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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 /* fall through */
38
39 case IEEE754_CLASS_QNAN:
40 y = ieee754sp_nan_fdp(xs, xm);
41 if (!ieee754_csr.nan2008) {
42 EXPLODEYSP;
43 if (!ieee754_class_nan(yc))
44 y = ieee754sp_indef();
45 }
46 return y;
47
48 case IEEE754_CLASS_INF:
49 return ieee754sp_inf(xs);
50
51 case IEEE754_CLASS_ZERO:
52 return ieee754sp_zero(xs);
53
54 case IEEE754_CLASS_DNORM:
55 /* can't possibly be sp representable */
56 ieee754_setcx(IEEE754_UNDERFLOW);
57 ieee754_setcx(IEEE754_INEXACT);
58 if ((ieee754_csr.rm == FPU_CSR_RU && !xs) ||
59 (ieee754_csr.rm == FPU_CSR_RD && xs))
60 return ieee754sp_mind(xs);
61 return ieee754sp_zero(xs);
62
63 case IEEE754_CLASS_NORM:
64 break;
65 }
66
67 /*
68 * Convert from DP_FBITS to SP_FBITS+3 with sticky right shift.
69 */
70 rm = (xm >> (DP_FBITS - (SP_FBITS + 3))) |
71 ((xm << (64 - (DP_FBITS - (SP_FBITS + 3)))) != 0);
72
73 return ieee754sp_format(xs, xe, rm);
74}