From 71160c71166cd6415b4bb3cb5cb991a2e8565f08 Mon Sep 17 00:00:00 2001
From: Gwilym Kuiper <gw@ilym.me>
Date: Thu, 15 Apr 2021 23:34:12 +0100
Subject: [PATCH] Really simple beep

---
 examples/beep.rs | 18 ++++++++++++++++++
 src/lib.rs       |  3 +++
 src/sound/mod.rs | 40 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 61 insertions(+)
 create mode 100644 examples/beep.rs
 create mode 100644 src/sound/mod.rs

diff --git a/examples/beep.rs b/examples/beep.rs
new file mode 100644
index 00000000..da35dfcc
--- /dev/null
+++ b/examples/beep.rs
@@ -0,0 +1,18 @@
+#![no_std]
+#![feature(start)]
+
+extern crate gba;
+
+use gba::display;
+
+#[start]
+fn main(_argc: isize, _argv: *const *const u8) -> isize {
+    let mut gba = gba::Gba::new();
+    let mut bitmap = gba.display.video.bitmap3();
+    let vblank = gba.display.vblank.get();
+
+    gba.sound.enable();
+    gba.sound.channel1().play_sound();
+
+    loop {}
+}
diff --git a/src/lib.rs b/src/lib.rs
index 92e1934d..8a91ce5e 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -9,6 +9,7 @@
 
 pub mod display;
 pub mod input;
+pub mod sound;
 
 mod interrupt;
 mod memory_mapped;
@@ -37,6 +38,7 @@ static mut GBASINGLE: single::Singleton<Gba> = single::Singleton::new(unsafe { G
 
 pub struct Gba {
     pub display: display::Display,
+    pub sound: sound::Sound,
 }
 
 impl Gba {
@@ -47,6 +49,7 @@ impl Gba {
     const unsafe fn single_new() -> Self {
         Self {
             display: display::Display::new(),
+            sound: sound::Sound::new(),
         }
     }
 }
diff --git a/src/sound/mod.rs b/src/sound/mod.rs
new file mode 100644
index 00000000..9fd4bb66
--- /dev/null
+++ b/src/sound/mod.rs
@@ -0,0 +1,40 @@
+use crate::memory_mapped::MemoryMapped;
+
+const CHANNEL_1_SWEEP: MemoryMapped<u16> = unsafe { MemoryMapped::new(0x0400_0060) };
+const CHANNEL_1_LENGTH_DUTY_ENVELOPE: MemoryMapped<u16> = unsafe { MemoryMapped::new(0x0400_0062) };
+const CHANNEL_1_FREQUENCY_CONTROL: MemoryMapped<u16> = unsafe { MemoryMapped::new(0x0400_0064) };
+
+const MASTER_SOUND_VOLUME_ENABLE: MemoryMapped<u16> = unsafe { MemoryMapped::new(0x0400_0080) };
+const MASTER_SOUND_VOLUME_MIXING: MemoryMapped<u16> = unsafe { MemoryMapped::new(0x0400_0082) };
+const MASTER_SOUND_STATUS: MemoryMapped<u16> = unsafe { MemoryMapped::new(0x0400_0084) };
+
+#[non_exhaustive]
+pub struct Sound {}
+
+impl Sound {
+    pub(crate) const unsafe fn new() -> Self {
+        Sound {}
+    }
+
+    pub fn channel1(&self) -> Channel1 {
+        Channel1 {}
+    }
+
+    pub fn enable(&self) {
+        MASTER_SOUND_STATUS.set_bits(1, 1, 7);
+
+        MASTER_SOUND_VOLUME_ENABLE.set(0b1111_1111_0_111_0_111);
+        MASTER_SOUND_VOLUME_MIXING.set(0b10);
+    }
+}
+
+#[non_exhaustive]
+pub struct Channel1 {}
+
+impl Channel1 {
+    pub fn play_sound(&self) {
+        CHANNEL_1_SWEEP.set(0b00000000_111_0_010);
+        CHANNEL_1_LENGTH_DUTY_ENVELOPE.set(0b111_1_001_01_111111);
+        CHANNEL_1_FREQUENCY_CONTROL.set(0b1_0_000_01000000000);
+    }
+}