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 #if defined(ELFOBJ)
  31 #pragma weak nearbyintl = __nearbyintl
  32 #endif
  33 
  34 #include "libm.h"
  35 #include "fma.h"
  36 #include "fenv_inlines.h"
  37 
  38 #if defined(__sparc)
  39 
  40 static union {
  41         unsigned i;
  42         float f;
  43 } snan = { 0x7f800001 };
  44 
  45 long double
  46 __nearbyintl(long double x) {
  47         union {
  48                 unsigned i[4];
  49                 long double q;
  50         } xx;
  51         unsigned hx, sx, i, frac;
  52         unsigned int fsr;
  53         int rm, j;
  54         volatile float  dummy;
  55 
  56         xx.q = x;
  57         sx = xx.i[0] & 0x80000000;
  58         hx = xx.i[0] & ~0x80000000;
  59 
  60         /* handle trivial cases */
  61         if (hx >= 0x406f0000) {      /* x is nan, inf, or already integral */
  62                 /* check for signaling nan */
  63                 if ((hx > 0x7fff0000 || (hx == 0x7fff0000 &&
  64                         (xx.i[1] | xx.i[2] | xx.i[3]))) && !(hx & 0x8000)) {
  65                         dummy = snan.f;
  66                         dummy += snan.f;
  67                         xx.i[0] = sx | hx | 0x8000;
  68                 }
  69                 return (xx.q);
  70         } else if ((hx | xx.i[1] | xx.i[2] | xx.i[3]) == 0)     /* x is zero */
  71                 return (x);
  72 
  73         /* get the rounding mode */
  74         __fenv_getfsr32(&fsr);
  75         rm = fsr >> 30;
  76 
  77         /* flip the sense of directed roundings if x is negative */
  78         if (sx)
  79                 rm ^= rm >> 1;
  80 
  81         /* handle |x| < 1 */
  82         if (hx < 0x3fff0000) {
  83                 if (rm == FSR_RP || (rm == FSR_RN && (hx >= 0x3ffe0000 &&
  84                         ((hx & 0xffff) | xx.i[1] | xx.i[2] | xx.i[3]))))
  85                         xx.i[0] = sx | 0x3fff0000;
  86                 else
  87                         xx.i[0] = sx;
  88                 xx.i[1] = xx.i[2] = xx.i[3] = 0;
  89                 return (xx.q);
  90         }
  91 
  92         /* round x at the integer bit */
  93         j = 0x406f - (hx >> 16);
  94         if (j >= 96) {
  95                 i = 1 << (j - 96);
  96                 frac = ((xx.i[0] << 1) << (127 - j)) | (xx.i[1] >> (j - 96));
  97                 if ((xx.i[1] & (i - 1)) | xx.i[2] | xx.i[3])
  98                         frac |= 1;
  99                 if (!frac)
 100                         return (x);
 101                 xx.i[1] = xx.i[2] = xx.i[3] = 0;
 102                 xx.i[0] &= ~(i - 1);
 103                 if (rm == FSR_RP || (rm == FSR_RN && (frac > 0x80000000u ||
 104                         (frac == 0x80000000 && (xx.i[0] & i)))))
 105                         xx.i[0] += i;
 106         } else if (j >= 64) {
 107                 i = 1 << (j - 64);
 108                 frac = ((xx.i[1] << 1) << (95 - j)) | (xx.i[2] >> (j - 64));
 109                 if ((xx.i[2] & (i - 1)) | xx.i[3])
 110                         frac |= 1;
 111                 if (!frac)
 112                         return (x);
 113                 xx.i[2] = xx.i[3] = 0;
 114                 xx.i[1] &= ~(i - 1);
 115                 if (rm == FSR_RP || (rm == FSR_RN && (frac > 0x80000000u ||
 116                         (frac == 0x80000000 && (xx.i[1] & i))))) {
 117                         xx.i[1] += i;
 118                         if (xx.i[1] == 0)
 119                                 xx.i[0]++;
 120                 }
 121         } else if (j >= 32) {
 122                 i = 1 << (j - 32);
 123                 frac = ((xx.i[2] << 1) << (63 - j)) | (xx.i[3] >> (j - 32));
 124                 if (xx.i[3] & (i - 1))
 125                         frac |= 1;
 126                 if (!frac)
 127                         return (x);
 128                 xx.i[3] = 0;
 129                 xx.i[2] &= ~(i - 1);
 130                 if (rm == FSR_RP || (rm == FSR_RN && (frac > 0x80000000u ||
 131                         (frac == 0x80000000 && (xx.i[2] & i))))) {
 132                         xx.i[2] += i;
 133                         if (xx.i[2] == 0)
 134                                 if (++xx.i[1] == 0)
 135                                         xx.i[0]++;
 136                 }
 137         } else {
 138                 i = 1 << j;
 139                 frac = (xx.i[3] << 1) << (31 - j);
 140                 if (!frac)
 141                         return (x);
 142                 xx.i[3] &= ~(i - 1);
 143                 if (rm == FSR_RP || (rm == FSR_RN && (frac > 0x80000000u ||
 144                         (frac == 0x80000000 && (xx.i[3] & i))))) {
 145                         xx.i[3] += i;
 146                         if (xx.i[3] == 0)
 147                                 if (++xx.i[2] == 0)
 148                                         if (++xx.i[1] == 0)
 149                                                 xx.i[0]++;
 150                 }
 151         }
 152 
 153         return (xx.q);
 154 }
 155 
 156 #elif defined(__x86)
 157 
 158 /* inline template */
 159 extern long double frndint(long double);
 160 
 161 long double
 162 __nearbyintl(long double x) {
 163         long double z;
 164         unsigned oldcwsw, cwsw;
 165 
 166         /* save the control and status words, mask the inexact exception */
 167         __fenv_getcwsw(&oldcwsw);
 168         cwsw = oldcwsw | 0x00200000;
 169         __fenv_setcwsw(&cwsw);
 170 
 171         z = frndint(x);
 172 
 173         /*
 174          * restore the control and status words, preserving all but the
 175          * inexact flag
 176          */
 177         __fenv_getcwsw(&cwsw);
 178         oldcwsw |= (cwsw & 0x1f);
 179         __fenv_setcwsw(&oldcwsw);
 180 
 181         return (z);
 182 }
 183 
 184 #else
 185 #error Unknown architecture
 186 #endif