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6502bench/docs/sgtutorial/string-formatting.html
Andy McFadden 909bdb1fa4 Tweak web page include structure
Renamed from "*-incl.html" to "incl-*.html" so they sort together.

Moved <div> for all but incl-head inside include file.

Overall this shouldn't do anything but move the magic comments around
inside the HTML files.
2021-07-10 18:48:42 -07:00

168 lines
6.9 KiB
HTML

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<title>String Formatting - SourceGen Tutorial</title>
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6502bench
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<a id="topnav-sgtutorial" class="active" href="../sgtutorial">SourceGen Tutorial</a>
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// Sidenav toggle function.
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// resizes around the "large" breakpoint.
function toggleSidenav() {
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<li id="sidenav-index"><a href="./">Introduction</a></li>
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<li id="sidenav-string-formatting" class="active"><a href="string-formatting.html">String Formatting</a></li>
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<div id="main">
<h2>String Formatting</h2>
<div class="grid-container">
<div class="grid-item-text">
<p>Programs can encode strings, such as human-readable text or
filenames, in a variety of ways. Assemblers generally support one
or more of these. SourceGen allows you to choose from a number of
different formats, and automatically generates appropriate assembler
directives.</p>
<p>The most popular formats are null-terminated (string data followed
by $00), length-delimited (first byte or two holds the string length),
and dextral character inverted (the high bit on the last byte is
flipped). Sometimes strings are stored in reverse, so the output
routine can decrement a register to zero.</p>
</div>
</div>
<div class="grid-container">
<div class="grid-item-image">
<img src="images/t2-str-null-term-start.png" alt="t2-str-null-term-start"/>
</div>
<div class="grid-item-text">
<p>Looking at the Tutorial2 code, there are four strings starting
at address $2004, each of which is followed by $00. These look like
null-terminated strings, so let's make it official.</p>
</div>
</div>
<div class="grid-container">
<div class="grid-item-image">
<img src="images/t2-str-null-term-bad.png" alt="t2-str-null-term-bad"/>
</div>
<div class="grid-item-text">
<p>First, let's do it wrong. Click on the line with
address $2004 to select it. Hold the shift key down, then double-click
on the operand field of the line with address $2031 (i.e. double-click on
the words "<samp>last string</samp>").</p>
<p>The Edit Data Operand dialog opens, but the null-terminated strings
option is not available. This is because we didn't include the null byte
on the last string. To be recognized as one of the "special" string types,
every selected string must match the expected pattern.</p>
</div>
</div>
<div class="grid-container">
<div class="grid-item-image">
<img src="images/t2-str-null-term-good.png" alt="t2-str-null-term-good"/>
</div>
<div class="grid-item-text">
<p>Cancel out of the dialog. Hold the shift key down, and double-click
on the operand on line $203C (<code>$00</code>).
With all 57 bytes selected,
you should now see "<samp>Null-terminated strings (4)</samp>" as an available
option (make sure the Character Encoding pop-up is set to
"<samp>Low or High ASCII</samp>"). Click on that, then click <samp>OK</samp>.
The strings are now shown as <samp>.ZSTR</samp> operands.</p>
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