Next tutorial target: key input

book/src/SUMMARY.md

@@ -9,3 +9,7 @@
   * [The Display Control Register](ch1/the_display_control_register.md)
   * [Video Memory Intro](ch1/video_memory_intro.md)
   * [hello2](ch1/hello2.md)
+* [Ch 2: User Input](ch2/index.md)
+  * [The Key Input Register](ch2/the_key_input_register.md)
+  * [The VCount Register](ch2/the_vcount_register.md)
+  * [gba_snake](ch2/gba_snake.md)

book/src/ch1/hello1.md

@@ -163,8 +163,9 @@ anyway. Sometimes that's right, but sometimes it's wrong.
 Marking a read or write as _volatile_ tells the compiler that it really must do
 that action, and in the exact order that we wrote it out. It says that there
 might even be special hardware side effects going on that the compiler isn't
-aware of. In this case, the Display Control write sets a video mode, and the
+aware of. In this case, the write to the display control register sets a video
-Video RAM writes set pixels that will show up on the screen.
+mode, and the writes to the Video RAM set pixels that will show up on the
+screen.
 
 Similar to "atomic" operations you might have heard about, all volatile
 operations are enforced to happen in the exact order that you specify them, but
@@ -176,15 +177,12 @@ a += b;
 d.volatile_write(7);
 ```
 
-might end up changing `a` either before or after the change to `c`, but the
+might end up changing `a` either before or after the change to `c` (since the
-write to `d` will _always_ happen after the write to `c`.
+value of `a` doesn't affect the write to `c`), but the write to `d` will
+_always_ happen after the write to `c` even though the compiler doesn't see any
+direct data dependency there.
 
 If you ever use volatile stuff on other platforms it's important to note that
 volatile doesn't make things thread-safe, you still need atomic for that.
 However, the GBA doesn't have threads, so we don't have to worry about thread
 safety concerns.
-
-Accordingly, our first bit of code for our library will be a _newtype_ over a
-normal `*mut T` so that it has volatile reads and writes as the default. We'll
-cover the details later on when we try writing a `hello2` program, once we know
-more of what's going on.

book/src/ch2/gba_snake.md

@@ -0,0 +1,3 @@
+# gba_snake
+
+TODO: make a "snake game" using arrow key input and vsync

book/src/ch2/index.md

@@ -0,0 +1,13 @@
+# Ch 2: User Input
+
+It's all well and good to draw three pixels, but they don't do anything yet. We
+want them to to something, and for that we need to get some input from the user.
+
+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.
+
+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.

book/src/ch2/the_key_input_register.md

@@ -0,0 +1,3 @@
+# The Key Input Register
+
+TODO: describe all the stuff about key input

book/src/ch2/the_vcount_register.md

@@ -0,0 +1,8 @@
+# The VCount Register
+
+TODO: describe all the stuff about vcount
+
+TODO: mention vblank and hblank
+
+TODO: mention that this just using this is a BAD way to vsync that will draw a
+ton of extra power

docs/ch0/index.html

@@ -72,7 +72,7 @@
         </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" class="active"><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"><strong aria-hidden="true">3.5.</strong> hello2</a></li></ol></li></ol>
+            <ol class="chapter"><li><a href="../introduction.html"><strong aria-hidden="true">1.</strong> Introduction</a></li><li><a href="../ch0/index.html" class="active"><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"><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>
 
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docs/ch1/hello1.html

@@ -72,7 +72,7 @@
         </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" class="active"><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"><strong aria-hidden="true">3.5.</strong> hello2</a></li></ol></li></ol>
+            <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" class="active"><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"><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">
@@ -280,8 +280,9 @@ anyway. Sometimes that's right, but sometimes it's wrong.</p>
 <p>Marking a read or write as <em>volatile</em> tells the compiler that it really must do
 that action, and in the exact order that we wrote it out. It says that there
 might even be special hardware side effects going on that the compiler isn't
-aware of. In this case, the Display Control write sets a video mode, and the
+aware of. In this case, the write to the display control register sets a video
-Video RAM writes set pixels that will show up on the screen.</p>
+mode, and the writes to the Video RAM set pixels that will show up on the
+screen.</p>
 <p>Similar to &quot;atomic&quot; operations you might have heard about, all volatile
 operations are enforced to happen in the exact order that you specify them, but
 only relative to other volatile operations. So something like</p>
@@ -292,16 +293,14 @@ c.volatile_write(5);
 a += b;
 d.volatile_write(7);
 #}</code></pre></pre>
-<p>might end up changing <code>a</code> either before or after the change to <code>c</code>, but the
+<p>might end up changing <code>a</code> either before or after the change to <code>c</code> (since the
-write to <code>d</code> will <em>always</em> happen after the write to <code>c</code>.</p>
+value of <code>a</code> doesn't affect the write to <code>c</code>), but the write to <code>d</code> will
+<em>always</em> happen after the write to <code>c</code> even though the compiler doesn't see any
+direct data dependency there.</p>
 <p>If you ever use volatile stuff on other platforms it's important to note that
 volatile doesn't make things thread-safe, you still need atomic for that.
 However, the GBA doesn't have threads, so we don't have to worry about thread
 safety concerns.</p>
-<p>Accordingly, our first bit of code for our library will be a <em>newtype</em> over a
-normal <code>*mut T</code> so that it has volatile reads and writes as the default. We'll
-cover the details later on when we try writing a <code>hello2</code> program, once we know
-more of what's going on.</p>
 
                     </main>
 

docs/ch1/hello2.html

@@ -72,7 +72,7 @@
         </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></ol>
+            <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>
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         <div id="page-wrapper" class="page-wrapper">
@@ -250,6 +250,10 @@ purposes it's often best to do it yourself at least once.</p>
                         
 
                         
+                            <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>
+                        
 
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@@ -264,6 +268,10 @@ purposes it's often best to do it yourself at least once.</p>
                 
 
                 
+                    <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>
+                
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docs/ch1/index.html

@@ -72,7 +72,7 @@
         </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" class="active"><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"><strong aria-hidden="true">3.5.</strong> hello2</a></li></ol></li></ol>
+            <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" class="active"><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"><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>
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docs/ch1/io_registers.html

@@ -72,7 +72,7 @@
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-            <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" class="active"><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"><strong aria-hidden="true">3.5.</strong> hello2</a></li></ol></li></ol>
+            <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" class="active"><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"><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>
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docs/ch1/the_display_control_register.html

@@ -72,7 +72,7 @@
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         <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" class="active"><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"><strong aria-hidden="true">3.5.</strong> hello2</a></li></ol></li></ol>
+            <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" class="active"><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"><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>
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@@ -72,7 +72,7 @@
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-            <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" class="active"><strong aria-hidden="true">3.4.</strong> Video Memory Intro</a></li><li><a href="../ch1/hello2.html"><strong aria-hidden="true">3.5.</strong> hello2</a></li></ol></li></ol>
+            <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" class="active"><strong aria-hidden="true">3.4.</strong> Video Memory Intro</a></li><li><a href="../ch1/hello2.html"><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>
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docs/ch2/gba_snake.html

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+<!DOCTYPE HTML>
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+                        <input type="search" name="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header">
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+                    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="#gba_snake" id="gba_snake"><h1>gba_snake</h1></a>
+<p>TODO: make a &quot;snake game&quot; using arrow key input and vsync</p>
+
+                    </main>
+
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+                        <!-- Mobile navigation buttons -->
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+<!DOCTYPE HTML>
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+        <!-- Book generated using mdBook -->
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+
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+        <script type="text/javascript">
+            var html = document.querySelector('html');
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+                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"><strong aria-hidden="true">3.5.</strong> hello2</a></li></ol></li><li><a href="../ch2/index.html" class="active"><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>
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+
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+                    </div>
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+                
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+                    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
+want them to to something, and for that we need to get some input from the user.</p>
+<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 &quot;too fast&quot;. 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>
+
+                    </main>
+
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+                        <!-- Mobile navigation buttons -->
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docs/ch2/the_key_input_register.html

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+<!DOCTYPE HTML>
+<html lang="en" class="sidebar-visible no-js">
+    <head>
+        <!-- Book generated using mdBook -->
+        <meta charset="UTF-8">
+        <title>The Key Input Register - Rust GBA Tutorials</title>
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+    <body class="light">
+        <!-- Provide site root to javascript -->
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+
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+
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+            var html = document.querySelector('html');
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+            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"><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" class="active"><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>
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+                    <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="#the-key-input-register" id="the-key-input-register"><h1>The Key Input Register</h1></a>
+<p>TODO: describe all the stuff about key input</p>
+
+                    </main>
+
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+                        <!-- Mobile navigation buttons -->
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@@ -0,0 +1,204 @@
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+            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"><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" class="active"><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>
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+                                <i id="print-button" class="fa fa-print"></i>
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+                    <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="#the-vcount-register" id="the-vcount-register"><h1>The VCount Register</h1></a>
+<p>TODO: describe all the stuff about vcount</p>
+<p>TODO: mention vblank and hblank</p>
+<p>TODO: mention that this just using this is a BAD way to vsync that will draw a
+ton of extra power</p>
+
+                    </main>
+
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+
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+
+    </body>
+</html>

docs/index.html

@@ -72,7 +72,7 @@
         </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"><strong aria-hidden="true">3.5.</strong> hello2</a></li></ol></li></ol>
+            <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"><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>
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docs/introduction.html

@@ -72,7 +72,7 @@
         </script>
 
         <nav id="sidebar" class="sidebar" aria-label="Table of contents">
-            <ol class="chapter"><li><a href="introduction.html" class="active"><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"><strong aria-hidden="true">3.5.</strong> hello2</a></li></ol></li></ol>
+            <ol class="chapter"><li><a href="introduction.html" class="active"><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"><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>
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@@ -72,7 +72,7 @@
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-            <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"><strong aria-hidden="true">3.5.</strong> hello2</a></li></ol></li></ol>
+            <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"><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>
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@@ -434,8 +434,9 @@ anyway. Sometimes that's right, but sometimes it's wrong.</p>
 <p>Marking a read or write as <em>volatile</em> tells the compiler that it really must do
 that action, and in the exact order that we wrote it out. It says that there
 might even be special hardware side effects going on that the compiler isn't
-aware of. In this case, the Display Control write sets a video mode, and the
+aware of. In this case, the write to the display control register sets a video
-Video RAM writes set pixels that will show up on the screen.</p>
+mode, and the writes to the Video RAM set pixels that will show up on the
+screen.</p>
 <p>Similar to &quot;atomic&quot; operations you might have heard about, all volatile
 operations are enforced to happen in the exact order that you specify them, but
 only relative to other volatile operations. So something like</p>
@@ -446,16 +447,14 @@ c.volatile_write(5);
 a += b;
 d.volatile_write(7);
 #}</code></pre></pre>
-<p>might end up changing <code>a</code> either before or after the change to <code>c</code>, but the
+<p>might end up changing <code>a</code> either before or after the change to <code>c</code> (since the
-write to <code>d</code> will <em>always</em> happen after the write to <code>c</code>.</p>
+value of <code>a</code> doesn't affect the write to <code>c</code>), but the write to <code>d</code> will
+<em>always</em> happen after the write to <code>c</code> even though the compiler doesn't see any
+direct data dependency there.</p>
 <p>If you ever use volatile stuff on other platforms it's important to note that
 volatile doesn't make things thread-safe, you still need atomic for that.
 However, the GBA doesn't have threads, so we don't have to worry about thread
 safety concerns.</p>
-<p>Accordingly, our first bit of code for our library will be a <em>newtype</em> over a
-normal <code>*mut T</code> so that it has volatile reads and writes as the default. We'll
-cover the details later on when we try writing a <code>hello2</code> program, once we know
-more of what's going on.</p>
 <a class="header" href="#io-registers" id="io-registers"><h1>IO Registers</h1></a>
 <p>The GBA has a large number of <strong>IO Registers</strong> (not to be confused with CPU
 registers). These are special memory locations from <code>0x04000000</code> to
@@ -776,6 +775,25 @@ pub unsafe fn mode3_pixel(col: isize, row: isize, color: u16) {
 <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>
+<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
+want them to to something, and for that we need to get some input from the user.</p>
+<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 &quot;too fast&quot;. 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>
+<a class="header" href="#the-key-input-register" id="the-key-input-register"><h1>The Key Input Register</h1></a>
+<p>TODO: describe all the stuff about key input</p>
+<a class="header" href="#the-vcount-register" id="the-vcount-register"><h1>The VCount Register</h1></a>
+<p>TODO: describe all the stuff about vcount</p>
+<p>TODO: mention vblank and hblank</p>
+<p>TODO: mention that this just using this is a BAD way to vsync that will draw a
+ton of extra power</p>
+<a class="header" href="#gba_snake" id="gba_snake"><h1>gba_snake</h1></a>
+<p>TODO: make a &quot;snake game&quot; using arrow key input and vsync</p>
 
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