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 *
   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 "ieee754dp.h"
  29
  30int ieee754dp_tint(ieee754dp x)
  31{
  32        COMPXDP;
  33
  34        CLEARCX;
  35
  36        EXPLODEXDP;
  37        FLUSHXDP;
  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(), "dp_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                /* Set invalid. We will only use overflow for floating
  53                   point overflow */
  54                SETCX(IEEE754_INVALID_OPERATION);
  55                return ieee754si_xcpt(ieee754si_indef(), "dp_tint", x);
  56        }
  57        /* oh gawd */
  58        if (xe > DP_MBITS) {
  59                xm <<= xe - DP_MBITS;
  60        } else if (xe < DP_MBITS) {
  61                u64 residue;
  62                int round;
  63                int sticky;
  64                int odd;
  65
  66                if (xe < -1) {
  67                        residue = xm;
  68                        round = 0;
  69                        sticky = residue != 0;
  70                        xm = 0;
  71                } else {
  72                        residue = xm << (64 - DP_MBITS + xe);
  73                        round = (residue >> 63) != 0;
  74                        sticky = (residue << 1) != 0;
  75                        xm >>= DP_MBITS - xe;
  76                }
  77                /* Note: At this point upper 32 bits of xm are guaranteed
  78                   to be zero */
  79                odd = (xm & 0x1) != 0x0;
  80                switch (ieee754_csr.rm) {
  81                case IEEE754_RN:
  82                        if (round && (sticky || odd))
  83                                xm++;
  84                        break;
  85                case IEEE754_RZ:
  86                        break;
  87                case IEEE754_RU:        /* toward +Infinity */
  88                        if ((round || sticky) && !xs)
  89                                xm++;
  90                        break;
  91                case IEEE754_RD:        /* toward -Infinity */
  92                        if ((round || sticky) && xs)
  93                                xm++;
  94                        break;
  95                }
  96                /* look for valid corner case 0x80000000 */
  97                if ((xm >> 31) != 0 && (xs == 0 || xm != 0x80000000)) {
  98                        /* This can happen after rounding */
  99                        SETCX(IEEE754_INVALID_OPERATION);
 100                        return ieee754si_xcpt(ieee754si_indef(), "dp_tint", x);
 101                }
 102                if (round || sticky)
 103                        SETCX(IEEE754_INEXACT);
 104        }
 105        if (xs)
 106                return -xm;
 107        else
 108                return xm;
 109}
 110
 111
 112unsigned int ieee754dp_tuns(ieee754dp x)
 113{
 114        ieee754dp hb = ieee754dp_1e31();
 115
 116        /* what if x < 0 ?? */
 117        if (ieee754dp_lt(x, hb))
 118                return (unsigned) ieee754dp_tint(x);
 119
 120        return (unsigned) ieee754dp_tint(ieee754dp_sub(x, hb)) |
 121            ((unsigned) 1 << 31);
 122}
 123