1/* IEEE754 floating point arithmetic
2 * double precision: common utilities
3 */
4/*
5 * MIPS floating point support
6 * Copyright (C) 1994-2000 Algorithmics Ltd.  All rights reserved.
7 * http://www.algor.co.uk
8 *
9 * ########################################################################
10 *
11 *  This program is free software; you can distribute it and/or modify it
12 *  under the terms of the GNU General Public License (Version 2) as
13 *  published by the Free Software Foundation.
14 *
15 *  This program is distributed in the hope it will be useful, but WITHOUT
16 *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
17 *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
18 *  for more details.
19 *
20 *  You should have received a copy of the GNU General Public License along
21 *  with this program; if not, write to the Free Software Foundation, Inc.,
22 *  59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
23 *
24 * ########################################################################
25 */
26
27
28#include "ieee754dp.h"
29
30ieee754dp ieee754dp_mul(ieee754dp x, ieee754dp y)
31{
32	COMPXDP;
33	COMPYDP;
34
35	EXPLODEXDP;
36	EXPLODEYDP;
37
38	CLEARCX;
39
40	FLUSHXDP;
41	FLUSHYDP;
42
43	switch (CLPAIR(xc, yc)) {
44	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
45	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
46	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
47	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
48	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
49	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
50	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
51	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
52	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
53	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
54	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
55		SETCX(IEEE754_INVALID_OPERATION);
56		return ieee754dp_nanxcpt(ieee754dp_indef(), "mul", x, y);
57
58	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
59	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
60	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
61	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
62		return y;
63
64	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
65	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
66	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
67	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
68	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
69		return x;
70
71
72		/* Infinity handeling */
73
74	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
75	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
76		SETCX(IEEE754_INVALID_OPERATION);
77		return ieee754dp_xcpt(ieee754dp_indef(), "mul", x, y);
78
79	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
80	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
81	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
82	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
83	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
84		return ieee754dp_inf(xs ^ ys);
85
86	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
87	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
88	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
89	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
90	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
91		return ieee754dp_zero(xs ^ ys);
92
93
94	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
95		DPDNORMX;
96
97	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
98		DPDNORMY;
99		break;
100
101	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
102		DPDNORMX;
103		break;
104
105	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
106		break;
107	}
108	/* rm = xm * ym, re = xe+ye basicly */
109	assert(xm & DP_HIDDEN_BIT);
110	assert(ym & DP_HIDDEN_BIT);
111	{
112		int re = xe + ye;
113		int rs = xs ^ ys;
114		u64 rm;
115
116		/* shunt to top of word */
117		xm <<= 64 - (DP_MBITS + 1);
118		ym <<= 64 - (DP_MBITS + 1);
119
120		/* multiply 32bits xm,ym to give high 32bits rm with stickness
121		 */
122
123		/* 32 * 32 => 64 */
124#define DPXMULT(x,y)	((u64)(x) * (u64)y)
125
126		{
127			unsigned lxm = xm;
128			unsigned hxm = xm >> 32;
129			unsigned lym = ym;
130			unsigned hym = ym >> 32;
131			u64 lrm;
132			u64 hrm;
133
134			lrm = DPXMULT(lxm, lym);
135			hrm = DPXMULT(hxm, hym);
136
137			{
138				u64 t = DPXMULT(lxm, hym);
139				{
140					u64 at =
141					    lrm + (t << 32);
142					hrm += at < lrm;
143					lrm = at;
144				}
145				hrm = hrm + (t >> 32);
146			}
147
148			{
149				u64 t = DPXMULT(hxm, lym);
150				{
151					u64 at =
152					    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		/*
162		 * sticky shift down to normal rounding precision
163		 */
164		if ((s64) rm < 0) {
165			rm =
166			    (rm >> (64 - (DP_MBITS + 1 + 3))) |
167			    ((rm << (DP_MBITS + 1 + 3)) != 0);
168			re++;
169		} else {
170			rm =
171			    (rm >> (64 - (DP_MBITS + 1 + 3 + 1))) |
172			    ((rm << (DP_MBITS + 1 + 3 + 1)) != 0);
173		}
174		assert(rm & (DP_HIDDEN_BIT << 3));
175		DPNORMRET2(rs, re, rm, "mul", x, y);
176	}
177}
178