1 // Copyright 2011 the V8 project authors. All rights reserved. 2 // Redistribution and use in source and binary forms, with or without 3 // modification, are permitted provided that the following conditions are 4 // met: 5 // 6 // * Redistributions of source code must retain the above copyright 7 // notice, this list of conditions and the following disclaimer. 8 // * Redistributions in binary form must reproduce the above 9 // copyright notice, this list of conditions and the following 10 // disclaimer in the documentation and/or other materials provided 11 // with the distribution. 12 // * Neither the name of Google Inc. nor the names of its 13 // contributors may be used to endorse or promote products derived 14 // from this software without specific prior written permission. 15 // 16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 28 #ifndef V8_CONVERSIONS_H_ 29 #define V8_CONVERSIONS_H_ 30 31 #include "utils.h" 32 33 namespace v8 { 34 namespace internal { 35 36 class UnicodeCache; 37 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; 46 47 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); 52 } 53 54 55 inline double SignedZero(bool negative) { 56 return negative ? -0.0 : 0.0; 57 } 58 59 60 // The fast double-to-(unsigned-)int conversion routine does not guarantee 61 // rounding towards zero. 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. 64 inline int FastD2I(double x) { 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(). 67 return static_cast<int>(x); 68 } 69 70 inline unsigned int FastD2UI(double x); 71 72 73 inline double FastI2D(int x) { 74 // There is no rounding involved in converting an integer to a 75 // double, so this code should compile to a few instructions without 76 // any FPU pipeline stalls. 77 return static_cast<double>(x); 78 } 79 80 81 inline double FastUI2D(unsigned x) { 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 84 // any FPU pipeline stalls. 85 return static_cast<double>(x); 86 } 87 88 89 // This function should match the exact semantics of ECMA-262 9.4. 90 inline double DoubleToInteger(double x); 91 92 93 // This function should match the exact semantics of ECMA-262 9.5. 94 inline int32_t DoubleToInt32(double x); 95 96 97 // This function should match the exact semantics of ECMA-262 9.6. 98 inline uint32_t DoubleToUint32(double x) { 99 return static_cast<uint32_t>(DoubleToInt32(x)); 100 } 101 102 103 // Enumeration for allowing octals and ignoring junk when converting 104 // strings to numbers. 105 enum ConversionFlags { 106 NO_FLAGS = 0, 107 ALLOW_HEX = 1, 108 ALLOW_OCTALS = 2, 109 ALLOW_TRAILING_JUNK = 4 110 }; 111 112 113 // Converts a string into a double value according to ECMA-262 9.3.1 114 double StringToDouble(UnicodeCache* unicode_cache, 115 Vector<const char> str, 116 int flags, 117 double empty_string_val = 0); 118 double StringToDouble(UnicodeCache* unicode_cache, 119 Vector<const uc16> str, 120 int flags, 121 double empty_string_val = 0); 122 // This version expects a zero-terminated character array. 123 double StringToDouble(UnicodeCache* unicode_cache, 124 const char* str, 125 int flags, 126 double empty_string_val = 0); 127 128 const int kDoubleToCStringMinBufferSize = 100; 129 130 // Converts a double to a string value according to ECMA-262 9.8.1. 131 // The buffer should be large enough for any floating point number. 132 // 100 characters is enough. 133 const char* DoubleToCString(double value, Vector<char> buffer); 134 135 // Convert an int to a null-terminated string. The returned string is 136 // located inside the buffer, but not necessarily at the start. 137 const char* IntToCString(int n, Vector<char> buffer); 138 139 // Additional number to string conversions for the number type. 140 // The caller is responsible for calling free on the returned pointer. 141 char* DoubleToFixedCString(double value, int f); 142 char* DoubleToExponentialCString(double value, int f); 143 char* DoubleToPrecisionCString(double value, int f); 144 char* DoubleToRadixCString(double value, int radix); 145 146 } } // namespace v8::internal 147 148 #endif // V8_CONVERSIONS_H_ 149
