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
|
/*---------------------------------------------------------------------------+
| reg_norm.S |
| |
| Copyright (C) 1992,1993,1994,1995,1997 |
| W. Metzenthen, 22 Parker St, Ormond, Vic 3163, |
| Australia. E-mail billm@suburbia.net |
| |
| Normalize the value in a FPU_REG. |
| |
| Call from C as: |
| int FPU_normalize(FPU_REG *n) |
| |
| int FPU_normalize_nuo(FPU_REG *n) |
| |
| Return value is the tag of the answer, or-ed with FPU_Exception if |
| one was raised, or -1 on internal error. |
| |
+---------------------------------------------------------------------------*/
#include "fpu_emu.h"
.text
ENTRY(FPU_normalize)
pushl %ebp
movl %esp,%ebp
pushl %ebx
movl PARAM1,%ebx
movl SIGH(%ebx),%edx
movl SIGL(%ebx),%eax
orl %edx,%edx /* ms bits */
js L_done /* Already normalized */
jnz L_shift_1 /* Shift left 1 - 31 bits */
orl %eax,%eax
jz L_zero /* The contents are zero */
movl %eax,%edx
xorl %eax,%eax
subw $32,EXP(%ebx) /* This can cause an underflow */
/* We need to shift left by 1 - 31 bits */
L_shift_1:
bsrl %edx,%ecx /* get the required shift in %ecx */
subl $31,%ecx
negl %ecx
shld %cl,%eax,%edx
shl %cl,%eax
subw %cx,EXP(%ebx) /* This can cause an underflow */
movl %edx,SIGH(%ebx)
movl %eax,SIGL(%ebx)
L_done:
cmpw EXP_OVER,EXP(%ebx)
jge L_overflow
cmpw EXP_UNDER,EXP(%ebx)
jle L_underflow
L_exit_valid:
movl TAG_Valid,%eax
/* Convert the exponent to 80x87 form. */
addw EXTENDED_Ebias,EXP(%ebx)
andw $0x7fff,EXP(%ebx)
L_exit:
popl %ebx
leave
ret
L_zero:
movw $0,EXP(%ebx)
movl TAG_Zero,%eax
jmp L_exit
L_underflow:
/* Convert the exponent to 80x87 form. */
addw EXTENDED_Ebias,EXP(%ebx)
push %ebx
call arith_underflow
pop %ebx
jmp L_exit
L_overflow:
/* Convert the exponent to 80x87 form. */
addw EXTENDED_Ebias,EXP(%ebx)
push %ebx
call arith_overflow
pop %ebx
jmp L_exit
/* Normalise without reporting underflow or overflow */
ENTRY(FPU_normalize_nuo)
pushl %ebp
movl %esp,%ebp
pushl %ebx
movl PARAM1,%ebx
movl SIGH(%ebx),%edx
movl SIGL(%ebx),%eax
orl %edx,%edx /* ms bits */
js L_exit_nuo_valid /* Already normalized */
jnz L_nuo_shift_1 /* Shift left 1 - 31 bits */
orl %eax,%eax
jz L_exit_nuo_zero /* The contents are zero */
movl %eax,%edx
xorl %eax,%eax
subw $32,EXP(%ebx) /* This can cause an underflow */
/* We need to shift left by 1 - 31 bits */
L_nuo_shift_1:
bsrl %edx,%ecx /* get the required shift in %ecx */
subl $31,%ecx
negl %ecx
shld %cl,%eax,%edx
shl %cl,%eax
subw %cx,EXP(%ebx) /* This can cause an underflow */
movl %edx,SIGH(%ebx)
movl %eax,SIGL(%ebx)
L_exit_nuo_valid:
movl TAG_Valid,%eax
popl %ebx
leave
ret
L_exit_nuo_zero:
movl TAG_Zero,%eax
movw EXP_UNDER,EXP(%ebx)
popl %ebx
leave
ret
|
