81 lines
2.0 KiB
C
81 lines
2.0 KiB
C
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/* @(#)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 <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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/* IEEE functions
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* nextafter(x,y)
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* return the next machine floating-point number of x in the
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* direction toward y.
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* Special cases:
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*/
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#include <float.h>
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#include "fpmath.h"
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#include "math.h"
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#include "math_private.h"
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#if LDBL_MAX_EXP != 0x4000
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#error "Unsupported long double format"
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#endif
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long double
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nextafterl(long double x, long double y)
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{
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volatile long double t;
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union IEEEl2bits ux, uy;
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ux.e = x;
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uy.e = y;
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if ((ux.bits.exp == 0x7fff &&
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((ux.bits.manh&~LDBL_NBIT)|ux.bits.manl) != 0) ||
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(uy.bits.exp == 0x7fff &&
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((uy.bits.manh&~LDBL_NBIT)|uy.bits.manl) != 0))
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return x+y; /* x or y is nan */
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if(x==y) return y; /* x=y, return y */
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if(x==0.0) {
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ux.bits.manh = 0; /* return +-minsubnormal */
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ux.bits.manl = 1;
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ux.bits.sign = uy.bits.sign;
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t = ux.e*ux.e;
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if(t==ux.e) return t; else return ux.e; /* raise underflow flag */
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}
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if(x>0.0 ^ x<y) { /* x -= ulp */
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if(ux.bits.manl==0) {
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if ((ux.bits.manh&~LDBL_NBIT)==0)
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ux.bits.exp -= 1;
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ux.bits.manh = (ux.bits.manh - 1) | (ux.bits.manh & LDBL_NBIT);
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}
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ux.bits.manl -= 1;
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} else { /* x += ulp */
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ux.bits.manl += 1;
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if(ux.bits.manl==0) {
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ux.bits.manh = (ux.bits.manh + 1) | (ux.bits.manh & LDBL_NBIT);
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if ((ux.bits.manh&~LDBL_NBIT)==0)
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ux.bits.exp += 1;
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}
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}
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if(ux.bits.exp==0x7fff) return x+x; /* overflow */
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if(ux.bits.exp==0) { /* underflow */
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mask_nbit_l(ux);
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t = ux.e * ux.e;
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if(t!=ux.e) /* raise underflow flag */
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return ux.e;
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}
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return ux.e;
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}
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__strong_reference(nextafterl, nexttowardl);
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