1 // Copyright 2011 the V8 project authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 
5 // Extra POSIX/ANSI routines for Win32 when using Visual Studio C++. Please
6 // refer to The Open Group Base Specification for specification of the correct
7 // semantics for these functions.
8 // (http://www.opengroup.org/onlinepubs/000095399/)
9 #if defined(_MSC_VER) && (_MSC_VER < 1800)
10 
11 #include "src/base/win32-headers.h"
12 #include <float.h>         // Required for DBL_MAX and on Win32 for finite()
13 #include <limits.h>        // Required for INT_MAX etc.
14 #include <cmath>
15 #include "src/base/win32-math.h"
16 
17 #include "src/base/logging.h"
18 
19 
20 namespace std {
21 
22 // Test for a NaN (not a number) value - usually defined in math.h
isnan(double x)23 int isnan(double x) {
24   return _isnan(x);
25 }
26 
27 
28 // Test for infinity - usually defined in math.h
isinf(double x)29 int isinf(double x) {
30   return (_fpclass(x) & (_FPCLASS_PINF | _FPCLASS_NINF)) != 0;
31 }
32 
33 
34 // Test for finite value - usually defined in math.h
isfinite(double x)35 int isfinite(double x) {
36   return _finite(x);
37 }
38 
39 
40 // Test if x is less than y and both nominal - usually defined in math.h
isless(double x,double y)41 int isless(double x, double y) {
42   return isnan(x) || isnan(y) ? 0 : x < y;
43 }
44 
45 
46 // Test if x is greater than y and both nominal - usually defined in math.h
isgreater(double x,double y)47 int isgreater(double x, double y) {
48   return isnan(x) || isnan(y) ? 0 : x > y;
49 }
50 
51 
52 // Classify floating point number - usually defined in math.h
fpclassify(double x)53 int fpclassify(double x) {
54   // Use the MS-specific _fpclass() for classification.
55   int flags = _fpclass(x);
56 
57   // Determine class. We cannot use a switch statement because
58   // the _FPCLASS_ constants are defined as flags.
59   if (flags & (_FPCLASS_PN | _FPCLASS_NN)) return FP_NORMAL;
60   if (flags & (_FPCLASS_PZ | _FPCLASS_NZ)) return FP_ZERO;
61   if (flags & (_FPCLASS_PD | _FPCLASS_ND)) return FP_SUBNORMAL;
62   if (flags & (_FPCLASS_PINF | _FPCLASS_NINF)) return FP_INFINITE;
63 
64   // All cases should be covered by the code above.
65   DCHECK(flags & (_FPCLASS_SNAN | _FPCLASS_QNAN));
66   return FP_NAN;
67 }
68 
69 
70 // Test sign - usually defined in math.h
signbit(double x)71 int signbit(double x) {
72   // We need to take care of the special case of both positive
73   // and negative versions of zero.
74   if (x == 0)
75     return _fpclass(x) & _FPCLASS_NZ;
76   else
77     return x < 0;
78 }
79 
80 }  // namespace std
81 
82 #endif  // _MSC_VER
83