1/* s_nexttoward.c 2 * Special i387 version 3 * Conversion from s_nextafter.c by Ulrich Drepper, Cygnus Support, 4 * drepper@cygnus.com. 5 */ 6 7/* 8 * ==================================================== 9 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 10 * 11 * Developed at SunPro, a Sun Microsystems, Inc. business. 12 * Permission to use, copy, modify, and distribute this 13 * software is freely granted, provided that this notice 14 * is preserved. 15 * ==================================================== 16 */ 17 18#if defined(LIBM_SCCS) && !defined(lint) 19static char rcsid[] = "$NetBSD: $"; 20#endif 21 22/* IEEE functions 23 * nexttoward(x,y) 24 * return the next machine floating-point number of x in the 25 * direction toward y. 26 * Special cases: 27 */ 28 29#include "math.h" 30#include "math_private.h" 31 32#ifdef __STDC__ 33 double __nexttoward(double x, long double y) 34#else 35 double __nexttoward(x,y) 36 double x; 37 long double y; 38#endif 39{ 40 int32_t hx,ix,iy; 41 u_int32_t lx,hy,ly,esy; 42 43 EXTRACT_WORDS(hx,lx,x); 44 GET_LDOUBLE_WORDS(esy,hy,ly,y); 45 ix = hx&0x7fffffff; /* |x| */ 46 iy = esy&0x7fff; /* |y| */ 47 48 /* Intel's extended format has the normally implicit 1 explicit 49 present. Sigh! */ 50 if(((ix>=0x7ff00000)&&((ix-0x7ff00000)|lx)!=0) || /* x is nan */ 51 ((iy>=0x7fff)&&((hy&0x7fffffff)|ly)!=0)) /* y is nan */ 52 return x+y; 53 if((long double) x==y) return y; /* x=y, return y */ 54 if((ix|lx)==0) { /* x == 0 */ 55 double x2; 56 INSERT_WORDS(x,(esy&0x8000)<<16,1); /* return +-minsub */ 57 x2 = x*x; 58 if(x2==x) return x2; else return x; /* raise underflow flag */ 59 } 60 if(hx>=0) { /* x > 0 */ 61 if (esy>=0x8000||((ix>>20)&0x7ff)>iy-0x3c00 62 || (((ix>>20)&0x7ff)==iy-0x3c00 63 && (((hx<<11)|(lx>>21))>(hy&0x7fffffff) 64 || (((hx<<11)|(lx>>21))==(hy&0x7fffffff) 65 && (lx<<11)>ly)))) { /* x > y, x -= ulp */ 66 if(lx==0) hx -= 1; 67 lx -= 1; 68 } else { /* x < y, x += ulp */ 69 lx += 1; 70 if(lx==0) hx += 1; 71 } 72 } else { /* x < 0 */ 73 if (esy<0x8000||((ix>>20)&0x7ff)>iy-0x3c00 74 || (((ix>>20)&0x7ff)==iy-0x3c00 75 && (((hx<<11)|(lx>>21))>(hy&0x7fffffff) 76 || (((hx<<11)|(lx>>21))==(hy&0x7fffffff) 77 && (lx<<11)>ly)))) {/* x < y, x -= ulp */ 78 if(lx==0) hx -= 1; 79 lx -= 1; 80 } else { /* x > y, x += ulp */ 81 lx += 1; 82 if(lx==0) hx += 1; 83 } 84 } 85 hy = hx&0x7ff00000; 86 if(hy>=0x7ff00000) { 87 x = x+x; /* overflow */ 88 /* Force conversion to double. */ 89 asm ("" : "=m"(x) : "m"(x)); 90 return x; 91 } 92 if(hy<0x00100000) { /* underflow */ 93 double x2 = x*x; 94 if(x2!=x) { /* raise underflow flag */ 95 INSERT_WORDS(x2,hx,lx); 96 return x2; 97 } 98 } 99 INSERT_WORDS(x,hx,lx); 100 return x; 101} 102weak_alias (__nexttoward, nexttoward) 103#ifdef NO_LONG_DOUBLE 104strong_alias (__nexttoward, __nexttowardl) 105weak_alias (__nexttoward, nexttowardl) 106#endif 107