2018-11-12 08:56:11 +11:00
<!DOCTYPE HTML>
< html lang = "en" class = "sidebar-visible no-js" >
< head >
<!-- Book generated using mdBook -->
< meta charset = "UTF-8" >
2018-11-18 11:14:42 +11:00
< title > Ch 2: User Input - Rust GBA Guide< / title >
2018-11-12 08:56:11 +11:00
< 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" type = "text/css" >
<!-- Highlight.js Stylesheets -->
< link rel = "stylesheet" href = "../highlight.css" >
< link rel = "stylesheet" href = "../tomorrow-night.css" >
< link rel = "stylesheet" href = "../ayu-highlight.css" >
<!-- Custom theme stylesheets -->
< / head >
< body class = "light" >
<!-- Provide site root to javascript -->
< script type = "text/javascript" > var path _to _root = "../" ; < / script >
<!-- Work around some values being stored in localStorage wrapped in quotes -->
< script type = "text/javascript" >
try {
var theme = localStorage.getItem('mdbook-theme');
var sidebar = localStorage.getItem('mdbook-sidebar');
if (theme.startsWith('"') & & theme.endsWith('"')) {
localStorage.setItem('mdbook-theme', theme.slice(1, theme.length - 1));
}
if (sidebar.startsWith('"') & & sidebar.endsWith('"')) {
localStorage.setItem('mdbook-sidebar', sidebar.slice(1, sidebar.length - 1));
}
} catch (e) { }
< / script >
<!-- Set the theme before any content is loaded, prevents flash -->
< script type = "text/javascript" >
var theme;
try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
if (theme === null || theme === undefined) { theme = 'light'; }
document.body.className = theme;
document.querySelector('html').className = theme + ' js';
< / script >
<!-- Hide / unhide sidebar before it is displayed -->
< script type = "text/javascript" >
var html = document.querySelector('html');
var sidebar = 'hidden';
if (document.body.clientWidth >= 1080) {
try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
sidebar = sidebar || 'visible';
}
html.classList.remove('sidebar-visible');
html.classList.add("sidebar-" + sidebar);
< / script >
< nav id = "sidebar" class = "sidebar" aria-label = "Table of contents" >
2018-11-20 20:57:43 +11:00
< ol class = "chapter" > < li > < a href = "../introduction.html" > < strong aria-hidden = "true" > 1.< / strong > Introduction< / a > < / li > < li > < a href = "../ch00/index.html" > < strong aria-hidden = "true" > 2.< / strong > Ch 0: Development Setup< / a > < / li > < li > < a href = "../ch01/index.html" > < strong aria-hidden = "true" > 3.< / strong > Ch 1: Hello GBA< / a > < / li > < li > < ol class = "section" > < li > < a href = "../ch01/hello1.html" > < strong aria-hidden = "true" > 3.1.< / strong > hello1< / a > < / li > < li > < a href = "../ch01/volatile.html" > < strong aria-hidden = "true" > 3.2.< / strong > Volatile< / a > < / li > < li > < a href = "../ch01/io_registers.html" > < strong aria-hidden = "true" > 3.3.< / strong > IO Registers< / a > < / li > < li > < a href = "../ch01/the_display_control_register.html" > < strong aria-hidden = "true" > 3.4.< / strong > The Display Control Register< / a > < / li > < li > < a href = "../ch01/video_memory_intro.html" > < strong aria-hidden = "true" > 3.5.< / strong > Video Memory Intro< / a > < / li > < li > < a href = "../ch01/hello2.html" > < strong aria-hidden = "true" > 3.6.< / strong > hello2< / a > < / li > < / ol > < / li > < li > < a href = "../ch02/index.html" class = "active" > < strong aria-hidden = "true" > 4.< / strong > Ch 2: User Input< / a > < / li > < li > < ol class = "section" > < li > < a href = "../ch02/the_key_input_register.html" > < strong aria-hidden = "true" > 4.1.< / strong > The Key Input Register< / a > < / li > < li > < a href = "../ch02/the_vcount_register.html" > < strong aria-hidden = "true" > 4.2.< / strong > The VCount Register< / a > < / li > < li > < a href = "../ch02/light_cycle.html" > < strong aria-hidden = "true" > 4.3.< / strong > light_cycle< / a > < / li > < / ol > < / li > < li > < a href = "../ch03/index.html" > < strong aria-hidden = "true" > 5.< / strong > Ch 3: Memory and Objects< / a > < / li > < li > < ol class = "section" > < li > < a href = "../ch03/gba_memory_mapping.html" > < strong aria-hidden = "true" > 5.1.< / strong > GBA Memory Mapping< / a > < / li > < li > < a href = "../ch03/tile_data.html" > < strong aria-hidden = "true" > 5.2.< / strong > Tile Data< / a > < / li > < li > < a href = "../ch03/regular_backgrounds.html" > < strong aria-hidden = "true" > 5.3.< / strong > Regular Backgrounds< / a > < / li > < li > < a href = "../ch03/object_basics.html" > < strong aria-hidden = "true" > 5.4.< / strong > Object Basics< / a > < / li > < li > < a href = "../ch03/gba_rng.html" > < strong aria-hidden = "true" > 5.5.< / strong > GBA RNG< / a > < / li > < li > < a href = "../ch03/memory_game.html" > < strong aria-hidden = "true" > 5.6.< / strong > memory_game< / a > < / li > < / ol > < / li > < / ol >
2018-11-12 08:56:11 +11:00
< / 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" id = "navy" > Navy< / button > < / li >
< li role = "none" > < button role = "menuitem" class = "theme" id = "ayu" > Ayu< / button > < / li >
< / ul >
< button id = "search-toggle" class = "icon-button" type = "button" title = "Search. (Shortkey: s)" aria-label = "Toggle Searchbar" aria-expanded = "false" aria-keyshortcuts = "S" aria-controls = "searchbar" >
< i class = "fa fa-search" > < / i >
< / button >
< / div >
2018-11-18 11:14:42 +11:00
< h1 class = "menu-title" > Rust GBA Guide< / h1 >
2018-11-12 08:56:11 +11:00
< 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 = "#ch-2-user-input" id = "ch-2-user-input" > < h1 > Ch 2: User Input< / h1 > < / a >
< p > It's all well and good to draw three pixels, but they don't do anything yet. We
2018-11-14 04:32:27 +11:00
want them to do something, and for that we need to get some input from the user.< / p >
2018-11-12 08:56:11 +11:00
< p > The GBA, as I'm sure you know, has an arrow pad, A and B, L and R, Start and
Select. That's a little more than the NES/GB/CGB had, and a little less than the
SNES had. As you can guess, we get key state info from an IO register.< / p >
< p > Also, we will need a way to keep the program from running " too fast" . On a
modern computer or console you do this with vsync info from the GPU and Monitor,
and on the GBA we'll be using vsync info from an IO register that tracks what
the display hardware is doing.< / p >
2018-11-14 04:32:27 +11:00
< p > As a way to apply our knowledge We'll make a simple " light cycle" game where
2018-11-13 10:29:17 +11:00
your dot leaves a trail behind them and you die if you go off the screen or if
you touch your own trail. We just make a copy of < code > hello2.rs< / code > named
< code > light_cycle.rs< / code > and then fill it in as we go through the chapter. Normally you
might not place the entire program into a single source file, particularly as it
grows over time, but since these are small examples it's much better to have
them be completely self contained than it is to have them be " properly
organized" for the long term.< / p >
2018-11-12 08:56:11 +11:00
< / main >
< nav class = "nav-wrapper" aria-label = "Page navigation" >
<!-- Mobile navigation buttons -->
2018-11-15 13:53:21 +11:00
< a rel = "prev" href = "../ch01/hello2.html" class = "mobile-nav-chapters previous" title = "Previous chapter" aria-label = "Previous chapter" aria-keyshortcuts = "Left" >
2018-11-12 08:56:11 +11:00
< i class = "fa fa-angle-left" > < / i >
< / a >
2018-11-15 13:53:21 +11:00
< a rel = "next" href = "../ch02/the_key_input_register.html" class = "mobile-nav-chapters next" title = "Next chapter" aria-label = "Next chapter" aria-keyshortcuts = "Right" >
2018-11-12 08:56:11 +11:00
< 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" >
2018-11-15 13:53:21 +11:00
< a href = "../ch01/hello2.html" class = "nav-chapters previous" title = "Previous chapter" aria-label = "Previous chapter" aria-keyshortcuts = "Left" >
2018-11-12 08:56:11 +11:00
< i class = "fa fa-angle-left" > < / i >
< / a >
2018-11-15 13:53:21 +11:00
< a href = "../ch02/the_key_input_register.html" class = "nav-chapters next" title = "Next chapter" aria-label = "Next chapter" aria-keyshortcuts = "Right" >
2018-11-12 08:56:11 +11:00
< 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 >
