LXR linux/arch/mips/math-emu/sp

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