Commit | Line | Data |
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1da177e4 LT |
1 | /* IEEE754 floating point arithmetic |
2 | * single precision | |
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 "ieee754sp.h" | |
29 | ||
30 | int ieee754sp_class(ieee754sp x) | |
31 | { | |
32 | COMPXSP; | |
33 | EXPLODEXSP; | |
34 | return xc; | |
35 | } | |
36 | ||
37 | int ieee754sp_isnan(ieee754sp x) | |
38 | { | |
39 | return ieee754sp_class(x) >= IEEE754_CLASS_SNAN; | |
40 | } | |
41 | ||
42 | int ieee754sp_issnan(ieee754sp x) | |
43 | { | |
44 | assert(ieee754sp_isnan(x)); | |
45 | return (SPMANT(x) & SP_MBIT(SP_MBITS-1)); | |
46 | } | |
47 | ||
48 | ||
49 | ieee754sp ieee754sp_xcpt(ieee754sp r, const char *op, ...) | |
50 | { | |
51 | struct ieee754xctx ax; | |
52 | ||
53 | if (!TSTX()) | |
54 | return r; | |
55 | ||
56 | ax.op = op; | |
57 | ax.rt = IEEE754_RT_SP; | |
58 | ax.rv.sp = r; | |
59 | va_start(ax.ap, op); | |
60 | ieee754_xcpt(&ax); | |
8142294d | 61 | va_end(ax.ap); |
1da177e4 LT |
62 | return ax.rv.sp; |
63 | } | |
64 | ||
65 | ieee754sp ieee754sp_nanxcpt(ieee754sp r, const char *op, ...) | |
66 | { | |
67 | struct ieee754xctx ax; | |
68 | ||
69 | assert(ieee754sp_isnan(r)); | |
70 | ||
71 | if (!ieee754sp_issnan(r)) /* QNAN does not cause invalid op !! */ | |
72 | return r; | |
73 | ||
74 | if (!SETANDTESTCX(IEEE754_INVALID_OPERATION)) { | |
75 | /* not enabled convert to a quiet NaN */ | |
76 | SPMANT(r) &= (~SP_MBIT(SP_MBITS-1)); | |
77 | if (ieee754sp_isnan(r)) | |
78 | return r; | |
79 | else | |
80 | return ieee754sp_indef(); | |
81 | } | |
82 | ||
83 | ax.op = op; | |
84 | ax.rt = 0; | |
85 | ax.rv.sp = r; | |
86 | va_start(ax.ap, op); | |
87 | ieee754_xcpt(&ax); | |
8142294d | 88 | va_end(ax.ap); |
1da177e4 LT |
89 | return ax.rv.sp; |
90 | } | |
91 | ||
92 | ieee754sp ieee754sp_bestnan(ieee754sp x, ieee754sp y) | |
93 | { | |
94 | assert(ieee754sp_isnan(x)); | |
95 | assert(ieee754sp_isnan(y)); | |
96 | ||
97 | if (SPMANT(x) > SPMANT(y)) | |
98 | return x; | |
99 | else | |
100 | return y; | |
101 | } | |
102 | ||
103 | ||
104 | static unsigned get_rounding(int sn, unsigned xm) | |
105 | { | |
106 | /* inexact must round of 3 bits | |
107 | */ | |
108 | if (xm & (SP_MBIT(3) - 1)) { | |
109 | switch (ieee754_csr.rm) { | |
110 | case IEEE754_RZ: | |
111 | break; | |
112 | case IEEE754_RN: | |
113 | xm += 0x3 + ((xm >> 3) & 1); | |
114 | /* xm += (xm&0x8)?0x4:0x3 */ | |
115 | break; | |
116 | case IEEE754_RU: /* toward +Infinity */ | |
117 | if (!sn) /* ?? */ | |
118 | xm += 0x8; | |
119 | break; | |
120 | case IEEE754_RD: /* toward -Infinity */ | |
121 | if (sn) /* ?? */ | |
122 | xm += 0x8; | |
123 | break; | |
124 | } | |
125 | } | |
126 | return xm; | |
127 | } | |
128 | ||
129 | ||
130 | /* generate a normal/denormal number with over,under handling | |
131 | * sn is sign | |
132 | * xe is an unbiased exponent | |
133 | * xm is 3bit extended precision value. | |
134 | */ | |
135 | ieee754sp ieee754sp_format(int sn, int xe, unsigned xm) | |
136 | { | |
137 | assert(xm); /* we don't gen exact zeros (probably should) */ | |
138 | ||
139 | assert((xm >> (SP_MBITS + 1 + 3)) == 0); /* no execess */ | |
140 | assert(xm & (SP_HIDDEN_BIT << 3)); | |
141 | ||
142 | if (xe < SP_EMIN) { | |
143 | /* strip lower bits */ | |
144 | int es = SP_EMIN - xe; | |
145 | ||
146 | if (ieee754_csr.nod) { | |
147 | SETCX(IEEE754_UNDERFLOW); | |
148 | SETCX(IEEE754_INEXACT); | |
149 | ||
150 | switch(ieee754_csr.rm) { | |
151 | case IEEE754_RN: | |
1da177e4 LT |
152 | case IEEE754_RZ: |
153 | return ieee754sp_zero(sn); | |
154 | case IEEE754_RU: /* toward +Infinity */ | |
155 | if(sn == 0) | |
156 | return ieee754sp_min(0); | |
157 | else | |
158 | return ieee754sp_zero(1); | |
159 | case IEEE754_RD: /* toward -Infinity */ | |
160 | if(sn == 0) | |
161 | return ieee754sp_zero(0); | |
162 | else | |
163 | return ieee754sp_min(1); | |
164 | } | |
165 | } | |
166 | ||
167 | if (xe == SP_EMIN - 1 | |
168 | && get_rounding(sn, xm) >> (SP_MBITS + 1 + 3)) | |
169 | { | |
170 | /* Not tiny after rounding */ | |
171 | SETCX(IEEE754_INEXACT); | |
172 | xm = get_rounding(sn, xm); | |
173 | xm >>= 1; | |
174 | /* Clear grs bits */ | |
175 | xm &= ~(SP_MBIT(3) - 1); | |
176 | xe++; | |
177 | } | |
178 | else { | |
179 | /* sticky right shift es bits | |
180 | */ | |
181 | SPXSRSXn(es); | |
182 | assert((xm & (SP_HIDDEN_BIT << 3)) == 0); | |
183 | assert(xe == SP_EMIN); | |
184 | } | |
185 | } | |
186 | if (xm & (SP_MBIT(3) - 1)) { | |
187 | SETCX(IEEE754_INEXACT); | |
188 | if ((xm & (SP_HIDDEN_BIT << 3)) == 0) { | |
189 | SETCX(IEEE754_UNDERFLOW); | |
190 | } | |
191 | ||
192 | /* inexact must round of 3 bits | |
193 | */ | |
194 | xm = get_rounding(sn, xm); | |
195 | /* adjust exponent for rounding add overflowing | |
196 | */ | |
197 | if (xm >> (SP_MBITS + 1 + 3)) { | |
198 | /* add causes mantissa overflow */ | |
199 | xm >>= 1; | |
200 | xe++; | |
201 | } | |
202 | } | |
203 | /* strip grs bits */ | |
204 | xm >>= 3; | |
205 | ||
206 | assert((xm >> (SP_MBITS + 1)) == 0); /* no execess */ | |
207 | assert(xe >= SP_EMIN); | |
208 | ||
209 | if (xe > SP_EMAX) { | |
210 | SETCX(IEEE754_OVERFLOW); | |
211 | SETCX(IEEE754_INEXACT); | |
212 | /* -O can be table indexed by (rm,sn) */ | |
213 | switch (ieee754_csr.rm) { | |
214 | case IEEE754_RN: | |
215 | return ieee754sp_inf(sn); | |
216 | case IEEE754_RZ: | |
217 | return ieee754sp_max(sn); | |
218 | case IEEE754_RU: /* toward +Infinity */ | |
219 | if (sn == 0) | |
220 | return ieee754sp_inf(0); | |
221 | else | |
222 | return ieee754sp_max(1); | |
223 | case IEEE754_RD: /* toward -Infinity */ | |
224 | if (sn == 0) | |
225 | return ieee754sp_max(0); | |
226 | else | |
227 | return ieee754sp_inf(1); | |
228 | } | |
229 | } | |
230 | /* gen norm/denorm/zero */ | |
231 | ||
232 | if ((xm & SP_HIDDEN_BIT) == 0) { | |
233 | /* we underflow (tiny/zero) */ | |
234 | assert(xe == SP_EMIN); | |
235 | if (ieee754_csr.mx & IEEE754_UNDERFLOW) | |
236 | SETCX(IEEE754_UNDERFLOW); | |
237 | return buildsp(sn, SP_EMIN - 1 + SP_EBIAS, xm); | |
238 | } else { | |
239 | assert((xm >> (SP_MBITS + 1)) == 0); /* no execess */ | |
240 | assert(xm & SP_HIDDEN_BIT); | |
241 | ||
242 | return buildsp(sn, xe + SP_EBIAS, xm & ~SP_HIDDEN_BIT); | |
243 | } | |
244 | } |