1 // SPDX-License-Identifier: GPL-2.0-only 1
2 /* IEEE754 floating point arithmetic
3 * double precision: common utilities
4 */
5 /*
6 * MIPS floating point support
7 * Copyright (C) 1994-2000 Algorithmics Ltd.
8 */
9
10 #include "ieee754dp.h"
11
12 s64 ieee754dp_tlong(union ieee754dp x)
13 {
14 u64 residue;
15 int round;
16 int sticky;
17 int odd;
18
19 COMPXDP;
20
21 ieee754_clearcx();
22
23 EXPLODEXDP;
24 FLUSHXDP;
25
26 switch (xc) {
27 case IEEE754_CLASS_SNAN:
28 case IEEE754_CLASS_QNAN:
29 ieee754_setcx(IEEE754_INVALID_
30 return ieee754di_indef();
31
32 case IEEE754_CLASS_INF:
33 ieee754_setcx(IEEE754_INVALID_
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 == DP
46 return -0x800000000000
47 /* Set invalid. We will only u
48 point overflow */
49 ieee754_setcx(IEEE754_INVALID_
50 return ieee754di_overflow(xs);
51 }
52 /* oh gawd */
53 if (xe > DP_FBITS) {
54 xm <<= xe - DP_FBITS;
55 } else if (xe < DP_FBITS) {
56 if (xe < -1) {
57 residue = xm;
58 round = 0;
59 sticky = residue != 0;
60 xm = 0;
61 } else {
62 /* Shifting a u64 64 t
63 * so we do it in two s
64 * may be -1 */
65 residue = xm << (xe +
66 residue <<= 63 - DP_FB
67 round = (residue >> 63
68 sticky = (residue << 1
69 xm >>= DP_FBITS - xe;
70 }
71 odd = (xm & 0x1) != 0x0;
72 switch (ieee754_csr.rm) {
73 case FPU_CSR_RN:
74 if (round && (sticky |
75 xm++;
76 break;
77 case FPU_CSR_RZ:
78 break;
79 case FPU_CSR_RU: /* tow
80 if ((round || sticky)
81 xm++;
82 break;
83 case FPU_CSR_RD: /* tow
84 if ((round || sticky)
85 xm++;
86 break;
87 }
88 if ((xm >> 63) != 0) {
89 /* This can happen aft
90 ieee754_setcx(IEEE754_
91 return ieee754di_overf
92 }
93 if (round || sticky)
94 ieee754_setcx(IEEE754_
95 }
96 if (xs)
97 return -xm;
98 else
99 return xm;
100 }
101
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