xref: /openbmc/linux/arch/mips/math-emu/dp_fint.c (revision fb574682)
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 
12 union ieee754dp ieee754dp_fint(int 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 == (1 << 31))
30 			xm = ((unsigned) 1 << 31);	/* max neg can't be safely negated */
31 		else
32 			xm = -x;
33 	} else {
34 		xm = x;
35 	}
36 
37 	/* normalize - result can never be inexact or overflow */
38 	xe = DP_FBITS;
39 	while ((xm >> DP_FBITS) == 0) {
40 		xm <<= 1;
41 		xe--;
42 	}
43 	return builddp(xs, xe + DP_EBIAS, xm & ~DP_HIDDEN_BIT);
44 }
45