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

   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
  31int 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                }
  73                else {
  74                        residue = xm << (64 - DP_MBITS + xe);
  75                        round = (residue >> 63) != 0;
  76                        sticky = (residue << 1) != 0;
  77                        xm >>= DP_MBITS - xe;
  78                }
  79                /* Note: At this point upper 32 bits of xm are guaranteed
  80                   to be zero */
  81                odd = (xm & 0x1) != 0x0;
  82                switch (ieee754_csr.rm) {
  83                case IEEE754_RN:
  84                        if (round && (sticky || odd))
  85                                xm++;
  86                        break;
  87                case IEEE754_RZ:
  88                        break;
  89                case IEEE754_RU:        /* toward +Infinity */
  90                        if ((round || sticky) && !xs)
  91                                xm++;
  92                        break;
  93                case IEEE754_RD:        /* toward -Infinity */
  94                        if ((round || sticky) && xs)
  95                                xm++;
  96                        break;
  97                }
  98                /* look for valid corner case 0x80000000 */
  99                if ((xm >> 31) != 0 && (xs == 0 || xm != 0x80000000)) {
 100                        /* This can happen after rounding */
 101                        SETCX(IEEE754_INVALID_OPERATION);
 102                        return ieee754si_xcpt(ieee754si_indef(), "dp_tint", x);
 103                }
 104                if (round || sticky)
 105                        SETCX(IEEE754_INEXACT);
 106        }
 107        if (xs)
 108                return -xm;
 109        else
 110                return xm;
 111}
 112
 113
 114unsigned int ieee754dp_tuns(ieee754dp x)
 115{
 116        ieee754dp hb = ieee754dp_1e31();
 117
 118        /* what if x < 0 ?? */
 119        if (ieee754dp_lt(x, hb))
 120                return (unsigned) ieee754dp_tint(x);
 121
 122        return (unsigned) ieee754dp_tint(ieee754dp_sub(x, hb)) |
 123            ((unsigned) 1 << 31);
 124}
 125