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
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<title>Mu - subx/ex4.subx</title>
<meta name="Generator" content="Vim/7.4">
<meta name="plugin-version" content="vim7.4_v2">
<meta name="syntax" content="none">
<meta name="settings" content="number_lines,use_css,pre_wrap,no_foldcolumn,expand_tabs,line_ids,prevent_copy=">
<meta name="colorscheme" content="minimal">
<style type="text/css">
<!--
pre { white-space: pre-wrap; font-family: monospace; color: #aaaaaa; background-color: #080808; }
body { font-size: 12pt; font-family: monospace; color: #aaaaaa; background-color: #080808; }
a { color:#eeeeee; text-decoration: none; }
a:hover { text-decoration: underline; }
* { font-size: 12pt; font-size: 1em; }
.SalientComment { color: #00ffff; }
.LineNr { color: #444444; }
.Comment { color: #9090ff; }
.Comment a { color:#0000ee; text-decoration:underline; }
-->
</style>
<script type='text/javascript'>
<!--
/* function to open any folds containing a jumped-to line before jumping to it */
function JumpToLine()
{
var lineNum;
lineNum = window.location.hash;
lineNum = lineNum.substr(1); /* strip off '#' */
if (lineNum.indexOf('L') == -1) {
lineNum = 'L'+lineNum;
}
lineElem = document.getElementById(lineNum);
/* Always jump to new location even if the line was hidden inside a fold, or
* we corrected the raw number to a line ID.
*/
if (lineElem) {
lineElem.scrollIntoView(true);
}
return true;
}
if ('onhashchange' in window) {
window.onhashchange = JumpToLine;
}
-->
</script>
</head>
<body onload='JumpToLine();'>
<pre id='vimCodeElement'>
<span id="L1" class="LineNr"> 1 </span><span class="SalientComment">## read a character from stdin, save it to a global, write it to stdout</span>
<span id="L2" class="LineNr"> 2 </span><span class="Comment">#</span>
<span id="L3" class="LineNr"> 3 </span><span class="Comment"># To run:</span>
<span id="L4" class="LineNr"> 4 </span><span class="Comment"># $ subx translate ex4.subx ex4</span>
<span id="L5" class="LineNr"> 5 </span><span class="Comment"># $ subx run ex4</span>
<span id="L6" class="LineNr"> 6 </span>
<span id="L7" class="LineNr"> 7 </span>== 0x08048074 <span class="Comment"># code segment, after leaving room for ELF header and segment headers</span>
<span id="L8" class="LineNr"> 8 </span><span class="Comment"># instruction effective address operand displacement immediate</span>
<span id="L9" class="LineNr"> 9 </span><span class="Comment"># op subop mod rm32 base index scale r32</span>
<span id="L10" class="LineNr">10 </span><span class="Comment"># 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</span>
<span id="L11" class="LineNr">11 </span>
<span id="L12" class="LineNr">12 </span> <span class="SalientComment">## read(stdin, x, 1)</span>
<span id="L13" class="LineNr">13 </span> <span class="Comment"># fd = 0 (stdin)</span>
<span id="L14" class="LineNr">14 </span> bb/copy 0/imm32 <span class="Comment"># copy 0 to EBX</span>
<span id="L15" class="LineNr">15 </span> <span class="Comment"># initialize x (location to write result to)</span>
<span id="L16" class="LineNr">16 </span> b9/copy 0x080490a7/imm32 <span class="Comment"># copy to ECX</span>
<span id="L17" class="LineNr">17 </span> <span class="Comment"># size = 1 character</span>
<span id="L18" class="LineNr">18 </span> ba/copy 1/imm32 <span class="Comment"># copy 1 to EDX</span>
<span id="L19" class="LineNr">19 </span> <span class="Comment"># read(fd, x, size)</span>
<span id="L20" class="LineNr">20 </span> b8/copy 3/imm32 <span class="Comment"># copy 3 to EAX</span>
<span id="L21" class="LineNr">21 </span> cd/syscall 0x80/imm8 <span class="Comment"># int 80h</span>
<span id="L22" class="LineNr">22 </span>
<span id="L23" class="LineNr">23 </span> <span class="SalientComment">## write(stdout, x, 1)</span>
<span id="L24" class="LineNr">24 </span> <span class="Comment"># fd = 1 (stdout)</span>
<span id="L25" class="LineNr">25 </span> bb/copy 1/imm32 <span class="Comment"># copy 1 to EBX</span>
<span id="L26" class="LineNr">26 </span> <span class="Comment"># initialize x (location to read from)</span>
<span id="L27" class="LineNr">27 </span> b9/copy 0x080490a7/imm32 <span class="Comment"># copy to ECX</span>
<span id="L28" class="LineNr">28 </span> <span class="Comment"># size = 1 character</span>
<span id="L29" class="LineNr">29 </span> ba/copy 1/imm32 <span class="Comment"># copy 1 to EDX</span>
<span id="L30" class="LineNr">30 </span> <span class="Comment"># write(fd, x, size)</span>
<span id="L31" class="LineNr">31 </span> b8/copy 4/imm32 <span class="Comment"># copy 4 to EAX</span>
<span id="L32" class="LineNr">32 </span> cd/syscall 0x80/imm8 <span class="Comment"># int 80h</span>
<span id="L33" class="LineNr">33 </span>
<span id="L34" class="LineNr">34 </span> <span class="SalientComment">## exit(EBX)</span>
<span id="L35" class="LineNr">35 </span> b8/copy 1/imm32 <span class="Comment"># copy 1 to EAX</span>
<span id="L36" class="LineNr">36 </span> cd/syscall 0x80/imm8 <span class="Comment"># int 80h</span>
<span id="L37" class="LineNr">37 </span>
<span id="L38" class="LineNr">38 </span>== 0x080490a7
<span id="L39" class="LineNr">39 </span>00 00 00 00 <span class="Comment"># space for read() to write to</span>
<span id="L40" class="LineNr">40 </span>
<span id="L41" class="LineNr">41 </span><span class="Comment"># vim:ft=subx:nowrap</span>
</pre>
</body>
</html>
<!-- vim: set foldmethod=manual : -->
|