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_mul(union ieee754sp x, union ieee754sp y)
25{
26	int re;
27	int rs;
28	unsigned rm;
29	unsigned short lxm;
30	unsigned short hxm;
31	unsigned short lym;
32	unsigned short hym;
33	unsigned lrm;
34	unsigned hrm;
35	unsigned t;
36	unsigned at;
37
38	COMPXSP;
39	COMPYSP;
40
41	EXPLODEXSP;
42	EXPLODEYSP;
43
44	ieee754_clearcx();
45
46	FLUSHXSP;
47	FLUSHYSP;
48
49	switch (CLPAIR(xc, yc)) {
50	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
51	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
52	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
53	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
54	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
55		return ieee754sp_nanxcpt(y);
56
57	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
58	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
59	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
60	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
61	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
62	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
63		return ieee754sp_nanxcpt(x);
64
65	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
66	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
67	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
68	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
69		return y;
70
71	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
72	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
73	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
74	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
75	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
76		return x;
77
78
79	/*
80	 * Infinity handling
81	 */
82	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
83	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
84		ieee754_setcx(IEEE754_INVALID_OPERATION);
85		return ieee754sp_indef();
86
87	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
88	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
89	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
90	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
91	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
92		return ieee754sp_inf(xs ^ ys);
93
94	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
95	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
96	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
97	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
98	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
99		return ieee754sp_zero(xs ^ ys);
100
101
102	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
103		SPDNORMX;
104
105	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
106		SPDNORMY;
107		break;
108
109	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
110		SPDNORMX;
111		break;
112
113	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
114		break;
115	}
116	/* rm = xm * ym, re = xe+ye basically */
117	assert(xm & SP_HIDDEN_BIT);
118	assert(ym & SP_HIDDEN_BIT);
119
120	re = xe + ye;
121	rs = xs ^ ys;
122
123	/* shunt to top of word */
124	xm <<= 32 - (SP_FBITS + 1);
125	ym <<= 32 - (SP_FBITS + 1);
126
127	/*
128	 * Multiply 32 bits xm, ym to give high 32 bits rm with stickness.
129	 */
130	lxm = xm & 0xffff;
131	hxm = xm >> 16;
132	lym = ym & 0xffff;
133	hym = ym >> 16;
134
135	lrm = lxm * lym;	/* 16 * 16 => 32 */
136	hrm = hxm * hym;	/* 16 * 16 => 32 */
137
138	t = lxm * hym; /* 16 * 16 => 32 */
139	at = lrm + (t << 16);
140	hrm += at < lrm;
141	lrm = at;
142	hrm = hrm + (t >> 16);
143
144	t = hxm * lym; /* 16 * 16 => 32 */
145	at = lrm + (t << 16);
146	hrm += at < lrm;
147	lrm = at;
148	hrm = hrm + (t >> 16);
149
150	rm = hrm | (lrm != 0);
151
152	/*
153	 * Sticky shift down to normal rounding precision.
154	 */
155	if ((int) rm < 0) {
156		rm = (rm >> (32 - (SP_FBITS + 1 + 3))) |
157		    ((rm << (SP_FBITS + 1 + 3)) != 0);
158		re++;
159	} else {
160		rm = (rm >> (32 - (SP_FBITS + 1 + 3 + 1))) |
161		     ((rm << (SP_FBITS + 1 + 3 + 1)) != 0);
162	}
163	assert(rm & (SP_HIDDEN_BIT << 3));
164
165	return ieee754sp_format(rs, re, rm);
166}
167