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
12 s64 ieee754sp_tlong(union ieee754sp x)
13 {
14 u32 residue;
15 int round;
16 int sticky;
17 int odd;
18
19 COMPXDP; /* <-- need 64-bit mantissa tmp */
20
21 ieee754_clearcx();
22
23 EXPLODEXSP;
24 FLUSHXSP;
25
26 switch (xc) {
27 case IEEE754_CLASS_SNAN:
28 case IEEE754_CLASS_QNAN:
29 ieee754_setcx(IEEE754_INVALID_OPERATION);
30 return ieee754di_indef();
31
32 case IEEE754_CLASS_INF:
33 ieee754_setcx(IEEE754_INVALID_OPERATION);
34 return ieee754di_overflow(xs);
35
36 case IEEE754_CLASS_ZERO:
37 return 0;
38
39 case IEEE754_CLASS_DNORM:
40 case IEEE754_CLASS_NORM:
41 break;
42 }
43 if (xe >= 63) {
44 /* look for valid corner case */
45 if (xe == 63 && xs && xm == SP_HIDDEN_BIT)
46 return -0x8000000000000000LL;
47 /* Set invalid. We will only use overflow for floating
48 point overflow */
49 ieee754_setcx(IEEE754_INVALID_OPERATION);
50 return ieee754di_overflow(xs);
51 }
52 /* oh gawd */
53 if (xe > SP_FBITS) {
54 xm <<= xe - SP_FBITS;
55 } else if (xe < SP_FBITS) {
56 if (xe < -1) {
57 residue = xm;
58 round = 0;
59 sticky = residue != 0;
60 xm = 0;
61 } else {
62 residue = xm << (32 - SP_FBITS + xe);
63 round = (residue >> 31) != 0;
64 sticky = (residue << 1) != 0;
65 xm >>= SP_FBITS - xe;
66 }
67 odd = (xm & 0x1) != 0x0;
68 switch (ieee754_csr.rm) {
69 case FPU_CSR_RN:
70 if (round && (sticky || odd))
71 xm++;
72 break;
73 case FPU_CSR_RZ:
74 break;
75 case FPU_CSR_RU: /* toward +Infinity */
76 if ((round || sticky) && !xs)
77 xm++;
78 break;
79 case FPU_CSR_RD: /* toward -Infinity */
80 if ((round || sticky) && xs)
81 xm++;
82 break;
83 }
84 if ((xm >> 63) != 0) {
85 /* This can happen after rounding */
86 ieee754_setcx(IEEE754_INVALID_OPERATION);
87 return ieee754di_overflow(xs);
88 }
89 if (round || sticky)
90 ieee754_setcx(IEEE754_INEXACT);
91 }
92 if (xs)
93 return -xm;
94 else
95 return xm;
96 }
97
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