You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
80 lines
2.3 KiB
80 lines
2.3 KiB
<div class="Box fold">
|
|
<h2>Alternate Character Sets</h2>
|
|
|
|
<div class="Row v">
|
|
<p>
|
|
ESPTerm implements Alternate Character Sets as a way to print box drawing characters
|
|
and special symbols. A character set can change what each received ASCII character
|
|
is printed as on the screen (eg. "{" is "π" in codepage `0`). The implementation is based
|
|
on the original VT devices.
|
|
</p>
|
|
|
|
<p>
|
|
Since ESPTerm also supports UTF-8, this feature is the most useful for applications
|
|
which can't print UTF-8 or already use alternate character sets for historical reasons.
|
|
</p>
|
|
|
|
<h3>Supported codepages</h3>
|
|
|
|
<ul>
|
|
<li>`B` - US ASCII (default)</li>
|
|
<li>`A` - UK ASCII: # replaced with £</li>
|
|
<li>`0` - Symbols and basic line drawing (standard DEC alternate character set)</li>
|
|
<li>`1` - Symbols and advanced line drawing (based on DOS codepage 437, ESPTerm specific)</li>
|
|
</ul>
|
|
|
|
<p>
|
|
All codepages use codes 32-127, 32 being space. A character with no entry in the active codepage
|
|
stays unchanged.
|
|
</p>
|
|
|
|
<?php
|
|
$codepages = load_esp_charsets();
|
|
foreach($codepages as $name => $cp) {
|
|
echo "<h4>Codepage `$name`</h4>\n";
|
|
echo '<div class="charset">';
|
|
foreach($cp as $point) {
|
|
$dis = $point[1]==$point[2]?' class="none"' : '';
|
|
echo "<div$dis><span>$point[0]</span><span>$point[1]</span><span>$point[2]</span></div>";
|
|
}
|
|
echo '</div>';
|
|
}
|
|
?>
|
|
|
|
<h3>Codepage switching commands</h3>
|
|
|
|
<p>
|
|
There are two character set slots, G0 and G1.
|
|
Those slots are selected as active using ASCII codes Shift In and Shift Out (those originally served for shifting
|
|
a red-black typewriter tape). Often only G0 is used for simplicity.
|
|
</p>
|
|
|
|
<p>
|
|
Each slot (G0 and G1) can have a different codepage assigned. G0 and G1 and the active slot number are
|
|
saved and restored with the cursor and cleared with a screen reset (<code>\ec</code>).
|
|
</p>
|
|
|
|
<p>The following commands are used:</p>
|
|
|
|
<table class="ansiref w100">
|
|
<thead><tr><th>Code</th><th>Meaning</th></tr></thead>
|
|
<tbody>
|
|
<tr>
|
|
<td>`\e(<i>x</i>`</td>
|
|
<td>Set G0 = codepage <i>x</i></td>
|
|
</tr>
|
|
<tr>
|
|
<td>`\e)<i>x</i>`</td>
|
|
<td>Set G1 = codepage <i>x</i></td>
|
|
</tr>
|
|
<tr>
|
|
<td>_SO_ (14)</td>
|
|
<td>Activate G0</td>
|
|
</tr>
|
|
<tr>
|
|
<td>_SI_ (15)</td>
|
|
<td>Activate G1</td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
</div>
|
|
|