131 lines
3.7 KiB
C++
131 lines
3.7 KiB
C++
/*
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* Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*
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*/
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#ifndef SHARE_VM_RUNTIME_SHAREDRUNTIMEMATH_HPP
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#define SHARE_VM_RUNTIME_SHAREDRUNTIMEMATH_HPP
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#include <math.h>
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// Used to access the lower/higher 32 bits of a double
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typedef union {
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double d;
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struct {
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#ifdef VM_LITTLE_ENDIAN
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int lo;
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int hi;
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#else
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int hi;
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int lo;
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#endif
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} split;
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} DoubleIntConv;
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static inline int high(double d) {
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DoubleIntConv x;
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x.d = d;
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return x.split.hi;
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}
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static inline int low(double d) {
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DoubleIntConv x;
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x.d = d;
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return x.split.lo;
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}
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static inline void set_high(double* d, int high) {
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DoubleIntConv conv;
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conv.d = *d;
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conv.split.hi = high;
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*d = conv.d;
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}
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static inline void set_low(double* d, int low) {
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DoubleIntConv conv;
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conv.d = *d;
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conv.split.lo = low;
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*d = conv.d;
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}
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static double copysignA(double x, double y) {
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DoubleIntConv convX;
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convX.d = x;
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convX.split.hi = (convX.split.hi & 0x7fffffff) | (high(y) & 0x80000000);
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return convX.d;
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}
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/*
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* ====================================================
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* Copyright (c) 1998 Oracle and/or its affiliates. All rights reserved.
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*
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* Developed at SunSoft, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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/*
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* scalbn (double x, int n)
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* scalbn(x,n) returns x* 2**n computed by exponent
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* manipulation rather than by actually performing an
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* exponentiation or a multiplication.
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*/
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static const double
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two54 = 1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */
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twom54 = 5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */
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hugeX = 1.0e+300,
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tiny = 1.0e-300;
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static double scalbnA(double x, int n) {
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int k,hx,lx;
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hx = high(x);
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lx = low(x);
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k = (hx&0x7ff00000)>>20; /* extract exponent */
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if (k==0) { /* 0 or subnormal x */
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if ((lx|(hx&0x7fffffff))==0) return x; /* +-0 */
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x *= two54;
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hx = high(x);
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k = ((hx&0x7ff00000)>>20) - 54;
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if (n< -50000) return tiny*x; /*underflow*/
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}
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if (k==0x7ff) return x+x; /* NaN or Inf */
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k = k+n;
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if (k > 0x7fe) return hugeX*copysignA(hugeX,x); /* overflow */
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if (k > 0) { /* normal result */
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set_high(&x, (hx&0x800fffff)|(k<<20));
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return x;
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}
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if (k <= -54) {
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if (n > 50000) /* in case integer overflow in n+k */
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return hugeX*copysignA(hugeX,x); /*overflow*/
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else return tiny*copysignA(tiny,x); /*underflow*/
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}
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k += 54; /* subnormal result */
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set_high(&x, (hx&0x800fffff)|(k<<20));
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return x*twom54;
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}
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#endif // SHARE_VM_RUNTIME_SHAREDRUNTIMEMATH_HPP
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