usr/src/lib/libm/common/R/rintf.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 /*
  23  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  24  */
  25 /*
  26  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
  27  * Use is subject to license terms.
  28  */
  29
  30 #pragma weak __rintf = rintf
  31
  32 /* INDENT OFF */
  33 /*
  34  * aintf(x)     return x chopped to integral value
  35  * anintf(x)    return sign(x)*(|x|+0.5) chopped to integral value
  36  * irintf(x)    return rint(x) in integer format
  37  * nintf(x)     return anint(x) in integer format
  38  * rintf(x)     return x rounded to integral according to the rounding direction
  39  *
  40  * NOTE: rintf(x), aintf(x) and anintf(x) return results with the same sign as
  41  * x's,  including 0.0.
  42  */
  43
  44 #include "libm.h"
  45
  46 static const float xf[] = {
  47 /* ZEROF */     0.0f,
  48 /* TWO_23F */   8.3886080000e6f,
  49 /* MTWO_23F */  -8.3886080000e6f,
  50 /* ONEF */      1.0f,
  51 /* MONEF */     -1.0f,
  52 /* HALFF */     0.5f,
  53 /* MHALFF */    -0.5f,
  54 /* HUGEF */     1.0e30f,
  55 };
  56
  57 #define ZEROF           xf[0]
  58 #define TWO_23F         xf[1]
  59 #define MTWO_23F        xf[2]
  60 #define ONEF            xf[3]
  61 #define MONEF           xf[4]
  62 #define HALFF           xf[5]
  63 #define MHALFF          xf[6]
  64 #define HUGEF           xf[7]
  65 /* INDENT ON */
  66
  67 float
  68 aintf(float x) {
  69         int hx, k;
  70         float y;
  71
  72         hx = *(int *) &x;
  73         k = (hx & ~0x80000000) >> 23;
  74         if (k < 150) {
  75                 y = (float) ((int) x);
  76                 /*
  77                  * make sure y has the same sign of x when |x|<0.5
  78                  * (i.e., y=0.0)
  79                  */
  80                 return (((k - 127) & hx) < 0 ? -y : y);
  81         } else
  82                 /* signal invalid if x is a SNaN */
  83                 return (x * ONEF);              /* +0 -> *1 for Cheetah */
  84 }
  85
  86 float
  87 anintf(float x) {
  88         volatile float dummy __unused;
  89         int hx, k, j, ix;
  90
  91         hx = *(int *) &x;
  92         ix = hx & ~0x80000000;
  93         k = ix >> 23;
  94         if (((k - 127) ^ (k - 150)) < 0) {
  95                 j = 1 << (149 - k);
  96                 k = j + j - 1;
  97                 if ((k & hx) != 0)
  98                         dummy = HUGEF + x;      /* raise inexact */
  99                 *(int *) &x = (hx + j) & ~k;
 100                 return (x);
 101         } else if (k <= 126) {
 102                 dummy = HUGEF + x;
 103                 *(int *) &x = (0x3f800000 & ((125 - k) >> 31)) |
 104                         (0x80000000 & hx);
 105                 return (x);
 106         } else
 107                 /* signal invalid if x is a SNaN */
 108                 return (x * ONEF);              /* +0 -> *1 for Cheetah */
 109 }
 110
 111 int
 112 irintf(float x) {
 113         float v;
 114         int hx, k;
 115
 116         hx = *(int *) &x;
 117         k = (hx & ~0x80000000) >> 23;
 118         v = xf[((k - 150) >> 31) & (1 - (hx >> 31))];
 119         return ((int) ((float) (x + v) - v));
 120 }
 121
 122 int
 123 nintf(float x) {
 124         int hx, ix, k, j, m;
 125         volatile float dummy __unused;
 126
 127         hx = *(int *) &x;
 128         k = (hx & ~0x80000000) >> 23;
 129         if (((k - 126) ^ (k - 150)) < 0) {
 130                 ix = (hx & 0x00ffffff) | 0x800000;
 131                 m = 149 - k;
 132                 j = 1 << m;
 133                 if ((ix & (j + j - 1)) != 0)
 134                         dummy = HUGEF + x;
 135                 hx = hx >> 31;
 136                 return ((((ix + j) >> (m + 1)) ^ hx) - hx);
 137         } else
 138                 return ((int) x);
 139 }
 140
 141 float
 142 rintf(float x) {
 143         float w, v;
 144         int hx, k;
 145
 146         hx = *(int *) &x;
 147         k = (hx & ~0x80000000) >> 23;
 148 #if defined(FPADD_TRAPS_INCOMPLETE_ON_NAN)
 149         if (k >= 150)
 150                 return (x * ONEF);
 151         v = xf[1 - (hx >> 31)];
 152 #else
 153         v = xf[((k - 150) >> 31) & (1 - (hx >> 31))];
 154 #endif
 155         w = (float) (x + v);
 156         if (k < 127 && w == v)
 157                 return (ZEROF * x);
 158         else
 159                 return (w - v);
 160 }