1/* IEEE754 floating point arithmetic
2 * single precision
3 */
4/*
5 * MIPS floating point support
6 * Copyright (C) 1994-2000 Algorithmics Ltd.
7 *
8 *  This program is free software; you can distribute it and/or modify it
9 *  under the terms of the GNU General Public License (Version 2) as
10 *  published by the Free Software Foundation.
11 *
12 *  This program is distributed in the hope it will be useful, but WITHOUT
13 *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
15 *  for more details.
16 *
17 *  You should have received a copy of the GNU General Public License along
18 *  with this program; if not, write to the Free Software Foundation, Inc.,
19 *  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA.
20 */
21
22#include "ieee754sp.h"
23
24union ieee754sp ieee754sp_div(union ieee754sp x, union ieee754sp y)
25{
26	unsigned rm;
27	int re;
28	unsigned bm;
29
30	COMPXSP;
31	COMPYSP;
32
33	EXPLODEXSP;
34	EXPLODEYSP;
35
36	ieee754_clearcx();
37
38	FLUSHXSP;
39	FLUSHYSP;
40
41	switch (CLPAIR(xc, yc)) {
42	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
43	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
44	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
45	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
46	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
47	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
48	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
49	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
50	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
51	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
52	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
53		ieee754_setcx(IEEE754_INVALID_OPERATION);
54		return ieee754sp_nanxcpt(ieee754sp_indef());
55
56	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
57	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
58	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
59	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
60		return y;
61
62	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
63	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
64	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
65	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
66	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
67		return x;
68
69
70	/*
71	 * Infinity handling
72	 */
73	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
74		ieee754_setcx(IEEE754_INVALID_OPERATION);
75		return ieee754sp_indef();
76
77	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
78	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
79	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
80		return ieee754sp_zero(xs ^ ys);
81
82	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
83	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
84	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
85		return ieee754sp_inf(xs ^ ys);
86
87	/*
88	 * Zero handling
89	 */
90	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
91		ieee754_setcx(IEEE754_INVALID_OPERATION);
92		return ieee754sp_indef();
93
94	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
95	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
96		ieee754_setcx(IEEE754_ZERO_DIVIDE);
97		return ieee754sp_inf(xs ^ ys);
98
99	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
100	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
101		return ieee754sp_zero(xs == ys ? 0 : 1);
102
103	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
104		SPDNORMX;
105
106	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
107		SPDNORMY;
108		break;
109
110	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
111		SPDNORMX;
112		break;
113
114	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
115		break;
116	}
117	assert(xm & SP_HIDDEN_BIT);
118	assert(ym & SP_HIDDEN_BIT);
119
120	/* provide rounding space */
121	xm <<= 3;
122	ym <<= 3;
123
124	/* now the dirty work */
125
126	rm = 0;
127	re = xe - ye;
128
129	for (bm = SP_MBIT(SP_FBITS + 2); bm; bm >>= 1) {
130		if (xm >= ym) {
131			xm -= ym;
132			rm |= bm;
133			if (xm == 0)
134				break;
135		}
136		xm <<= 1;
137	}
138
139	rm <<= 1;
140	if (xm)
141		rm |= 1;	/* have remainder, set sticky */
142
143	assert(rm);
144
145	/* normalise rm to rounding precision ?
146	 */
147	while ((rm >> (SP_FBITS + 3)) == 0) {
148		rm <<= 1;
149		re--;
150	}
151
152	return ieee754sp_format(xs == ys ? 0 : 1, re, rm);
153}
154