66 lines
1.7 KiB
C
66 lines
1.7 KiB
C
/* @(#)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 <openlibm_math.h>
|
|
|
|
#include "math_private.h"
|
|
|
|
float
|
|
nexttowardf(float x, long double y)
|
|
{
|
|
int32_t hx,ix;
|
|
int64_t hy,iy;
|
|
u_int64_t ly;
|
|
|
|
GET_FLOAT_WORD(hx,x);
|
|
GET_LDOUBLE_WORDS64(hy,ly,y);
|
|
ix = hx&0x7fffffff; /* |x| */
|
|
iy = hy&0x7fffffffffffffffLL; /* |y| */
|
|
|
|
if((ix>0x7f800000) || /* x is nan */
|
|
((iy>=0x7fff000000000000LL)&&((iy-0x7fff000000000000LL)|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,(u_int32_t)((hy>>32)&0x80000000)|1);/* return +-minsub*/
|
|
u = x;
|
|
u = u * u; /* raise underflow flag */
|
|
return x;
|
|
}
|
|
if(hx>=0) { /* x > 0 */
|
|
if(hy<0||(ix>>23)>(iy>>48)-0x3f80
|
|
|| ((ix>>23)==(iy>>48)-0x3f80
|
|
&& (ix&0x7fffff)>((hy>>25)&0x7fffff))) {/* x > y, x -= ulp */
|
|
hx -= 1;
|
|
} else { /* x < y, x += ulp */
|
|
hx += 1;
|
|
}
|
|
} else { /* x < 0 */
|
|
if(hy>=0||(ix>>23)>(iy>>48)-0x3f80
|
|
|| ((ix>>23)==(iy>>48)-0x3f80
|
|
&& (ix&0x7fffff)>((hy>>25)&0x7fffff))) {/* x < y, x -= ulp */
|
|
hx -= 1;
|
|
} else { /* x > y, x += ulp */
|
|
hx += 1;
|
|
}
|
|
}
|
|
hy = hx&0x7f800000;
|
|
if(hy>=0x7f800000) return x+x; /* overflow */
|
|
if(hy<0x00800000) {
|
|
volatile float u = x*x; /* underflow */
|
|
}
|
|
SET_FLOAT_WORD(x,hx);
|
|
return x;
|
|
}
|