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4537f24958
Biggest changes were to the address region handling in Tutorial1 and the use of StdInline.cs for the inline strings in Tutorial4. Also, fixed the off-by-one error in Tutorial1.
169 lines
7.0 KiB
HTML
169 lines
7.0 KiB
HTML
<!DOCTYPE html>
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<html lang="en">
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<head>
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<title>String Formatting - SourceGen Tutorial</title>
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6502bench
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<a id="topnav-home" href=".././">HOME</a>
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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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<ul>
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<li id="sidenav-index"><a href="./">Introduction</a></li>
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<li id="sidenav-about-disasm"><a href="about-disasm.html">About Disassembly</a></li>
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<li id="sidenav-using-sourcegen"><a href="using-sourcegen.html">Using SourceGen</a>
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<ul>
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<li id="sidenav-moving-around"><a href="moving-around.html">Moving Around</a></li>
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<li id="sidenav-making-edits"><a href="making-edits.html">Making Edits</a></li>
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<li id="sidenav-labels-symbols"><a href="labels-symbols.html">Labels & Symbols</a></li>
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<li id="sidenav-editing-data"><a href="editing-data.html">Editing Data Operands</a></li>
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<li id="sidenav-generating-code"><a href="generating-code.html">Generating Code</a></li>
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</ul></li>
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<li id="sidenav-digging-deeper"><a href="digging-deeper.html">Digging Deeper</a>
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<li id="sidenav-string-formatting" class="active"><a href="string-formatting.html">String Formatting</a></li>
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<li id="sidenav-local-variables"><a href="local-variables.html">Local Variables</a></li>
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<li id="sidenav-inline-data"><a href="inline-data.html">Inline Data</a></li>
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<ul>
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<li id="sidenav-address-tables"><a href="address-tables.html">Address Tables</a></li>
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<li id="sidenav-extension-scripts"><a href="extension-scripts.html">Extension Scripts</a></li>
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<li id="sidenav-visualizations"><a href="visualizations.html">Visualizations</a></li>
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<div id="main">
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<h2>String Formatting</h2>
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<div class="grid-container">
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<div class="grid-item-text">
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<p>Programs can encode strings, such as human-readable text or
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filenames, in a variety of ways. Assemblers generally support one
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or more of these. SourceGen allows you to choose from a number of
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different formats, and automatically generates appropriate assembler
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directives.</p>
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<p>The most popular formats are null-terminated (string data followed
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by $00), length-delimited (first byte or two holds the string length),
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and dextral character inverted (the high bit on the last byte is
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flipped). Sometimes strings are stored in reverse, so the output
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routine can decrement a register to zero.</p>
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</div>
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</div>
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<div class="grid-container">
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<div class="grid-item-image">
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<img src="images/t2-str-null-term-start.png" alt="t2-str-null-term-start"/>
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</div>
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<div class="grid-item-text">
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<p>Looking at the Tutorial2 code, there are four strings starting
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at address $2004, each of which is followed by $00. These look like
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null-terminated strings, so let's make it official.</p>
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</div>
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</div>
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<div class="grid-container">
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<div class="grid-item-image">
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<img src="images/t2-str-null-term-bad.png" alt="t2-str-null-term-bad"/>
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</div>
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<div class="grid-item-text">
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<p>First, let's do it wrong. Click on the line with
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address $2004 to select it. Hold the shift key down, then double-click
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on the operand field of the line with address $2031 (i.e. double-click on
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the words "<samp>last string</samp>").</p>
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<p>The Edit Data Operand dialog opens, but the null-terminated strings
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option is not available. This is because we didn't include the null byte
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on the last string. To be recognized as one of the "special" string types,
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every selected string must match the expected pattern.</p>
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</div>
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</div>
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<div class="grid-container">
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<div class="grid-item-image">
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<img src="images/t2-str-null-term-good.png" alt="t2-str-null-term-good"/>
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</div>
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<div class="grid-item-text">
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<p>Cancel out of the dialog. Hold the shift key down, and double-click
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on the operand on line $203C (<code>$00</code>).
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With all 57 bytes selected,
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you should now see "<samp>Null-terminated strings (4)</samp>" as an available
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option (make sure the Character Encoding pop-up is set to
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"<samp>Low or High ASCII</samp>"). Click on that, then click <samp>OK</samp>.
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The strings are now shown as <samp>.ZSTR</samp> operands.</p>
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