alex/gba
1
0
Fork 0
mirror of https://github.com/italicsjenga/gba.git synced 2024-12-25 03:31:36 +11:00
Code Issues Packages Projects Releases Wiki Activity
gba/docs/02-concepts/06-vram.html

223 lines
14 KiB
HTML
Raw Normal View History

prep for github pages
2018-11-08 15:20:40 +11:00
<!DOCTYPE HTML>
<html lang="en" class="sidebar-visible no-js">
<head>
<!-- Book generated using mdBook -->
<meta charset="UTF-8">
ch 00: rewrite done
2018-12-10 19:48:06 +11:00
<title>Video RAM - Rust GBA Guide</title>
prep for github pages
2018-11-08 15:20:40 +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" />
almost chapter 1
2018-11-10 20:03:37 +11:00
<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">
prep for github pages
2018-11-08 15:20:40 +11:00
<!-- Fonts -->
almost chapter 1
2018-11-10 20:03:37 +11:00
<link rel="stylesheet" href="../FontAwesome/css/font-awesome.css">
prep for github pages
2018-11-08 15:20:40 +11:00
<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 -->
almost chapter 1
2018-11-10 20:03:37 +11:00
<link rel="stylesheet" href="../highlight.css">
<link rel="stylesheet" href="../tomorrow-night.css">
<link rel="stylesheet" href="../ayu-highlight.css">
prep for github pages
2018-11-08 15:20:40 +11:00
<!-- Custom theme stylesheets -->
</head>
<body class="light">
<!-- Provide site root to javascript -->
almost chapter 1
2018-11-10 20:03:37 +11:00
<script type="text/javascript">var path_to_root = "../";</script>
prep for github pages
2018-11-08 15:20:40 +11:00
<!-- 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">
Deploy rust-console/gba to github.com/rust-console/gba.git:master
2018-12-25 07:24:29 +11:00
<ol class="chapter"><li><a href="../00-introduction/00-index.html"><strong aria-hidden="true">1.</strong> Introduction</a></li><li><ol class="section"><li><a href="../00-introduction/01-requirements.html"><strong aria-hidden="true">1.1.</strong> Reader Requirements</a></li><li><a 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"><strong aria-hidden="true">1.4.</strong> Hello, Magic</a></li><li><a href="../00-introduction/05-help_and_resources.html"><strong aria-hidden="true">1.5.</strong> Help and Resources</a></li></ol></li><li><a href="../01-quirks/00-index.html"><strong aria-hidden="true">2.</strong> Quirks</a></li><li><ol class="section"><li><a href="../01-quirks/01-no_std.html"><strong aria-hidden="true">2.1.</strong> No Std</a></li><li><a href="../01-quirks/02-fixed_only.html"><strong aria-hidden="true">2.2.</strong> Fixed Only</a></li><li><a href="../01-quirks/03-volatile_destination.html"><strong aria-hidden="true">2.3.</strong> Volatile Destination</a></li><li><a href="../01-quirks/04-newtype.html"><strong aria-hidden="true">2.4.</strong> Newtype</a></li><li><a href="../01-quirks/05-const_asserts.html"><strong aria-hidden="true">2.5.</strong> Const Asserts</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" class="active"><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-link_cable.html"><strong aria-hidden="true">5.6.</strong> Link Cable</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></ol>
prep for github pages
2018-11-08 15:20:40 +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>
edits, cleanups, and a goal for ch3
2018-11-18 11:14:42 +11:00
<h1 class="menu-title">Rust GBA Guide</h1>
prep for github pages
2018-11-08 15:20:40 +11:00
<div class="right-buttons">
almost chapter 1
2018-11-10 20:03:37 +11:00
<a href="../print.html" title="Print this book" aria-label="Print this book">
prep for github pages
2018-11-08 15:20:40 +11:00
<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>
Deploy rust-console/gba to github.com/rust-console/gba.git:master
2018-12-21 11:30:01 +11:00
<a class="header" href="#video-ram-vram" id="video-ram-vram"><h1>Video RAM (VRAM)</h1></a>
<ul>
<li><strong>Address Span:</strong> <code>0x600_0000</code> to <code>0x601_7FFF</code> (96k)</li>
</ul>
<p>We've used this before! VRAM has a 16-bit bus and no wait. However, the same as
with PALRAM, the &quot;you might have to wait if the display controller is looking at
it&quot; rule applies here.</p>
<p>Unfortunately there's not much more exact detail that can be given about VRAM.
The use of the memory depends on the video mode that you're using.</p>
<p>One general detail of note is that you can't write individual bytes to any part
of VRAM. Depending on mode and location, you'll either get your bytes doubled
into both the upper and lower parts of the 16-bit location targeted, or you
won't even affect the memory. This usually isn't a big deal, except in two
situations:</p>
<ul>
<li>In Mode 4, if you want to change just 1 pixel, you'll have to be very careful
to read the old <code>u16</code>, overwrite just the byte you wanted to change, and then
write that back.</li>
<li>In any display mode, avoid using <code>memcopy</code> to place things into VRAM.
It's written to be byte oriented, and only does 32-bit transfers under select
conditions. The rest of the time it'll copy one byte at a time and you'll get
either garbage or nothing at all.</li>
</ul>
prep for github pages
2018-11-08 15:20:40 +11:00
</main>
<nav class="nav-wrapper" aria-label="Page navigation">
<!-- Mobile navigation buttons -->
ch 00: rewrite done
2018-12-10 19:48:06 +11:00
<a rel="prev" href="../02-concepts/05-palram.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
almost chapter 1
2018-11-10 20:03:37 +11:00
<i class="fa fa-angle-left"></i>
</a>
prep for github pages
2018-11-08 15:20:40 +11:00
ch 00: rewrite done
2018-12-10 19:48:06 +11:00
<a rel="next" href="../02-concepts/07-oam.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
almost chapter 1
2018-11-10 20:03:37 +11:00
<i class="fa fa-angle-right"></i>
</a>
prep for github pages
2018-11-08 15:20:40 +11:00
<div style="clear: both"></div>
</nav>
</div>
</div>
<nav class="nav-wide-wrapper" aria-label="Page navigation">
ch 00: rewrite done
2018-12-10 19:48:06 +11:00
<a href="../02-concepts/05-palram.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
almost chapter 1
2018-11-10 20:03:37 +11:00
<i class="fa fa-angle-left"></i>
</a>
prep for github pages
2018-11-08 15:20:40 +11:00
ch 00: rewrite done
2018-12-10 19:48:06 +11:00
<a href="../02-concepts/07-oam.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
almost chapter 1
2018-11-10 20:03:37 +11:00
<i class="fa fa-angle-right"></i>
</a>
prep for github pages
2018-11-08 15:20:40 +11:00
</nav>
</div>
almost chapter 1
2018-11-10 20:03:37 +11:00
<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>
prep for github pages
2018-11-08 15:20:40 +11:00
almost chapter 1
2018-11-10 20:03:37 +11:00
<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>
prep for github pages
2018-11-08 15:20:40 +11:00
<!-- Custom JS scripts -->
</body>
</html>
Reference in a new issue Copy permalink