kernel/arch/mips/math-emu/sp_tlong.c

   1 /* IEEE754 floating point arithmetic
   2  * single precision
   3  */
   4 /*
   5  * MIPS floating point support
   6  * Copyright (C) 1994-2000 Algorithmics Ltd.
   7  *
   8  *  This program is free software; you can distribute it and/or modify it
   9  *  under the terms of the GNU General Public License (Version 2) as
  10  *  published by the Free Software Foundation.
  11  *
  12  *  This program is distributed in the hope it will be useful, but WITHOUT
  13  *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14  *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15  *  for more details.
  16  *
  17  *  You should have received a copy of the GNU General Public License along
  18  *  with this program; if not, write to the Free Software Foundation, Inc.,
  19  *  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA.
  20  */
  21
  22 #include "ieee754sp.h"
  23 #include "ieee754dp.h"
  24
  25 s64 ieee754sp_tlong(union ieee754sp x)
  26 {
  27         u32 residue;
  28         int round;
  29         int sticky;
  30         int odd;
  31
  32         COMPXDP;                /* <-- need 64-bit mantissa tmp */
  33
  34         ieee754_clearcx();
  35
  36         EXPLODEXSP;
  37         FLUSHXSP;
  38
  39         switch (xc) {
  40         case IEEE754_CLASS_SNAN:
  41         case IEEE754_CLASS_QNAN:
  42         case IEEE754_CLASS_INF:
  43                 ieee754_setcx(IEEE754_INVALID_OPERATION);
  44                 return ieee754di_indef();
  45
  46         case IEEE754_CLASS_ZERO:
  47                 return 0;
  48
  49         case IEEE754_CLASS_DNORM:
  50         case IEEE754_CLASS_NORM:
  51                 break;
  52         }
  53         if (xe >= 63) {
  54                 /* look for valid corner case */
  55                 if (xe == 63 && xs && xm == SP_HIDDEN_BIT)
  56                         return -0x8000000000000000LL;
  57                 /* Set invalid. We will only use overflow for floating
  58                    point overflow */
  59                 ieee754_setcx(IEEE754_INVALID_OPERATION);
  60                 return ieee754di_indef();
  61         }
  62         /* oh gawd */
  63         if (xe > SP_FBITS) {
  64                 xm <<= xe - SP_FBITS;
  65         } else if (xe < SP_FBITS) {
  66                 if (xe < -1) {
  67                         residue = xm;
  68                         round = 0;
  69                         sticky = residue != 0;
  70                         xm = 0;
  71                 } else {
  72                         residue = xm << (32 - SP_FBITS + xe);
  73                         round = (residue >> 31) != 0;
  74                         sticky = (residue << 1) != 0;
  75                         xm >>= SP_FBITS - xe;
  76                 }
  77                 odd = (xm & 0x1) != 0x0;
  78                 switch (ieee754_csr.rm) {
  79                 case FPU_CSR_RN:
  80                         if (round && (sticky || odd))
  81                                 xm++;
  82                         break;
  83                 case FPU_CSR_RZ:
  84                         break;
  85                 case FPU_CSR_RU:        /* toward +Infinity */
  86                         if ((round || sticky) && !xs)
  87                                 xm++;
  88                         break;
  89                 case FPU_CSR_RD:        /* toward -Infinity */
  90                         if ((round || sticky) && xs)
  91                                 xm++;
  92                         break;
  93                 }
  94                 if ((xm >> 63) != 0) {
  95                         /* This can happen after rounding */
  96                         ieee754_setcx(IEEE754_INVALID_OPERATION);
  97                         return ieee754di_indef();
  98                 }
  99                 if (round || sticky)
 100                         ieee754_setcx(IEEE754_INEXACT);
 101         }
 102         if (xs)
 103                 return -xm;
 104         else
 105                 return xm;
 106 }