const std = @import("std"); const io = @import("bus/io.zig"); const EventKind = @import("scheduler.zig").EventKind; 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); 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, sched: *Scheduler, framebuf: []u8, alloc: Allocator, pub fn init(alloc: Allocator, sched: *Scheduler) !Self { // Queue first Hblank sched.push(.Draw, sched.tick + (240 * 4)); const framebuf = try alloc.alloc(u8, framebuf_pitch * height); std.mem.set(u8, framebuf, 0); return Self{ .vram = try Vram.init(alloc), .palette = try Palette.init(alloc), .oam = try Oam.init(alloc), .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 }, }; } pub fn deinit(self: Self) void { self.alloc.free(self.framebuf); self.vram.deinit(); self.palette.deinit(); } pub fn drawScanline(self: *Self) void { const bg_mode = self.dispcnt.bg_mode.read(); const scanline = self.vcount.scanline.read(); switch (bg_mode) { 0x0 => { // Mode 0 }, 0x3 => { const start = framebuf_pitch * @as(usize, scanline); std.mem.copy(u8, self.framebuf[start..][0..framebuf_pitch], self.vram.buf[start..][0..framebuf_pitch]); }, 0x4 => { const select = self.dispcnt.frame_select.read(); const vram_start = width * @as(usize, scanline); const buf_start = vram_start * @sizeOf(u16); const start = vram_start + if (select) 0xA000 else @as(usize, 0); const end = start + width; // Each Entry is only a byte long // Render Current Scanline for (self.vram.buf[start..end]) |byte, i| { const id = byte * 2; const j = i * @sizeOf(u16); std.mem.copy(u8, self.framebuf[(buf_start + j)..][0..2], self.palette.buf[id..][0..2]); } }, else => std.debug.panic("[PPU] TODO: Implement BG Mode {}", .{bg_mode}), } } }; const Palette = struct { const Self = @This(); buf: []u8, alloc: Allocator, fn init(alloc: Allocator) !Self { const buf = try alloc.alloc(u8, 0x400); std.mem.set(u8, buf, 0); return Self{ .buf = buf, .alloc = alloc, }; } fn deinit(self: Self) void { self.alloc.free(self.buf); } pub fn get32(self: *const Self, idx: usize) u32 { return (@as(u32, self.get16(idx + 2)) << 16) | @as(u32, self.get16(idx)); } pub fn set32(self: *Self, idx: usize, word: u32) void { self.set16(idx + 2, @truncate(u16, word >> 16)); self.set16(idx, @truncate(u16, word)); } pub fn get16(self: *const Self, idx: usize) u16 { return (@as(u16, self.buf[idx + 1]) << 8) | @as(u16, self.buf[idx]); } pub fn set16(self: *Self, idx: usize, halfword: u16) void { self.buf[idx + 1] = @truncate(u8, halfword >> 8); self.buf[idx] = @truncate(u8, halfword); } pub fn get8(self: *const Self, idx: usize) u8 { return self.buf[idx]; } }; const Vram = struct { const Self = @This(); buf: []u8, alloc: Allocator, fn init(alloc: Allocator) !Self { const buf = try alloc.alloc(u8, 0x18000); std.mem.set(u8, buf, 0); return Self{ .buf = buf, .alloc = alloc, }; } fn deinit(self: Self) void { self.alloc.free(self.buf); } pub fn get32(self: *const Self, idx: usize) u32 { return (@as(u32, self.get16(idx + 2)) << 16) | @as(u32, self.get16(idx)); } pub fn set32(self: *Self, idx: usize, word: u32) void { self.set16(idx + 2, @truncate(u16, word >> 16)); self.set16(idx, @truncate(u16, word)); } pub fn get16(self: *const Self, idx: usize) u16 { return (@as(u16, self.buf[idx + 1]) << 8) | @as(u16, self.buf[idx]); } pub fn set16(self: *Self, idx: usize, halfword: u16) void { self.buf[idx + 1] = @truncate(u8, halfword >> 8); self.buf[idx] = @truncate(u8, halfword); } pub fn get8(self: *const Self, idx: usize) u8 { return self.buf[idx]; } }; const Oam = struct { const Self = @This(); buf: []u8, alloc: Allocator, fn init(alloc: Allocator) !Self { const buf = try alloc.alloc(u8, 0x400); std.mem.set(u8, buf, 0); return Self{ .buf = buf, .alloc = alloc, }; } pub fn get32(self: *const Self, idx: usize) u32 { return (@as(u32, self.buf[idx + 3]) << 24) | (@as(u32, self.buf[idx + 2]) << 16) | (@as(u32, self.buf[idx + 1]) << 8) | (@as(u32, self.buf[idx])); } pub fn set32(self: *Self, idx: usize, word: u32) void { self.buf[idx + 3] = @truncate(u8, word >> 24); self.buf[idx + 2] = @truncate(u8, word >> 16); self.buf[idx + 1] = @truncate(u8, word >> 8); self.buf[idx] = @truncate(u8, word); } pub fn get16(self: *const Self, idx: usize) u16 { return (@as(u16, self.buf[idx + 1]) << 8) | @as(u16, self.buf[idx]); } pub fn set16(self: *Self, idx: usize, halfword: u16) void { self.buf[idx + 1] = @truncate(u8, halfword >> 8); self.buf[idx] = @truncate(u8, halfword); } pub fn get8(self: *const Self, idx: usize) u8 { 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 }, }; } };