src/Bus.zig

@@ -8,7 +8,6 @@ const Iwram = @import("bus/Iwram.zig");
 const Ppu = @import("ppu.zig").Ppu;
 const Scheduler = @import("scheduler.zig").Scheduler;
 
-const io = @import("bus/io.zig");
 const Allocator = std.mem.Allocator;
 const log = std.log.scoped(.Bus);
 const Self = @This();
@@ -45,7 +44,7 @@ pub fn read32(self: *const Self, addr: u32) u32 {
         0x0000_0000...0x0000_3FFF => self.bios.get32(addr),
         0x0200_0000...0x0203_FFFF => self.iwram.get32(addr - 0x0200_0000),
         0x0300_0000...0x0300_7FFF => self.ewram.get32(addr - 0x0300_0000),
-        0x0400_0000...0x0400_03FE => io.read32(self, addr),
+        0x0400_0000...0x0400_03FE => self.io.read32(addr),
 
         // Internal Display Memory
         0x0500_0000...0x0500_03FF => self.ppu.palette.get32(addr - 0x0500_0000),
@@ -71,7 +70,7 @@ pub fn write32(self: *Self, addr: u32, word: u32) void {
         // General Internal Memory
         0x0200_0000...0x0203_FFFF => self.iwram.set32(addr - 0x0200_0000, word),
         0x0300_0000...0x0300_7FFF => self.ewram.set32(addr - 0x0300_0000, word),
-        0x0400_0000...0x0400_03FE => io.write32(self, addr, word),
+        0x0400_0000...0x0400_03FE => self.io.write32(addr, word),
 
         // Internal Display Memory
         0x0500_0000...0x0500_03FF => self.ppu.palette.set32(addr - 0x0500_0000, word),
@@ -88,7 +87,7 @@ pub fn read16(self: *const Self, addr: u32) u16 {
         0x0000_0000...0x0000_3FFF => self.bios.get16(addr),
         0x0200_0000...0x0203_FFFF => self.iwram.get16(addr - 0x0200_0000),
         0x0300_0000...0x0300_7FFF => self.ewram.get16(addr - 0x0300_0000),
-        0x0400_0000...0x0400_03FE => io.read16(self, addr),
+        0x0400_0000...0x0400_03FE => self.io.read16(addr),
 
         // Internal Display Memory
         0x0500_0000...0x0500_03FF => self.ppu.palette.get16(addr - 0x0500_0000),
@@ -113,7 +112,7 @@ pub fn write16(self: *Self, addr: u32, halfword: u16) void {
         // General Internal Memory
         0x0200_0000...0x0203_FFFF => self.iwram.set16(addr - 0x0200_0000, halfword),
         0x0300_0000...0x0300_7FFF => self.ewram.set16(addr - 0x0300_0000, halfword),
-        0x0400_0000...0x0400_03FE => io.write16(self, addr, halfword),
+        0x0400_0000...0x0400_03FE => self.io.write16(addr, halfword),
 
         // Internal Display Memory
         0x0500_0000...0x0500_03FF => self.ppu.palette.set16(addr - 0x0500_0000, halfword),
@@ -130,7 +129,7 @@ pub fn read8(self: *const Self, addr: u32) u8 {
         0x0000_0000...0x0000_3FFF => self.bios.get8(addr),
         0x0200_0000...0x0203_FFFF => self.iwram.get8(addr - 0x0200_0000),
         0x0300_0000...0x0300_7FFF => self.ewram.get8(addr - 0x0300_0000),
-        0x0400_0000...0x0400_03FE => io.read8(self, addr),
+        0x0400_0000...0x0400_03FE => self.io.read8(addr),
 
         // Internal Display Memory
         0x0500_0000...0x0500_03FF => self.ppu.palette.get8(addr - 0x0500_0000),
@@ -155,7 +154,7 @@ pub fn write8(self: *Self, addr: u32, byte: u8) void {
         // General Internal Memory
         0x0200_0000...0x0203_FFFF => self.iwram.set8(addr - 0x0200_0000, byte),
         0x0300_0000...0x0300_7FFF => self.ewram.set8(addr - 0x0300_0000, byte),
-        0x0400_0000...0x0400_03FE => io.write8(self, addr, byte),
+        0x0400_0000...0x0400_03FE => self.io.write8(addr, byte),
 
         // External Memory (Game Pak)
         0x0E00_0000...0x0E00_FFFF => std.debug.panic("[Bus:8] write 0x{X:} to 0x{X:} in Game Pak SRAM", .{ byte, addr }),

src/bus/io.zig

@@ -2,30 +2,88 @@ const std = @import("std");
 
 const Bit = @import("bitfield").Bit;
 const Bitfield = @import("bitfield").Bitfield;
-const Bus = @import("../Bus.zig");
 
 pub const Io = struct {
     const Self = @This();
 
+    dispcnt: DisplayControl,
+    dispstat: DisplayStatus,
+    vcount: VCount,
     /// Read / Write
     ime: bool,
     ie: InterruptEnable,
-    irq: InterruptRequest,
-
     keyinput: KeyInput,
 
     pub fn init() Self {
         return .{
+            .dispcnt = .{ .raw = 0x0000 },
+            .dispstat = .{ .raw = 0x0000 },
+            .vcount = .{ .raw = 0x0000 },
             .ime = false,
             .ie = .{ .raw = 0x0000 },
-            .irq = .{ .raw = 0x0000 },
             .keyinput = .{ .raw = 0x03FF },
         };
     }
+
+    pub fn read32(self: *const Self, addr: u32) u32 {
+        return switch (addr) {
+            0x0400_0000 => self.dispcnt.raw,
+            0x0400_0004 => self.dispstat.raw,
+            0x0400_0006 => self.vcount.raw,
+            0x0400_0200 => self.ie.raw,
+            0x0400_0208 => @boolToInt(self.ime),
+            else => std.debug.panic("[I/O:32] tried to read from {X:}", .{addr}),
+        };
+    }
+
+    pub fn write32(self: *Self, addr: u32, word: u32) void {
+        switch (addr) {
+            0x0400_0000 => self.dispcnt.raw = @truncate(u16, word),
+            0x0400_0200 => self.ie.raw = @truncate(u16, word),
+            0x0400_0208 => self.ime = word & 1 == 1,
+            else => std.debug.panic("[I/O:32] tried to write 0x{X:} to 0x{X:}", .{ word, addr }),
+        }
+    }
+
+    pub fn read16(self: *const Self, addr: u32) u16 {
+        return switch (addr) {
+            0x0400_0000 => self.dispcnt.raw,
+            0x0400_0004 => self.dispstat.raw,
+            0x0400_0006 => self.vcount.raw,
+            0x0400_0130 => self.keyinput.raw,
+            0x0400_0200 => self.ie.raw,
+            0x0400_0208 => @boolToInt(self.ime),
+            else => std.debug.panic("[I/O:16] tried to read from {X:}", .{addr}),
+        };
+    }
+
+    pub fn write16(self: *Self, addr: u32, halfword: u16) void {
+        switch (addr) {
+            0x0400_0000 => self.dispcnt.raw = halfword,
+            0x0400_0004 => self.dispstat.raw = halfword,
+            0x0400_0200 => self.ie.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 }),
+        }
+    }
+
+    pub fn read8(self: *const Self, addr: u32) u8 {
+        return switch (addr) {
+            0x0400_0000 => @truncate(u8, self.dispcnt.raw),
+            0x0400_0004 => @truncate(u8, self.dispstat.raw),
+            0x0400_0200 => @truncate(u8, self.ie.raw),
+            0x0400_0006 => @truncate(u8, self.vcount.raw),
+            else => std.debug.panic("[I/O:8] tried to read from {X:}", .{addr}),
+        };
+    }
+
+    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 });
+    }
 };
 
 /// Read / Write
-pub const DisplayControl = extern union {
+const DisplayControl = extern union {
     bg_mode: Bitfield(u16, 0, 3),
     frame_select: Bit(u16, 4),
     hblank_interval_free: Bit(u16, 5),
@@ -39,7 +97,7 @@ pub const DisplayControl = extern union {
 };
 
 /// Read / Write
-pub const DisplayStatus = extern union {
+const DisplayStatus = extern union {
     vblank: Bit(u16, 0),
     hblank: Bit(u16, 1),
     coincidence: Bit(u16, 2),
@@ -51,7 +109,7 @@ pub const DisplayStatus = extern union {
 };
 
 /// Read Only
-pub const VCount = extern union {
+const VCount = extern union {
     scanline: Bitfield(u16, 0, 8),
     raw: u16,
 };
@@ -90,103 +148,3 @@ const KeyInput = extern union {
     shoulder_l: Bit(u16, 9),
     raw: u16,
 };
-
-// Read / Write
-pub 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,
-};
-
-/// Write Only
-pub const BackgroundOffset = extern union {
-    offset: Bitfield(u16, 0, 9),
-    raw: u16,
-};
-
-/// Read / Write
-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,
-};
-
-pub fn read32(bus: *const Bus, addr: u32) u32 {
-    return switch (addr) {
-        0x0400_0000 => bus.ppu.dispcnt.raw,
-        0x0400_0004 => bus.ppu.dispstat.raw,
-        0x0400_0006 => bus.ppu.vcount.raw,
-        0x0400_0200 => bus.io.ie.raw,
-        0x0400_0208 => @boolToInt(bus.io.ime),
-        else => std.debug.panic("[I/O:32] tried to read from {X:}", .{addr}),
-    };
-}
-
-pub fn write32(bus: *Bus, addr: u32, word: u32) void {
-    switch (addr) {
-        0x0400_0000 => bus.ppu.dispcnt.raw = @truncate(u16, word),
-        0x0400_0200 => bus.io.ie.raw = @truncate(u16, word),
-        0x0400_0208 => bus.io.ime = word & 1 == 1,
-        else => std.debug.panic("[I/O:32] tried to write 0x{X:} to 0x{X:}", .{ word, addr }),
-    }
-}
-
-pub fn read16(bus: *const Bus, addr: u32) u16 {
-    return switch (addr) {
-        0x0400_0000 => bus.ppu.dispcnt.raw,
-        0x0400_0004 => bus.ppu.dispstat.raw,
-        0x0400_0006 => bus.ppu.vcount.raw,
-        0x0400_0130 => bus.io.keyinput.raw,
-        0x0400_0200 => bus.io.ie.raw,
-        0x0400_0208 => @boolToInt(bus.io.ime),
-        else => std.debug.panic("[I/O:16] tried to read from {X:}", .{addr}),
-    };
-}
-
-pub fn write16(bus: *Bus, addr: u32, halfword: u16) void {
-    switch (addr) {
-        0x0400_0000 => bus.ppu.dispcnt.raw = halfword,
-        0x0400_0004 => bus.ppu.dispstat.raw = halfword,
-        0x0400_0008 => bus.ppu.bg0.cnt.raw = halfword,
-        0x0400_0010 => bus.ppu.bg0.hofs.raw = halfword,
-        0x0400_0012 => bus.ppu.bg0.vofs.raw = halfword,
-        0x0400_0200 => bus.io.ie.raw = halfword,
-        0x0400_0202 => bus.io.irq.raw = halfword,
-        0x0400_0208 => bus.io.ime = halfword & 1 == 1,
-        else => std.debug.panic("[I/O:16] tried to write 0x{X:} to 0x{X:}", .{ halfword, addr }),
-    }
-}
-
-pub fn read8(bus: *const Bus, addr: u32) u8 {
-    return switch (addr) {
-        0x0400_0000 => @truncate(u8, bus.ppu.dispcnt.raw),
-        0x0400_0004 => @truncate(u8, bus.ppu.dispstat.raw),
-        0x0400_0200 => @truncate(u8, bus.io.ie.raw),
-        0x0400_0006 => @truncate(u8, bus.ppu.vcount.raw),
-        else => std.debug.panic("[I/O:8] tried to read from {X:}", .{addr}),
-    };
-}
-
-pub fn write8(self: *Bus, addr: u32, byte: u8) void {
-    switch (addr) {
-        0x0400_0208 => self.io.ime = byte & 1 == 1,
-        else => std.debug.panic("[I/0:8] tried to write 0x{X:} to 0x{X:}", .{ byte, addr }),
-    }
-}

src/ppu.zig

@@ -1,11 +1,10 @@
 const std = @import("std");
-const io = @import("bus/io.zig");
 
 const EventKind = @import("scheduler.zig").EventKind;
+const Io = @import("bus/io.zig").Io;
 const Scheduler = @import("scheduler.zig").Scheduler;
 
 const Allocator = std.mem.Allocator;
-
 pub const width = 240;
 pub const height = 160;
 pub const framebuf_pitch = width * @sizeOf(u16);
@@ -13,16 +12,6 @@ pub const framebuf_pitch = width * @sizeOf(u16);
 pub const Ppu = struct {
     const Self = @This();
 
-    // Registers
-    bg0: Background,
-    bg1: Background,
-    bg2: Background,
-    bg3: Background,
-
-    dispcnt: io.DisplayControl,
-    dispstat: io.DisplayStatus,
-    vcount: io.VCount,
-
     vram: Vram,
     palette: Palette,
     oam: Oam,
@@ -44,15 +33,6 @@ pub const Ppu = struct {
             .sched = sched,
             .framebuf = framebuf,
             .alloc = alloc,
-
-            // Registers
-            .bg0 = Background.init(),
-            .bg1 = Background.init(),
-            .bg2 = Background.init(),
-            .bg3 = Background.init(),
-            .dispcnt = .{ .raw = 0x0000 },
-            .dispstat = .{ .raw = 0x0000 },
-            .vcount = .{ .raw = 0x0000 },
         };
     }
 
@@ -62,15 +42,11 @@ pub const Ppu = struct {
         self.palette.deinit();
     }
 
-    pub fn drawScanline(self: *Self) void {
+    pub fn drawScanline(self: *Self, io: *const Io) void {
-        const bg_mode = self.dispcnt.bg_mode.read();
+        const bg_mode = io.dispcnt.bg_mode.read();
-        const scanline = self.vcount.scanline.read();
+        const scanline = io.vcount.scanline.read();
 
         switch (bg_mode) {
-            0x0 => {
-                // Mode 0
-
-            },
             0x3 => {
                 const start = framebuf_pitch * @as(usize, scanline);
                 const end = start + framebuf_pitch;
@@ -78,7 +54,7 @@ pub const Ppu = struct {
                 std.mem.copy(u8, self.framebuf[start..end], self.vram.buf[start..end]);
             },
             0x4 => {
-                const select = self.dispcnt.frame_select.read();
+                const select = io.dispcnt.frame_select.read();
                 const vram_start = width * @as(usize, scanline);
                 const buf_start = vram_start * @sizeOf(u16);
 
@@ -94,7 +70,7 @@ pub const Ppu = struct {
                     self.framebuf[buf_start + j] = self.palette.buf[id];
                 }
             },
-            else => std.debug.panic("[PPU] TODO: Implement BG Mode {}", .{bg_mode}),
+            else => {}, // std.debug.panic("[PPU] TODO: Implement BG Mode {}", .{bg_mode}),
         }
     }
 };
@@ -225,22 +201,3 @@ const Oam = struct {
         return self.buf[idx];
     }
 };
-
-const Background = struct {
-    const Self = @This();
-
-    /// Read / Write
-    cnt: io.BackgroundControl,
-    /// Write Only
-    hofs: io.BackgroundOffset,
-    /// Write Only
-    vofs: io.BackgroundOffset,
-
-    fn init() Self {
-        return .{
-            .cnt = .{ .raw = 0x0000 },
-            .hofs = .{ .raw = 0x0000 },
-            .vofs = .{ .raw = 0x0000 },
-        };
-    }
-};

src/scheduler.zig

@@ -38,28 +38,28 @@ pub const Scheduler = struct {
                 },
                 .HBlank => {
                     // The End of a Hblank (During Draw or Vblank)
-                    const old_scanline = bus.ppu.vcount.scanline.read();
+                    const old_scanline = bus.io.vcount.scanline.read();
                     const scanline = (old_scanline + 1) % 228;
 
-                    bus.ppu.vcount.scanline.write(scanline);
+                    bus.io.vcount.scanline.write(scanline);
-                    bus.ppu.dispstat.hblank.unset();
+                    bus.io.dispstat.hblank.unset();
 
                     if (scanline < 160) {
                         // Transitioning to another Draw
                         self.push(.Draw, self.tick + (240 * 4));
                     } else {
                         // Transitioning to a Vblank
-                        if (scanline < 227) bus.ppu.dispstat.vblank.set() else bus.ppu.dispstat.vblank.unset();
+                        if (scanline < 227) bus.io.dispstat.vblank.set() else bus.io.dispstat.vblank.unset();
 
                         self.push(.VBlank, self.tick + (240 * 4));
                     }
                 },
                 .Draw => {
                     // The end of a Draw
-                    bus.ppu.drawScanline();
+                    bus.ppu.drawScanline(&bus.io);
 
                     // Transitioning to a Hblank
-                    bus.ppu.dispstat.hblank.set();
+                    bus.io.dispstat.hblank.set();
                     self.push(.HBlank, self.tick + (68 * 4));
                 },
                 .VBlank => {