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 
ieee754sp_rint(union ieee754sp x)14 union 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