<!DOCTYPE HTML> <html lang="en" class="sidebar-visible no-js"> <head> <!-- Book generated using mdBook --> <meta charset="UTF-8"> <title>Hello, Magic - Rust GBA Guide</title> <meta content="text/html; charset=utf-8" http-equiv="Content-Type"> <meta name="description" content=""> <meta name="viewport" content="width=device-width, initial-scale=1"> <meta name="theme-color" content="#ffffff" /> <link rel="shortcut icon" href="../favicon.png"> <link rel="stylesheet" href="../css/variables.css"> <link rel="stylesheet" href="../css/general.css"> <link rel="stylesheet" href="../css/chrome.css"> <link rel="stylesheet" href="../css/print.css" media="print"> <!-- Fonts --> <link rel="stylesheet" href="../FontAwesome/css/font-awesome.css"> <link href="https://fonts.googleapis.com/css?family=Open+Sans:300italic,400italic,600italic,700italic,800italic,400,300,600,700,800" rel="stylesheet" type="text/css"> <link href="https://fonts.googleapis.com/css?family=Source+Code+Pro:500" rel="stylesheet" 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href="../00-introduction/02-goals_and_style.html"><strong aria-hidden="true">1.2.</strong> Book Goals and Style</a></li><li><a href="../00-introduction/03-development-setup.html"><strong aria-hidden="true">1.3.</strong> Development Setup</a></li><li><a href="../00-introduction/04-hello-magic.html" class="active"><strong aria-hidden="true">1.4.</strong> Hello, Magic</a></li><li><a href="../00-introduction/05-newtype.html"><strong aria-hidden="true">1.5.</strong> Newtype</a></li><li><a href="../00-introduction/06-help_and_resources.html"><strong aria-hidden="true">1.6.</strong> Help and Resources</a></li></ol></li><li><a href="../01-limitations/00-index.html"><strong aria-hidden="true">2.</strong> Limitations</a></li><li><ol class="section"><li><a href="../01-limitations/01-no_floats.html"><strong aria-hidden="true">2.1.</strong> No Floats</a></li><li><a href="../01-limitations/02-core_only.html"><strong aria-hidden="true">2.2.</strong> Core Only</a></li><li><a href="../01-limitations/03-volatile_destination.html"><strong aria-hidden="true">2.3.</strong> Volatile Destination</a></li></ol></li><li><a href="../02-concepts/00-index.html"><strong aria-hidden="true">3.</strong> Concepts</a></li><li><ol class="section"><li><a href="../02-concepts/01-cpu.html"><strong aria-hidden="true">3.1.</strong> CPU</a></li><li><a href="../02-concepts/02-bios.html"><strong aria-hidden="true">3.2.</strong> BIOS</a></li><li><a href="../02-concepts/03-wram.html"><strong aria-hidden="true">3.3.</strong> Work RAM</a></li><li><a href="../02-concepts/04-io-registers.html"><strong aria-hidden="true">3.4.</strong> IO Registers</a></li><li><a href="../02-concepts/05-palram.html"><strong aria-hidden="true">3.5.</strong> Palette RAM</a></li><li><a href="../02-concepts/06-vram.html"><strong aria-hidden="true">3.6.</strong> Video RAM</a></li><li><a href="../02-concepts/07-oam.html"><strong aria-hidden="true">3.7.</strong> Object Attribute Memory</a></li><li><a href="../02-concepts/08-rom.html"><strong aria-hidden="true">3.8.</strong> Game Pak ROM / Flash ROM</a></li><li><a href="../02-concepts/09-sram.html"><strong aria-hidden="true">3.9.</strong> Save RAM</a></li></ol></li><li><a href="../03-video/00-index.html"><strong aria-hidden="true">4.</strong> Video</a></li><li><ol class="section"><li><a href="../03-video/01-rgb15.html"><strong aria-hidden="true">4.1.</strong> RBG15 Color</a></li><li><a href="../03-video/TODO.html"><strong aria-hidden="true">4.2.</strong> TODO</a></li></ol></li><li><a href="../04-non-video/00-index.html"><strong aria-hidden="true">5.</strong> Non-Video</a></li><li><ol class="section"><li><a href="../04-non-video/01-buttons.html"><strong aria-hidden="true">5.1.</strong> Buttons</a></li><li><a href="../04-non-video/02-timers.html"><strong aria-hidden="true">5.2.</strong> Timers</a></li><li><a href="../04-non-video/03-dma.html"><strong aria-hidden="true">5.3.</strong> Direct Memory Access</a></li><li><a href="../04-non-video/04-sound.html"><strong aria-hidden="true">5.4.</strong> Sound</a></li><li><a href="../04-non-video/05-interrupts.html"><strong aria-hidden="true">5.5.</strong> Interrupts</a></li><li><a href="../04-non-video/06-network.html"><strong aria-hidden="true">5.6.</strong> Network</a></li><li><a href="../04-non-video/07-game_pak.html"><strong aria-hidden="true">5.7.</strong> Game Pak</a></li></ol></li><li><a href="../05-examples/00-index.html"><strong aria-hidden="true">6.</strong> Examples</a></li><li><ol class="section"><li><a href="../05-examples/01-hello_magic.html"><strong aria-hidden="true">6.1.</strong> hello_magic</a></li><li><a href="../05-examples/02-hello_world.html"><strong aria-hidden="true">6.2.</strong> hello_world</a></li><li><a href="../05-examples/03-light_cycle.html"><strong aria-hidden="true">6.3.</strong> light_cycle</a></li><li><a href="../05-examples/04-bg_demo.html"><strong aria-hidden="true">6.4.</strong> bg_demo</a></li></ol></li></ol> </nav> <div id="page-wrapper" class="page-wrapper"> <div class="page"> <div id="menu-bar" class="menu-bar"> <div id="menu-bar-sticky-container"> <div class="left-buttons"> <button id="sidebar-toggle" class="icon-button" type="button" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar"> <i class="fa fa-bars"></i> </button> <button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list"> <i class="fa fa-paint-brush"></i> </button> <ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu"> <li role="none"><button role="menuitem" class="theme" id="light">Light <span class="default">(default)</span></button></li> <li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li> <li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li> <li role="none"><button role="menuitem" class="theme" 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(Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar"> <i class="fa fa-search"></i> </button> </div> <h1 class="menu-title">Rust GBA Guide</h1> <div class="right-buttons"> <a href="../print.html" title="Print this book" aria-label="Print this book"> <i id="print-button" class="fa fa-print"></i> </a> </div> </div> </div> <div id="search-wrapper" class="hidden"> <form id="searchbar-outer" class="searchbar-outer"> <input type="search" name="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header"> </form> <div id="searchresults-outer" class="searchresults-outer hidden"> <div id="searchresults-header" class="searchresults-header"></div> <ul id="searchresults"> </ul> </div> </div> <!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM --> <script type="text/javascript"> document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible'); document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible'); Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) { link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1); }); </script> <div id="content" class="content"> <main> <a class="header" href="#hello-magic" id="hello-magic"><h1>Hello, Magic</h1></a> <p>So we know all the steps to build our source, we just need some source.</p> <p>We're beginners, so we'll start small. With normal programming there's usually a console available, so the minimal program prints "Hello, world" to the terminal. On a GBA we don't have a terminal and standard out and all that, so the minimal program draws a red, blue, and green dot to the screen.</p> <p>At the lowest level of device programming, it's all <a href="https://en.wikipedia.org/wiki/Magic_number_(programming)">Magic Numbers</a>. You write special values to special places and then the hardware does something. A clear API makes every magic number and magic location easy to understand. A clear <em>and good</em> API also prevents you from using the wrong magic number in the wrong place and causing problems for yourself.</p> <p>This is the minimal example to just test that our build system is all set, so just this once we'll go <em>full</em> magic number crazy town, for fun. Ready? Here goes:</p> <p><code>hello_magic.rs</code>:</p> <pre><pre class="playpen"><code class="language-rust">#![feature(start)] #![no_std] #[panic_handler] fn panic(_info: &core::panic::PanicInfo) -> ! { loop {} } #[start] fn main(_argc: isize, _argv: *const *const u8) -> isize { unsafe { (0x400_0000 as *mut u16).write_volatile(0x0403); (0x600_0000 as *mut u16).offset(120 + 80 * 240).write_volatile(0x001F); (0x600_0000 as *mut u16).offset(136 + 80 * 240).write_volatile(0x03E0); (0x600_0000 as *mut u16).offset(120 + 96 * 240).write_volatile(0x7C00); loop {} } } </code></pre></pre> <p>Throw that into your project skeleton, build the program, and give it a run. You should see a red, green, and blue dot close-ish to the middle of the screen. If you don't, something <em>already</em> went wrong. Double check things, phone a friend, write your senators, try asking <code>Lokathor</code> or <code>Ketsuban</code> on the <a href="https://discordapp.com/invite/aVESxV8">Rust Community Discord</a>, until you're eventually able to get your three dots going.</p> <p>Of course, I'm sure you want to know why those numbers are the numbers to use. Well that's what the whole rest of the book is about!</p> </main> <nav class="nav-wrapper" aria-label="Page navigation"> <!-- Mobile navigation buttons --> <a rel="prev" href="../00-introduction/03-development-setup.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left"> <i class="fa fa-angle-left"></i> </a> <a rel="next" href="../00-introduction/05-newtype.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right"> <i class="fa fa-angle-right"></i> </a> <div style="clear: both"></div> </nav> </div> </div> <nav class="nav-wide-wrapper" aria-label="Page navigation"> <a href="../00-introduction/03-development-setup.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left"> <i class="fa fa-angle-left"></i> </a> <a href="../00-introduction/05-newtype.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right"> <i class="fa fa-angle-right"></i> </a> </nav> </div> <script src="../elasticlunr.min.js" type="text/javascript" charset="utf-8"></script> <script src="../mark.min.js" type="text/javascript" charset="utf-8"></script> <script src="../searcher.js" type="text/javascript" charset="utf-8"></script> <script src="../clipboard.min.js" type="text/javascript" charset="utf-8"></script> <script src="../highlight.js" type="text/javascript" charset="utf-8"></script> <script src="../book.js" type="text/javascript" charset="utf-8"></script> <!-- Custom JS scripts --> </body> </html>