Untangle eggAudio a bit (#61)

* Untangle eggAudio a bit

* eggAudioRmtSpeakerMgr with a regswap

* Fix eggAudioRmtSpeakerMgr (thanks Cuyler!)

* eggAudioUtility with two regswaps

src/egg/audio/eggAudioSystem.cpp

@@ -1,3 +1,53 @@
 #include <egg/audio/eggAudioSystem.h>
+#include <nw4r/snd/snd_SoundSystem.h>
 
-namespace EGG {} // namespace EGG
+namespace EGG {
+
+AudioSystem *AudioSystem::sInstanse;
+
+AudioSystem::AudioSystem() {
+    field_0x00 = 1.0f;
+    field_0x08 = 0;
+    field_0x04 = 0;
+    sInstanse = this;
+}
+
+AudioSystem::~AudioSystem() {}
+
+void AudioSystem::fn_804B7270(s32 frame) {
+    if (field_0x08 == 0 && field_0x04 == 0) {
+        field_0x00 = nw4r::snd::SoundSystem::GetMasterVolume();
+        nw4r::snd::SoundSystem::SetMasterVolume(0.0f, frame * 16.666667f);
+        field_0x04 = 1;
+    }
+}
+
+void AudioSystem::fn_804B7370() {
+    if (field_0x08 == 0) {
+        nw4r::snd::SoundSystem::SetMasterVolume(field_0x00, 0);
+        field_0x04 = 0;
+    }
+}
+
+void AudioSystem::fn_804B73D0(s32 frame) {
+    if (field_0x08 == 0) {
+        field_0x08 = 1;
+        nw4r::snd::SoundSystem::SetMasterVolume(0.0f, frame * 16.666667f);
+    }
+}
+
+void AudioSystem::calc() {
+    f32 masterVolume = nw4r::snd::SoundSystem::GetMasterVolume();
+
+    if (field_0x08 == 1 && masterVolume == 0.0f) {
+        nw4r::snd::SoundSystem::PrepareReset();
+        nw4r::snd::SoundSystem::WaitForResetReady();
+        field_0x08 = 2;
+    }
+
+    if (field_0x08 != 2 && field_0x04 == 1 && masterVolume == 0.0f) {
+        field_0x04 = 2;
+    }
+}
+
+} // namespace EGG