about summary refs log tree commit diff stats
path: root/html/102keyboard.subx.html
blob: 59581ccf61b41851390b31aa1cca3ff582f5e619 (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
<!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 - 102keyboard.subx</title>
<meta name="Generator" content="Vim/8.1">
<meta name="plugin-version" content="vim8.1_v1">
<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-light">
<style type="text/css">
<!--
pre { white-space: pre-wrap; font-family: monospace; color: #000000; background-color: #ffffd7; }
body { font-size:12pt; font-family: monospace; color: #000000; background-color: #ffffd7; }
a { color:inherit; }
* { font-size:12pt; font-size: 1em; }
.subxComment { color: #005faf; }
.LineNr { }
.SpecialChar { color: #d70000; }
.subxS1Comment { color: #0000af; }
.subxFunction { color: #af5f00; text-decoration: underline; }
.Constant { color: #008787; }
-->
</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;
  }
  var 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();'>
<a href='https://github.com/akkartik/mu/blob/main/102keyboard.subx'>https://github.com/akkartik/mu/blob/main/102keyboard.subx</a>
<pre id='vimCodeElement'>
<span id="L1" class="LineNr"> 1 </span><span class="subxComment"># check keyboard for a key</span>
<span id="L2" class="LineNr"> 2 </span><span class="subxComment"># return 0 on no keypress or unrecognized key</span>
<span id="L3" class="LineNr"> 3 </span><span class="subxComment">#</span>
<span id="L4" class="LineNr"> 4 </span><span class="subxComment"># We need to do this in machine code because Mu doesn't have global variables</span>
<span id="L5" class="LineNr"> 5 </span><span class="subxComment"># yet (for the keyboard buffer).</span>
<span id="L6" class="LineNr"> 6 </span>
<span id="L7" class="LineNr"> 7 </span>== code
<span id="L8" class="LineNr"> 8 </span>
<span id="L9" class="LineNr"> 9 </span><span class="subxComment"># Most keys correspond to their ASCII/Unicode values.</span>
<span id="L10" class="LineNr">10 </span><span class="subxComment"># TODO: Support for international keyboards and multi-byte Unicode.</span>
<span id="L11" class="LineNr">11 </span><span class="subxComment">#</span>
<span id="L12" class="LineNr">12 </span><span class="subxComment"># However there are some exceptions that have no assigned place in Unicode</span>
<span id="L13" class="LineNr">13 </span><span class="subxComment"># (and with good reason):</span>
<span id="L14" class="LineNr">14 </span><span class="subxComment">#   0x80 = left arrow ←</span>
<span id="L15" class="LineNr">15 </span><span class="subxComment">#   0x81 = down arrow ↓</span>
<span id="L16" class="LineNr">16 </span><span class="subxComment">#   0x82 = up arrow ↑</span>
<span id="L17" class="LineNr">17 </span><span class="subxComment">#   0x83 = right arrow →</span>
<span id="L18" class="LineNr">18 </span><span class="subxComment"># These code points are not used by Unicode and their semantics are agreed to</span>
<span id="L19" class="LineNr">19 </span><span class="subxComment"># be context-sensitive: <a href="https://en.wikipedia.org/wiki/C0_and_C1_control_codes#C1_controls.">https://en.wikipedia.org/wiki/C0_and_C1_control_codes#C1_controls.</a></span>
<span id="L20" class="LineNr">20 </span><span class="subxComment"># Mu cannibalizes them in yet another non-standard way.</span>
<span id="L21" class="LineNr">21 </span><span class="subxFunction">read-key</span>:  <span class="subxComment"># kbd: (addr keyboard) -&gt; result/eax: byte</span>
<span id="L22" class="LineNr">22 </span>    <span class="subxS1Comment"># . prologue</span>
<span id="L23" class="LineNr">23 </span>    55/push-ebp
<span id="L24" class="LineNr">24 </span>    89/&lt;- %ebp 4/r32/esp
<span id="L25" class="LineNr">25 </span>    <span class="subxS1Comment"># . save registers</span>
<span id="L26" class="LineNr">26 </span>    51/push-ecx
<span id="L27" class="LineNr">27 </span>    <span class="subxComment"># result = 0</span>
<span id="L28" class="LineNr">28 </span>    b8/copy-to-eax 0/imm32
<span id="L29" class="LineNr">29 </span>    <span class="subxComment"># ecx = keyboard</span>
<span id="L30" class="LineNr">30 </span>    8b/-&gt; *(ebp+8) 1/r32/ecx
<span id="L31" class="LineNr">31 </span>    81 7/subop/compare %ecx 0/imm32
<span id="L32" class="LineNr">32 </span>    {
<span id="L33" class="LineNr">33 </span>      75/jump-if-!= <span class="Constant">break</span>/disp8
<span id="L34" class="LineNr">34 </span>      <span class="subxComment"># var buffer-byte-addr/ecx: (addr byte)</span>
<span id="L35" class="LineNr">35 </span>      8b/-&gt; *<span class="SpecialChar">Keyboard-buffer</span>:read 1/r32/CL
<span id="L36" class="LineNr">36 </span>      81 0/subop/add %ecx <span class="SpecialChar">Keyboard-buffer</span>:data/imm32
<span id="L37" class="LineNr">37 </span>      <span class="subxComment"># var next-key/eax: byte = *buffer-byte-addr</span>
<span id="L38" class="LineNr">38 </span>      8a/byte-&gt; *ecx 0/r32/AL
<span id="L39" class="LineNr">39 </span>      <span class="subxComment"># if (next-key != 0) lock and remove from keyboard buffer</span>
<span id="L40" class="LineNr">40 </span>      3d/compare-eax-with 0/imm32
<span id="L41" class="LineNr">41 </span>      {
<span id="L42" class="LineNr">42 </span>        74/jump-if-= <span class="Constant">break</span>/disp8
<span id="L43" class="LineNr">43 </span>        fa/disable-interrupts
<span id="L44" class="LineNr">44 </span>        c6 0/subop/copy-byte *ecx 0/imm8
<span id="L45" class="LineNr">45 </span>        ff 0/subop/increment *<span class="SpecialChar">Keyboard-buffer</span>:read
<span id="L46" class="LineNr">46 </span>        81 4/subop/and *<span class="SpecialChar">Keyboard-buffer</span>:read 0x0f/imm32
<span id="L47" class="LineNr">47 </span>        fb/enable-interrupts
<span id="L48" class="LineNr">48 </span>      }
<span id="L49" class="LineNr">49 </span>      <span class="subxComment"># return</span>
<span id="L50" class="LineNr">50 </span>      eb $read-key:end/disp8
<span id="L51" class="LineNr">51 </span>    }
<span id="L52" class="LineNr">52 </span>    <span class="subxComment"># TODO: fake keyboard</span>
<span id="L53" class="LineNr">53 </span><span class="Constant">$read-key:end</span>:
<span id="L54" class="LineNr">54 </span>    <span class="subxS1Comment"># . restore registers</span>
<span id="L55" class="LineNr">55 </span>    59/pop-to-ecx
<span id="L56" class="LineNr">56 </span>    <span class="subxS1Comment"># . epilogue</span>
<span id="L57" class="LineNr">57 </span>    89/&lt;- %esp 5/r32/ebp
<span id="L58" class="LineNr">58 </span>    5d/pop-to-ebp
<span id="L59" class="LineNr">59 </span>    c3/return
</pre>
</body>
</html>
<!-- vim: set foldmethod=manual : -->