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
13 static 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
19 union 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
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