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 * 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
  31int 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
 118unsigned 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}
 129