mirror of
https://github.com/italicsjenga/gba.git
synced 2024-12-25 19:51:30 +11:00
302 lines
14 KiB
HTML
302 lines
14 KiB
HTML
<!DOCTYPE HTML>
|
|
<html lang="en" class="sidebar-visible no-js">
|
|
<head>
|
|
<!-- Book generated using mdBook -->
|
|
<meta charset="UTF-8">
|
|
<title>hello2 - Rust GBA Tutorials</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" 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">
|
|
<ol class="chapter"><li><a href="../introduction.html"><strong aria-hidden="true">1.</strong> Introduction</a></li><li><a href="../ch0/index.html"><strong aria-hidden="true">2.</strong> Ch 0: Development Setup</a></li><li><a href="../ch1/index.html"><strong aria-hidden="true">3.</strong> Ch 1: Hello GBA</a></li><li><ol class="section"><li><a href="../ch1/hello1.html"><strong aria-hidden="true">3.1.</strong> hello1</a></li><li><a href="../ch1/io_registers.html"><strong aria-hidden="true">3.2.</strong> IO Registers</a></li><li><a href="../ch1/the_display_control_register.html"><strong aria-hidden="true">3.3.</strong> The Display Control Register</a></li><li><a href="../ch1/video_memory_intro.html"><strong aria-hidden="true">3.4.</strong> Video Memory Intro</a></li><li><a href="../ch1/hello2.html" class="active"><strong aria-hidden="true">3.5.</strong> hello2</a></li></ol></li><li><a href="../ch2/index.html"><strong aria-hidden="true">4.</strong> Ch 2: User Input</a></li><li><ol class="section"><li><a href="../ch2/the_key_input_register.html"><strong aria-hidden="true">4.1.</strong> The Key Input Register</a></li><li><a href="../ch2/the_vcount_register.html"><strong aria-hidden="true">4.2.</strong> The VCount Register</a></li><li><a href="../ch2/gba_snake.html"><strong aria-hidden="true">4.3.</strong> gba_snake</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" 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>
|
|
|
|
<h1 class="menu-title">Rust GBA Tutorials</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="#hello2" id="hello2"><h1>hello2</h1></a>
|
|
<p>Okay so let's have a look again:</p>
|
|
<p><code>hello1</code></p>
|
|
<pre><pre class="playpen"><code class="language-rust">#![feature(start)]
|
|
#![no_std]
|
|
|
|
#[cfg(not(test))]
|
|
#[panic_handler]
|
|
fn panic(_info: &core::panic::PanicInfo) -> ! {
|
|
loop {}
|
|
}
|
|
|
|
#[start]
|
|
fn main(_argc: isize, _argv: *const *const u8) -> isize {
|
|
unsafe {
|
|
(0x04000000 as *mut u16).write_volatile(0x0403);
|
|
(0x06000000 as *mut u16).offset(120 + 80 * 240).write_volatile(0x001F);
|
|
(0x06000000 as *mut u16).offset(136 + 80 * 240).write_volatile(0x03E0);
|
|
(0x06000000 as *mut u16).offset(120 + 96 * 240).write_volatile(0x7C00);
|
|
loop {}
|
|
}
|
|
}
|
|
</code></pre></pre>
|
|
<p>Now let's clean this up so that it's clearer what's going on.</p>
|
|
<p>First we'll label that display control stuff:</p>
|
|
<pre><pre class="playpen"><code class="language-rust">
|
|
# #![allow(unused_variables)]
|
|
#fn main() {
|
|
pub const DISPCNT: *mut u16 = 0x04000000 as *mut u16;
|
|
pub const MODE3: u16 = 3;
|
|
pub const BG2: u16 = 0b100_0000_0000;
|
|
#}</code></pre></pre>
|
|
<p>Next we make some const values for the actual pixel drawing</p>
|
|
<pre><pre class="playpen"><code class="language-rust">
|
|
# #![allow(unused_variables)]
|
|
#fn main() {
|
|
pub const VRAM: usize = 0x06000000;
|
|
pub const SCREEN_WIDTH: isize = 240;
|
|
#}</code></pre></pre>
|
|
<p>And then we want a small helper function for putting together a color value.</p>
|
|
<p>Happily, this one can even be declared as a const function. At the time of
|
|
writing, we've got the "minimal const fn" support in nightly. It really is quite
|
|
limited, but I'm happy to let rustc and LLVM pre-compute as much as they can
|
|
when it comes to the GBA's tiny CPU.</p>
|
|
<pre><pre class="playpen"><code class="language-rust">
|
|
# #![allow(unused_variables)]
|
|
#fn main() {
|
|
pub const fn rgb16(red: u16, green: u16, blue: u16) -> u16 {
|
|
blue << 10 | green << 5 | red
|
|
}
|
|
#}</code></pre></pre>
|
|
<p>Finally, we'll make a function for drawing a pixel in Mode 3. Even though it's
|
|
just a one-liner, having the "important parts" be labeled as function arguments
|
|
usually helps you think about it a lot better.</p>
|
|
<pre><pre class="playpen"><code class="language-rust">
|
|
# #![allow(unused_variables)]
|
|
#fn main() {
|
|
pub unsafe fn mode3_pixel(col: isize, row: isize, color: u16) {
|
|
(VRAM as *mut u16).offset(col + row * SCREEN_WIDTH).write_volatile(color);
|
|
}
|
|
#}</code></pre></pre>
|
|
<p>So now we've got this:</p>
|
|
<p><code>hello2</code></p>
|
|
<pre><pre class="playpen"><code class="language-rust">#![feature(start)]
|
|
#![no_std]
|
|
|
|
#[cfg(not(test))]
|
|
#[panic_handler]
|
|
fn panic(_info: &core::panic::PanicInfo) -> ! {
|
|
loop {}
|
|
}
|
|
|
|
#[start]
|
|
fn main(_argc: isize, _argv: *const *const u8) -> isize {
|
|
unsafe {
|
|
DISPCNT.write_volatile(MODE3 | BG2);
|
|
mode3_pixel(120, 80, rgb16(31, 0, 0));
|
|
mode3_pixel(136, 80, rgb16(0, 31, 0));
|
|
mode3_pixel(120, 96, rgb16(0, 0, 31));
|
|
loop {}
|
|
}
|
|
}
|
|
|
|
pub const DISPCNT: *mut u16 = 0x04000000 as *mut u16;
|
|
pub const MODE3: u16 = 3;
|
|
pub const BG2: u16 = 0b100_0000_0000;
|
|
|
|
pub const VRAM: usize = 0x06000000;
|
|
pub const SCREEN_WIDTH: isize = 240;
|
|
|
|
pub const fn rgb16(red: u16, green: u16, blue: u16) -> u16 {
|
|
blue << 10 | green << 5 | red
|
|
}
|
|
|
|
pub unsafe fn mode3_pixel(col: isize, row: isize, color: u16) {
|
|
(VRAM as *mut u16).offset(col + row * SCREEN_WIDTH).write_volatile(color);
|
|
}
|
|
</code></pre></pre>
|
|
<p>Exact same program that we started with, but much easier to read.</p>
|
|
<p>Of course, in the full <code>gba</code> crate that this book is a part of we have these and
|
|
other elements all labeled and sorted out for you. Still, for educational
|
|
purposes it's often best to do it yourself at least once.</p>
|
|
|
|
</main>
|
|
|
|
<nav class="nav-wrapper" aria-label="Page navigation">
|
|
<!-- Mobile navigation buttons -->
|
|
|
|
<a rel="prev" href="../ch1/video_memory_intro.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="../ch2/index.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="../ch1/video_memory_intro.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="../ch2/index.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>
|