From 20ded5f56c9ba6839b682e7b2783af6804a95331 Mon Sep 17 00:00:00 2001
From: Theron Spiegl <tspiegl@gmail.com>
Date: Mon, 16 Dec 2019 23:43:10 -0600
Subject: [PATCH] apu

---
 src/apu/mod.rs    |  4 +++-
 src/apu/square.rs | 29 ++++++++++++++++++++++++++++-
 2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/src/apu/mod.rs b/src/apu/mod.rs
index 9bfb431..1cd7e42 100644
--- a/src/apu/mod.rs
+++ b/src/apu/mod.rs
@@ -21,6 +21,8 @@ use dmc::DMC;
 // need all samples, it needs one from the stream 44100 time per second. So just an if statement, if time has passed grab a sample.
 // But then that won't be running during PPU 60Hz sleep... So run audio in its own thread... Except then it won't work on Windows because of SDL...
 // So just run the console in its own thread and video/audio in the main thread... But that's annoying.
+// No. Don't have to be concerned about the audio device, that's solved by the buffer, and the 44100 samples get fed in batches of 4096 from the large buffer,
+// when the device needs them, which is accomplished just by calling .resume() before the main loop starts. So a large buffer really should allow for the 60Hz sleep lock.
 
 pub struct Apu {
     square1:  Square,
@@ -84,6 +86,7 @@ impl Apu {
             0x4006 => self.square2.timer_low(value),
             0x4007 => self.square2.timer_high(value),
             0x4008 => self.triangle.counter(value),
+            0x4009 => (),
             0x400A => self.triangle.timer_low(value),
             0x400B => self.triangle.timer_high(value),
             0x400C => self.noise.envelope(value),
@@ -204,7 +207,6 @@ impl Apu {
         if self.dmc.interrupt {
             val |= 1<<7;
         }
-        
 
         // Reading this register clears the frame interrupt flag (but not the DMC interrupt flag).
         self.frame_interrupt = false;
diff --git a/src/apu/square.rs b/src/apu/square.rs
index 699f5fc..779e504 100644
--- a/src/apu/square.rs
+++ b/src/apu/square.rs
@@ -16,6 +16,9 @@ pub struct Square {
     envelope: usize,
     sweep: usize,
     pub enabled: bool,
+    decay_counter: u8,
+    start: bool,
+    divider: usize,
 }
 
 impl Square {
@@ -31,6 +34,9 @@ impl Square {
             sweep: 0,
             sample: 0,
             enabled: false,
+            decay_counter: 0,
+            start: false,
+            divider: 0,
         }
     }
 
@@ -38,21 +44,42 @@ impl Square {
 
     }
 
+    pub fn clock_frame_counter(&mut self) {
+
+    }
+
+    pub fn clock_envelope(&mut self) {
+        if self.start {
+            self.envelope -= 1;
+            self.start = false;
+        } else {
+
+        }
+    }
+
+    // $4000/$4004
     pub fn duty(&mut self, value: u8) {
         self.duty_cycle = duty_cycle_sequences[(value >> 6) as usize];
         self.length_counter_halt = value & (1<<5) != 0;
         self.constant_volume_flag = value & (1<<4) != 0;
-        
+        if self.constant_volume_flag {
+            self.envelope = value & 0b1111;
+        } else {
+            self.envelope = self.decay_counter;
+        }
     }
 
+    // $4001/$4005
     pub fn sweep(&mut self, value: u8) {
         
     }
 
+    // $4002/$4006
     pub fn timer_low(&mut self, value: u8) {
 
     }
 
+    // $4003/$4007
     pub fn timer_high(&mut self, value: u8) {
         
     }