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 33namespace v8 { 34namespace internal { 35 36class 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. 45const int kMaxSignificantDigits = 772; 46 47 48inline 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 55inline 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. 64inline 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 70inline unsigned int FastD2UI(double x); 71 72 73inline 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 81inline 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. 90inline double DoubleToInteger(double x); 91 92 93// This function should match the exact semantics of ECMA-262 9.5. 94inline int32_t DoubleToInt32(double x); 95 96 97// This function should match the exact semantics of ECMA-262 9.6. 98inline 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. 105enum 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 114double StringToDouble(UnicodeCache* unicode_cache, 115 Vector<const char> str, 116 int flags, 117 double empty_string_val = 0); 118double 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. 123double StringToDouble(UnicodeCache* unicode_cache, 124 const char* str, 125 int flags, 126 double empty_string_val = 0); 127 128const 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. 133const 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. 137const 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. 141char* DoubleToFixedCString(double value, int f); 142char* DoubleToExponentialCString(double value, int f); 143char* DoubleToPrecisionCString(double value, int f); 144char* DoubleToRadixCString(double value, int radix); 145 146} } // namespace v8::internal 147 148#endif // V8_CONVERSIONS_H_ 149