1 /* origin: FreeBSD /usr/src/lib/msun/src/s_nextafter.c */
3 * ====================================================
4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
6 * Developed at SunPro, a Sun Microsystems, Inc. business.
7 * Permission to use, copy, modify, and distribute this
8 * software is freely granted, provided that this notice
10 * ====================================================
14 * return the next machine floating-point number of x in the
21 double nextafter(double x, double y)
27 EXTRACT_WORDS(hx, lx, x);
28 EXTRACT_WORDS(hy, ly, y);
29 ix = hx & 0x7fffffff; /* |x| */
30 iy = hy & 0x7fffffff; /* |y| */
32 if ((ix >= 0x7ff00000 && (ix-0x7ff00000)|lx) != 0 || /* x is nan */
33 (iy >= 0x7ff00000 && (iy-0x7ff00000)|ly) != 0) /* y is nan */
35 if (x == y) /* x == y */
37 if ((ix|lx) == 0) { /* x == 0 */
38 INSERT_WORDS(x, hy&0x80000000, 1); /* return +-minsubnormal */
39 /* raise underflow flag */
45 if (hx >= 0) { /* x > 0 */
46 if (hx > hy || (hx == hy && lx > ly)) { /* x > y, x -= ulp */
50 } else { /* x < y, x += ulp */
56 if (hy >= 0 || hx > hy || (hx == hy && lx > ly)) { /* x < y, x -= ulp */
60 } else { /* x > y, x += ulp */
67 if (hy >= 0x7ff00000) /* overflow */
69 if (hy < 0x00100000) { /* underflow */
70 /* raise underflow flag */
73 INSERT_WORDS(y, hx, lx);
77 INSERT_WORDS(x, hx, lx);