diff --git a/src/core/bus/GamePak.zig b/src/core/bus/GamePak.zig index 98504d1..0429136 100644 --- a/src/core/bus/GamePak.zig +++ b/src/core/bus/GamePak.zig @@ -1,5 +1,7 @@ const std = @import("std"); +const Bit = @import("bitfield").Bit; +const Bitfield = @import("bitfield").Bitfield; const Backup = @import("backup.zig").Backup; const Allocator = std.mem.Allocator; const log = std.log.scoped(.GamePak); @@ -10,6 +12,7 @@ title: [12]u8, buf: []u8, alloc: Allocator, backup: Backup, +gpio: Gpio, pub fn init(alloc: Allocator, rom_path: []const u8, save_path: ?[]const u8) !Self { const file = try std.fs.cwd().openFile(rom_path, .{}); @@ -19,10 +22,11 @@ pub fn init(alloc: Allocator, rom_path: []const u8, save_path: ?[]const u8) !Sel const title = parseTitle(file_buf); const kind = Backup.guessKind(file_buf) orelse .None; - const pak = Self{ + var pak = Self{ .buf = file_buf, .alloc = alloc, .title = title, + .gpio = Gpio.init(alloc, .Rtc), .backup = try Backup.init(alloc, kind, title, save_path), }; pak.parseHeader(); @@ -30,6 +34,24 @@ pub fn init(alloc: Allocator, rom_path: []const u8, save_path: ?[]const u8) !Sel return pak; } +/// Configures any GPIO Device that may be enabled +/// +/// Fundamentally, this just passes a pointer to the initialized GPIO struct to whatever heap allocated GPIO Device struct +/// we happen to be using +/// +/// WARNIG: As far as I know, this method must be called in main() or else we'll have a dangling pointer issue +/// Despite using the General Purpose Allocator, Zig doesn't prevent me from doing this :sadface: +pub fn setupGpio(self: *Self) void { + switch (self.gpio.device.kind) { + .Rtc => { + const ptr = self.gpio.device.ptr orelse @panic("RTC ptr is missing despite GPIO Device Kind"); + const clock = @ptrCast(*Clock, @alignCast(@alignOf(*Clock), ptr)); + Clock.init(clock, &self.gpio); + }, + .None => {}, + } +} + fn parseHeader(self: *const Self) void { const title = parseTitle(self.buf); const code = self.buf[0xAC..0xB0]; @@ -61,6 +83,7 @@ inline fn isLarge(self: *const Self) bool { pub fn deinit(self: Self) void { self.alloc.free(self.buf); self.backup.deinit(); + self.gpio.deinit(self.alloc); } pub fn read(self: *Self, comptime T: type, address: u32) T { @@ -82,6 +105,35 @@ pub fn read(self: *Self, comptime T: type, address: u32) T { } } + if (self.gpio.cnt == 1) { + // GPIO Can be read from + // We assume that this will only be true when a ROM actually does want something from GPIO + + switch (T) { + u32 => switch (address) { + // TODO: Do I even need to implement these? + 0x0800_00C4 => std.debug.panic("Handle 32-bit GPIO Data/Direction Reads", .{}), + 0x0800_00C6 => std.debug.panic("Handle 32-bit GPIO Direction/Control Reads", .{}), + 0x0800_00C8 => std.debug.panic("Handle 32-bit GPIO Control Reads", .{}), + else => {}, + }, + u16 => switch (address) { + // FIXME: What do 16-bit GPIO Reads look like? + 0x0800_00C4 => return self.gpio.read(.Data), + 0x0800_00C6 => return self.gpio.read(.Direction), + 0x0800_00C8 => return self.gpio.read(.Control), + else => {}, + }, + u8 => switch (address) { + 0x0800_00C4 => return self.gpio.read(.Data), + 0x0800_00C6 => return self.gpio.read(.Direction), + 0x0800_00C8 => return self.gpio.read(.Control), + else => {}, + }, + else => @compileError("GamePak[GPIO]: Unsupported read width"), + } + } + return switch (T) { u32 => (@as(T, self.get(addr + 3)) << 24) | (@as(T, self.get(addr + 2)) << 16) | (@as(T, self.get(addr + 1)) << 8) | (@as(T, self.get(addr))), u16 => (@as(T, self.get(addr + 1)) << 8) | @as(T, self.get(addr)), @@ -140,17 +192,23 @@ pub fn write(self: *Self, comptime T: type, word_count: u16, address: u32, value switch (T) { u32 => switch (address) { - 0x0800_00C4 => log.debug("Wrote {} 0x{X:} to I/O Port Data and Direction", .{ T, value }), - 0x0800_00C6 => log.debug("Wrote {} 0x{X:} to I/O Port Direction and Control", .{ T, value }), - else => {}, + 0x0800_00C4 => { + self.gpio.write(.Data, @truncate(u4, value)); + self.gpio.write(.Direction, @truncate(u4, value >> 16)); + }, + 0x0800_00C6 => { + self.gpio.write(.Direction, @truncate(u4, value)); + self.gpio.write(.Control, @truncate(u1, value >> 16)); + }, + else => log.err("Wrote {} 0x{X:0>8} to 0x{X:0>8}, Unhandled", .{ T, value, address }), }, u16 => switch (address) { - 0x0800_00C4 => log.debug("Wrote {} 0x{X:} to I/O Port Data", .{ T, value }), - 0x0800_00C6 => log.debug("Wrote {} 0x{X:} to I/O Port Direction", .{ T, value }), - 0x0800_00C8 => log.debug("Wrote {} 0x{X:} to I/O Port Control", .{ T, value }), - else => {}, + 0x0800_00C4 => self.gpio.write(.Data, @truncate(u4, value)), + 0x0800_00C6 => self.gpio.write(.Direction, @truncate(u4, value)), + 0x0800_00C8 => self.gpio.write(.Control, @truncate(u1, value)), + else => log.err("Wrote {} 0x{X:0>4} to 0x{X:0>8}, Unhandled", .{ T, value, address }), }, - u8 => log.debug("Wrote {} 0x{X:} to 0x{X:0>8}, Ignored.", .{ T, value, address }), + u8 => log.debug("Wrote {} 0x{X:0>2} to 0x{X:0>8}, Ignored.", .{ T, value, address }), else => @compileError("GamePak: Unsupported write width"), } } @@ -182,3 +240,343 @@ test "OOB Access" { std.debug.assert(pak.get(4) == 0x02); // 0x0002 std.debug.assert(pak.get(5) == 0x00); } + +/// GPIO Register Implementation +const Gpio = struct { + const This = @This(); + + data: u4, + direction: u4, + cnt: u1, + + device: Device, + + const Device = struct { + ptr: ?*anyopaque, + // TODO: Maybe make this comptime known? Removes some if statements + kind: Kind, + + const Kind = enum { + Rtc, + None, + }; + + fn step(self: *Device, value: u4) void { + switch (self.kind) { + .Rtc => { + const ptr = self.ptr orelse @panic("Device.ptr should != null when Device.kind == .Rtc"); + const clock = @ptrCast(*Clock, @alignCast(@alignOf(*Clock), ptr)); + + clock.step(Clock.GpioData{ .raw = value }); + }, + .None => {}, + } + } + + fn init(kind: Kind, ptr: ?*anyopaque) Device { + return .{ .kind = kind, .ptr = ptr }; + } + }; + + const Register = enum { + Data, + Direction, + Control, + }; + + fn init(allocator: Allocator, kind: Device.Kind) This { + return .{ + .data = 0b0000, + .direction = 0b1111, // TODO: What is GPIO Direction set to by default? + .cnt = 0b0, + + .device = switch (kind) { + .Rtc => blk: { + const ptr = allocator.create(Clock) catch @panic("Failed to allocate RTC struct on heap"); + break :blk Device{ .kind = kind, .ptr = ptr }; + }, + .None => Device{ .kind = kind, .ptr = null }, + }, + }; + } + + fn deinit(self: This, allocator: Allocator) void { + switch (self.device.kind) { + .Rtc => { + const ptr = self.device.ptr orelse @panic("Device.ptr should != null when Device.kind == .Rtc"); + allocator.destroy(@ptrCast(*Clock, @alignCast(@alignOf(*Clock), ptr))); + }, + .None => {}, + } + } + + fn write(self: *This, comptime reg: Register, value: if (reg == .Control) u1 else u4) void { + log.debug("RTC: Wrote 0b{b:0>4} to {}", .{ value, reg }); + + // if (reg == .Data) + // log.err("original: 0b{b:0>4} masked: 0b{b:0>4} result: 0b{b:0>4}", .{ self.data, value & self.direction, self.data | (value & self.direction) }); + + switch (reg) { + .Data => { + const masked_value = value & self.direction; + + self.device.step(masked_value); + self.data = masked_value; + }, + .Direction => self.direction = value, + .Control => self.cnt = value, + } + } + + fn read(self: *const This, comptime reg: Register) if (reg == .Control) u1 else u4 { + if (self.cnt == 0) return 0; + + return switch (reg) { + .Data => self.data & ~self.direction, + .Direction => self.direction, + .Control => self.cnt, + }; + } +}; + +/// GBA Real Time Clock +const Clock = struct { + const This = @This(); + + cmd: Command, + writer: Writer, + state: State, + cnt: Control, + + year: u8, + month: u5, + day: u6, + day_of_week: u3, + hour: u6, + minute: u7, + second: u7, + + gpio: *const Gpio, + + const Register = enum { + Control, + DateTime, + Time, + }; + + const State = union(enum) { + Idle, + CommandInput, + Write: Register, + Read: Register, + }; + + const Writer = struct { + buf: u8, + i: u4, + + /// The Number of bytes written to since last reset + count: u8, + + fn push(self: *Writer, value: u1) void { + const idx = @intCast(u3, self.i); + self.buf = (self.buf & ~(@as(u8, 1) << idx)) | @as(u8, value) << idx; + self.i += 1; + } + + fn lap(self: *Writer) void { + self.buf = 0; + self.i = 0; + self.count += 1; + } + + fn reset(self: *Writer) void { + self.buf = 0; + self.i = 0; + self.count = 0; + } + + fn isFinished(self: *const Writer) bool { + return self.i >= 8; + } + + fn getCount(self: *const Writer) u8 { + return self.count; + } + + fn getValue(self: *const Writer) u8 { + return self.buf; + } + }; + + const Command = struct { + buf: u8, + i: u4, + + fn push(self: *Command, value: u1) void { + const idx = @intCast(u3, self.i); + self.buf = (self.buf & ~(@as(u8, 1) << idx)) | @as(u8, value) << idx; + self.i += 1; + } + + fn reset(self: *Command) void { + self.buf = 0; + self.i = 0; + } + + fn isFinished(self: *const Command) bool { + return self.i >= 8; + } + + fn getCommand(self: *const Command) u8 { + // If high Nybble does not contain 0x6, reverse the order of the nybbles. + // For some reason RTC commands can be LSB or MSB which is funny + return if (self.buf >> 4 & 0xF == 0x6) self.buf else (self.buf & 0xF) << 4 | (self.buf >> 4 & 0xF); + } + + fn handleCommand(self: *const Command, rtc: *Clock) State { + log.info("RTC: Failed to handle Command 0b{b:0>8} aka 0x{X:0>2}", .{ self.buf, self.buf }); + const command = self.getCommand(); + + const is_write = command & 1 == 0; + const rtc_register = @intCast(u3, command >> 1 & 0x7); // TODO: Make Truncate + + if (is_write) { + return switch (rtc_register) { + 0 => blk: { + rtc.reset(); + break :blk .Idle; + }, + 1 => .{ .Write = .Control }, + 2 => .{ .Write = .DateTime }, + 3 => .{ .Write = .Time }, + 6 => blk: { + rtc.irq(); + break :blk .Idle; + }, + 4, 5, 7 => .Idle, + }; + } else { + return switch (rtc_register) { + 1 => .{ .Read = .Control }, + 2 => .{ .Read = .DateTime }, + 3 => .{ .Read = .Time }, + 0, 4, 5, 6, 7 => .Idle, // Do Nothing + }; + } + } + }; + + const GpioData = extern union { + sck: Bit(u4, 0), + sio: Bit(u4, 1), + cs: Bit(u4, 2), + raw: u4, + }; + + const Control = extern union { + /// Unknown, value should be preserved though + unk: Bit(u8, 1), + /// Per-minute IRQ + /// If set, fire a Gamepak IRQ every 30s, + irq: Bit(u8, 3), + /// 12/24 Hour Bit + /// If set, 12h mode + /// If cleared, 24h mode + mode: Bit(u8, 6), + /// Read-Only, bit cleared on read + /// If is set, means that there has been a failure / time has been lost + off: Bit(u8, 7), + raw: u8, + }; + + fn init(ptr: *This, gpio: *const Gpio) void { + ptr.* = .{ + .cmd = .{ .buf = 0, .i = 0 }, + .writer = .{ .buf = 0, .i = 0, .count = 0 }, + .state = .Idle, + .cnt = .{ .raw = 0 }, + .year = 0, + .month = 0, + .day = 0, + .day_of_week = 0, + .hour = 0, + .minute = 0, + .second = 0, + .gpio = gpio, + }; + } + + fn attachGpio(self: *This, gpio: *const Gpio) void { + self.gpio = gpio; + } + + fn step(self: *This, value: GpioData) void { + const cache: GpioData = .{ .raw = self.gpio.data }; + + switch (self.state) { + .Idle => { + // If SCK is high and CS rises, then prepare for Command + // FIXME: Maybe check incoming value to see if SCK is also high? + if (cache.sck.read()) { + if (!cache.cs.read() and value.cs.read()) { + log.err("RTC: Entering Command Mode", .{}); + self.state = .CommandInput; + self.cmd.reset(); + } + } + }, + .CommandInput => { + if (!value.cs.read()) log.err("RTC: Expected CS to be set during {}, however CS was cleared", .{self.state}); + + if (!cache.sck.read() and value.sck.read()) { + // If SCK rises, sample SIO + log.debug("RTC: Sampled 0b{b:0>1} from SIO", .{@boolToInt(value.sio.read())}); + self.cmd.push(@boolToInt(value.sio.read())); + + if (self.cmd.isFinished()) { + self.state = self.cmd.handleCommand(self); + } + } + }, + State{ .Write = .Control } => { + if (!value.cs.read()) log.err("RTC: Expected CS to be set during {}, however CS was cleared", .{self.state}); + + if (!cache.sck.read() and value.sck.read()) { + // If SCK rises, sample SIO + + log.debug("RTC: Sampled 0b{b:0>1} from SIO", .{@boolToInt(value.sio.read())}); + self.writer.push(@boolToInt(value.sio.read())); + + if (self.writer.isFinished()) { + self.writer.lap(); + self.cnt.raw = self.writer.getValue(); + + // FIXME: Move this to a constant or something + if (self.writer.getCount() == 1) { + self.writer.reset(); + self.state = .Idle; + } + } + } + }, + else => { + // TODO: Implement Read/Writes for Date/Time and Time and Control + log.err("RTC: Ignored request to handle {} command", .{self.state}); + self.state = .Idle; + }, + } + } + + fn reset(self: *This) void { + // mGBA and NBA only zero the control register + // we'll do the same + self.cnt.raw = 0; + log.info("RTC: Reset executed (control register was zeroed)", .{}); + } + + fn irq(_: *const This) void { + // TODO: Force GamePak IRQ + log.err("RTC: TODO: Force GamePak IRQ", .{}); + } +}; diff --git a/src/main.zig b/src/main.zig index 62a2518..28cc851 100644 --- a/src/main.zig +++ b/src/main.zig @@ -45,6 +45,7 @@ pub fn main() anyerror!void { defer scheduler.deinit(); var bus = try Bus.init(allocator, &scheduler, paths); + bus.pak.setupGpio(); // FIXME: Can I not call this in main()? defer bus.deinit(); var arm7tdmi = Arm7tdmi.init(&scheduler, &bus);