1/* IEEE754 floating point arithmetic
2 * double precision: common utilities
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 "ieee754dp.h"
23
24union ieee754dp ieee754dp_mul(union ieee754dp x, union ieee754dp y)
25{
26	int re;
27	int rs;
28	u64 rm;
29	unsigned lxm;
30	unsigned hxm;
31	unsigned lym;
32	unsigned hym;
33	u64 lrm;
34	u64 hrm;
35	u64 t;
36	u64 at;
37
38	COMPXDP;
39	COMPYDP;
40
41	EXPLODEXDP;
42	EXPLODEYDP;
43
44	ieee754_clearcx();
45
46	FLUSHXDP;
47	FLUSHYDP;
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 ieee754dp_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 ieee754dp_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 ieee754dp_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 ieee754dp_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 ieee754dp_zero(xs ^ ys);
100
101
102	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
103		DPDNORMX;
104
105	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
106		DPDNORMY;
107		break;
108
109	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
110		DPDNORMX;
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 & DP_HIDDEN_BIT);
118	assert(ym & DP_HIDDEN_BIT);
119
120	re = xe + ye;
121	rs = xs ^ ys;
122
123	/* shunt to top of word */
124	xm <<= 64 - (DP_FBITS + 1);
125	ym <<= 64 - (DP_FBITS + 1);
126
127	/*
128	 * Multiply 32 bits xm, ym to give high 32 bits rm with stickness.
129	 */
130
131	/* 32 * 32 => 64 */
132#define DPXMULT(x, y)	((u64)(x) * (u64)y)
133
134	lxm = xm;
135	hxm = xm >> 32;
136	lym = ym;
137	hym = ym >> 32;
138
139	lrm = DPXMULT(lxm, lym);
140	hrm = DPXMULT(hxm, hym);
141
142	t = DPXMULT(lxm, hym);
143
144	at = lrm + (t << 32);
145	hrm += at < lrm;
146	lrm = at;
147
148	hrm = hrm + (t >> 32);
149
150	t = DPXMULT(hxm, lym);
151
152	at = lrm + (t << 32);
153	hrm += at < lrm;
154	lrm = at;
155
156	hrm = hrm + (t >> 32);
157
158	rm = hrm | (lrm != 0);
159
160	/*
161	 * Sticky shift down to normal rounding precision.
162	 */
163	if ((s64) rm < 0) {
164		rm = (rm >> (64 - (DP_FBITS + 1 + 3))) |
165		     ((rm << (DP_FBITS + 1 + 3)) != 0);
166			re++;
167	} else {
168		rm = (rm >> (64 - (DP_FBITS + 1 + 3 + 1))) |
169		     ((rm << (DP_FBITS + 1 + 3 + 1)) != 0);
170	}
171	assert(rm & (DP_HIDDEN_BIT << 3));
172
173	return ieee754dp_format(rs, re, rm);
174}
175