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91 lines
3.4 KiB
C
91 lines
3.4 KiB
C
/*
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* Copyright (c) 1998, 2001, 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. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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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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/* IEEE functions
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* nextafter(x,y)
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* return the next machine floating-point number of x in the
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* direction toward y.
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* Special cases:
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*/
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#include "fdlibm.h"
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#ifdef __STDC__
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double nextafter(double x, double y)
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#else
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double nextafter(x,y)
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double x,y;
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#endif
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{
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int hx,hy,ix,iy;
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unsigned lx,ly;
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hx = __HI(x); /* high word of x */
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lx = __LO(x); /* low word of x */
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hy = __HI(y); /* high word of y */
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ly = __LO(y); /* low word of y */
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ix = hx&0x7fffffff; /* |x| */
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iy = hy&0x7fffffff; /* |y| */
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if(((ix>=0x7ff00000)&&((ix-0x7ff00000)|lx)!=0) || /* x is nan */
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((iy>=0x7ff00000)&&((iy-0x7ff00000)|ly)!=0)) /* y is nan */
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return x+y;
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if(x==y) return x; /* x=y, return x */
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if((ix|lx)==0) { /* x == 0 */
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__HI(x) = hy&0x80000000; /* return +-minsubnormal */
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__LO(x) = 1;
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y = x*x;
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if(y==x) return y; else return x; /* raise underflow flag */
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}
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if(hx>=0) { /* x > 0 */
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if(hx>hy||((hx==hy)&&(lx>ly))) { /* x > y, x -= ulp */
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if(lx==0) hx -= 1;
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lx -= 1;
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} else { /* x < y, x += ulp */
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lx += 1;
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if(lx==0) hx += 1;
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}
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} else { /* x < 0 */
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if(hy>=0||hx>hy||((hx==hy)&&(lx>ly))){/* x < y, x -= ulp */
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if(lx==0) hx -= 1;
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lx -= 1;
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} else { /* x > y, x += ulp */
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lx += 1;
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if(lx==0) hx += 1;
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}
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}
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hy = hx&0x7ff00000;
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if(hy>=0x7ff00000) return x+x; /* overflow */
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if(hy<0x00100000) { /* underflow */
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y = x*x;
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if(y!=x) { /* raise underflow flag */
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__HI(y) = hx; __LO(y) = lx;
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return y;
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}
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}
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__HI(x) = hx; __LO(x) = lx;
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return x;
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}
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