that the following conditions are
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28 #ifndef V8_CONVERSIONS_H_
29 #define V8_CONVERSIONS_H_
38 // Maximum number of significant digits in decimal representation.
39 // The longest possible double in decimal representation is
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
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
44 // we don't need to preserve all the digits.
45 const int kMaxSignificantDigits = 772;
48 inline bool isDigit(int x, int radix) {
49 return (x >= '0' && x <= '9' && x < '0' + radix)
50 || (radix > 10 && x >= 'a' && x < 'a' + radix - 10)
51 || (radix > 10 && x >= 'A' && x < 'A' + radix - 10);
55 inline bool isBinaryDigit(int x) {
56 return x == '0' || x == '1';
60 // The fast double-to-(unsigned-)int conversion routine does not guarantee
61 // rounding towards zero.
62 // For NaN and values outside the int range, return INT_MIN or INT_MAX.
63 inline int FastD2IChecked(double x) {
64 if (!(x >= INT_MIN)) return INT_MIN; // Negation to catch NaNs.
65 if (x > INT_MAX) return INT_MAX;
66 return static_cast<int>(x);
70 // The fast double-to-(unsigned-)int conversion routine does not guarantee
71 // rounding towards zero.
72 // The result is unspecified if x is infinite or NaN, or if the rounded
73 // integer value is outside the range of type int.
74 inline int FastD2I(double x) {
75 return static_cast<int32_t>(x);
78 inline unsigned int FastD2UI(double x);
81 inline double FastI2D(int x) {
82 // There is no rounding involved in converting an integer to a
83 // double, so this code should compile to a few instructions without
84 // any FPU pipeline stalls.
85 return static_cast<double>(x);
89 inline double FastUI2D(unsigned x) {
90 // There is no rounding involved in converting an unsigned integer to a
91 // double, so this code should compile to a few instructions without
92 // any FPU pipeline stalls.
93 return static_cast<double>(x);
97 // This function should match the exact semantics of ECMA-262 9.4.
98 inline double DoubleToInteger(double x);
101 // This function should match the exact semantics of ECMA-262 9.5.
102 inline int32_t DoubleToInt32(double x);
105 // This function should match the exact semantics of ECMA-262 9.6.
106 inline uint32_t DoubleToUint32(double x) {
107 return static_cast<uint32_t>(DoubleToInt32(x));
111 // Enumeration for allowing octals and ignoring junk when converting
112 // strings to numbers.
113 enum ConversionFlags {
117 ALLOW_IMPLICIT_OCTAL = 4,
119 ALLOW_TRAILING_JUNK = 16
123 // Converts a string into a double value according to ECMA-262 9.3.1
124 double StringToDouble(UnicodeCache* unicode_cache,
125 Vector<const char> str,
127 double empty_string_val = 0);
128 double StringToDouble(UnicodeCache* unicode_cache,
129 Vector<const uc16> str,
131 double empty_string_val = 0);
132 // This version expects a zero-terminated character array.
133 double StringToDouble(UnicodeCache* unicode_cache,
136 double empty_string_val = 0);
138 const int kDoubleToCStringMinBufferSize = 100;
140 // Converts a double to a string value according to ECMA-262 9.8.1.
141 // The buffer should be large enough for any floating point number.
142 // 100 characters is enough.
143 const char* DoubleToCString(double value, Vector<char> buffer);
145 // Convert an int to a null-terminated string. The returned string is
146 // located inside the buffer, but not necessarily at the start.
147 const char* IntToCString(int n, Vector<char> buffer);
149 // Additional number to string conversions for the number type.
150 // The caller is responsible for calling free on the returned pointer.
151 char* DoubleToFixedCString(double value, int f);
152 char* DoubleToExponentialCString(double value, int f);
153 char* DoubleToPrecisionCString(double value, int f);
154 char* DoubleToRadixCString(double value, int radix);
156 } } // namespace v8::internal
158 #endif // V8_CONVERSIONS_H_