xref: /linux/arch/mips/math-emu/sp_flong.c (revision 827634added7f38b7d724cab1dccdb2b004c13c3)
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 
24 union ieee754sp ieee754sp_flong(s64 x)
25 {
26 	u64 xm;		/* <--- need 64-bit mantissa temp */
27 	int xe;
28 	int xs;
29 
30 	ieee754_clearcx();
31 
32 	if (x == 0)
33 		return ieee754sp_zero(0);
34 	if (x == 1 || x == -1)
35 		return ieee754sp_one(x < 0);
36 	if (x == 10 || x == -10)
37 		return ieee754sp_ten(x < 0);
38 
39 	xs = (x < 0);
40 	if (xs) {
41 		if (x == (1ULL << 63))
42 			xm = (1ULL << 63);	/* max neg can't be safely negated */
43 		else
44 			xm = -x;
45 	} else {
46 		xm = x;
47 	}
48 	xe = SP_FBITS + 3;
49 
50 	if (xm >> (SP_FBITS + 1 + 3)) {
51 		/* shunt out overflow bits
52 		 */
53 		while (xm >> (SP_FBITS + 1 + 3)) {
54 			SPXSRSX1();
55 		}
56 	} else {
57 		/* normalize in grs extended single precision */
58 		while ((xm >> (SP_FBITS + 3)) == 0) {
59 			xm <<= 1;
60 			xe--;
61 		}
62 	}
63 	return ieee754sp_format(xs, xe, xm);
64 }
65