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   1 /* IEEE754 floating point arithmetic
   2  * single precision
   3  */
   4 /*
   5  * MIPS floating point support
   6  * Copyright (C) 1994-2000 Algorithmics Ltd.
   7  * http://www.algor.co.uk
   8  *
   9  * ########################################################################
  10  *
  11  *  This program is free software; you can distribute it and/or modify it
  12  *  under the terms of the GNU General Public License (Version 2) as
  13  *  published by the Free Software Foundation.
  14  *
  15  *  This program is distributed in the hope it will be useful, but WITHOUT
  16  *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  17  *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  18  *  for more details.
  19  *
  20  *  You should have received a copy of the GNU General Public License along
  21  *  with this program; if not, write to the Free Software Foundation, Inc.,
  22  *  59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
  23  *
  24  * ########################################################################
  25  */
  26
  27
  28 #include <linux/kernel.h>
  29 #include "ieee754sp.h"
  30
  31 int ieee754sp_tint(ieee754sp x)
  32 {
  33         COMPXSP;
  34
  35         CLEARCX;
  36
  37         EXPLODEXSP;
  38         FLUSHXSP;
  39
  40         switch (xc) {
  41         case IEEE754_CLASS_SNAN:
  42         case IEEE754_CLASS_QNAN:
  43         case IEEE754_CLASS_INF:
  44                 SETCX(IEEE754_INVALID_OPERATION);
  45                 return ieee754si_xcpt(ieee754si_indef(), "sp_tint", x);
  46         case IEEE754_CLASS_ZERO:
  47                 return 0;
  48         case IEEE754_CLASS_DNORM:
  49         case IEEE754_CLASS_NORM:
  50                 break;
  51         }
  52         if (xe >= 31) {
  53                 /* look for valid corner case */
  54                 if (xe == 31 && xs && xm == SP_HIDDEN_BIT)
  55                         return -0x80000000;
  56                 /* Set invalid. We will only use overflow for floating
  57                    point overflow */
  58                 SETCX(IEEE754_INVALID_OPERATION);
  59                 return ieee754si_xcpt(ieee754si_indef(), "sp_tint", x);
  60         }
  61         /* oh gawd */
  62         if (xe > SP_MBITS) {
  63                 xm <<= xe - SP_MBITS;
  64         } else {
  65                 u32 residue;
  66                 int round;
  67                 int sticky;
  68                 int odd;
  69
  70                 if (xe < -1) {
  71                         residue = xm;
  72                         round = 0;
  73                         sticky = residue != 0;
  74                         xm = 0;
  75                 }
  76                 else {
  77                         /* Shifting a u32 32 times does not work,
  78                         * so we do it in two steps. Be aware that xe
  79                         * may be -1 */
  80                         residue = xm << (xe + 1);
  81                         residue <<= 31 - SP_MBITS;
  82                         round = (residue >> 31) != 0;
  83                         sticky = (residue << 1) != 0;
  84                         xm >>= SP_MBITS - xe;
  85                 }
  86                 odd = (xm & 0x1) != 0x0;
  87                 switch (ieee754_csr.rm) {
  88                 case IEEE754_RN:
  89                         if (round && (sticky || odd))
  90                                 xm++;
  91                         break;
  92                 case IEEE754_RZ:
  93                         break;
  94                 case IEEE754_RU:        /* toward +Infinity */
  95                         if ((round || sticky) && !xs)
  96                                 xm++;
  97                         break;
  98                 case IEEE754_RD:        /* toward -Infinity */
  99                         if ((round || sticky) && xs)
 100                                 xm++;
 101                         break;
 102                 }
 103                 if ((xm >> 31) != 0) {
 104                         /* This can happen after rounding */
 105                         SETCX(IEEE754_INVALID_OPERATION);
 106                         return ieee754si_xcpt(ieee754si_indef(), "sp_tint", x);
 107                 }
 108                 if (round || sticky)
 109                         SETCX(IEEE754_INEXACT);
 110         }
 111         if (xs)
 112                 return -xm;
 113         else
 114                 return xm;
 115 }
 116
 117
 118 unsigned int ieee754sp_tuns(ieee754sp x)
 119 {
 120         ieee754sp hb = ieee754sp_1e31();
 121
 122         /* what if x < 0 ?? */
 123         if (ieee754sp_lt(x, hb))
 124                 return (unsigned) ieee754sp_tint(x);
 125
 126         return (unsigned) ieee754sp_tint(ieee754sp_sub(x, hb)) |
 127             ((unsigned) 1 << 31);
 128 }