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
|
/*---------------------------------------------------------------------------+
| reg_divide.c |
| |
| Divide one FPU_REG by another and put the result in a destination FPU_REG.|
| |
| Copyright (C) 1996 |
| W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia |
| E-mail billm@jacobi.maths.monash.edu.au |
| |
| Return value is the tag of the answer, or-ed with FPU_Exception if |
| one was raised, or -1 on internal error. |
| |
+---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------+
| The destination may be any FPU_REG, including one of the source FPU_REGs. |
+---------------------------------------------------------------------------*/
#include "exception.h"
#include "reg_constant.h"
#include "fpu_emu.h"
#include "fpu_system.h"
/*
Divide one register by another and put the result into a third register.
*/
int FPU_div(int flags, int rm, int control_w)
{
FPU_REG x, y;
FPU_REG const *a, *b, *st0_ptr, *st_ptr;
FPU_REG *dest;
u_char taga, tagb, signa, signb, sign, saved_sign;
int tag, deststnr;
if ( flags & DEST_RM )
deststnr = rm;
else
deststnr = 0;
if ( flags & REV )
{
b = &st(0);
st0_ptr = b;
tagb = FPU_gettag0();
if ( flags & LOADED )
{
a = (FPU_REG *)rm;
taga = flags & 0x0f;
}
else
{
a = &st(rm);
st_ptr = a;
taga = FPU_gettagi(rm);
}
}
else
{
a = &st(0);
st0_ptr = a;
taga = FPU_gettag0();
if ( flags & LOADED )
{
b = (FPU_REG *)rm;
tagb = flags & 0x0f;
}
else
{
b = &st(rm);
st_ptr = b;
tagb = FPU_gettagi(rm);
}
}
signa = getsign(a);
signb = getsign(b);
sign = signa ^ signb;
dest = &st(deststnr);
saved_sign = getsign(dest);
if ( !(taga | tagb) )
{
/* Both regs Valid, this should be the most common case. */
reg_copy(a, &x);
reg_copy(b, &y);
setpositive(&x);
setpositive(&y);
tag = FPU_u_div(&x, &y, dest, control_w, sign);
if ( tag < 0 )
return tag;
FPU_settagi(deststnr, tag);
return tag;
}
if ( taga == TAG_Special )
taga = FPU_Special(a);
if ( tagb == TAG_Special )
tagb = FPU_Special(b);
if ( ((taga == TAG_Valid) && (tagb == TW_Denormal))
|| ((taga == TW_Denormal) && (tagb == TAG_Valid))
|| ((taga == TW_Denormal) && (tagb == TW_Denormal)) )
{
if ( denormal_operand() < 0 )
return FPU_Exception;
FPU_to_exp16(a, &x);
FPU_to_exp16(b, &y);
tag = FPU_u_div(&x, &y, dest, control_w, sign);
if ( tag < 0 )
return tag;
FPU_settagi(deststnr, tag);
return tag;
}
else if ( (taga <= TW_Denormal) && (tagb <= TW_Denormal) )
{
if ( tagb != TAG_Zero )
{
/* Want to find Zero/Valid */
if ( tagb == TW_Denormal )
{
if ( denormal_operand() < 0 )
return FPU_Exception;
}
/* The result is zero. */
FPU_copy_to_regi(&CONST_Z, TAG_Zero, deststnr);
setsign(dest, sign);
return TAG_Zero;
}
/* We have an exception condition, either 0/0 or Valid/Zero. */
if ( taga == TAG_Zero )
{
/* 0/0 */
return arith_invalid(deststnr);
}
/* Valid/Zero */
return FPU_divide_by_zero(deststnr, sign);
}
/* Must have infinities, NaNs, etc */
else if ( (taga == TW_NaN) || (tagb == TW_NaN) )
{
if ( flags & LOADED )
return real_2op_NaN((FPU_REG *)rm, flags & 0x0f, 0, st0_ptr);
if ( flags & DEST_RM )
{
int tag;
tag = FPU_gettag0();
if ( tag == TAG_Special )
tag = FPU_Special(st0_ptr);
return real_2op_NaN(st0_ptr, tag, rm, (flags & REV) ? st0_ptr : &st(rm));
}
else
{
int tag;
tag = FPU_gettagi(rm);
if ( tag == TAG_Special )
tag = FPU_Special(&st(rm));
return real_2op_NaN(&st(rm), tag, 0, (flags & REV) ? st0_ptr : &st(rm));
}
}
else if (taga == TW_Infinity)
{
if (tagb == TW_Infinity)
{
/* infinity/infinity */
return arith_invalid(deststnr);
}
else
{
/* tagb must be Valid or Zero */
if ( (tagb == TW_Denormal) && (denormal_operand() < 0) )
return FPU_Exception;
/* Infinity divided by Zero or Valid does
not raise and exception, but returns Infinity */
FPU_copy_to_regi(a, TAG_Special, deststnr);
setsign(dest, sign);
return taga;
}
}
else if (tagb == TW_Infinity)
{
if ( (taga == TW_Denormal) && (denormal_operand() < 0) )
return FPU_Exception;
/* The result is zero. */
FPU_copy_to_regi(&CONST_Z, TAG_Zero, deststnr);
setsign(dest, sign);
return TAG_Zero;
}
#ifdef PARANOID
else
{
EXCEPTION(EX_INTERNAL|0x102);
return FPU_Exception;
}
#endif /* PARANOID */
return 0;
}
|
