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
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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