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 * Copyright (C) 2017 Imagination Technologies, Ltd.
9 * Author: Aleksandar Markovic <aleksandar.markovic@imgtec.com>
10 */
11
12#include "ieee754sp.h"
13
14union ieee754sp ieee754sp_rint(union ieee754sp x)
15{
16	union ieee754sp ret;
17	u32 residue;
18	int sticky;
19	int round;
20	int odd;
21
22	COMPXDP;		/* <-- DP needed for 64-bit mantissa tmp */
23
24	ieee754_clearcx();
25
26	EXPLODEXSP;
27	FLUSHXSP;
28
29	if (xc == IEEE754_CLASS_SNAN)
30		return ieee754sp_nanxcpt(x);
31
32	if ((xc == IEEE754_CLASS_QNAN) ||
33	    (xc == IEEE754_CLASS_INF) ||
34	    (xc == IEEE754_CLASS_ZERO))
35		return x;
36
37	if (xe >= SP_FBITS)
38		return x;
39
40	if (xe < -1) {
41		residue = xm;
42		round = 0;
43		sticky = residue != 0;
44		xm = 0;
45	} else {
46		residue = xm << (xe + 1);
47		residue <<= 31 - SP_FBITS;
48		round = (residue >> 31) != 0;
49		sticky = (residue << 1) != 0;
50		xm >>= SP_FBITS - xe;
51	}
52
53	odd = (xm & 0x1) != 0x0;
54
55	switch (ieee754_csr.rm) {
56	case FPU_CSR_RN:	/* toward nearest */
57		if (round && (sticky || odd))
58			xm++;
59		break;
60	case FPU_CSR_RZ:	/* toward zero */
61		break;
62	case FPU_CSR_RU:	/* toward +infinity */
63		if ((round || sticky) && !xs)
64			xm++;
65		break;
66	case FPU_CSR_RD:	/* toward -infinity */
67		if ((round || sticky) && xs)
68			xm++;
69		break;
70	}
71
72	if (round || sticky)
73		ieee754_setcx(IEEE754_INEXACT);
74
75	ret = ieee754sp_flong(xm);
76	SPSIGN(ret) = xs;
77
78	return ret;
79}
80