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 bool isBinaryDigit(int x) {
56  return x == '0' || x == '1';
57}
58
59
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.
63inline 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);
67}
68
69
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.
74inline int FastD2I(double x) {
75  return static_cast<int>(x);
76}
77
78inline unsigned int FastD2UI(double x);
79
80
81inline 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);
86}
87
88
89inline 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);
94}
95
96
97// This function should match the exact semantics of ECMA-262 9.4.
98inline double DoubleToInteger(double x);
99
100
101// This function should match the exact semantics of ECMA-262 9.5.
102inline int32_t DoubleToInt32(double x);
103
104
105// This function should match the exact semantics of ECMA-262 9.6.
106inline uint32_t DoubleToUint32(double x) {
107  return static_cast<uint32_t>(DoubleToInt32(x));
108}
109
110
111// Enumeration for allowing octals and ignoring junk when converting
112// strings to numbers.
113enum ConversionFlags {
114  NO_FLAGS = 0,
115  ALLOW_HEX = 1,
116  ALLOW_OCTAL = 2,
117  ALLOW_IMPLICIT_OCTAL = 4,
118  ALLOW_BINARY = 8,
119  ALLOW_TRAILING_JUNK = 16
120};
121
122
123// Converts a string into a double value according to ECMA-262 9.3.1
124double StringToDouble(UnicodeCache* unicode_cache,
125                      Vector<const char> str,
126                      int flags,
127                      double empty_string_val = 0);
128double StringToDouble(UnicodeCache* unicode_cache,
129                      Vector<const uc16> str,
130                      int flags,
131                      double empty_string_val = 0);
132// This version expects a zero-terminated character array.
133double StringToDouble(UnicodeCache* unicode_cache,
134                      const char* str,
135                      int flags,
136                      double empty_string_val = 0);
137
138const int kDoubleToCStringMinBufferSize = 100;
139
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.
143const char* DoubleToCString(double value, Vector<char> buffer);
144
145// Convert an int to a null-terminated string. The returned string is
146// located inside the buffer, but not necessarily at the start.
147const char* IntToCString(int n, Vector<char> buffer);
148
149// Additional number to string conversions for the number type.
150// The caller is responsible for calling free on the returned pointer.
151char* DoubleToFixedCString(double value, int f);
152char* DoubleToExponentialCString(double value, int f);
153char* DoubleToPrecisionCString(double value, int f);
154char* DoubleToRadixCString(double value, int radix);
155
156} }  // namespace v8::internal
157
158#endif  // V8_CONVERSIONS_H_
159