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_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 ieee754dp_nanxcpt(ieee754dp_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 ieee754dp_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 ieee754dp_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 ieee754dp_zero(xs ^ ys);
99
100
101	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
102		DPDNORMX;
103
104	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
105		DPDNORMY;
106		break;
107
108	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
109		DPDNORMX;
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 & DP_HIDDEN_BIT);
117	assert(ym & DP_HIDDEN_BIT);
118
119	re = xe + ye;
120	rs = xs ^ ys;
121
122	/* shunt to top of word */
123	xm <<= 64 - (DP_FBITS + 1);
124	ym <<= 64 - (DP_FBITS + 1);
125
126	/*
127	 * Multiply 32 bits xm, ym to give high 32 bits rm with stickness.
128	 */
129
130	/* 32 * 32 => 64 */
131#define DPXMULT(x, y)	((u64)(x) * (u64)y)
132
133	lxm = xm;
134	hxm = xm >> 32;
135	lym = ym;
136	hym = ym >> 32;
137
138	lrm = DPXMULT(lxm, lym);
139	hrm = DPXMULT(hxm, hym);
140
141	t = DPXMULT(lxm, hym);
142
143	at = lrm + (t << 32);
144	hrm += at < lrm;
145	lrm = at;
146
147	hrm = hrm + (t >> 32);
148
149	t = DPXMULT(hxm, lym);
150
151	at = lrm + (t << 32);
152	hrm += at < lrm;
153	lrm = at;
154
155	hrm = hrm + (t >> 32);
156
157	rm = hrm | (lrm != 0);
158
159	/*
160	 * Sticky shift down to normal rounding precision.
161	 */
162	if ((s64) rm < 0) {
163		rm = (rm >> (64 - (DP_FBITS + 1 + 3))) |
164		     ((rm << (DP_FBITS + 1 + 3)) != 0);
165			re++;
166	} else {
167		rm = (rm >> (64 - (DP_FBITS + 1 + 3 + 1))) |
168		     ((rm << (DP_FBITS + 1 + 3 + 1)) != 0);
169	}
170	assert(rm & (DP_HIDDEN_BIT << 3));
171
172	return ieee754dp_format(rs, re, rm);
173}
174