From b238a3e8f3ebc4e46fdfe10f84f0d260a587d3da Mon Sep 17 00:00:00 2001
From: Rekai Musuka <rekai@musuka.dev>
Date: Sun, 13 Feb 2022 03:23:09 -0400
Subject: [PATCH] feat: impelemnt BG0,1,2CNT and IF

---
 src/bus/io.zig | 54 ++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 52 insertions(+), 2 deletions(-)

diff --git a/src/bus/io.zig b/src/bus/io.zig
index 64a1884..66561ec 100644
--- a/src/bus/io.zig
+++ b/src/bus/io.zig
@@ -10,8 +10,19 @@ pub const Io = struct {
     dispstat: DisplayStatus,
     vcount: VCount,
     /// Read / Write
+    bg0cnt: BackgroundControl,
+    /// Read / Write
+    bg1cnt: BackgroundControl,
+    /// Read / Write
+    bg2cnt: BackgroundControl,
+    /// Read / Write
+    bg3cnt: BackgroundControl,
+    /// Read / Write
     ime: bool,
     ie: InterruptEnable,
+    /// Read / Write
+    irq: InterruptRequest,
+
     keyinput: KeyInput,
 
     pub fn init() Self {
@@ -19,8 +30,13 @@ pub const Io = struct {
             .dispcnt = .{ .raw = 0x0000 },
             .dispstat = .{ .raw = 0x0000 },
             .vcount = .{ .raw = 0x0000 },
+            .bg0cnt = .{ .raw = 0x0000 },
+            .bg1cnt = .{ .raw = 0x0000 },
+            .bg2cnt = .{ .raw = 0x0000 },
+            .bg3cnt = .{ .raw = 0x0000 },
             .ime = false,
             .ie = .{ .raw = 0x0000 },
+            .irq = .{ .raw = 0x0000 },
             .keyinput = .{ .raw = 0x03FF },
         };
     }
@@ -61,7 +77,9 @@ pub const Io = struct {
         switch (addr) {
             0x0400_0000 => self.dispcnt.raw = halfword,
             0x0400_0004 => self.dispstat.raw = halfword,
+            0x0400_0008 => self.bg0cnt.raw = halfword,
             0x0400_0200 => self.ie.raw = halfword,
+            0x0400_0202 => self.irq.raw = halfword,
             0x0400_0208 => self.ime = halfword & 1 == 1,
             else => std.debug.panic("[I/O:16] tried to write 0x{X:} to 0x{X:}", .{ halfword, addr }),
         }
@@ -77,8 +95,11 @@ pub const Io = struct {
         };
     }
 
-    pub fn write8(_: *Self, addr: u32, byte: u8) void {
-        std.debug.panic("[I/0:8] tried to write 0x{X:} to 0x{X:}", .{ byte, addr });
+    pub fn write8(self: *Self, addr: u32, byte: u8) void {
+        switch (addr) {
+            0x0400_0208 => self.ime = byte & 1 == 1,
+            else => std.debug.panic("[I/0:8] tried to write 0x{X:} to 0x{X:}", .{ byte, addr }),
+        }
     }
 };
 
@@ -148,3 +169,32 @@ const KeyInput = extern union {
     shoulder_l: Bit(u16, 9),
     raw: u16,
 };
+
+const BackgroundControl = extern union {
+    bg_priority: Bitfield(u16, 0, 2),
+    char_base: Bitfield(u16, 2, 2),
+    mosaic_enable: Bit(u16, 6),
+    palette_type: Bit(u16, 7),
+    screen_base: Bitfield(u16, 8, 5),
+    display_overflow: Bit(u16, 13),
+    screen_size: Bitfield(u16, 14, 2),
+    raw: u16,
+};
+
+const InterruptRequest = extern union {
+    vblank: Bit(u16, 0),
+    hblank: Bit(u16, 1),
+    coincidence: Bit(u16, 2),
+    tim0_overflow: Bit(u16, 3),
+    tim1_overflow: Bit(u16, 4),
+    tim2_overflow: Bit(u16, 5),
+    tim3_overflow: Bit(u16, 6),
+    serial: Bit(u16, 7),
+    dma0: Bit(u16, 8),
+    dma1: Bit(u16, 9),
+    dma2: Bit(u16, 10),
+    dma3: Bit(u16, 11),
+    keypad: Bit(u16, 12),
+    game_pak: Bit(u16, 13),
+    raw: u16,
+};