arch/mips/math-emu/dp_fsp.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  *
   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 static inline union ieee754dp ieee754dp_nan_fsp(int xs, u64 xm)
  26 {
  27         return builddp(xs, DP_EMAX + 1 + DP_EBIAS,
  28                        xm << (DP_FBITS - SP_FBITS));
  29 }
  30
  31 union ieee754dp ieee754dp_fsp(union ieee754sp x)
  32 {
  33         COMPXSP;
  34
  35         EXPLODEXSP;
  36
  37         ieee754_clearcx();
  38
  39         FLUSHXSP;
  40
  41         switch (xc) {
  42         case IEEE754_CLASS_SNAN:
  43                 return ieee754dp_nanxcpt(ieee754dp_nan_fsp(xs, xm));
  44
  45         case IEEE754_CLASS_QNAN:
  46                 return ieee754dp_nan_fsp(xs, xm);
  47
  48         case IEEE754_CLASS_INF:
  49                 return ieee754dp_inf(xs);
  50
  51         case IEEE754_CLASS_ZERO:
  52                 return ieee754dp_zero(xs);
  53
  54         case IEEE754_CLASS_DNORM:
  55                 /* normalize */
  56                 while ((xm >> SP_FBITS) == 0) {
  57                         xm <<= 1;
  58                         xe--;
  59                 }
  60                 break;
  61
  62         case IEEE754_CLASS_NORM:
  63                 break;
  64         }
  65
  66         /*
  67          * Can't possibly overflow,underflow, or need rounding
  68          */
  69
  70         /* drop the hidden bit */
  71         xm &= ~SP_HIDDEN_BIT;
  72
  73         return builddp(xs, xe + DP_EBIAS,
  74                        (u64) xm << (DP_FBITS - SP_FBITS));
  75 }