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
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
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