| The Android Open Source Project | a27d2ba | 2008-10-21 07:00:00 -0700 | [diff] [blame^] | 1 | /* @(#)s_nextafter.c 5.1 93/09/24 */ |
| 2 | /* |
| 3 | * ==================================================== |
| 4 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
| 5 | * |
| 6 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
| 7 | * Permission to use, copy, modify, and distribute this |
| 8 | * software is freely granted, provided that this notice |
| 9 | * is preserved. |
| 10 | * ==================================================== |
| 11 | */ |
| 12 | |
| 13 | #ifndef lint |
| 14 | static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_nextafterl.c,v 1.1 2005/03/07 04:56:46 das Exp $"; |
| 15 | #endif |
| 16 | |
| 17 | /* IEEE functions |
| 18 | * nextafter(x,y) |
| 19 | * return the next machine floating-point number of x in the |
| 20 | * direction toward y. |
| 21 | * Special cases: |
| 22 | */ |
| 23 | |
| 24 | #include <sys/cdefs.h> |
| 25 | #include <float.h> |
| 26 | |
| 27 | #include "fpmath.h" |
| 28 | #include "math.h" |
| 29 | #include "math_private.h" |
| 30 | |
| 31 | #if LDBL_MAX_EXP != 0x4000 |
| 32 | #error "Unsupported long double format" |
| 33 | #endif |
| 34 | |
| 35 | long double |
| 36 | nextafterl(long double x, long double y) |
| 37 | { |
| 38 | volatile long double t; |
| 39 | union IEEEl2bits ux, uy; |
| 40 | |
| 41 | ux.e = x; |
| 42 | uy.e = y; |
| 43 | |
| 44 | if ((ux.bits.exp == 0x7fff && |
| 45 | ((ux.bits.manh&~LDBL_NBIT)|ux.bits.manl) != 0) || |
| 46 | (uy.bits.exp == 0x7fff && |
| 47 | ((uy.bits.manh&~LDBL_NBIT)|uy.bits.manl) != 0)) |
| 48 | return x+y; /* x or y is nan */ |
| 49 | if(x==y) return y; /* x=y, return y */ |
| 50 | if(x==0.0) { |
| 51 | ux.bits.manh = 0; /* return +-minsubnormal */ |
| 52 | ux.bits.manl = 1; |
| 53 | ux.bits.sign = uy.bits.sign; |
| 54 | t = ux.e*ux.e; |
| 55 | if(t==ux.e) return t; else return ux.e; /* raise underflow flag */ |
| 56 | } |
| 57 | if(x>0.0 ^ x<y) { /* x -= ulp */ |
| 58 | if(ux.bits.manl==0) { |
| 59 | if ((ux.bits.manh&~LDBL_NBIT)==0) |
| 60 | ux.bits.exp -= 1; |
| 61 | ux.bits.manh = (ux.bits.manh - 1) | (ux.bits.manh & LDBL_NBIT); |
| 62 | } |
| 63 | ux.bits.manl -= 1; |
| 64 | } else { /* x += ulp */ |
| 65 | ux.bits.manl += 1; |
| 66 | if(ux.bits.manl==0) { |
| 67 | ux.bits.manh = (ux.bits.manh + 1) | (ux.bits.manh & LDBL_NBIT); |
| 68 | if ((ux.bits.manh&~LDBL_NBIT)==0) |
| 69 | ux.bits.exp += 1; |
| 70 | } |
| 71 | } |
| 72 | if(ux.bits.exp==0x7fff) return x+x; /* overflow */ |
| 73 | if(ux.bits.exp==0) { /* underflow */ |
| 74 | mask_nbit_l(ux); |
| 75 | t = ux.e * ux.e; |
| 76 | if(t!=ux.e) /* raise underflow flag */ |
| 77 | return ux.e; |
| 78 | } |
| 79 | return ux.e; |
| 80 | } |
| 81 | |
| 82 | __strong_reference(nextafterl, nexttowardl); |