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
12union 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