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
12s64 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