From bb471a7de7b815932e642bd91650baf7d8c28f72 Mon Sep 17 00:00:00 2001
From: Franco Colmenarez <info@francoacg.com>
Date: Fri, 22 Oct 2021 13:30:17 -0500
Subject: [PATCH] Definitions for LCD status and control

---
 src/ppu.rs | 110 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 108 insertions(+), 2 deletions(-)

diff --git a/src/ppu.rs b/src/ppu.rs
index d46e02b..0d0f8a2 100644
--- a/src/ppu.rs
+++ b/src/ppu.rs
@@ -1,3 +1,10 @@
+use crate::utils::{
+    BitIndex,
+    get_bit,
+    set_bit,
+};
+use crate::bus::Bus;
+
 struct ColorPalette(u8, u8, u8, u8);
 
 struct Tile {
@@ -7,10 +14,109 @@ struct Tile {
 struct Sprite {
 }
 
-pub struct PPU;
+
+pub enum LCDControl {
+    DisplayEnable,
+    WindowTileMapAddress,
+    WindowEnable,
+    BackgroundWindowTileAddress,
+    BackgroundTileMapAddress,
+    ObjectSize,
+    ObjectEnable,
+    BackgroundPriority,
+}
+
+pub enum LCDStatusModeFlag {
+    HBlank,
+    VBlank,
+    SearchingOAM,
+    TransferringToLCD,
+}
+
+pub enum LCDStatus {
+    LYCInterrupt,
+    Mode2OAMInterrupt,
+    Mode1VBlankInterrupt,
+    Mode0HBlankInterrupt,
+    LYCFlag,
+    ModeFlag(LCDStatusModeFlag),
+}
+
+pub struct Window {
+    x: u8,
+    y: u8,
+}
+
+impl Window {
+    pub fn new() -> Self {
+        Self {
+            x: 0,
+            y: 0,
+        }
+    }
+}
+
+pub struct PPU {
+    scroll_y: u8,
+    scroll_x: u8,
+    window: Window,
+}
+
+const LCD_CONTROL_ADDRESS: u16 = 0xFF40;
+const LCD_STATUS_ADDRESS: u16 = 0xFF41;
 
 impl PPU {
     pub fn new() -> Self {
-        Self{}
+        Self {
+            scroll_x: 0,
+            scroll_y: 0,
+            window: Window::new(),
+        }
+    }
+
+    fn get_lcd_control(bus: &Bus, control: LCDControl) -> bool {
+        let byte = bus.read(LCD_CONTROL_ADDRESS);
+        match control {
+            LCDControl::DisplayEnable => get_bit(byte, BitIndex::I7),
+            LCDControl::WindowTileMapAddress => get_bit(byte, BitIndex::I6),
+            LCDControl::WindowEnable =>  get_bit(byte, BitIndex::I5),
+            LCDControl::BackgroundWindowTileAddress =>  get_bit(byte, BitIndex::I4),
+            LCDControl::BackgroundTileMapAddress =>  get_bit(byte, BitIndex::I3),
+            LCDControl::ObjectSize =>  get_bit(byte, BitIndex::I2),
+            LCDControl::ObjectEnable =>  get_bit(byte, BitIndex::I1),
+            LCDControl::BackgroundPriority =>  get_bit(byte, BitIndex::I0),
+        }
+    }
+
+    fn set_lcd_control(bus: &mut Bus, control: LCDControl, val: bool) {
+        let mut byte = bus.read(LCD_CONTROL_ADDRESS);
+        match control {
+            LCDControl::DisplayEnable => byte = set_bit(byte, val, BitIndex::I7),
+            LCDControl::WindowTileMapAddress => byte = set_bit(byte, val, BitIndex::I6),
+            LCDControl::WindowEnable => byte = set_bit(byte, val, BitIndex::I5),
+            LCDControl::BackgroundWindowTileAddress => byte = set_bit(byte, val, BitIndex::I4),
+            LCDControl::BackgroundTileMapAddress => byte = set_bit(byte, val, BitIndex::I3),
+            LCDControl::ObjectSize => byte = set_bit(byte, val, BitIndex::I2),
+            LCDControl::ObjectEnable => byte = set_bit(byte, val, BitIndex::I1),
+            LCDControl::BackgroundPriority => byte = set_bit(byte, val, BitIndex::I0),
+        };
+        bus.write(LCD_CONTROL_ADDRESS, byte);
+    }
+
+    fn get_lcd_status(bus: &Bus, status: LCDStatus) -> bool {
+        let byte = bus.read(LCD_STATUS_ADDRESS);
+        match status {
+            LCDStatus::LYCInterrupt => get_bit(byte, BitIndex::I6),
+            LCDStatus::Mode2OAMInterrupt => get_bit(byte, BitIndex::I5),
+            LCDStatus::Mode1VBlankInterrupt => get_bit(byte, BitIndex::I4),
+            LCDStatus::Mode0HBlankInterrupt => get_bit(byte, BitIndex::I3),
+            LCDStatus::LYCFlag => get_bit(byte, BitIndex::I2),
+            LCDStatus::ModeFlag(mode) => match mode {
+                LCDStatusModeFlag::HBlank => (byte & 0b00000011) == 0,
+                LCDStatusModeFlag::VBlank => (byte & 0b00000011) == 1,
+                LCDStatusModeFlag::SearchingOAM => (byte & 0b00000011) == 2,
+                LCDStatusModeFlag::TransferringToLCD => (byte & 0b00000011) == 3,
+            },
+        }
     }
 }