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sp_fdp.c
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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 
29 ieee754sp ieee754sp_fdp(ieee754dp x)
30 {
31  COMPXDP;
32  ieee754sp nan;
33 
34  EXPLODEXDP;
35 
36  CLEARCX;
37 
38  FLUSHXDP;
39 
40  switch (xc) {
41  case IEEE754_CLASS_SNAN:
43  return ieee754sp_nanxcpt(ieee754sp_indef(), "fdp");
44  case IEEE754_CLASS_QNAN:
45  nan = buildsp(xs, SP_EMAX + 1 + SP_EBIAS, (u32)
46  (xm >> (DP_MBITS - SP_MBITS)));
47  if (!ieee754sp_isnan(nan))
48  nan = ieee754sp_indef();
49  return ieee754sp_nanxcpt(nan, "fdp", x);
50  case IEEE754_CLASS_INF:
51  return ieee754sp_inf(xs);
52  case IEEE754_CLASS_ZERO:
53  return ieee754sp_zero(xs);
55  /* can't possibly be sp representable */
58  if ((ieee754_csr.rm == IEEE754_RU && !xs) ||
59  (ieee754_csr.rm == IEEE754_RD && xs))
60  return ieee754sp_xcpt(ieee754sp_mind(xs), "fdp", x);
61  return ieee754sp_xcpt(ieee754sp_zero(xs), "fdp", x);
62  case IEEE754_CLASS_NORM:
63  break;
64  }
65 
66  {
67  u32 rm;
68 
69  /* convert from DP_MBITS to SP_MBITS+3 with sticky right shift
70  */
71  rm = (xm >> (DP_MBITS - (SP_MBITS + 3))) |
72  ((xm << (64 - (DP_MBITS - (SP_MBITS + 3)))) != 0);
73 
74  SPNORMRET1(xs, xe, rm, "fdp", x);
75  }
76 }