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
|
invalid_msg:
.asciz "Invalid instruction at %X\n"
.global _m68k_invalid
_m68k_invalid:
push %ecx
push invalid_msg
xor %eax, %eax
call _printf
push $1
call _exit
.global _bcd_add
_bcd_add:
xchg %eax, %edi
mov %cl, %ch
mov %al, %ah
and $0xF, %ch
and $0xF, %ah
and $0xF0, %cl
and $0xF0, %al
add %ah, %ch
cmp $10, %ch
jb no_adjust
add $6, %ch
no_adjust:
add %ch, %al
add %al, %cl
mov $0, %ch
jc def_adjust
cmp $0xA0, %cl
jb no_adjust_h
def_adjust:
add $0x60, %cl
mov $1, %ch
no_adjust_h:
mov %edi, %eax
ret
.global _bcd_sub
_bcd_sub:
xchg %eax, %edi
mov %cl, %ch
mov %al, %ah
and $0xF, %ch
and $0xF, %ah
and $0xF0, %cl
and $0xF0, %al
sub %ah, %ch
cmp $10, %ch
jb no_adjusts
sub $6, %ch
no_adjusts:
add %ch, %cl
sub %al, %cl
mov $0, %ch
jc def_adjusts
cmp $0xA0, %cl
jb no_adjust_hs
def_adjusts:
sub $0x60, %cl
mov $1, %ch
no_adjust_hs:
mov %edi, %eax
ret
|
