blob: 8f58d6c525180c8328f7b420acd78ee9abfa26f1 (
plain) (
blame)
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
|
== code
# instruction effective address register displacement immediate
# . op subop mod rm32 base index scale r32
# . 1-3 bytes 3 bits 2 bits 3 bits 3 bits 3 bits 2 bits 2 bits 0/1/2/4 bytes 0/1/2/4 bytes
# read all bytes from 'f' and store them into 's'
# abort if 's' is too small
slurp: # f: (addr buffered-file), s: (addr stream byte)
# pseudocode:
# while true
# if (s->write >= s->length) abort
# if (f->read >= f->write) populate stream from file
# if (f->write == 0) break
# AL = f->data[f->read]
# s->data[s->write] = AL
# ++f->read
# ++s->write
# . prologue
55/push-ebp
89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
# . save registers
50/push-eax
51/push-ecx
52/push-edx
56/push-esi
57/push-edi
# esi = f
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 6/r32/esi 8/disp8 . # copy *(ebp+8) to esi
# ecx = f->read
8b/copy 1/mod/*+disp8 6/rm32/esi . . . 1/r32/ecx 8/disp8 . # copy *(esi+8) to ecx
# edi = s
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 7/r32/edi 0xc/disp8 . # copy *(ebp+12) to edi
# edx = s->write
8b/copy 0/mod/indirect 7/rm32/edi . . . 2/r32/edx . . # copy *edi to edx
$slurp:loop:
# if (s->write >= s->length) abort
3b/compare 1/mod/*+disp8 7/rm32/edi . . . 2/r32/edx 8/disp8 . # compare edx with *(edi+8)
7d/jump-if->= $slurp:abort/disp8
# if (f->read >= f->write) populate stream from file
3b/compare 1/mod/*+disp8 6/rm32/esi . . . 1/r32/ecx 4/disp8 . # compare ecx with *(esi+4)
7c/jump-if-< $slurp:from-stream/disp8
# . clear-stream(stream = f+4)
# . . push args
8d/copy-address 1/mod/*+disp8 6/rm32/esi . . . 0/r32/eax 4/disp8 . # copy esi+4 to eax
50/push-eax
# . . call
e8/call clear-stream/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
# . f->read must now be 0; update its cache at ecx
31/xor 3/mod/direct 1/rm32/ecx . . . 1/r32/ecx . . # clear ecx
# . eax = read(f->fd, stream = f+4)
# . . push args
50/push-eax
ff 6/subop/push 0/mod/indirect 6/rm32/esi . . . . . . # push *esi
# . . call
e8/call read/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# if (f->write == 0) break
# since f->read was initially 0, eax is the same as f->write
# . if (eax == 0) return true
3d/compare-eax-and 0/imm32
74/jump-if-= $slurp:end/disp8
$slurp:from-stream:
# var c/eax: byte = f->data[f->read]
31/xor 3/mod/direct 0/rm32/eax . . . 0/r32/eax . . # clear eax
8a/copy-byte 1/mod/*+disp8 4/rm32/sib 6/base/esi 1/index/ecx . 0/r32/AL 0x10/disp8 . # copy byte at *(esi+ecx+16) to AL
# s->data[s->write] = c
88/copy-byte 1/mod/*+disp8 4/rm32/sib 7/base/edi 2/index/edx . 0/r32/AL 0xc/disp8 . # copy AL to *(edi+edx+12)
# ++f->read
41/increment-ecx
# ++s->write
42/increment-edx
eb/jump $slurp:loop/disp8
$slurp:end:
# save f->read
89/copy 1/mod/*+disp8 6/rm32/esi . . . 1/r32/ecx 8/disp8 . # copy ecx to *(esi+8)
# save s->write
89/copy 0/mod/indirect 7/rm32/edi . . . 2/r32/edx . . # copy edx to *edi
# . restore registers
5f/pop-to-edi
5e/pop-to-esi
5a/pop-to-edx
59/pop-to-ecx
58/pop-to-eax
# . epilogue
89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
5d/pop-to-ebp
c3/return
$slurp:abort:
# . _write(2/stderr, error)
# . . push args
68/push "slurp: destination too small\n"/imm32
68/push 2/imm32/stderr
# . . call
e8/call _write/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# . syscall(exit, 1)
bb/copy-to-ebx 1/imm32
b8/copy-to-eax 1/imm32/exit
cd/syscall 0x80/imm8
# never gets here
test-slurp:
# setup
# . clear-stream(_test-stream)
# . . push args
68/push _test-stream/imm32
# . . call
e8/call clear-stream/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
# . clear-stream($_test-buffered-file->buffer)
# . . push args
68/push $_test-buffered-file->buffer/imm32
# . . call
e8/call clear-stream/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
# . clear-stream(_test-tmp-stream)
# . . push args
68/push _test-tmp-stream/imm32
# . . call
e8/call clear-stream/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 4/imm32 # add to esp
# write(_test-stream, "ab\ncd")
# . . push args
68/push "ab\ncd"/imm32
68/push _test-stream/imm32
# . . call
e8/call write/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# read a line from _test-stream (buffered by _test-buffered-file) into _test-tmp-stream
# . eax = slurp(_test-buffered-file, _test-tmp-stream)
# . . push args
68/push _test-tmp-stream/imm32
68/push _test-buffered-file/imm32
# . . call
e8/call slurp/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# check-stream-equal(_test-tmp-stream, "ab\ncd", msg)
# . . push args
68/push "F - test-slurp"/imm32
68/push "ab\ncd"/imm32
68/push _test-tmp-stream/imm32
# . . call
e8/call check-stream-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# end
c3/return
# . . vim:nowrap:textwidth=0
|