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107 lines
2.8 KiB
C
107 lines
2.8 KiB
C
/* s_nexttoward.c
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* Conversion from s_nextafter.c by Ulrich Drepper, Cygnus Support,
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* drepper@cygnus.com and Jakub Jelinek, jj@ultra.linux.cz.
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*/
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunPro, 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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#if defined(LIBM_SCCS) && !defined(lint)
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static char rcsid[] = "$NetBSD: $";
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#endif
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/* IEEE functions
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* nexttoward(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 "math.h"
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#include "math_private.h"
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#include <math_ldbl_opt.h>
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#include <float.h>
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#ifdef __STDC__
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double __nexttoward(double x, long double y)
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#else
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double __nexttoward(x,y)
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double x;
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long double y;
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#endif
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{
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int32_t hx,ix;
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int64_t hy,iy;
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u_int32_t lx;
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u_int64_t ly,uly;
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EXTRACT_WORDS(hx,lx,x);
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GET_LDOUBLE_WORDS64(hy,ly,y);
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ix = hx&0x7fffffff; /* |x| */
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iy = hy&0x7fffffffffffffffLL; /* |y| */
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uly = ly&0x7fffffffffffffffLL; /* |y| */
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if(((ix>=0x7ff00000)&&((ix-0x7ff00000)|lx)!=0) || /* x is nan */
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((iy>=0x7ff0000000000000LL)&&((iy-0x7ff0000000000000LL)|uly)!=0))
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/* y is nan */
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return x+y;
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if((long double) x==y) return y; /* x=y, return y */
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if((ix|lx)==0) { /* x == 0 */
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double x2;
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INSERT_WORDS(x,(u_int32_t)((hy>>32)&0x80000000),1);/* return +-minsub */
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x2 = x*x;
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if(x2==x) return x2; else return x; /* raise underflow flag */
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}
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if(hx>=0) { /* x > 0 */
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if (hy<0||(ix>>20)>(iy>>52)
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|| ((ix>>20)==(iy>>52)
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&& (((((int64_t)hx)<<32)|(lx))>(hy&0x000fffffffffffffLL)
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|| (((((int64_t)hx)<<32)|(lx))==(hy&0x000fffffffffffffLL)
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)))) { /* 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||(ix>>20)>(iy>>52)
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|| ((ix>>20)==(iy>>52)
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&& (((((int64_t)hx)<<32)|(lx))>(hy&0x000fffffffffffffLL)
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|| (((((int64_t)hx)<<32)|(lx))==(hy&0x000fffffffffffffLL)
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)))) { /* 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) {
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x = x+x; /* overflow */
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if (FLT_EVAL_METHOD != 0 && FLT_EVAL_METHOD != 1)
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/* Force conversion to float. */
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asm ("" : "=m"(x) : "m"(x));
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return x;
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}
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if(hy<0x00100000) { /* underflow */
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double x2 = x*x;
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if(x2!=x) { /* raise underflow flag */
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INSERT_WORDS(x2,hx,lx);
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return x2;
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}
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}
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INSERT_WORDS(x,hx,lx);
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return x;
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}
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long_double_symbol (libm, __nexttoward, nexttoward);
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