usr/src/lib/libm/common/Q/rndintl.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 /*
  22  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  23  */
  24 /*
  25  * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
  26  * Use is subject to license terms.
  27  */
  28
  29 /*
  30  * aintl(x)     return x chopped to integral value
  31  * anintl(x)    return sign(x)*(|x|+0.5) chopped to integral value
  32  * irintl(x)    return rint(x) in integer format
  33  * nintl(x)     return anint(x) in integer format
  34  *
  35  * NOTE: aintl(x), anintl(x), ceill(x), floorl(x), and rintl(x) return result
  36  * with the same sign as x's,  including 0.0.
  37  */
  38
  39 #include "libm.h"
  40 #include "longdouble.h"
  41
  42 extern enum fp_direction_type __swapRD(enum fp_direction_type);
  43
  44 static const long double qone = 1.0L, qhalf = 0.5L, qmhalf = -0.5L;
  45
  46 long double
  47 aintl(long double x) {
  48         long double t, w;
  49
  50         if (!finitel(x))
  51                 return (x + x);
  52         w = fabsl(x);
  53         t = rintl(w);
  54         if (t <= w)
  55                 return (copysignl(t, x));       /* NaN or already aint(|x|) */
  56         else    /* |t|>|x| case */
  57                 return (copysignl(t - qone, x));        /* |t-1|*sign(x) */
  58 }
  59
  60 long double
  61 anintl(long double x) {
  62         long double t, w, z;
  63
  64         if (!finitel(x))
  65                 return (x + x);
  66         w = fabsl(x);
  67         t = rintl(w);
  68         if (t == w)
  69                 return (copysignl(t, x));
  70         z = t - w;
  71         if (z > qhalf)
  72                 t = t - qone;
  73         else if (z <= qmhalf)
  74                 t = t + qone;
  75         return (copysignl(t, x));
  76 }
  77
  78 int
  79 irintl(long double x) {
  80         enum fp_direction_type rd;
  81
  82         rd = __swapRD(fp_nearest);
  83         (void) __swapRD(rd);    /* restore Rounding Direction */
  84         switch (rd) {
  85         case fp_nearest:
  86                 if (x < 2147483647.5L && x >= -2147483648.5L)
  87                         return ((int)rintl(x));
  88                 break;
  89         case fp_tozero:
  90                 if (x < 2147483648.0L && x > -2147483649.0L)
  91                         return ((int)rintl(x));
  92                 break;
  93         case fp_positive:
  94                 if (x <= 2147483647.0L && x > -2147483649.0L)
  95                         return ((int)rintl(x));
  96                 break;
  97         case fp_negative:
  98                 if (x < 2147483648.0L && x >= -2147483648.0L)
  99                         return ((int)rintl(x));
 100                 break;
 101         }
 102         return ((int)copysignl(1.0e100L, x));
 103 }
 104
 105 int
 106 nintl(long double x) {
 107         if ((x < 2147483647.5L) && (x > -2147483648.5L))
 108                 return ((int)anintl(x));
 109         else
 110                 return ((int)copysignl(1.0e100L, x));
 111 }