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
|
! bcc 386 floating point routines (version 2)
! --- fpdenormal, fperror, fpinfinity, fpNaN, fpoverflow, fpunderflow,fpdivzero
! author: Bruce Evans
#include "fperr.h"
#include "fplib.h"
.extern _fperr
! Cause a denormal-operand exception
! Preserves all general registers if signal handler returns
.globl fpdenormal
.align ALIGNMENT
fpdenormal:
#if 0
push eax
mov eax,#EFDENORMAL
call fperror
pop eax
#endif
ret
! Cause an exception with error code eax, preserving all genregs except eax
.globl fperror
.align ALIGNMENT
fperror:
push ebp ! set up usual frame ...
mov ebp,esp ! ... for debugging
push edx ! save default
push ecx
push eax ! error code is arg to C routine
call _fperr
add esp,#GENREG_SIZE
pop ecx ! restore default
pop edx
pop ebp
ret
.align ALIGNMENT
fphuge:
mov ecx,#D_HUGE_LOW ! prepare number +-HUGEVAL
or edx,#D_HUGE_HIGH ! ... in case signal handler returns
jmp fperror
! Cause an infinite-operand exception
! Return +-HUGEVAL in edx:ecx with sign from edx
.globl fpinfinity
.align ALIGNMENT
fpinfinity:
mov eax,#EFINFINITY
jmp fphuge ! almost right
! Cause an NaN-operand exception
! Return +-HUGEVAL in edx:ecx with sign from edx
.globl fpNaN
.align ALIGNMENT
fpNaN:
mov eax,#EFNAN ! there are different types of NaNs but...
jmp fphuge ! WRONG
! Cause an overflow exception
! Return +-HUGEVAL in edx:ecx with sign from edx
.globl fpoverflow
.align ALIGNMENT
fpoverflow:
mov eax,#EFOVERFLOW
jmp fphuge ! almost right
! Cause an underflow exception (actually assume it is masked for now)
! Return denormal or 0.0 in edx:ecx
! XXX - this should cause a denormal exception or none for the denormal case
! Args: sign in edx, fraction in esi:eax, right shift in edi
! Returns: denormalized number in edx:eax
.globl fpunderflow
.align ALIGNMENT
fpunderflow:
#if 0
mov eax,#EFUNDERFLOW
jmp fperror
#endif
cmp edi,#REG_BIT
jb denormalize1
mov eax,esi
sub esi,esi
sub edi,#REG_BIT
cmp edi,#REG_BIT
jb denormalize1
denormalize_underflow:
#if 0
mov eax,#EFUNDERFLOW
jmp fperror
#endif
sub eax,eax
mov edx,eax
ret
.align ALIGNMENT
denormalize1:
mov ecx,edi
shrd eax,esi,cl
shr esi,cl
mov ecx,esi
or ecx,eax
jz denormalize_underflow
and edx,#D_SIGN_MASK
or edx,esi
ret
! Cause an fp division by zero exception
! Return +-HUGEVAL in edx:ecx with sign from edx
.globl fpdivzero
.align ALIGNMENT
fpdivzero:
mov eax,#EFDIVZERO
test edx,#D_EXP_MASK
jnz fphuge ! almost right
sub ecx,ecx
mov edx,ecx
jmp fperror
|
