152 lines
4.2 KiB
Zig
152 lines
4.2 KiB
Zig
const std = @import("std");
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const EventKind = @import("scheduler.zig").EventKind;
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const Io = @import("bus/io.zig").Io;
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const Scheduler = @import("scheduler.zig").Scheduler;
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const Allocator = std.mem.Allocator;
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const width = 240;
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const height = 160;
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pub const buf_pitch = width * @sizeOf(u16);
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const buf_len = buf_pitch * height;
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pub const Ppu = struct {
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const Self = @This();
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vram: Vram,
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palette: Palette,
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sched: *Scheduler,
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frame_buf: []u8,
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alloc: Allocator,
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pub fn init(alloc: Allocator, sched: *Scheduler) !Self {
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// Queue first Hblank
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sched.push(.Draw, sched.tick + (240 * 4));
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return Self{
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.vram = try Vram.init(alloc),
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.palette = try Palette.init(alloc),
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.sched = sched,
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.frame_buf = try alloc.alloc(u8, buf_len),
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.alloc = alloc,
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};
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}
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pub fn deinit(self: Self) void {
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self.alloc.free(self.frame_buf);
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self.vram.deinit();
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self.palette.deinit();
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}
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pub fn drawScanline(self: *Self, io: *const Io) void {
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const bg_mode = io.dispcnt.bg_mode.read();
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const scanline = io.vcount.scanline.read();
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switch (bg_mode) {
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0x3 => {
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const start = buf_pitch * @as(usize, scanline);
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const end = start + buf_pitch;
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std.mem.copy(u8, self.frame_buf[start..end], self.vram.buf[start..end]);
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},
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0x4 => {
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const frame_select = io.dispcnt.frame_select.read();
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const fb_start = buf_pitch * @as(usize, scanline);
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const vram_start = fb_start >> 1;
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const start = if (frame_select) 0xA000 + vram_start else vram_start;
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const end = start + width;
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for (self.vram.buf[start..end]) |byte, i| {
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const fb_i = i * @sizeOf(u16);
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self.frame_buf[fb_start + fb_i + 1] = self.palette.buf[byte + 1];
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self.frame_buf[fb_start + fb_i] = self.palette.buf[byte];
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}
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},
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else => std.debug.panic("[PPU] TODO: Implement BG Mode {}", .{bg_mode}),
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}
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}
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};
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const Palette = struct {
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const Self = @This();
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buf: []u8,
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alloc: Allocator,
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fn init(alloc: Allocator) !Self {
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return Self{
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.buf = try alloc.alloc(u8, 0x400),
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.alloc = alloc,
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};
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}
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fn deinit(self: Self) void {
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self.alloc.free(self.buf);
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}
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pub fn get32(self: *const Self, idx: usize) u32 {
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return (@as(u32, self.get16(idx + 2)) << 16) | @as(u32, self.get16(idx));
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}
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pub fn set32(self: *Self, idx: usize, word: u32) void {
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self.set16(idx + 2, @truncate(u16, word >> 16));
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self.set16(idx, @truncate(u16, word));
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}
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pub fn get16(self: *const Self, idx: usize) u16 {
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return (@as(u16, self.buf[idx + 1]) << 8) | @as(u16, self.buf[idx]);
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}
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pub fn set16(self: *Self, idx: usize, halfword: u16) void {
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self.buf[idx + 1] = @truncate(u8, halfword >> 8);
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self.buf[idx] = @truncate(u8, halfword);
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}
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pub fn get8(self: *const Self, idx: usize) u8 {
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return self.buf[idx];
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}
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};
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const Vram = struct {
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const Self = @This();
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buf: []u8,
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alloc: Allocator,
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fn init(alloc: Allocator) !Self {
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return Self{
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.buf = try alloc.alloc(u8, 0x18000),
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.alloc = alloc,
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};
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}
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fn deinit(self: Self) void {
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self.alloc.free(self.buf);
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}
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pub fn get32(self: *const Self, idx: usize) u32 {
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return (@as(u32, self.get16(idx + 2)) << 16) | @as(u32, self.get16(idx));
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}
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pub fn set32(self: *Self, idx: usize, word: u32) void {
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self.set16(idx + 2, @truncate(u16, word >> 16));
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self.set16(idx, @truncate(u16, word));
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}
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pub fn get16(self: *const Self, idx: usize) u16 {
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return (@as(u16, self.buf[idx + 1]) << 8) | @as(u16, self.buf[idx]);
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}
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pub fn set16(self: *Self, idx: usize, halfword: u16) void {
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self.buf[idx + 1] = @truncate(u8, halfword >> 8);
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self.buf[idx] = @truncate(u8, halfword);
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}
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pub fn get8(self: *const Self, idx: usize) u8 {
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return self.buf[idx];
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}
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};
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