arch/mips/math-emu/sp_fdp.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 static inline union ieee754sp ieee754sp_nan_fdp(int xs, u64 xm)
  26 {
  27         return buildsp(xs, SP_EMAX + 1 + SP_EBIAS,
  28                        xm >> (DP_FBITS - SP_FBITS));
  29 }
  30
  31 union ieee754sp ieee754sp_fdp(union ieee754dp x)
  32 {
  33         union ieee754sp y;
  34         u32 rm;
  35
  36         COMPXDP;
  37         COMPYSP;
  38
  39         EXPLODEXDP;
  40
  41         ieee754_clearcx();
  42
  43         FLUSHXDP;
  44
  45         switch (xc) {
  46         case IEEE754_CLASS_SNAN:
  47                 x = ieee754dp_nanxcpt(x);
  48                 EXPLODEXDP;
  49                 /* fall through */
  50
  51         case IEEE754_CLASS_QNAN:
  52                 y = ieee754sp_nan_fdp(xs, xm);
  53                 if (!ieee754_csr.nan2008) {
  54                         EXPLODEYSP;
  55                         if (!ieee754_class_nan(yc))
  56                                 y = ieee754sp_indef();
  57                 }
  58                 return y;
  59
  60         case IEEE754_CLASS_INF:
  61                 return ieee754sp_inf(xs);
  62
  63         case IEEE754_CLASS_ZERO:
  64                 return ieee754sp_zero(xs);
  65
  66         case IEEE754_CLASS_DNORM:
  67                 /* can't possibly be sp representable */
  68                 ieee754_setcx(IEEE754_UNDERFLOW);
  69                 ieee754_setcx(IEEE754_INEXACT);
  70                 if ((ieee754_csr.rm == FPU_CSR_RU && !xs) ||
  71                                 (ieee754_csr.rm == FPU_CSR_RD && xs))
  72                         return ieee754sp_mind(xs);
  73                 return ieee754sp_zero(xs);
  74
  75         case IEEE754_CLASS_NORM:
  76                 break;
  77         }
  78
  79         /*
  80          * Convert from DP_FBITS to SP_FBITS+3 with sticky right shift.
  81          */
  82         rm = (xm >> (DP_FBITS - (SP_FBITS + 3))) |
  83              ((xm << (64 - (DP_FBITS - (SP_FBITS + 3)))) != 0);
  84
  85         return ieee754sp_format(xs, xe, rm);
  86 }