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path: root/src/math/s_nextafter.c
blob: 46d298ecd13d8b4298fa2318570cfe7ceda77899 (plain)
 ```1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 ``` ``````/* @(#)s_nextafter.c 5.1 93/09/24 */ /* * ==================================================== * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. * * Developed at SunPro, a Sun Microsystems, Inc. business. * Permission to use, copy, modify, and distribute this * software is freely granted, provided that this notice * is preserved. * ==================================================== */ /* IEEE functions * nextafter(x,y) * return the next machine floating-point number of x in the * direction toward y. * Special cases: */ #include #include "math_private.h" double nextafter(double x, double y) { volatile double t; int32_t hx,hy,ix,iy; uint32_t lx,ly; EXTRACT_WORDS(hx,lx,x); EXTRACT_WORDS(hy,ly,y); ix = hx&0x7fffffff; /* |x| */ iy = hy&0x7fffffff; /* |y| */ if(((ix>=0x7ff00000)&&((ix-0x7ff00000)|lx)!=0) || /* x is nan */ ((iy>=0x7ff00000)&&((iy-0x7ff00000)|ly)!=0)) /* y is nan */ return x+y; if(x==y) return y; /* x=y, return y */ if((ix|lx)==0) { /* x == 0 */ INSERT_WORDS(x,hy&0x80000000,1); /* return +-minsubnormal */ t = x*x; if(t==x) return t; else return x; /* raise underflow flag */ } if(hx>=0) { /* x > 0 */ if(hx>hy||((hx==hy)&&(lx>ly))) { /* x > y, x -= ulp */ if(lx==0) hx -= 1; lx -= 1; } else { /* x < y, x += ulp */ lx += 1; if(lx==0) hx += 1; } } else { /* x < 0 */ if(hy>=0||hx>hy||((hx==hy)&&(lx>ly))){/* x < y, x -= ulp */ if(lx==0) hx -= 1; lx -= 1; } else { /* x > y, x += ulp */ lx += 1; if(lx==0) hx += 1; } } hy = hx&0x7ff00000; if(hy>=0x7ff00000) return x+x; /* overflow */ if(hy<0x00100000) { /* underflow */ t = x*x; if(t!=x) { /* raise underflow flag */ INSERT_WORDS(y,hx,lx); return y; } } INSERT_WORDS(x,hx,lx); return x; } ``````