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nextafterq.c revision 1.1 
      1 /* s_nextafterl.c -- long double version of s_nextafter.c.
      2  * Conversion to IEEE quad long double by Jakub Jelinek, jj (at) ultra.linux.cz.
      3  */
      4 
      5 /*
      6  * ====================================================
      7  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
      8  *
      9  * Developed at SunPro, a Sun Microsystems, Inc. business.
     10  * Permission to use, copy, modify, and distribute this
     11  * software is freely granted, provided that this notice
     12  * is preserved.
     13  * ====================================================
     14  */
     15 
     16 #if defined(LIBM_SCCS) && !defined(lint)
     17 static char rcsid[] = "NetBSD: ";
     18 #endif
     19 
     20 /* IEEE functions
     21  *	nextafterq(x,y)
     22  *	return the next machine floating-point number of x in the
     23  *	direction toward y.
     24  *   Special cases:
     25  */
     26 
     27 #include "quadmath-imp.h"
     28 
     29 __float128 nextafterq(__float128 x, __float128 y)
     30 {
     31 	int64_t hx,hy,ix,iy;
     32 	uint64_t lx,ly;
     33 
     34 	GET_FLT128_WORDS64(hx,lx,x);
     35 	GET_FLT128_WORDS64(hy,ly,y);
     36 	ix = hx&0x7fffffffffffffffLL;		/* |x| */
     37 	iy = hy&0x7fffffffffffffffLL;		/* |y| */
     38 
     39 	if(((ix>=0x7fff000000000000LL)&&((ix-0x7fff000000000000LL)|lx)!=0) ||   /* x is nan */
     40 	   ((iy>=0x7fff000000000000LL)&&((iy-0x7fff000000000000LL)|ly)!=0))     /* y is nan */
     41 	   return x+y;
     42 	if(x==y) return y;		/* x=y, return y */
     43 	if((ix|lx)==0) {			/* x == 0 */
     44 	    __float128 u;
     45 	    SET_FLT128_WORDS64(x,hy&0x8000000000000000ULL,1);/* return +-minsubnormal */
     46 	    u = math_opt_barrier (x);
     47 	    u = u * u;
     48 	    math_force_eval (u);		/* raise underflow flag */
     49 	    return x;
     50 	}
     51 	if(hx>=0) {			/* x > 0 */
     52 	    if(hx>hy||((hx==hy)&&(lx>ly))) {	/* x > y, x -= ulp */
     53 		if(lx==0) hx--;
     54 		lx--;
     55 	    } else {				/* x < y, x += ulp */
     56 		lx++;
     57 		if(lx==0) hx++;
     58 	    }
     59 	} else {				/* x < 0 */
     60 	    if(hy>=0||hx>hy||((hx==hy)&&(lx>ly))){/* x < y, x -= ulp */
     61 		if(lx==0) hx--;
     62 		lx--;
     63 	    } else {				/* x > y, x += ulp */
     64 		lx++;
     65 		if(lx==0) hx++;
     66 	    }
     67 	}
     68 	hy = hx&0x7fff000000000000LL;
     69 	if(hy==0x7fff000000000000LL) {
     70 	    __float128 u = x + x;		/* overflow  */
     71 	    math_force_eval (u);
     72 	    errno = ERANGE;
     73 	}
     74 	if(hy==0) {
     75 	    __float128 u = x*x;		/* underflow */
     76 	    math_force_eval (u);		/* raise underflow flag */
     77 	    errno = ERANGE;
     78 	}
     79 	SET_FLT128_WORDS64(x,hx,lx);
     80 	return x;
     81 }
     82