| 1 | /* @(#)s_nextafter.c 5.1 93/09/24 */
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| 2 | /*
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| 3 | * ====================================================
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| 4 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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| 5 | *
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| 6 | * Developed at SunPro, a Sun Microsystems, Inc. business.
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| 7 | * Permission to use, copy, modify, and distribute this
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| 8 | * software is freely granted, provided that this notice
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| 9 | * is preserved.
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| 10 | * ====================================================
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| 11 | */
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| 12 |
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| 13 | #ifndef lint
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| 14 | static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_nextafterl.c,v 1.1 2005/03/07 04:56:46 das Exp $";
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| 15 | #endif
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| 16 |
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| 17 | /* IEEE functions
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| 18 | * nextafter(x,y)
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| 19 | * return the next machine floating-point number of x in the
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| 20 | * direction toward y.
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| 21 | * Special cases:
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| 22 | */
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| 23 |
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| 24 | #include <sys/cdefs.h>
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| 25 | #include <float.h>
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| 26 |
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| 27 | #include "fpmath.h"
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| 28 | #include "math.h"
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| 29 | #include "math_private.h"
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| 30 |
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| 31 | #if LDBL_MAX_EXP != 0x4000
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| 32 | #error "Unsupported long double format"
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| 33 | #endif
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| 34 |
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| 35 | long double
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| 36 | nextafterl(long double x, long double y)
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| 37 | {
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| 38 | volatile long double t;
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| 39 | union IEEEl2bits ux, uy;
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| 40 |
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| 41 | ux.e = x;
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| 42 | uy.e = y;
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| 43 |
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| 44 | if ((ux.bits.exp == 0x7fff &&
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| 45 | ((ux.bits.manh&~LDBL_NBIT)|ux.bits.manl) != 0) ||
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| 46 | (uy.bits.exp == 0x7fff &&
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| 47 | ((uy.bits.manh&~LDBL_NBIT)|uy.bits.manl) != 0))
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| 48 | return x+y; /* x or y is nan */
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| 49 | if(x==y) return y; /* x=y, return y */
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| 50 | if(x==0.0) {
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| 51 | ux.bits.manh = 0; /* return +-minsubnormal */
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| 52 | ux.bits.manl = 1;
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| 53 | ux.bits.sign = uy.bits.sign;
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| 54 | t = ux.e*ux.e;
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| 55 | if(t==ux.e) return t; else return ux.e; /* raise underflow flag */
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| 56 | }
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| 57 | if(x>0.0 ^ x<y) { /* x -= ulp */
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| 58 | if(ux.bits.manl==0) {
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| 59 | if ((ux.bits.manh&~LDBL_NBIT)==0)
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| 60 | ux.bits.exp -= 1;
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| 61 | ux.bits.manh = (ux.bits.manh - 1) | (ux.bits.manh & LDBL_NBIT);
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| 62 | }
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| 63 | ux.bits.manl -= 1;
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| 64 | } else { /* x += ulp */
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| 65 | ux.bits.manl += 1;
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| 66 | if(ux.bits.manl==0) {
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| 67 | ux.bits.manh = (ux.bits.manh + 1) | (ux.bits.manh & LDBL_NBIT);
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| 68 | if ((ux.bits.manh&~LDBL_NBIT)==0)
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| 69 | ux.bits.exp += 1;
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| 70 | }
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| 71 | }
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| 72 | if(ux.bits.exp==0x7fff) return x+x; /* overflow */
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| 73 | if(ux.bits.exp==0) { /* underflow */
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| 74 | mask_nbit_l(ux);
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| 75 | t = ux.e * ux.e;
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| 76 | if(t!=ux.e) /* raise underflow flag */
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| 77 | return ux.e;
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| 78 | }
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| 79 | return ux.e;
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| 80 | }
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| 81 |
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| 82 | __strong_reference(nextafterl, nexttowardl);
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