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