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187 lines
7.2 KiB
HTML
187 lines
7.2 KiB
HTML
<!DOCTYPE html>
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<html lang="en">
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<head>
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<!-- START: /incl-head.html -->
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<!-- common head elements -->
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<meta charset="utf-8"/>
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<meta name="viewport" content="width=device-width, initial-scale=1"/>
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<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.6.0/jquery.min.js"
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integrity="sha384-vtXRMe3mGCbOeY7l30aIg8H9p3GdeSe4IFlP6G8JMa7o7lXvnz3GFKzPxzJdPfGK" crossorigin="anonymous"></script>
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<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css"/>
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<link rel="stylesheet" href="../main.css"/>
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<!-- END: /incl-head.html -->
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<title>Inline Data - SourceGen Tutorial</title>
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</head>
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<body>
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<!-- START: /incl-masthead.html -->
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<div id="masthead">
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<!--<div class="masthead-title" style="background-image: url('images/screenshot-mainwin.png');">-->
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<div class="masthead-title">
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6502bench
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</div>
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</div>
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<!-- END: /incl-masthead.html -->
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<!-- START: /incl-topnav.html active:#topnav-sgtutorial -->
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<div id="topnav">
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<!-- top navigation bar contents -->
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<nav>
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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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<a id="topnav-menuicon" href="javascript:void(0);" class="icon" onclick="toggleSidenav()">
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<i class="fa fa-bars"></i>
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</a>
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</nav>
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<script>
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// Sidenav toggle function.
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//
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// Use a jQuery function to toggle the sidenav bar. The initial state
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// is undefined / inherited, so it will pop in and out as the screen
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// resizes around the "large" breakpoint.
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function toggleSidenav() {
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$("#sidenav").toggle("fast");
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}
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</script>
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</div>
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<!-- END: /incl-topnav.html -->
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<!-- START: incl-sidenav.html active:#sidenav-inline-data -->
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<div id="sidenav">
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<!-- side navigation bar contents -->
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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-simple-edits"><a href="simple-edits.html">Simple 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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<ul>
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<li id="sidenav-string-formatting"><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" class="active"><a href="inline-data.html">Inline Data</a></li>
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<li id="sidenav-odds-ends"><a href="odds-ends.html">Odds & Ends</a></li>
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</ul></li>
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<li id="sidenav-advanced-topics"><a href="advanced-topics.html">Advanced Topics</a>
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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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</ul></li>
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<li id="sidenav-suggestions"><a href="suggestions.html">Suggestions</a></li>
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</ul>
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</div>
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<!-- END: incl-sidenav.html -->
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<div id="main">
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<h2>Inline Data</h2>
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<div class="grid-container">
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<div class="grid-item-image">
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<img src="images/t2-206b.png" alt="t2-206b"/>
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</div>
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<div class="grid-item-text">
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<p>Consider the code at address $206B. It's a <code>JSR</code> followed by some
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ASCII text, then a $00 byte, and then what might be code.</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/t2-20ab-1.png" alt="t2-20ab-1"/>
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<br/>
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...
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<br/>
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<img src="images/t2-20ab-2.png" alt="t2-20ab-2"/>
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</div>
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<div class="grid-item-text">
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<p>Double-click on the <code>JSR</code> opcode
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to jump to $20AB to see the function. It pulls the
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call address off the stack, and uses it as a pointer. When it encounters
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a zero byte, it breaks out of the loop, pushes the adjusted pointer
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value back onto the stack, and returns.</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-text">
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<p>This is an example of "inline data", where a function uses the return
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address to get a pointer to data. The return address is adjusted to
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point past the inline data before returning (technically, it points at
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the very last byte of the inline data, because
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<code>RTS</code> jumps to address + 1).</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-inline-tag.png" alt="t2-inline-tag"/>
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</div>
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<div class="grid-item-text">
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<p>To format the data, we first need to tell SourceGen that there's data
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in line with the code. Select the line at address $206E, then
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shift-click the line at address $2077. Use
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<samp>Actions > Tag Bytes As Inline Data</samp>
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(<kbd class="key">Ctrl+H</kbd><kbd class="key">Ctrl+I</kbd>).</p>
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<p>Unlike code start and end tags, where you only tag the byte
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where the code starts or stops, for inline data you need to tag
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every byte.</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-inline-after.png" alt="t2-inline-after"/>
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</div>
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<div class="grid-item-text">
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<p>The data turns to single-byte values, and we now see the code
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continuing at address $2078. We can format the data as a string by
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using <samp>Actions > Edit Operand</samp>,
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setting the Character Encoding to <samp>Low or High ASCII</samp>,
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and selecting <samp>null-terminated strings</samp>.</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-text">
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<p>That's pretty straightforward, but this could quickly become tedious if
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there were a lot of these. SourceGen allows you to define scripts to
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automate common formatting tasks. This is covered in the "Extension
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Scripts" tutorial.</p>
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</div>
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</div>
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</div> <!-- #main -->
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<div id="prevnext">
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</div>
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<div id="footer">
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<hr/>
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<p>Copyright 2021 faddenSoft</p>
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