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 "ieee754sp.h"
  28
  29s64 ieee754sp_tlong(ieee754sp x)
  30{
  31        COMPXDP;                /* <-- need 64-bit mantissa tmp */
  32
  33        CLEARCX;
  34
  35        EXPLODEXSP;
  36        FLUSHXSP;
  37
  38        switch (xc) {
  39        case IEEE754_CLASS_SNAN:
  40        case IEEE754_CLASS_QNAN:
  41        case IEEE754_CLASS_INF:
  42                SETCX(IEEE754_INVALID_OPERATION);
  43                return ieee754di_xcpt(ieee754di_indef(), "sp_tlong", x);
  44        case IEEE754_CLASS_ZERO:
  45                return 0;
  46        case IEEE754_CLASS_DNORM:
  47        case IEEE754_CLASS_NORM:
  48                break;
  49        }
  50        if (xe >= 63) {
  51                /* look for valid corner case */
  52                if (xe == 63 && xs && xm == SP_HIDDEN_BIT)
  53                        return -0x8000000000000000LL;
  54                /* Set invalid. We will only use overflow for floating
  55                   point overflow */
  56                SETCX(IEEE754_INVALID_OPERATION);
  57                return ieee754di_xcpt(ieee754di_indef(), "sp_tlong", x);
  58        }
  59        /* oh gawd */
  60        if (xe > SP_MBITS) {
  61                xm <<= xe - SP_MBITS;
  62        } else if (xe < SP_MBITS) {
  63                u32 residue;
  64                int round;
  65                int sticky;
  66                int odd;
  67
  68                if (xe < -1) {
  69                        residue = xm;
  70                        round = 0;
  71                        sticky = residue != 0;
  72                        xm = 0;
  73                } else {
  74                        residue = xm << (32 - SP_MBITS + xe);
  75                        round = (residue >> 31) != 0;
  76                        sticky = (residue << 1) != 0;
  77                        xm >>= SP_MBITS - xe;
  78                }
  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                if ((xm >> 63) != 0) {
  97                        /* This can happen after rounding */
  98                        SETCX(IEEE754_INVALID_OPERATION);
  99                        return ieee754di_xcpt(ieee754di_indef(), "sp_tlong", x);
 100                }
 101                if (round || sticky)
 102                        SETCX(IEEE754_INEXACT);
 103        }
 104        if (xs)
 105                return -xm;
 106        else
 107                return xm;
 108}
 109
 110
 111u64 ieee754sp_tulong(ieee754sp x)
 112{
 113        ieee754sp hb = ieee754sp_1e63();
 114
 115        /* what if x < 0 ?? */
 116        if (ieee754sp_lt(x, hb))
 117                return (u64) ieee754sp_tlong(x);
 118
 119        return (u64) ieee754sp_tlong(ieee754sp_sub(x, hb)) |
 120            (1ULL << 63);
 121}
 122