1 // SPDX-License-Identifier: GPL-2.0-only
2 /* IEEE754 floating point arithmetic
3  * double precision: common utilities
4  */
5 /*
6  * MIPS floating point support
7  * Copyright (C) 1994-2000 Algorithmics Ltd.
8  */
9 
10 #include "ieee754dp.h"
11 
ieee754dp_flong(s64 x)12 union ieee754dp ieee754dp_flong(s64 x)
13 {
14 	u64 xm;
15 	int xe;
16 	int xs;
17 
18 	ieee754_clearcx();
19 
20 	if (x == 0)
21 		return ieee754dp_zero(0);
22 	if (x == 1 || x == -1)
23 		return ieee754dp_one(x < 0);
24 	if (x == 10 || x == -10)
25 		return ieee754dp_ten(x < 0);
26 
27 	xs = (x < 0);
28 	if (xs) {
29 		if (x == (1ULL << 63))
30 			xm = (1ULL << 63);	/* max neg can't be safely negated */
31 		else
32 			xm = -x;
33 	} else {
34 		xm = x;
35 	}
36 
37 	/* normalize */
38 	xe = DP_FBITS + 3;
39 	if (xm >> (DP_FBITS + 1 + 3)) {
40 		/* shunt out overflow bits */
41 		while (xm >> (DP_FBITS + 1 + 3)) {
42 			XDPSRSX1();
43 		}
44 	} else {
45 		/* normalize in grs extended double precision */
46 		while ((xm >> (DP_FBITS + 3)) == 0) {
47 			xm <<= 1;
48 			xe--;
49 		}
50 	}
51 
52 	return ieee754dp_format(xs, xe, xm);
53 }
54