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
|
.section .data
buf:
.byte 0 // input/output character buffer
.section .text
.global _start
_start:
mov x19, #0 // value
mov x20, #0 // count
loop:
mov x8, #63 // read
mov x0, #0 // stdin
adr x1, buf
mov x2, #1
svc 0
cmp x0, #0 // count of bytes read; 0 means EOF
b.ne 1f
exit:
mov x8, #93 // exit
mov x0, #0 // error code (no error)
svc 0
1:
adr x1, buf
ldurb w9, [x1]
cmp w9, #92 // backslash; start of comment
b.ne 2f
comment:
mov x8, #63 // read
mov x0, #0 // stdin
adr x1, buf
mov x2, #1
svc 0
cmp x0, #0
b.eq exit
adr x1, buf
ldurb w9, [x1]
cmp w9, '\n'
b.ne comment
b loop
2:
cmp w9, '0'
b.lt 3f
cmp w9, '9'
b.gt 3f
sub w9, w9, '0'
b 4f
3:
cmp w9, 'a'
b.lt 5f
cmp w9, 'f'
b.gt 5f
sub w9, w9, ('a' - 10)
b 4f
4:
lsl x19, x19, #4
add x19, x19, w9, uxtb
add x20, x20, #1
b loop
5:
cmp w9, ' '
b.ne loop
tst x20, #1
cinc x20, x20, ne
lsr x20, x20, #1
6:
cmp x20, #0
b.eq loop
mov x8, #64 // write
mov x0, #1 // stdout
adr x1, buf
sturb w19, [x1]
mov x2, #1
svc 0
lsr x19, x19, #8
sub x20, x20, #1
b 6b
|
