1// SPDX-License-Identifier: GPL-2.0-only
2/* IEEE754 floating point arithmetic
3 * single precision
4 */
5/*
6 * MIPS floating point support
7 * Copyright (C) 1994-2000 Algorithmics Ltd.
8 */
9
10#include "ieee754sp.h"
11#include "ieee754dp.h"
12
13static inline union ieee754sp ieee754sp_nan_fdp(int xs, u64 xm)
14{
15	return buildsp(xs, SP_EMAX + 1 + SP_EBIAS,
16		       xm >> (DP_FBITS - SP_FBITS));
17}
18
19union ieee754sp ieee754sp_fdp(union ieee754dp x)
20{
21	union ieee754sp y;
22	u32 rm;
23
24	COMPXDP;
25	COMPYSP;
26
27	EXPLODEXDP;
28
29	ieee754_clearcx();
30
31	FLUSHXDP;
32
33	switch (xc) {
34	case IEEE754_CLASS_SNAN:
35		x = ieee754dp_nanxcpt(x);
36		EXPLODEXDP;
37		fallthrough;
38	case IEEE754_CLASS_QNAN:
39		y = ieee754sp_nan_fdp(xs, xm);
40		if (!ieee754_csr.nan2008) {
41			EXPLODEYSP;
42			if (!ieee754_class_nan(yc))
43				y = ieee754sp_indef();
44		}
45		return y;
46
47	case IEEE754_CLASS_INF:
48		return ieee754sp_inf(xs);
49
50	case IEEE754_CLASS_ZERO:
51		return ieee754sp_zero(xs);
52
53	case IEEE754_CLASS_DNORM:
54		/* can't possibly be sp representable */
55		ieee754_setcx(IEEE754_UNDERFLOW);
56		ieee754_setcx(IEEE754_INEXACT);
57		if ((ieee754_csr.rm == FPU_CSR_RU && !xs) ||
58				(ieee754_csr.rm == FPU_CSR_RD && xs))
59			return ieee754sp_mind(xs);
60		return ieee754sp_zero(xs);
61
62	case IEEE754_CLASS_NORM:
63		break;
64	}
65
66	/*
67	 * Convert from DP_FBITS to SP_FBITS+3 with sticky right shift.
68	 */
69	rm = (xm >> (DP_FBITS - (SP_FBITS + 3))) |
70	     ((xm << (64 - (DP_FBITS - (SP_FBITS + 3)))) != 0);
71
72	return ieee754sp_format(xs, xe, rm);
73}
74