1 /* 2 * ==================================================== 3 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 4 * 5 * Developed at SunPro, a Sun Microsystems, Inc. business. 6 * Permission to use, copy, modify, and distribute this 7 * software is freely granted, provided that this notice 8 * is preserved. 9 * ==================================================== 10 */ 11 12 #include <sys/cdefs.h> 13 /* IEEE functions 14 * nextafter(x,y) 15 * return the next machine floating-point number of x in the 16 * direction toward y. 17 * Special cases: 18 */ 19 20 #include <float.h> 21 22 #include "math.h" 23 #include "math_private.h" 24 25 double 26 nextafter(double x, double y) 27 { 28 volatile double t; 29 int32_t hx,hy,ix,iy; 30 u_int32_t lx,ly; 31 32 EXTRACT_WORDS(hx,lx,x); 33 EXTRACT_WORDS(hy,ly,y); 34 ix = hx&0x7fffffff; /* |x| */ 35 iy = hy&0x7fffffff; /* |y| */ 36 37 if(((ix>=0x7ff00000)&&((ix-0x7ff00000)|lx)!=0) || /* x is nan */ 38 ((iy>=0x7ff00000)&&((iy-0x7ff00000)|ly)!=0)) /* y is nan */ 39 return x+y; 40 if(x==y) return y; /* x=y, return y */ 41 if((ix|lx)==0) { /* x == 0 */ 42 INSERT_WORDS(x,hy&0x80000000,1); /* return +-minsubnormal */ 43 t = x*x; 44 if(t==x) return t; else return x; /* raise underflow flag */ 45 } 46 if(hx>=0) { /* x > 0 */ 47 if(hx>hy||((hx==hy)&&(lx>ly))) { /* x > y, x -= ulp */ 48 if(lx==0) hx -= 1; 49 lx -= 1; 50 } else { /* x < y, x += ulp */ 51 lx += 1; 52 if(lx==0) hx += 1; 53 } 54 } else { /* x < 0 */ 55 if(hy>=0||hx>hy||((hx==hy)&&(lx>ly))){/* x < y, x -= ulp */ 56 if(lx==0) hx -= 1; 57 lx -= 1; 58 } else { /* x > y, x += ulp */ 59 lx += 1; 60 if(lx==0) hx += 1; 61 } 62 } 63 hy = hx&0x7ff00000; 64 if(hy>=0x7ff00000) return x+x; /* overflow */ 65 if(hy<0x00100000) { /* underflow */ 66 t = x*x; 67 if(t!=x) { /* raise underflow flag */ 68 INSERT_WORDS(y,hx,lx); 69 return y; 70 } 71 } 72 INSERT_WORDS(x,hx,lx); 73 return x; 74 } 75 76 #if (LDBL_MANT_DIG == 53) 77 __weak_reference(nextafter, nexttoward); 78 __weak_reference(nextafter, nexttowardl); 79 __weak_reference(nextafter, nextafterl); 80 #endif 81