1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
|
/* $NetBSD: fpu_explode.c,v 1.3 1996/03/14 19:41:54 christos Exp $ */
/*
* Copyright (c) 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* This software was developed by the Computer Systems Engineering group
* at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
* contributed to Berkeley.
*
* All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Lawrence Berkeley Laboratory.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)fpu_explode.c 8.1 (Berkeley) 6/11/93
*/
/*
* FPU subroutines: `explode' the machine's `packed binary' format numbers
* into our internal format.
*/
#include <sys/types.h>
#include <sys/systm.h>
#include <machine/ieee.h>
#include <machine/instr.h>
#include <machine/reg.h>
#include <fpu/fpu_arith.h>
#include <fpu/fpu_emu.h>
#include <fpu/fpu_extern.h>
/*
* N.B.: in all of the following, we assume the FP format is
*
* ---------------------------
* | s | exponent | fraction |
* ---------------------------
*
* (which represents -1**s * 1.fraction * 2**exponent), so that the
* sign bit is way at the top (bit 31), the exponent is next, and
* then the remaining bits mark the fraction. A zero exponent means
* zero or denormalized (0.fraction rather than 1.fraction), and the
* maximum possible exponent, 2bias+1, signals inf (fraction==0) or NaN.
*
* Since the sign bit is always the topmost bit---this holds even for
* integers---we set that outside all the *tof functions. Each function
* returns the class code for the new number (but note that we use
* FPC_QNAN for all NaNs; fpu_explode will fix this if appropriate).
*/
/*
* int -> fpn.
*/
int
fpu_itof(fp, i)
register struct fpn *fp;
register u_int i;
{
if (i == 0)
return (FPC_ZERO);
/*
* The value FP_1 represents 2^FP_LG, so set the exponent
* there and let normalization fix it up. Convert negative
* numbers to sign-and-magnitude. Note that this relies on
* fpu_norm()'s handling of `supernormals'; see fpu_subr.c.
*/
fp->fp_exp = FP_LG;
fp->fp_mant[0] = (int)i < 0 ? -i : i;
fp->fp_mant[1] = 0;
fp->fp_mant[2] = 0;
fp->fp_mant[3] = 0;
fpu_norm(fp);
return (FPC_NUM);
}
#define mask(nbits) ((1 << (nbits)) - 1)
/*
* All external floating formats convert to internal in the same manner,
* as defined here. Note that only normals get an implied 1.0 inserted.
*/
#define FP_TOF(exp, expbias, allfrac, f0, f1, f2, f3) \
if (exp == 0) { \
if (allfrac == 0) \
return (FPC_ZERO); \
fp->fp_exp = 1 - expbias; \
fp->fp_mant[0] = f0; \
fp->fp_mant[1] = f1; \
fp->fp_mant[2] = f2; \
fp->fp_mant[3] = f3; \
fpu_norm(fp); \
return (FPC_NUM); \
} \
if (exp == (2 * expbias + 1)) { \
if (allfrac == 0) \
return (FPC_INF); \
fp->fp_mant[0] = f0; \
fp->fp_mant[1] = f1; \
fp->fp_mant[2] = f2; \
fp->fp_mant[3] = f3; \
return (FPC_QNAN); \
} \
fp->fp_exp = exp - expbias; \
fp->fp_mant[0] = FP_1 | f0; \
fp->fp_mant[1] = f1; \
fp->fp_mant[2] = f2; \
fp->fp_mant[3] = f3; \
return (FPC_NUM)
/*
* 32-bit single precision -> fpn.
* We assume a single occupies at most (64-FP_LG) bits in the internal
* format: i.e., needs at most fp_mant[0] and fp_mant[1].
*/
int
fpu_stof(fp, i)
register struct fpn *fp;
register u_int i;
{
register int exp;
register u_int frac, f0, f1;
#define SNG_SHIFT (SNG_FRACBITS - FP_LG)
exp = (i >> (32 - 1 - SNG_EXPBITS)) & mask(SNG_EXPBITS);
frac = i & mask(SNG_FRACBITS);
f0 = frac >> SNG_SHIFT;
f1 = frac << (32 - SNG_SHIFT);
FP_TOF(exp, SNG_EXP_BIAS, frac, f0, f1, 0, 0);
}
/*
* 64-bit double -> fpn.
* We assume this uses at most (96-FP_LG) bits.
*/
int
fpu_dtof(fp, i, j)
register struct fpn *fp;
register u_int i, j;
{
register int exp;
register u_int frac, f0, f1, f2;
#define DBL_SHIFT (DBL_FRACBITS - 32 - FP_LG)
exp = (i >> (32 - 1 - DBL_EXPBITS)) & mask(DBL_EXPBITS);
frac = i & mask(DBL_FRACBITS - 32);
f0 = frac >> DBL_SHIFT;
f1 = (frac << (32 - DBL_SHIFT)) | (j >> DBL_SHIFT);
f2 = j << (32 - DBL_SHIFT);
frac |= j;
FP_TOF(exp, DBL_EXP_BIAS, frac, f0, f1, f2, 0);
}
/*
* 128-bit extended -> fpn.
*/
int
fpu_xtof(fp, i, j, k, l)
register struct fpn *fp;
register u_int i, j, k, l;
{
register int exp;
register u_int frac, f0, f1, f2, f3;
#define EXT_SHIFT (-(EXT_FRACBITS - 3 * 32 - FP_LG)) /* left shift! */
/*
* Note that ext and fpn `line up', hence no shifting needed.
*/
exp = (i >> (32 - 1 - EXT_EXPBITS)) & mask(EXT_EXPBITS);
frac = i & mask(EXT_FRACBITS - 3 * 32);
f0 = (frac << EXT_SHIFT) | (j >> (32 - EXT_SHIFT));
f1 = (j << EXT_SHIFT) | (k >> (32 - EXT_SHIFT));
f2 = (k << EXT_SHIFT) | (l >> (32 - EXT_SHIFT));
f3 = l << EXT_SHIFT;
frac |= j | k | l;
FP_TOF(exp, EXT_EXP_BIAS, frac, f0, f1, f2, f3);
}
/*
* Explode the contents of a register / regpair / regquad.
* If the input is a signalling NaN, an NV (invalid) exception
* will be set. (Note that nothing but NV can occur until ALU
* operations are performed.)
*/
void
fpu_explode(fe, fp, type, reg)
register struct fpemu *fe;
register struct fpn *fp;
int type, reg;
{
register u_int s, *space;
space = &fe->fe_fpstate->fs_regs[reg];
s = space[0];
fp->fp_sign = s >> 31;
fp->fp_sticky = 0;
switch (type) {
case FTYPE_INT:
s = fpu_itof(fp, s);
break;
case FTYPE_SNG:
s = fpu_stof(fp, s);
break;
case FTYPE_DBL:
s = fpu_dtof(fp, s, space[1]);
break;
case FTYPE_EXT:
s = fpu_xtof(fp, s, space[1], space[2], space[3]);
break;
default:
panic("fpu_explode");
}
if (s == FPC_QNAN && (fp->fp_mant[0] & FP_QUIETBIT) == 0) {
/*
* Input is a signalling NaN. All operations that return
* an input NaN operand put it through a ``NaN conversion'',
* which basically just means ``turn on the quiet bit''.
* We do this here so that all NaNs internally look quiet
* (we can tell signalling ones by their class).
*/
fp->fp_mant[0] |= FP_QUIETBIT;
fe->fe_cx = FSR_NV; /* assert invalid operand */
s = FPC_SNAN;
}
fp->fp_class = s;
}
|
