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65 lines
1.7 KiB
C
65 lines
1.7 KiB
C
/* @(#)s_nextafter.c 5.1 93/09/24 */
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/*
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* ====================================================
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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*
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* Developed at SunPro, a Sun Microsystems, Inc. business.
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* Permission to use, copy, modify, and distribute this
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* software is freely granted, provided that this notice
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* is preserved.
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* ====================================================
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*/
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#include <math.h>
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#include "math_private.h"
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float
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nexttowardf(float x, long double y)
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{
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int32_t hx,ix;
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int64_t hy,iy;
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u_int64_t ly;
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GET_FLOAT_WORD(hx,x);
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GET_LDOUBLE_WORDS64(hy,ly,y);
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ix = hx&0x7fffffff; /* |x| */
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iy = hy&0x7fffffffffffffffLL; /* |y| */
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if((ix>0x7f800000) || /* x is nan */
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((iy>=0x7fff000000000000LL)&&((iy-0x7fff000000000000LL)|ly)!=0))
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/* y is nan */
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return x+y;
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if((long double) x==y) return y; /* x=y, return y */
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if(ix==0) { /* x == 0 */
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volatile float u;
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SET_FLOAT_WORD(x,(u_int32_t)((hy>>32)&0x80000000)|1);/* return +-minsub*/
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u = x;
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u = u * u; /* raise underflow flag */
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return x;
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}
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if(hx>=0) { /* x > 0 */
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if(hy<0||(ix>>23)>(iy>>48)-0x3f80
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|| ((ix>>23)==(iy>>48)-0x3f80
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&& (ix&0x7fffff)>((hy>>25)&0x7fffff))) {/* x > y, x -= ulp */
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hx -= 1;
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} else { /* x < y, x += ulp */
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hx += 1;
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}
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} else { /* x < 0 */
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if(hy>=0||(ix>>23)>(iy>>48)-0x3f80
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|| ((ix>>23)==(iy>>48)-0x3f80
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&& (ix&0x7fffff)>((hy>>25)&0x7fffff))) {/* x < y, x -= ulp */
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hx -= 1;
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} else { /* x > y, x += ulp */
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hx += 1;
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}
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}
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hy = hx&0x7f800000;
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if(hy>=0x7f800000) return x+x; /* overflow */
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if(hy<0x00800000) {
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volatile float u = x*x; /* underflow */
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}
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SET_FLOAT_WORD(x,hx);
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return x;
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}
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