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/* origin: FreeBSD /usr/src/lib/msun/src/s_nextafter.c */
/*
* ====================================================
* 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 "libm.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) /* x == y */
return y;
if ((ix|lx) == 0) { /* x == 0 */
INSERT_WORDS(x, hy&0x80000000, 1); /* return +-minsubnormal */
/* raise underflow flag */
t = x*x;
if (t == x)
return t;
return x;
}
if (hx >= 0) { /* x > 0 */
if (hx > hy || (hx == hy && lx > ly)) { /* x > y, x -= ulp */
if (lx == 0)
hx--;
lx--;
} else { /* x < y, x += ulp */
lx++;
if (lx == 0)
hx++;
}
} else { /* x < 0 */
if (hy >= 0 || hx > hy || (hx == hy && lx > ly)) { /* x < y, x -= ulp */
if (lx == 0)
hx--;
lx--;
} else { /* x > y, x += ulp */
lx++;
if (lx == 0)
hx++;
}
}
hy = hx & 0x7ff00000;
if (hy >= 0x7ff00000) /* overflow */
return x+x;
if (hy < 0x00100000) { /* underflow */
/* raise underflow flag */
t = x*x;
if (t != x) {
INSERT_WORDS(y, hx, lx);
return y;
}
}
INSERT_WORDS(x, hx, lx);
return x;
}
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