Delete unused ieee754_cname[] and declaration.
[linux-2.6] / arch / mips / math-emu / ieee754dp.c
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
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
30 int ieee754dp_class(ieee754dp x)
31 {
32         COMPXDP;
33         EXPLODEXDP;
34         return xc;
35 }
36
37 int ieee754dp_isnan(ieee754dp x)
38 {
39         return ieee754dp_class(x) >= IEEE754_CLASS_SNAN;
40 }
41
42 int ieee754dp_issnan(ieee754dp x)
43 {
44         assert(ieee754dp_isnan(x));
45         return ((DPMANT(x) & DP_MBIT(DP_MBITS-1)) == DP_MBIT(DP_MBITS-1));
46 }
47
48
49 ieee754dp ieee754dp_xcpt(ieee754dp r, const char *op, ...)
50 {
51         struct ieee754xctx ax;
52         if (!TSTX())
53                 return r;
54
55         ax.op = op;
56         ax.rt = IEEE754_RT_DP;
57         ax.rv.dp = r;
58         va_start(ax.ap, op);
59         ieee754_xcpt(&ax);
60         return ax.rv.dp;
61 }
62
63 ieee754dp ieee754dp_nanxcpt(ieee754dp r, const char *op, ...)
64 {
65         struct ieee754xctx ax;
66
67         assert(ieee754dp_isnan(r));
68
69         if (!ieee754dp_issnan(r))       /* QNAN does not cause invalid op !! */
70                 return r;
71
72         if (!SETANDTESTCX(IEEE754_INVALID_OPERATION)) {
73                 /* not enabled convert to a quiet NaN */
74                 DPMANT(r) &= (~DP_MBIT(DP_MBITS-1));
75                 if (ieee754dp_isnan(r))
76                         return r;
77                 else
78                         return ieee754dp_indef();
79         }
80
81         ax.op = op;
82         ax.rt = 0;
83         ax.rv.dp = r;
84         va_start(ax.ap, op);
85         ieee754_xcpt(&ax);
86         return ax.rv.dp;
87 }
88
89 ieee754dp ieee754dp_bestnan(ieee754dp x, ieee754dp y)
90 {
91         assert(ieee754dp_isnan(x));
92         assert(ieee754dp_isnan(y));
93
94         if (DPMANT(x) > DPMANT(y))
95                 return x;
96         else
97                 return y;
98 }
99
100
101 static u64 get_rounding(int sn, u64 xm)
102 {
103         /* inexact must round of 3 bits
104          */
105         if (xm & (DP_MBIT(3) - 1)) {
106                 switch (ieee754_csr.rm) {
107                 case IEEE754_RZ:
108                         break;
109                 case IEEE754_RN:
110                         xm += 0x3 + ((xm >> 3) & 1);
111                         /* xm += (xm&0x8)?0x4:0x3 */
112                         break;
113                 case IEEE754_RU:        /* toward +Infinity */
114                         if (!sn)        /* ?? */
115                                 xm += 0x8;
116                         break;
117                 case IEEE754_RD:        /* toward -Infinity */
118                         if (sn) /* ?? */
119                                 xm += 0x8;
120                         break;
121                 }
122         }
123         return xm;
124 }
125
126
127 /* generate a normal/denormal number with over,under handling
128  * sn is sign
129  * xe is an unbiased exponent
130  * xm is 3bit extended precision value.
131  */
132 ieee754dp ieee754dp_format(int sn, int xe, u64 xm)
133 {
134         assert(xm);             /* we don't gen exact zeros (probably should) */
135
136         assert((xm >> (DP_MBITS + 1 + 3)) == 0);        /* no execess */
137         assert(xm & (DP_HIDDEN_BIT << 3));
138
139         if (xe < DP_EMIN) {
140                 /* strip lower bits */
141                 int es = DP_EMIN - xe;
142
143                 if (ieee754_csr.nod) {
144                         SETCX(IEEE754_UNDERFLOW);
145                         SETCX(IEEE754_INEXACT);
146
147                         switch(ieee754_csr.rm) {
148                         case IEEE754_RN:
149                                 return ieee754dp_zero(sn);
150                         case IEEE754_RZ:
151                                 return ieee754dp_zero(sn);
152                         case IEEE754_RU:    /* toward +Infinity */
153                                 if(sn == 0)
154                                         return ieee754dp_min(0);
155                                 else
156                                         return ieee754dp_zero(1);
157                         case IEEE754_RD:    /* toward -Infinity */
158                                 if(sn == 0)
159                                         return ieee754dp_zero(0);
160                                 else
161                                         return ieee754dp_min(1);
162                         }
163                 }
164
165                 if (xe == DP_EMIN - 1
166                                 && get_rounding(sn, xm) >> (DP_MBITS + 1 + 3))
167                 {
168                         /* Not tiny after rounding */
169                         SETCX(IEEE754_INEXACT);
170                         xm = get_rounding(sn, xm);
171                         xm >>= 1;
172                         /* Clear grs bits */
173                         xm &= ~(DP_MBIT(3) - 1);
174                         xe++;
175                 }
176                 else {
177                         /* sticky right shift es bits
178                          */
179                         xm = XDPSRS(xm, es);
180                         xe += es;
181                         assert((xm & (DP_HIDDEN_BIT << 3)) == 0);
182                         assert(xe == DP_EMIN);
183                 }
184         }
185         if (xm & (DP_MBIT(3) - 1)) {
186                 SETCX(IEEE754_INEXACT);
187                 if ((xm & (DP_HIDDEN_BIT << 3)) == 0) {
188                         SETCX(IEEE754_UNDERFLOW);
189                 }
190
191                 /* inexact must round of 3 bits
192                  */
193                 xm = get_rounding(sn, xm);
194                 /* adjust exponent for rounding add overflowing
195                  */
196                 if (xm >> (DP_MBITS + 3 + 1)) {
197                         /* add causes mantissa overflow */
198                         xm >>= 1;
199                         xe++;
200                 }
201         }
202         /* strip grs bits */
203         xm >>= 3;
204
205         assert((xm >> (DP_MBITS + 1)) == 0);    /* no execess */
206         assert(xe >= DP_EMIN);
207
208         if (xe > DP_EMAX) {
209                 SETCX(IEEE754_OVERFLOW);
210                 SETCX(IEEE754_INEXACT);
211                 /* -O can be table indexed by (rm,sn) */
212                 switch (ieee754_csr.rm) {
213                 case IEEE754_RN:
214                         return ieee754dp_inf(sn);
215                 case IEEE754_RZ:
216                         return ieee754dp_max(sn);
217                 case IEEE754_RU:        /* toward +Infinity */
218                         if (sn == 0)
219                                 return ieee754dp_inf(0);
220                         else
221                                 return ieee754dp_max(1);
222                 case IEEE754_RD:        /* toward -Infinity */
223                         if (sn == 0)
224                                 return ieee754dp_max(0);
225                         else
226                                 return ieee754dp_inf(1);
227                 }
228         }
229         /* gen norm/denorm/zero */
230
231         if ((xm & DP_HIDDEN_BIT) == 0) {
232                 /* we underflow (tiny/zero) */
233                 assert(xe == DP_EMIN);
234                 if (ieee754_csr.mx & IEEE754_UNDERFLOW)
235                         SETCX(IEEE754_UNDERFLOW);
236                 return builddp(sn, DP_EMIN - 1 + DP_EBIAS, xm);
237         } else {
238                 assert((xm >> (DP_MBITS + 1)) == 0);    /* no execess */
239                 assert(xm & DP_HIDDEN_BIT);
240
241                 return builddp(sn, xe + DP_EBIAS, xm & ~DP_HIDDEN_BIT);
242         }
243 }