arch/mips/math-emu/dp_tint.c

   1 /* IEEE754 floating point arithmetic
   2  * double precision: common utilities
   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 "ieee754dp.h"
  30
  31 int ieee754dp_tint(ieee754dp x)
  32 {
  33         COMPXDP;
  34
  35         CLEARCX;
  36
  37         EXPLODEXDP;
  38         FLUSHXDP;
  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(), "dp_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                 /* Set invalid. We will only use overflow for floating
  54                    point overflow */
  55                 SETCX(IEEE754_INVALID_OPERATION);
  56                 return ieee754si_xcpt(ieee754si_indef(), "dp_tint", x);
  57         }
  58         /* oh gawd */
  59         if (xe > DP_MBITS) {
  60                 xm <<= xe - DP_MBITS;
  61         } else if (xe < DP_MBITS) {
  62                 u64 residue;
  63                 int round;
  64                 int sticky;
  65                 int odd;
  66
  67                 if (xe < -1) {
  68                         residue = xm;
  69                         round = 0;
  70                         sticky = residue != 0;
  71                         xm = 0;
  72                 } else {
  73                         residue = xm << (64 - DP_MBITS + xe);
  74                         round = (residue >> 63) != 0;
  75                         sticky = (residue << 1) != 0;
  76                         xm >>= DP_MBITS - xe;
  77                 }
  78                 /* Note: At this point upper 32 bits of xm are guaranteed
  79                    to be zero */
  80                 odd = (xm & 0x1) != 0x0;
  81                 switch (ieee754_csr.rm) {
  82                 case IEEE754_RN:
  83                         if (round && (sticky || odd))
  84                                 xm++;
  85                         break;
  86                 case IEEE754_RZ:
  87                         break;
  88                 case IEEE754_RU:        /* toward +Infinity */
  89                         if ((round || sticky) && !xs)
  90                                 xm++;
  91                         break;
  92                 case IEEE754_RD:        /* toward -Infinity */
  93                         if ((round || sticky) && xs)
  94                                 xm++;
  95                         break;
  96                 }
  97                 /* look for valid corner case 0x80000000 */
  98                 if ((xm >> 31) != 0 && (xs == 0 || xm != 0x80000000)) {
  99                         /* This can happen after rounding */
 100                         SETCX(IEEE754_INVALID_OPERATION);
 101                         return ieee754si_xcpt(ieee754si_indef(), "dp_tint", x);
 102                 }
 103                 if (round || sticky)
 104                         SETCX(IEEE754_INEXACT);
 105         }
 106         if (xs)
 107                 return -xm;
 108         else
 109                 return xm;
 110 }
 111
 112
 113 unsigned int ieee754dp_tuns(ieee754dp x)
 114 {
 115         ieee754dp hb = ieee754dp_1e31();
 116
 117         /* what if x < 0 ?? */
 118         if (ieee754dp_lt(x, hb))
 119                 return (unsigned) ieee754dp_tint(x);
 120
 121         return (unsigned) ieee754dp_tint(ieee754dp_sub(x, hb)) |
 122             ((unsigned) 1 << 31);
 123 }