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94 lines
2.3 KiB
C
94 lines
2.3 KiB
C
/* s_nexttoward.c
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* Special i387 version
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* Conversion from s_nextafter.c by Ulrich Drepper, Cygnus Support,
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* drepper@cygnus.com.
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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 <float.h>
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double __nexttoward(double x, long double y)
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{
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int32_t hx,ix,iy;
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u_int32_t lx,hy,ly,esy;
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EXTRACT_WORDS(hx,lx,x);
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GET_LDOUBLE_WORDS(esy,hy,ly,y);
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ix = hx&0x7fffffff; /* |x| */
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iy = esy&0x7fff; /* |y| */
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/* Intel's extended format has the normally implicit 1 explicit
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present. Sigh! */
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if(((ix>=0x7ff00000)&&((ix-0x7ff00000)|lx)!=0) || /* x is nan */
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((iy>=0x7fff)&&((hy&0x7fffffff)|ly)!=0)) /* 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 u;
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INSERT_WORDS(x,(esy&0x8000)<<16,1); /* return +-minsub */
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u = math_opt_barrier (x);
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u = u * u;
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math_force_eval (u); /* raise underflow flag */
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return x;
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}
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if(hx>=0) { /* x > 0 */
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if (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 (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 double. */
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asm ("" : "+m"(x));
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return x;
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}
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if(hy<0x00100000) {
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double u = x*x; /* underflow */
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math_force_eval (u); /* raise underflow flag */
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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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weak_alias (__nexttoward, nexttoward)
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#ifdef NO_LONG_DOUBLE
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strong_alias (__nexttoward, __nexttowardl)
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weak_alias (__nexttoward, nexttowardl)
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#endif
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