Merge git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6
[wrt350n-kernel.git] / arch / mips / math-emu / dp_div.c
blob6acedce3b32df2f483fd88f543786f15abd58712
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 * http://www.algor.co.uk
9 * ########################################################################
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.
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.
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.
24 * ########################################################################
28 #include "ieee754dp.h"
30 ieee754dp ieee754dp_div(ieee754dp x, ieee754dp y)
32 COMPXDP;
33 COMPYDP;
35 EXPLODEXDP;
36 EXPLODEYDP;
38 CLEARCX;
40 FLUSHXDP;
41 FLUSHYDP;
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(), "div", x, y);
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;
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;
72 /* Infinity handling
75 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
76 SETCX(IEEE754_INVALID_OPERATION);
77 return ieee754dp_xcpt(ieee754dp_indef(), "div", x, y);
79 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
80 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
81 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
82 return ieee754dp_zero(xs ^ ys);
84 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
85 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
86 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
87 return ieee754dp_inf(xs ^ ys);
89 /* Zero handling
92 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
93 SETCX(IEEE754_INVALID_OPERATION);
94 return ieee754dp_xcpt(ieee754dp_indef(), "div", x, y);
96 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
97 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
98 SETCX(IEEE754_ZERO_DIVIDE);
99 return ieee754dp_xcpt(ieee754dp_inf(xs ^ ys), "div", x, y);
101 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
102 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
103 return ieee754dp_zero(xs == ys ? 0 : 1);
105 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
106 DPDNORMX;
108 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
109 DPDNORMY;
110 break;
112 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
113 DPDNORMX;
114 break;
116 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
117 break;
119 assert(xm & DP_HIDDEN_BIT);
120 assert(ym & DP_HIDDEN_BIT);
122 /* provide rounding space */
123 xm <<= 3;
124 ym <<= 3;
127 /* now the dirty work */
129 u64 rm = 0;
130 int re = xe - ye;
131 u64 bm;
133 for (bm = DP_MBIT(DP_MBITS + 2); bm; bm >>= 1) {
134 if (xm >= ym) {
135 xm -= ym;
136 rm |= bm;
137 if (xm == 0)
138 break;
140 xm <<= 1;
142 rm <<= 1;
143 if (xm)
144 rm |= 1; /* have remainder, set sticky */
146 assert(rm);
148 /* normalise rm to rounding precision ?
150 while ((rm >> (DP_MBITS + 3)) == 0) {
151 rm <<= 1;
152 re--;
155 DPNORMRET2(xs == ys ? 0 : 1, re, rm, "div", x, y);