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
12int ieee754sp_tint(union ieee754sp x)
13{
14	u32 residue;
15	int round;
16	int sticky;
17	int odd;
18
19	COMPXSP;
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 ieee754si_indef();
31
32	case IEEE754_CLASS_INF:
33		ieee754_setcx(IEEE754_INVALID_OPERATION);
34		return ieee754si_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 >= 31) {
44		/* look for valid corner case */
45		if (xe == 31 && xs && xm == SP_HIDDEN_BIT)
46			return -0x80000000;
47		/* Set invalid. We will only use overflow for floating
48		   point overflow */
49		ieee754_setcx(IEEE754_INVALID_OPERATION);
50		return ieee754si_overflow(xs);
51	}
52	/* oh gawd */
53	if (xe > SP_FBITS) {
54		xm <<= xe - SP_FBITS;
55	} else {
56		if (xe < -1) {
57			residue = xm;
58			round = 0;
59			sticky = residue != 0;
60			xm = 0;
61		} else {
62			/* Shifting a u32 32 times does not work,
63			* so we do it in two steps. Be aware that xe
64			* may be -1 */
65			residue = xm << (xe + 1);
66			residue <<= 31 - SP_FBITS;
67			round = (residue >> 31) != 0;
68			sticky = (residue << 1) != 0;
69			xm >>= SP_FBITS - xe;
70		}
71		odd = (xm & 0x1) != 0x0;
72		switch (ieee754_csr.rm) {
73		case FPU_CSR_RN:
74			if (round && (sticky || odd))
75				xm++;
76			break;
77		case FPU_CSR_RZ:
78			break;
79		case FPU_CSR_RU:	/* toward +Infinity */
80			if ((round || sticky) && !xs)
81				xm++;
82			break;
83		case FPU_CSR_RD:	/* toward -Infinity */
84			if ((round || sticky) && xs)
85				xm++;
86			break;
87		}
88		if ((xm >> 31) != 0) {
89			/* This can happen after rounding */
90			ieee754_setcx(IEEE754_INVALID_OPERATION);
91			return ieee754si_overflow(xs);
92		}
93		if (round || sticky)
94			ieee754_setcx(IEEE754_INEXACT);
95	}
96	if (xs)
97		return -xm;
98	else
99		return xm;
100}
101