1 /*
2 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_VM_RUNTIME_SHAREDRUNTIMEMATH_HPP
26 #define SHARE_VM_RUNTIME_SHAREDRUNTIMEMATH_HPP
27
28 #include <math.h>
29
30 // Used to access the lower/higher 32 bits of a double
31 typedef union {
32 double d;
33 struct {
34 #ifdef VM_LITTLE_ENDIAN
35 int lo;
36 int hi;
37 #else
38 int hi;
39 int lo;
40 #endif
41 } split;
42 } DoubleIntConv;
43
44 static inline int high(double d) {
45 DoubleIntConv x = { d };
46 return x.split.hi;
47 }
48
49 static inline int low(double d) {
50 DoubleIntConv x = { d };
51 return x.split.lo;
52 }
53
54 static inline void set_high(double* d, int high) {
55 DoubleIntConv conv = { *d };
56 conv.split.hi = high;
57 *d = conv.d;
58 }
59
60 static inline void set_low(double* d, int low) {
61 DoubleIntConv conv = { *d };
62 conv.split.lo = low;
63 *d = conv.d;
64 }
65
66 static double copysignA(double x, double y) {
67 DoubleIntConv convX = { x };
68 convX.split.hi = (convX.split.hi & 0x7fffffff) | (high(y) & 0x80000000);
69 return convX.d;
70 }
71
72 /*
73 * ====================================================
74 * Copyright (c) 1998 Oracle and/or its affiliates. All rights reserved.
75 *
76 * Developed at SunSoft, a Sun Microsystems, Inc. business.
77 * Permission to use, copy, modify, and distribute this
78 * software is freely granted, provided that this notice
79 * is preserved.
80 * ====================================================
81 */
82
83 /*
84 * scalbn (double x, int n)
85 * scalbn(x,n) returns x* 2**n computed by exponent
86 * manipulation rather than by actually performing an
87 * exponentiation or a multiplication.
88 */
89
90 static const double
91 two54 = 1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */
92 twom54 = 5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */
93 hugeX = 1.0e+300,
94 tiny = 1.0e-300;
95
96 static double scalbnA(double x, int n) {
97 int k,hx,lx;
98 hx = high(x);
99 lx = low(x);
100 k = (hx&0x7ff00000)>>20; /* extract exponent */
101 if (k==0) { /* 0 or subnormal x */
102 if ((lx|(hx&0x7fffffff))==0) return x; /* +-0 */
103 x *= two54;
104 hx = high(x);
105 k = ((hx&0x7ff00000)>>20) - 54;
106 if (n< -50000) return tiny*x; /*underflow*/
107 }
108 if (k==0x7ff) return x+x; /* NaN or Inf */
109 k = k+n;
110 if (k > 0x7fe) return hugeX*copysignA(hugeX,x); /* overflow */
111 if (k > 0) { /* normal result */
112 set_high(&x, (hx&0x800fffff)|(k<<20));
113 return x;
114 }
115 if (k <= -54) {
116 if (n > 50000) /* in case integer overflow in n+k */
117 return hugeX*copysignA(hugeX,x); /*overflow*/
118 else return tiny*copysignA(tiny,x); /*underflow*/
119 }
120 k += 54; /* subnormal result */
121 set_high(&x, (hx&0x800fffff)|(k<<20));
122 return x*twom54;
123 }
124
125 #endif // SHARE_VM_RUNTIME_SHAREDRUNTIMEMATH_HPP