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
|
|
| x_store.sa 3.2 1/24/91
|
| store --- store operand to memory or register
|
| Used by underflow and overflow handlers.
|
| a6 = points to fp value to be stored.
|
| Copyright (C) Motorola, Inc. 1990
| All Rights Reserved
|
| For details on the license for this file, please see the
| file, README, in this same directory.
X_STORE: |idnt 2,1 | Motorola 040 Floating Point Software Package
|section 8
fpreg_mask:
.byte 0x80,0x40,0x20,0x10,0x08,0x04,0x02,0x01
#include "fpsp.h"
|xref mem_write
|xref get_fline
|xref g_opcls
|xref g_dfmtou
|xref reg_dest
.global dest_ext
.global dest_dbl
.global dest_sgl
.global store
store:
btstb #E3,E_BYTE(%a6)
beqs E1_sto
E3_sto:
movel CMDREG3B(%a6),%d0
bfextu %d0{#6:#3},%d0 |isolate dest. reg from cmdreg3b
sto_fp:
lea fpreg_mask,%a1
moveb (%a1,%d0.w),%d0 |convert reg# to dynamic register mask
tstb LOCAL_SGN(%a0)
beqs is_pos
bsetb #sign_bit,LOCAL_EX(%a0)
is_pos:
fmovemx (%a0),%d0 |move to correct register
|
| if fp0-fp3 is being modified, we must put a copy
| in the USER_FPn variable on the stack because all exception
| handlers restore fp0-fp3 from there.
|
cmpb #0x80,%d0
bnes not_fp0
fmovemx %fp0-%fp0,USER_FP0(%a6)
rts
not_fp0:
cmpb #0x40,%d0
bnes not_fp1
fmovemx %fp1-%fp1,USER_FP1(%a6)
rts
not_fp1:
cmpb #0x20,%d0
bnes not_fp2
fmovemx %fp2-%fp2,USER_FP2(%a6)
rts
not_fp2:
cmpb #0x10,%d0
bnes not_fp3
fmovemx %fp3-%fp3,USER_FP3(%a6)
rts
not_fp3:
rts
E1_sto:
bsrl g_opcls |returns opclass in d0
cmpib #3,%d0
beq opc011 |branch if opclass 3
movel CMDREG1B(%a6),%d0
bfextu %d0{#6:#3},%d0 |extract destination register
bras sto_fp
opc011:
bsrl g_dfmtou |returns dest format in d0
| ;ext=00, sgl=01, dbl=10
movel %a0,%a1 |save source addr in a1
movel EXC_EA(%a6),%a0 |get the address
cmpil #0,%d0 |if dest format is extended
beq dest_ext |then branch
cmpil #1,%d0 |if dest format is single
beq dest_sgl |then branch
|
| fall through to dest_dbl
|
|
| dest_dbl --- write double precision value to user space
|
|Input
| a0 -> destination address
| a1 -> source in extended precision
|Output
| a0 -> destroyed
| a1 -> destroyed
| d0 -> 0
|
|Changes extended precision to double precision.
| Note: no attempt is made to round the extended value to double.
| dbl_sign = ext_sign
| dbl_exp = ext_exp - $3fff(ext bias) + $7ff(dbl bias)
| get rid of ext integer bit
| dbl_mant = ext_mant{62:12}
|
| --------------- --------------- ---------------
| extended -> |s| exp | |1| ms mant | | ls mant |
| --------------- --------------- ---------------
| 95 64 63 62 32 31 11 0
| | |
| | |
| | |
| v v
| --------------- ---------------
| double -> |s|exp| mant | | mant |
| --------------- ---------------
| 63 51 32 31 0
|
dest_dbl:
clrl %d0 |clear d0
movew LOCAL_EX(%a1),%d0 |get exponent
subw #0x3fff,%d0 |subtract extended precision bias
cmpw #0x4000,%d0 |check if inf
beqs inf |if so, special case
addw #0x3ff,%d0 |add double precision bias
swap %d0 |d0 now in upper word
lsll #4,%d0 |d0 now in proper place for dbl prec exp
tstb LOCAL_SGN(%a1)
beqs get_mant |if positive, go process mantissa
bsetl #31,%d0 |if negative, put in sign information
| ; before continuing
bras get_mant |go process mantissa
inf:
movel #0x7ff00000,%d0 |load dbl inf exponent
clrl LOCAL_HI(%a1) |clear msb
tstb LOCAL_SGN(%a1)
beqs dbl_inf |if positive, go ahead and write it
bsetl #31,%d0 |if negative put in sign information
dbl_inf:
movel %d0,LOCAL_EX(%a1) |put the new exp back on the stack
bras dbl_wrt
get_mant:
movel LOCAL_HI(%a1),%d1 |get ms mantissa
bfextu %d1{#1:#20},%d1 |get upper 20 bits of ms
orl %d1,%d0 |put these bits in ms word of double
movel %d0,LOCAL_EX(%a1) |put the new exp back on the stack
movel LOCAL_HI(%a1),%d1 |get ms mantissa
movel #21,%d0 |load shift count
lsll %d0,%d1 |put lower 11 bits in upper bits
movel %d1,LOCAL_HI(%a1) |build lower lword in memory
movel LOCAL_LO(%a1),%d1 |get ls mantissa
bfextu %d1{#0:#21},%d0 |get ls 21 bits of double
orl %d0,LOCAL_HI(%a1) |put them in double result
dbl_wrt:
movel #0x8,%d0 |byte count for double precision number
exg %a0,%a1 |a0=supervisor source, a1=user dest
bsrl mem_write |move the number to the user's memory
rts
|
| dest_sgl --- write single precision value to user space
|
|Input
| a0 -> destination address
| a1 -> source in extended precision
|
|Output
| a0 -> destroyed
| a1 -> destroyed
| d0 -> 0
|
|Changes extended precision to single precision.
| sgl_sign = ext_sign
| sgl_exp = ext_exp - $3fff(ext bias) + $7f(sgl bias)
| get rid of ext integer bit
| sgl_mant = ext_mant{62:12}
|
| --------------- --------------- ---------------
| extended -> |s| exp | |1| ms mant | | ls mant |
| --------------- --------------- ---------------
| 95 64 63 62 40 32 31 12 0
| | |
| | |
| | |
| v v
| ---------------
| single -> |s|exp| mant |
| ---------------
| 31 22 0
|
dest_sgl:
clrl %d0
movew LOCAL_EX(%a1),%d0 |get exponent
subw #0x3fff,%d0 |subtract extended precision bias
cmpw #0x4000,%d0 |check if inf
beqs sinf |if so, special case
addw #0x7f,%d0 |add single precision bias
swap %d0 |put exp in upper word of d0
lsll #7,%d0 |shift it into single exp bits
tstb LOCAL_SGN(%a1)
beqs get_sman |if positive, continue
bsetl #31,%d0 |if negative, put in sign first
bras get_sman |get mantissa
sinf:
movel #0x7f800000,%d0 |load single inf exp to d0
tstb LOCAL_SGN(%a1)
beqs sgl_wrt |if positive, continue
bsetl #31,%d0 |if negative, put in sign info
bras sgl_wrt
get_sman:
movel LOCAL_HI(%a1),%d1 |get ms mantissa
bfextu %d1{#1:#23},%d1 |get upper 23 bits of ms
orl %d1,%d0 |put these bits in ms word of single
sgl_wrt:
movel %d0,L_SCR1(%a6) |put the new exp back on the stack
movel #0x4,%d0 |byte count for single precision number
tstl %a0 |users destination address
beqs sgl_Dn |destination is a data register
exg %a0,%a1 |a0=supervisor source, a1=user dest
leal L_SCR1(%a6),%a0 |point a0 to data
bsrl mem_write |move the number to the user's memory
rts
sgl_Dn:
bsrl get_fline |returns fline word in d0
andw #0x7,%d0 |isolate register number
movel %d0,%d1 |d1 has size:reg formatted for reg_dest
orl #0x10,%d1 |reg_dest wants size added to reg#
bral reg_dest |size is X, rts in reg_dest will
| ;return to caller of dest_sgl
dest_ext:
tstb LOCAL_SGN(%a1) |put back sign into exponent word
beqs dstx_cont
bsetb #sign_bit,LOCAL_EX(%a1)
dstx_cont:
clrb LOCAL_SGN(%a1) |clear out the sign byte
movel #0x0c,%d0 |byte count for extended number
exg %a0,%a1 |a0=supervisor source, a1=user dest
bsrl mem_write |move the number to the user's memory
rts
|end
|
