1*05a0b428SJohn Marino /* @(#)s_nextafter.c 5.1 93/09/24 */
2*05a0b428SJohn Marino /*
3*05a0b428SJohn Marino * ====================================================
4*05a0b428SJohn Marino * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
5*05a0b428SJohn Marino *
6*05a0b428SJohn Marino * Developed at SunPro, a Sun Microsystems, Inc. business.
7*05a0b428SJohn Marino * Permission to use, copy, modify, and distribute this
8*05a0b428SJohn Marino * software is freely granted, provided that this notice
9*05a0b428SJohn Marino * is preserved.
10*05a0b428SJohn Marino * ====================================================
11*05a0b428SJohn Marino */
12*05a0b428SJohn Marino
13*05a0b428SJohn Marino #include <math.h>
14*05a0b428SJohn Marino #include <float.h>
15*05a0b428SJohn Marino
16*05a0b428SJohn Marino #include "math_private.h"
17*05a0b428SJohn Marino
18*05a0b428SJohn Marino float
nexttowardf(float x,long double y)19*05a0b428SJohn Marino nexttowardf(float x, long double y)
20*05a0b428SJohn Marino {
21*05a0b428SJohn Marino int32_t hx,ix,iy;
22*05a0b428SJohn Marino u_int32_t hy,ly,esy;
23*05a0b428SJohn Marino
24*05a0b428SJohn Marino GET_FLOAT_WORD(hx,x);
25*05a0b428SJohn Marino GET_LDOUBLE_WORDS(esy,hy,ly,y);
26*05a0b428SJohn Marino ix = hx&0x7fffffff; /* |x| */
27*05a0b428SJohn Marino iy = esy&0x7fff; /* |y| */
28*05a0b428SJohn Marino
29*05a0b428SJohn Marino if((ix>0x7f800000) || /* x is nan */
30*05a0b428SJohn Marino (iy>=0x7fff&&((hy|ly)!=0))) /* y is nan */
31*05a0b428SJohn Marino return x+y;
32*05a0b428SJohn Marino if((long double) x==y) return y; /* x=y, return y */
33*05a0b428SJohn Marino if(ix==0) { /* x == 0 */
34*05a0b428SJohn Marino volatile float u;
35*05a0b428SJohn Marino SET_FLOAT_WORD(x,((esy&0x8000)<<16)|1);/* return +-minsub*/
36*05a0b428SJohn Marino u = x;
37*05a0b428SJohn Marino u = u * u; /* raise underflow flag */
38*05a0b428SJohn Marino return x;
39*05a0b428SJohn Marino }
40*05a0b428SJohn Marino if(hx>=0) { /* x > 0 */
41*05a0b428SJohn Marino if(esy>=0x8000||((ix>>23)&0xff)>iy-0x3f80
42*05a0b428SJohn Marino || (((ix>>23)&0xff)==iy-0x3f80
43*05a0b428SJohn Marino && ((ix&0x7fffff)<<8)>(hy&0x7fffffff))) {/* x > y, x -= ulp */
44*05a0b428SJohn Marino hx -= 1;
45*05a0b428SJohn Marino } else { /* x < y, x += ulp */
46*05a0b428SJohn Marino hx += 1;
47*05a0b428SJohn Marino }
48*05a0b428SJohn Marino } else { /* x < 0 */
49*05a0b428SJohn Marino if(esy<0x8000||((ix>>23)&0xff)>iy-0x3f80
50*05a0b428SJohn Marino || (((ix>>23)&0xff)==iy-0x3f80
51*05a0b428SJohn Marino && ((ix&0x7fffff)<<8)>(hy&0x7fffffff))) {/* x < y, x -= ulp */
52*05a0b428SJohn Marino hx -= 1;
53*05a0b428SJohn Marino } else { /* x > y, x += ulp */
54*05a0b428SJohn Marino hx += 1;
55*05a0b428SJohn Marino }
56*05a0b428SJohn Marino }
57*05a0b428SJohn Marino hy = hx&0x7f800000;
58*05a0b428SJohn Marino if(hy>=0x7f800000) {
59*05a0b428SJohn Marino x = x+x; /* overflow */
60*05a0b428SJohn Marino return x;
61*05a0b428SJohn Marino }
62*05a0b428SJohn Marino if(hy<0x00800000) {
63*05a0b428SJohn Marino volatile float u = x*x; /* underflow */
64*05a0b428SJohn Marino }
65*05a0b428SJohn Marino SET_FLOAT_WORD(x,hx);
66*05a0b428SJohn Marino return x;
67*05a0b428SJohn Marino }
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