From f0a8a978b29ca7e4b579746dbe3abb0bca34509a Mon Sep 17 00:00:00 2001
From: Alex Janka <alex@alexjanka.com>
Date: Mon, 13 Feb 2023 13:22:50 +1100
Subject: [PATCH] apu handles memory

---
 src/processor/memory.rs          | 44 ++++++++---------------
 src/processor/memory/mmio/apu.rs | 62 +++++++++++++++++++++++++++++---
 2 files changed, 72 insertions(+), 34 deletions(-)

diff --git a/src/processor/memory.rs b/src/processor/memory.rs
index 7acc887..d16fc42 100644
--- a/src/processor/memory.rs
+++ b/src/processor/memory.rs
@@ -1,4 +1,4 @@
-use self::mmio::Joypad;
+use self::mmio::{Apu, Joypad};
 pub use self::rom::Rom;
 use crate::{processor::SplitRegister, verbose_println};
 use gilrs::ConnectedGamepadsIterator;
@@ -26,7 +26,7 @@ pub struct Memory {
     io: [u8; 76],
     pub(super) user_mode: bool,
     joypad: Joypad,
-    pub(super) apu_enabled: bool,
+    apu: Apu,
 }
 
 impl Memory {
@@ -46,7 +46,7 @@ impl Memory {
             io: [0xFF; 76],
             user_mode: false,
             joypad: Joypad::default(),
-            apu_enabled: true,
+            apu: Apu::default(),
         }
     }
 
@@ -119,10 +119,11 @@ impl Memory {
     }
 
     fn get_io(&self, address: Address) -> u8 {
-        if address == 0xFF00 {
-            return self.joypad.as_register();
+        match address {
+            0xFF00 => self.joypad.as_register(),
+            0xFF10..0xFF40 => self.apu.get_register(address),
+            _ => self.io[(address - 0xFF00) as usize],
         }
-        self.io[(address - 0xFF00) as usize]
     }
 
     fn set_io(&mut self, address: Address, data: u8) {
@@ -144,19 +145,7 @@ impl Memory {
                 0xFF04 => self.io[addr_l] = 0,
                 0xFF07 => self.masked_io(addr_l, data, 0b111),
                 0xFF0F => self.masked_io(addr_l, data, 0b11111),
-                0xFF10 => self.masked_io(addr_l, data, 0b01111111),
-                0xFF1A => self.masked_io(addr_l, data, 0b10000000),
-                0xFF1C => self.masked_io(addr_l, data, 0b1100000),
-                0xFF20 => self.masked_io(addr_l, data, 0b111111),
-                0xFF23 => self.io[addr_l] = (self.io[addr_l] & 0b10111111) | (data & 0b01000000),
-                0xFF26 => {
-                    self.io[addr_l] = (self.io[addr_l] & 0b1111111) | (data & 0b10000000);
-                    self.apu_enabled = self.io[addr_l] & 0b10000000 == 0b10000000
-                }
-                0xFF11 | 0xFF14 | 0xFF16 | 0xFF19 | 0xFF1E => {
-                    // sound
-                    self.io[addr_l] = data;
-                }
+                0xFF10..0xFF40 => self.apu.mmio_write(address, data),
                 0xFF41 => {
                     // mixed read/write
                     self.masked_io(addr_l, data, 0b01111000);
@@ -165,16 +154,7 @@ impl Memory {
                     // cgb only
                     self.io[addr_l] = data;
                 }
-                0xFF03
-                | 0xFF08..0xFF0F
-                | 0xFF15
-                | 0xFF1F
-                | 0xFF27
-                | 0xFF28
-                | 0xFF29
-                | 0xFF44
-                | 0xFF76
-                | 0xFF77 => {
+                0xFF03 | 0xFF08..0xFF0F | 0xFF44 | 0xFF76 | 0xFF77 => {
                     // read-only addresses
                     println!("BANNED write: {data:#X} to {address:#X}");
                 }
@@ -198,7 +178,7 @@ impl Memory {
     }
 
     fn masked_io(&mut self, addr_l: usize, data: u8, mask: u8) {
-        self.io[addr_l] = (self.io[addr_l] & (!mask)) | (data & mask);
+        self.io[addr_l] = masked_update(self.io[addr_l], data, mask);
     }
 
     pub fn update_pressed_keys(
@@ -235,3 +215,7 @@ impl Memory {
         }
     }
 }
+
+pub fn masked_update(current: u8, data: u8, mask: u8) -> u8 {
+    (current & (!mask)) | (data & mask)
+}
diff --git a/src/processor/memory/mmio/apu.rs b/src/processor/memory/mmio/apu.rs
index 6c057ce..e7f8950 100644
--- a/src/processor/memory/mmio/apu.rs
+++ b/src/processor/memory/mmio/apu.rs
@@ -1,7 +1,61 @@
-pub struct Apu {}
+use crate::{
+    processor::memory::{masked_update, Address},
+    util::get_bit,
+};
 
-impl Apu {
-    fn init() -> Self {
-        Self {}
+const MEM_START: usize = 0xFF10;
+const MEM_SIZE: usize = 0xFF40 - MEM_START;
+
+const fn reg(a: Address) -> usize {
+    (a as usize) - MEM_START
+}
+
+pub struct Apu {
+    mem: [u8; MEM_SIZE],
+}
+
+impl Default for Apu {
+    fn default() -> Self {
+        Self {
+            mem: [0x0; MEM_SIZE],
+        }
+    }
+}
+
+impl Apu {
+    pub fn get_register(&self, addr: Address) -> u8 {
+        if addr == 0xFF26
+            || addr == 0xFF11
+            || addr == 0xFF16
+            || addr == 0xFF1B
+            || addr == 0xFF20
+            || get_bit(self.mem[reg(0xFF26)], 7)
+        {
+            self.mem[reg(addr)]
+        } else {
+            0xFF
+        }
+    }
+
+    pub fn mmio_write(&mut self, addr: Address, data: u8) {
+        match addr {
+            0xFF10 => self.masked_io(reg(addr), data, 0b01111111),
+            0xFF1A => self.masked_io(reg(addr), data, 0b10000000),
+            0xFF1C => self.masked_io(reg(addr), data, 0b1100000),
+            0xFF20 => self.masked_io(reg(addr), data, 0b111111),
+            0xFF23 => {
+                self.mem[reg(addr)] = (self.mem[reg(addr)] & 0b10111111) | (data & 0b01000000)
+            }
+            0xFF26 => self.mem[reg(addr)] = (self.mem[reg(addr)] & 0b1111111) | (data & 0b10000000),
+            0xFF11 | 0xFF14 | 0xFF16 | 0xFF19 | 0xFF1E => self.mem[reg(addr)] = data,
+            0xFF15 | 0xFF1F | 0xFF27 | 0xFF28 | 0xFF29 => {
+                println!("BANNED write in APU: {data:#X} to {addr:#X}")
+            }
+            _ => panic!("non-apu addr in apu"),
+        }
+    }
+
+    fn masked_io(&mut self, addr_el: usize, data: u8, mask: u8) {
+        self.mem[addr_el] = masked_update(self.mem[addr_el], data, mask);
     }
 }