OpenLibm/ld80/s_nexttowardf.c

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/* @(#)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.
* ====================================================
*/
#include <float.h>
#include <openlibm_math.h>
#include "math_private.h"
float
nexttowardf(float x, long double y)
{
int32_t hx,ix,iy;
u_int32_t hy,ly,esy;
GET_FLOAT_WORD(hx,x);
GET_LDOUBLE_WORDS(esy,hy,ly,y);
ix = hx&0x7fffffff; /* |x| */
iy = esy&0x7fff; /* |y| */
if((ix>0x7f800000) || /* x is nan */
(iy>=0x7fff&&((hy|ly)!=0))) /* y is nan */
return x+y;
if((long double) x==y) return y; /* x=y, return y */
if(ix==0) { /* x == 0 */
volatile float u;
SET_FLOAT_WORD(x,((esy&0x8000)<<16)|1);/* return +-minsub*/
u = x;
u = u * u; /* raise underflow flag */
return x;
}
if(hx>=0) { /* x > 0 */
if(esy>=0x8000||((ix>>23)&0xff)>iy-0x3f80
|| (((ix>>23)&0xff)==iy-0x3f80
&& ((ix&0x7fffff)<<8)>(hy&0x7fffffff))) {/* x > y, x -= ulp */
hx -= 1;
} else { /* x < y, x += ulp */
hx += 1;
}
} else { /* x < 0 */
if(esy<0x8000||((ix>>23)&0xff)>iy-0x3f80
|| (((ix>>23)&0xff)==iy-0x3f80
&& ((ix&0x7fffff)<<8)>(hy&0x7fffffff))) {/* x < y, x -= ulp */
hx -= 1;
} else { /* x > y, x += ulp */
hx += 1;
}
}
hy = hx&0x7f800000;
if(hy>=0x7f800000) {
x = x+x; /* overflow */
return x;
}
if(hy<0x00800000) {
volatile float u = x*x; /* underflow */
}
SET_FLOAT_WORD(x,hx);
return x;
}