| /* Adapted for use as nearbyint by Ulrich Drepper <drepper@cygnus.com>. */ |
| /* |
| * ==================================================== |
| * 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. |
| * ==================================================== |
| */ |
| |
| #if defined(LIBM_SCCS) && !defined(lint) |
| static char rcsid[] = "$NetBSD: s_rint.c,v 1.8 1995/05/10 20:48:04 jtc Exp $"; |
| #endif |
| |
| /* |
| * rint(x) |
| * Return x rounded to integral value according to the prevailing |
| * rounding mode. |
| * Method: |
| * Using floating addition. |
| * Exception: |
| * Inexact flag raised if x not equal to rint(x). |
| */ |
| |
| #include <fenv.h> |
| #include <math.h> |
| #include <math_private.h> |
| |
| static const double |
| TWO52[2] = { |
| 4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */ |
| -4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */ |
| }; |
| |
| double |
| __nearbyint (double x) |
| { |
| fenv_t env; |
| int32_t i0, j0, sx; |
| double w, t; |
| GET_HIGH_WORD (i0, x); |
| sx = (i0 >> 31) & 1; |
| j0 = ((i0 >> 20) & 0x7ff) - 0x3ff; |
| if (j0 < 52) |
| { |
| if (j0 < 0) |
| { |
| libc_feholdexcept (&env); |
| w = TWO52[sx] + x; |
| t = w - TWO52[sx]; |
| math_force_eval (t); |
| libc_fesetenv (&env); |
| GET_HIGH_WORD (i0, t); |
| SET_HIGH_WORD (t, (i0 & 0x7fffffff) | (sx << 31)); |
| return t; |
| } |
| } |
| else |
| { |
| if (j0 == 0x400) |
| return x + x; /* inf or NaN */ |
| else |
| return x; /* x is integral */ |
| } |
| libc_feholdexcept (&env); |
| w = TWO52[sx] + x; |
| t = w - TWO52[sx]; |
| math_force_eval (t); |
| libc_fesetenv (&env); |
| return t; |
| } |
| weak_alias (__nearbyint, nearbyint) |
| #ifdef NO_LONG_DOUBLE |
| strong_alias (__nearbyint, __nearbyintl) |
| weak_alias (__nearbyint, nearbyintl) |
| #endif |
