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
|
# Helper to allocate a stream on the heap.
== 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
new-stream: # ad: (addr allocation-descriptor), length: int, elemsize: int, out: (addr handle stream _)
# . prologue
55/push-ebp
89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
# . save registers
50/push-eax
52/push-edx
# var size/edx: int = elemsize*length (clobbering eax)
# . eax = elemsize
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 0/r32/eax 0x10/disp8 . # copy *(ebp+16) to eax
# . eax *= length
31/xor 3/mod/direct 2/rm32/edx . . . 2/r32/edx . . # clear edx
f7 4/subop/multiply 1/mod/*+disp8 5/rm32/ebp . . 0xc/disp8 . # multiply *(ebp+12) into eax
# . if overflow abort
81 7/subop/compare 3/mod/direct 2/rm32/edx . . . . . 0/imm32 # compare edx
75/jump-if-!= $new-stream:abort/disp8
# . edx = elemsize*length
89/copy 3/mod/direct 2/rm32/edx . . . 0/r32/eax . . # copy eax to edx
# var n/eax: int = size + 12 (for read, write and size)
05/add-to-eax 0xc/imm32
# allocate(ad, n, out)
# . . push args
ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 0x14/disp8 . # push *(ebp+20)
50/push-eax
ff 6/subop/push 1/mod/*+disp8 5/rm32/ebp . . . . 8/disp8 . # push *(ebp+8)
# . . call
e8/call allocate/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# eax = out->payload
8b/copy 1/mod/*+disp8 5/rm32/ebp . . . 0/r32/eax 0x14/disp8 . # copy *(ebp+20) to eax
8b/copy 1/mod/*+disp8 0/rm32/eax . . . 0/r32/eax 4/disp8 . # copy *(eax+4) to eax
# skip payload->allocid
05/add-to-eax 4/imm32
# eax->size = size
89/copy 1/mod/*+disp8 0/rm32/eax . . . 2/r32/edx 8/disp8 . # copy edx to *(eax+8)
# clear-stream(eax)
# . . push args
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
$new-stream:end:
# . restore registers
5a/pop-to-edx
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
$new-stream:abort:
# . _write(2/stderr, error)
# . . push args
68/push "new-stream: size too large\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
e8/call syscall_exit/disp32
# never gets here
test-new-stream:
# . prologue
55/push-ebp
89/copy 3/mod/direct 5/rm32/ebp . . . 4/r32/esp . . # copy esp to ebp
# var heap/ecx: allocation-descriptor
68/push 0/imm32/limit
68/push 0/imm32/curr
89/copy 3/mod/direct 1/rm32/ecx . . . 4/r32/esp . . # copy esp to ecx
# heap = new-segment(512)
# . . push args
51/push-ecx
68/push 0x200/imm32
# . . call
e8/call new-segment/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 8/imm32 # add to esp
# var start/edx = ad->curr
8b/copy 0/mod/indirect 1/rm32/ecx . . . 2/r32/edx . . # copy *ecx to edx
# var h/ebx: (handle stream byte)
68/push 0/imm32
68/push 0/imm32
89/copy 3/mod/direct 3/rm32/ebx . . . 4/r32/esp . . # copy esp to ebx
# new-stream(heap, 3, 2, h)
# . . push args
53/push-ebx
68/push 2/imm32
68/push 3/imm32
51/push-ecx
# . . call
e8/call new-stream/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0x10/imm32 # add to esp
# eax = out->payload
8b/copy 1/mod/*+disp8 3/rm32/ebx . . . 0/r32/eax 4/disp8 . # copy *(ebx+4) to eax
# check-ints-equal(eax, edx, msg)
# . . push args
68/push "F - test-new-stream: returns current pointer of allocation descriptor"/imm32
52/push-edx
50/push-eax
# . . call
e8/call check-ints-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# skip payload->allocid
05/add-to-eax 4/imm32
# check-ints-equal(eax->size, 6, msg)
# . . push args
68/push "F - test-new-stream: sets size correctly"/imm32
68/push 6/imm32
ff 6/subop/push 1/mod/*+disp8 0/rm32/eax . . . . . 8/disp8 # push *(eax+8)
# . . call
e8/call check-ints-equal/disp32
# . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# the rest is delegated to clear-stream() so we won't bother checking it
# . reclaim locals
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0x10/imm32 # add to esp
# . epilogue
89/copy 3/mod/direct 4/rm32/esp . . . 5/r32/ebp . . # copy ebp to esp
5d/pop-to-ebp
c3/return
# . . vim:nowrap:textwidth=0
|