release/src-rt-6.x.4708/linux/linux-2.6.36/arch/mips/math-emu/dp_tlong.c

   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 "ieee754dp.h"
  29
  30 s64 ieee754dp_tlong(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 ieee754di_xcpt(ieee754di_indef(), "dp_tlong", 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 >= 63) {
  52                 /* look for valid corner case */
  53                 if (xe == 63 && xs && xm == DP_HIDDEN_BIT)
  54                         return -0x8000000000000000LL;
  55                 /* Set invalid. We will only use overflow for floating
  56                    point overflow */
  57                 SETCX(IEEE754_INVALID_OPERATION);
  58                 return ieee754di_xcpt(ieee754di_indef(), "dp_tlong", x);
  59         }
  60         /* oh gawd */
  61         if (xe > DP_MBITS) {
  62                 xm <<= xe - DP_MBITS;
  63         } else if (xe < DP_MBITS) {
  64                 u64 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 u64 64 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 <<= 63 - DP_MBITS;
  80                         round = (residue >> 63) != 0;
  81                         sticky = (residue << 1) != 0;
  82                         xm >>= DP_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 >> 63) != 0) {
 102                         /* This can happen after rounding */
 103                         SETCX(IEEE754_INVALID_OPERATION);
 104                         return ieee754di_xcpt(ieee754di_indef(), "dp_tlong", 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
 116 u64 ieee754dp_tulong(ieee754dp x)
 117 {
 118         ieee754dp hb = ieee754dp_1e63();
 119
 120         /* what if x < 0 ?? */
 121         if (ieee754dp_lt(x, hb))
 122                 return (u64) ieee754dp_tlong(x);
 123
 124         return (u64) ieee754dp_tlong(ieee754dp_sub(x, hb)) |
 125             (1ULL << 63);
 126 }