Commit | Line | Data |
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1da177e4 LT |
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 | } |