.gitmodules

@@ -10,3 +10,6 @@
 [submodule "lib/zig-datetime"]
 	path = lib/zig-datetime
 	url = https://github.com/frmdstryr/zig-datetime
+[submodule "lib/zig-toml"]
+	path = lib/zig-toml
+	url = https://github.com/aeronavery/zig-toml

build.zig

@@ -28,6 +28,9 @@ pub fn build(b: *std.build.Builder) void {
     // Argument Parsing Library
     exe.addPackagePath("clap", "lib/zig-clap/clap.zig");
 
+    // TOML Library
+    exe.addPackagePath("toml", "lib/zig-toml/src/toml.zig");
+
     // Zig SDL Bindings: https://github.com/MasterQ32/SDL.zig
     const sdk = Sdk.init(b);
     sdk.link(exe, .dynamic);

src/config.zig

@@ -0,0 +1,74 @@
+const std = @import("std");
+const toml = @import("toml");
+
+const Allocator = std.mem.Allocator;
+
+var state: Config = .{};
+
+const Config = struct {
+    host: Host = .{},
+    guest: Guest = .{},
+    debug: Debug = .{},
+
+    /// Settings related to the Computer the Emulator is being run on
+    const Host = struct {
+        /// Using Nearest-Neighbor, multiply the resolution of the GBA Window
+        win_scale: i64 = 3,
+        /// Enable Vsync
+        ///
+        /// Note: This does not affect whether Emulation is synced to 59Hz
+        vsync: bool = true,
+    };
+
+    // Settings realted to the emulation itself
+    const Guest = struct {
+        /// Whether Emulation thread to sync to Audio Callbacks
+        audio_sync: bool = true,
+        /// Whether Emulation thread should sync to 59Hz
+        video_sync: bool = true,
+        /// Whether RTC I/O should always be enabled
+        force_rtc: bool = false,
+    };
+
+    /// Settings related to debugging ZBA
+    const Debug = struct {
+        /// Enable CPU Trace logs
+        cpu_trace: bool = false,
+        /// If false and ZBA is build in debug mode, ZBA will panic on unhandled I/O
+        unhandled_io: bool = true,
+    };
+};
+
+pub fn config() *const Config {
+    return &state;
+}
+
+/// Reads a config file and then loads it into the global state
+pub fn load(allocator: Allocator, config_path: []const u8) !void {
+    var config_file = try std.fs.cwd().openFile(config_path, .{});
+    defer config_file.close();
+
+    const contents = try config_file.readToEndAlloc(allocator, try config_file.getEndPos());
+    defer allocator.free(contents);
+
+    const table = try toml.parseContents(allocator, contents, null);
+    defer table.deinit();
+
+    // TODO: Report unknown config options
+
+    if (table.keys.get("Host")) |host| {
+        if (host.Table.keys.get("win_scale")) |scale| state.host.win_scale = scale.Integer;
+        if (host.Table.keys.get("vsync")) |vsync| state.host.vsync = vsync.Boolean;
+    }
+
+    if (table.keys.get("Guest")) |guest| {
+        if (guest.Table.keys.get("audio_sync")) |sync| state.guest.audio_sync = sync.Boolean;
+        if (guest.Table.keys.get("video_sync")) |sync| state.guest.video_sync = sync.Boolean;
+        if (guest.Table.keys.get("force_rtc")) |forced| state.guest.force_rtc = forced.Boolean;
+    }
+
+    if (table.keys.get("Debug")) |debug| {
+        if (debug.Table.keys.get("cpu_trace")) |trace| state.debug.cpu_trace = trace.Boolean;
+        if (debug.Table.keys.get("unhandled_io")) |unhandled| state.debug.unhandled_io = unhandled.Boolean;
+    }
+}

src/core/bus/GamePak.zig

@@ -1,4 +1,6 @@
 const std = @import("std");
+const config = @import("../../config.zig");
+
 const Bit = @import("bitfield").Bit;
 const Bitfield = @import("bitfield").Bitfield;
 const DateTime = @import("datetime").datetime.Datetime;
@@ -8,7 +10,6 @@ const Backup = @import("backup.zig").Backup;
 const Gpio = @import("gpio.zig").Gpio;
 const Allocator = std.mem.Allocator;
 
-const force_rtc = @import("../emu.zig").force_rtc;
 const log = std.log.scoped(.GamePak);
 
 const Self = @This();
@@ -190,7 +191,7 @@ pub fn init(allocator: Allocator, cpu: *Arm7tdmi, rom_path: []const u8, save_pat
     const file_buf = try file.readToEndAlloc(allocator, try file.getEndPos());
     const title = file_buf[0xA0..0xAC].*;
     const kind = Backup.guess(file_buf);
-    const device = if (force_rtc) .Rtc else guessDevice(file_buf);
+    const device = if (config.config().guest.force_rtc) .Rtc else guessDevice(file_buf);
 
     logHeader(file_buf, &title);
 

src/core/cpu.zig

@@ -236,7 +236,6 @@ pub const thumb = struct {
     }
 };
 
-const cpu_logging = @import("emu.zig").cpu_logging;
 const log = std.log.scoped(.Arm7Tdmi);
 
 pub const Arm7tdmi = struct {
@@ -428,12 +427,12 @@ pub const Arm7tdmi = struct {
     pub fn step(self: *Self) void {
         if (self.cpsr.t.read()) {
             const opcode = self.fetch(u16);
-            if (cpu_logging) self.logger.?.mgbaLog(self, opcode);
+            if (self.logger) |*trace| trace.mgbaLog(self, opcode);
 
             thumb.lut[thumb.idx(opcode)](self, self.bus, opcode);
         } else {
             const opcode = self.fetch(u32);
-            if (cpu_logging) self.logger.?.mgbaLog(self, opcode);
+            if (self.logger) |*trace| trace.mgbaLog(self, opcode);
 
             if (checkCond(self.cpsr, @truncate(u4, opcode >> 28))) {
                 arm.lut[arm.idx(opcode)](self, self.bus, opcode);

src/core/emu.zig

@@ -1,5 +1,6 @@
 const std = @import("std");
 const SDL = @import("sdl2");
+const config = @import("../config.zig");
 
 const Bus = @import("Bus.zig");
 const Scheduler = @import("scheduler.zig").Scheduler;
@@ -12,14 +13,6 @@ const Thread = std.Thread;
 const Atomic = std.atomic.Atomic;
 const Allocator = std.mem.Allocator;
 
-// TODO: Move these to a TOML File
-const sync_audio = false; // Enable Audio Sync
-const sync_video: RunKind = .LimitedFPS; // Configure Video Sync
-pub const win_scale = 4; // 1x, 2x, 3x, etc. Window Scaling
-pub const cpu_logging = false; // Enable detailed CPU logging
-pub const allow_unhandled_io = true; // Only relevant in Debug Builds
-pub const force_rtc = false;
-
 // 228 Lines which consist of 308 dots (which are 4 cycles long)
 const cycles_per_frame: u64 = 228 * (308 * 4); //280896
 const clock_rate: u64 = 1 << 24; // 16.78MHz
@@ -40,18 +33,57 @@ const RunKind = enum {
     UnlimitedFPS,
     Limited,
     LimitedFPS,
-    LimitedBusy,
 };
 
-pub fn run(quit: *Atomic(bool), fps: *FpsTracker, sched: *Scheduler, cpu: *Arm7tdmi) void {
-    if (sync_audio) log.info("Audio sync enabled", .{});
+pub fn run(quit: *Atomic(bool), scheduler: *Scheduler, cpu: *Arm7tdmi, tracker: *FpsTracker) void {
+    const audio_sync = config.config().guest.audio_sync;
+    if (audio_sync) log.info("Audio sync enabled", .{});
 
-    switch (sync_video) {
-        .Unlimited => runUnsynchronized(quit, sched, cpu, null),
-        .Limited => runSynchronized(quit, sched, cpu, null),
-        .UnlimitedFPS => runUnsynchronized(quit, sched, cpu, fps),
-        .LimitedFPS => runSynchronized(quit, sched, cpu, fps),
-        .LimitedBusy => runBusyLoop(quit, sched, cpu),
+    if (config.config().guest.video_sync) {
+        inner(.LimitedFPS, audio_sync, quit, scheduler, cpu, tracker);
+    } else {
+        inner(.UnlimitedFPS, audio_sync, quit, scheduler, cpu, tracker);
+    }
+}
+
+fn inner(comptime kind: RunKind, audio_sync: bool, quit: *Atomic(bool), scheduler: *Scheduler, cpu: *Arm7tdmi, tracker: ?*FpsTracker) void {
+    if (kind == .UnlimitedFPS or kind == .LimitedFPS) {
+        std.debug.assert(tracker != null);
+        log.info("FPS tracking enabled", .{});
+    }
+
+    switch (kind) {
+        .Unlimited, .UnlimitedFPS => {
+            log.info("Emulation w/out video sync", .{});
+
+            while (!quit.load(.SeqCst)) {
+                runFrame(scheduler, cpu);
+                audioSync(audio_sync, cpu.bus.apu.stream, &cpu.bus.apu.is_buffer_full);
+
+                if (kind == .UnlimitedFPS) tracker.?.tick();
+            }
+        },
+        .Limited, .LimitedFPS => {
+            log.info("Emulation w/ video sync", .{});
+            var timer = Timer.start() catch @panic("failed to initalize std.timer.Timer");
+            var wake_time: u64 = frame_period;
+
+            while (!quit.load(.SeqCst)) {
+                runFrame(scheduler, cpu);
+                const new_wake_time = videoSync(&timer, wake_time);
+
+                // Spin to make up the difference of OS scheduler innacuracies
+                // If we happen to also be syncing to audio, we choose to spin on
+                // the amount of time needed for audio to catch up rather than
+                // our expected wake-up time
+
+                audioSync(audio_sync, cpu.bus.apu.stream, &cpu.bus.apu.is_buffer_full);
+                if (!audio_sync) spinLoop(&timer, wake_time);
+                wake_time = new_wake_time;
+
+                if (kind == .LimitedFPS) tracker.?.tick();
+            }
+        },
     }
 }
 
@@ -72,7 +104,7 @@ pub fn runFrame(sched: *Scheduler, cpu: *Arm7tdmi) void {
     }
 }
 
-fn syncToAudio(stream: *SDL.SDL_AudioStream, is_buffer_full: *bool) void {
+fn audioSync(audio_sync: bool, stream: *SDL.SDL_AudioStream, is_buffer_full: *bool) void {
     const sample_size = 2 * @sizeOf(u16);
     const max_buf_size: c_int = 0x400;
 
@@ -85,90 +117,20 @@ fn syncToAudio(stream: *SDL.SDL_AudioStream, is_buffer_full: *bool) void {
 
     while (true) {
         still_full = SDL.SDL_AudioStreamAvailable(stream) > sample_size * max_buf_size >> 1;
-        if (!sync_audio or !still_full) break;
+        if (!audio_sync or !still_full) break;
     }
 }
 
-pub fn runUnsynchronized(quit: *Atomic(bool), sched: *Scheduler, cpu: *Arm7tdmi, fps: ?*FpsTracker) void {
-    log.info("Emulation thread w/out video sync", .{});
-
-    if (fps) |tracker| {
-        log.info("FPS Tracking Enabled", .{});
-
-        while (!quit.load(.SeqCst)) {
-            runFrame(sched, cpu);
-            syncToAudio(cpu.bus.apu.stream, &cpu.bus.apu.is_buffer_full);
-
-            tracker.tick();
-        }
-    } else {
-        while (!quit.load(.SeqCst)) {
-            runFrame(sched, cpu);
-            syncToAudio(cpu.bus.apu.stream, &cpu.bus.apu.is_buffer_full);
-        }
-    }
-}
-
-pub fn runSynchronized(quit: *Atomic(bool), sched: *Scheduler, cpu: *Arm7tdmi, fps: ?*FpsTracker) void {
-    log.info("Emulation thread w/ video sync", .{});
-    var timer = Timer.start() catch std.debug.panic("Failed to initialize std.timer.Timer", .{});
-    var wake_time: u64 = frame_period;
-
-    if (fps) |tracker| {
-        log.info("FPS Tracking Enabled", .{});
-
-        while (!quit.load(.SeqCst)) {
-            runFrame(sched, cpu);
-            const new_wake_time = blockOnVideo(&timer, wake_time);
-
-            // Spin to make up the difference of OS scheduler innacuracies
-            // If we happen to also be syncing to audio, we choose to spin on
-            // the amount of time needed for audio to catch up rather than
-            // our expected wake-up time
-            syncToAudio(cpu.bus.apu.stream, &cpu.bus.apu.is_buffer_full);
-            if (!sync_audio) spinLoop(&timer, wake_time);
-            wake_time = new_wake_time;
-
-            tracker.tick();
-        }
-    } else {
-        while (!quit.load(.SeqCst)) {
-            runFrame(sched, cpu);
-            const new_wake_time = blockOnVideo(&timer, wake_time);
-
-            // see above comment
-            syncToAudio(cpu.bus.apu.stream, &cpu.bus.apu.is_buffer_full);
-            if (!sync_audio) spinLoop(&timer, wake_time);
-            wake_time = new_wake_time;
-        }
-    }
-}
-
-inline fn blockOnVideo(timer: *Timer, wake_time: u64) u64 {
+fn videoSync(timer: *Timer, wake_time: u64) u64 {
     // Use the OS scheduler to put the emulation thread to sleep
-    const maybe_recalc_wake_time = sleep(timer, wake_time);
+    const recalculated = sleep(timer, wake_time);
 
     // If sleep() determined we need to adjust our wake up time, do so
     // otherwise predict our next wake up time according to the frame period
-    return if (maybe_recalc_wake_time) |recalc| recalc else wake_time + frame_period;
-}
-
-pub fn runBusyLoop(quit: *Atomic(bool), sched: *Scheduler, cpu: *Arm7tdmi) void {
-    log.info("Emulation thread with video sync using busy loop", .{});
-    var timer = Timer.start() catch unreachable;
-    var wake_time: u64 = frame_period;
-
-    while (!quit.load(.SeqCst)) {
-        runFrame(sched, cpu);
-        spinLoop(&timer, wake_time);
-
-        syncToAudio(cpu.bus.apu.stream, &cpu.bus.apu.is_buffer_full);
-
-        // Update to the new wake time
-        wake_time += frame_period;
-    }
+    return recalculated orelse wake_time + frame_period;
 }
 
+// TODO: Better sleep impl?
 fn sleep(timer: *Timer, wake_time: u64) ?u64 {
     // const step = std.time.ns_per_ms * 10; // 10ms
     const timestamp = timer.read();

src/main.zig

@@ -1,9 +1,10 @@
 const std = @import("std");
 const builtin = @import("builtin");
-
 const known_folders = @import("known_folders");
 const clap = @import("clap");
 
+const config = @import("config.zig");
+
 const Gui = @import("platform.zig").Gui;
 const Bus = @import("core/Bus.zig");
 const Arm7tdmi = @import("core/cpu.zig").Arm7tdmi;
@@ -14,11 +15,8 @@ const Allocator = std.mem.Allocator;
 const log = std.log.scoped(.Cli);
 const width = @import("core/ppu.zig").width;
 const height = @import("core/ppu.zig").height;
-const cpu_logging = @import("core/emu.zig").cpu_logging;
 pub const log_level = if (builtin.mode != .Debug) .info else std.log.default_level;
 
-// TODO: Reimpl Logging
-
 // CLI Arguments + Help Text
 const params = clap.parseParamsComptime(
     \\-h, --help            Display this help and exit.
@@ -33,14 +31,27 @@ pub fn main() anyerror!void {
     defer std.debug.assert(!gpa.deinit());
     const allocator = gpa.allocator();
 
+    // TODO: Make Error message not Linux Specific
+    const data_path = try known_folders.getPath(allocator, .data) orelse exit("Unable to Determine XDG Data Path", .{});
+    defer allocator.free(data_path);
+
+    const config_path = try configFilePath(allocator, data_path);
+    defer allocator.free(config_path);
+
+    const save_path = try savePath(allocator, data_path);
+    defer allocator.free(save_path);
+
+    try config.load(allocator, config_path);
+
     // Handle CLI Input
     const result = try clap.parse(clap.Help, &params, clap.parsers.default, .{});
     defer result.deinit();
 
-    const paths = try handleArguments(allocator, &result);
+    const paths = try handleArguments(allocator, data_path, &result);
     defer if (paths.save) |path| allocator.free(path);
 
-    const log_file: ?std.fs.File = if (cpu_logging) try std.fs.cwd().createFile("zba.log", .{}) else null;
+    const cpu_trace = config.config().debug.cpu_trace;
+    const log_file: ?std.fs.File = if (cpu_trace) try std.fs.cwd().createFile("zba.log", .{}) else null;
     defer if (log_file) |file| file.close();
 
     // TODO: Take Emulator Init Code out of main.zig
@@ -60,39 +71,15 @@ pub fn main() anyerror!void {
     try gui.run(&cpu, &scheduler);
 }
 
-fn getSavePath(allocator: Allocator) !?[]const u8 {
-    const save_subpath = "zba" ++ [_]u8{std.fs.path.sep} ++ "save";
-
-    const maybe_data_path = try known_folders.getPath(allocator, .data);
-    defer if (maybe_data_path) |path| allocator.free(path);
-
-    const save_path = if (maybe_data_path) |base| try std.fs.path.join(allocator, &[_][]const u8{ base, "zba", "save" }) else null;
-
-    if (save_path) |_| {
-        // If we've determined what our save path should be, ensure the prereq directories
-        // are present so that we can successfully write to the path when necessary
-        const maybe_data_dir = try known_folders.open(allocator, .data, .{});
-        if (maybe_data_dir) |data_dir| try data_dir.makePath(save_subpath);
-    }
-
-    return save_path;
-}
-
-fn getRomPath(result: *const clap.Result(clap.Help, &params, clap.parsers.default)) ![]const u8 {
-    return switch (result.positionals.len) {
-        1 => result.positionals[0],
-        0 => std.debug.panic("ZBA requires a positional path to a GamePak ROM.\n", .{}),
-        else => std.debug.panic("ZBA received too many arguments.\n", .{}),
-    };
-}
-
-pub fn handleArguments(allocator: Allocator, result: *const clap.Result(clap.Help, &params, clap.parsers.default)) !FilePaths {
-    const rom_path = try getRomPath(result);
+pub fn handleArguments(allocator: Allocator, data_path: []const u8, result: *const clap.Result(clap.Help, &params, clap.parsers.default)) !FilePaths {
+    const rom_path = romPath(result);
     log.info("ROM path: {s}", .{rom_path});
+
     const bios_path = result.args.bios;
     if (bios_path) |path| log.info("BIOS path: {s}", .{path}) else log.info("No BIOS provided", .{});
-    const save_path = try getSavePath(allocator);
-    if (save_path) |path| log.info("Save path: {s}", .{path});
+
+    const save_path = try savePath(allocator, data_path);
+    log.info("Save path: {s}", .{save_path});
 
     return FilePaths{
         .rom = rom_path,
@@ -100,3 +87,42 @@ pub fn handleArguments(allocator: Allocator, result: *const clap.Result(clap.Hel
         .save = save_path,
     };
 }
+
+fn configFilePath(allocator: Allocator, data_path: []const u8) ![]const u8 {
+    const path = try std.fs.path.join(allocator, &[_][]const u8{ data_path, "zba", "config.toml" });
+
+    // We try to create the file exclusively, meaning that we err out if the file already exists.
+    // All we care about is a file being there so we can just ignore that error in particular and
+    // continue down the happy pathj
+    std.fs.accessAbsolute(path, .{}) catch {
+        const file_handle = try std.fs.createFileAbsolute(path, .{});
+        file_handle.close();
+    };
+
+    return path;
+}
+
+fn savePath(allocator: Allocator, data_path: []const u8) ![]const u8 {
+    var dir = try std.fs.openDirAbsolute(data_path, .{});
+    defer dir.close();
+
+    // Will either make the path recursively, or just exit early since it already exists
+    try dir.makePath("zba" ++ [_]u8{std.fs.path.sep} ++ "save");
+
+    // FIXME: Do we have to allocate? :sad:
+    return try std.fs.path.join(allocator, &[_][]const u8{ data_path, "zba", "save" });
+}
+
+fn romPath(result: *const clap.Result(clap.Help, &params, clap.parsers.default)) []const u8 {
+    return switch (result.positionals.len) {
+        1 => result.positionals[0],
+        0 => exit("ZBA requires a path to a GamePak ROM\n", .{}),
+        else => exit("ZBA received too many positional arguments. \n", .{}),
+    };
+}
+
+fn exit(comptime format: []const u8, args: anytype) noreturn {
+    const stderr = std.io.getStdErr().writer();
+    stderr.print(format, args) catch {}; // Just exit already...
+    std.os.exit(1);
+}

src/platform.zig

@@ -1,6 +1,7 @@
 const std = @import("std");
 const SDL = @import("sdl2");
 const emu = @import("core/emu.zig");
+const config = @import("config.zig");
 
 const Apu = @import("core/apu.zig").Apu;
 const Arm7tdmi = @import("core/cpu.zig").Arm7tdmi;
@@ -10,8 +11,6 @@ const FpsTracker = @import("util.zig").FpsTracker;
 const span = @import("util.zig").span;
 
 const pitch = @import("core/ppu.zig").framebuf_pitch;
-const scale = @import("core/emu.zig").win_scale;
-
 const default_title: []const u8 = "ZBA";
 
 pub const Gui = struct {
@@ -28,16 +27,19 @@ pub const Gui = struct {
         const ret = SDL.SDL_Init(SDL.SDL_INIT_VIDEO | SDL.SDL_INIT_EVENTS | SDL.SDL_INIT_AUDIO | SDL.SDL_INIT_GAMECONTROLLER);
         if (ret < 0) panic();
 
+        const win_scale = @intCast(c_int, config.config().host.win_scale);
+
         const window = SDL.SDL_CreateWindow(
             default_title.ptr,
             SDL.SDL_WINDOWPOS_CENTERED,
             SDL.SDL_WINDOWPOS_CENTERED,
-            @as(c_int, width * scale),
-            @as(c_int, height * scale),
+            @as(c_int, width * win_scale),
+            @as(c_int, height * win_scale),
             SDL.SDL_WINDOW_SHOWN,
         ) orelse panic();
 
-        const renderer = SDL.SDL_CreateRenderer(window, -1, SDL.SDL_RENDERER_ACCELERATED | SDL.SDL_RENDERER_PRESENTVSYNC) orelse panic();
+        const renderer_flags = SDL.SDL_RENDERER_ACCELERATED | if (config.config().host.vsync) SDL.SDL_RENDERER_PRESENTVSYNC else 0;
+        const renderer = SDL.SDL_CreateRenderer(window, -1, @bitCast(u32, renderer_flags)) orelse panic();
 
         const texture = SDL.SDL_CreateTexture(
             renderer,
@@ -58,9 +60,9 @@ pub const Gui = struct {
 
     pub fn run(self: *Self, cpu: *Arm7tdmi, scheduler: *Scheduler) !void {
         var quit = std.atomic.Atomic(bool).init(false);
-        var frame_rate = FpsTracker.init();
+        var tracker = FpsTracker.init();
 
-        const thread = try std.Thread.spawn(.{}, emu.run, .{ &quit, &frame_rate, scheduler, cpu });
+        const thread = try std.Thread.spawn(.{}, emu.run, .{ &quit, scheduler, cpu, &tracker });
         defer thread.join();
 
         var title_buf: [0x100]u8 = [_]u8{0} ** 0x100;
@@ -127,7 +129,7 @@ pub const Gui = struct {
             _ = SDL.SDL_RenderCopy(self.renderer, self.texture, null, null);
             SDL.SDL_RenderPresent(self.renderer);
 
-            const dyn_title = std.fmt.bufPrint(&title_buf, "ZBA | {s} [Emu: {}fps] ", .{ self.title, frame_rate.value() }) catch unreachable;
+            const dyn_title = std.fmt.bufPrint(&title_buf, "ZBA | {s} [Emu: {}fps] ", .{ self.title, tracker.value() }) catch unreachable;
             SDL.SDL_SetWindowTitle(self.window, dyn_title.ptr);
         }
 

src/util.zig

@@ -1,10 +1,10 @@
 const std = @import("std");
 const builtin = @import("builtin");
+const config = @import("config.zig");
+
 const Log2Int = std.math.Log2Int;
 const Arm7tdmi = @import("core/cpu.zig").Arm7tdmi;
 
-const allow_unhandled_io = @import("core/emu.zig").allow_unhandled_io;
-
 // Sign-Extend value of type `T` to type `U`
 pub fn sext(comptime T: type, comptime U: type, value: T) T {
     // U must have less bits than T
@@ -144,8 +144,10 @@ pub const io = struct {
         }
 
         pub fn undef(comptime T: type, log: anytype, comptime format: []const u8, args: anytype) ?T {
+            const unhandled_io = config.config().debug.unhandled_io;
+
             log.warn(format, args);
-            if (builtin.mode == .Debug and !allow_unhandled_io) std.debug.panic("TODO: Implement I/O Register", .{});
+            if (builtin.mode == .Debug and !unhandled_io) std.debug.panic("TODO: Implement I/O Register", .{});
 
             return null;
         }
@@ -153,8 +155,10 @@ pub const io = struct {
 
     pub const write = struct {
         pub fn undef(log: anytype, comptime format: []const u8, args: anytype) void {
+            const unhandled_io = config.config().debug.unhandled_io;
+
             log.warn(format, args);
-            if (builtin.mode == .Debug and !allow_unhandled_io) std.debug.panic("TODO: Implement I/O Register", .{});
+            if (builtin.mode == .Debug and !unhandled_io) std.debug.panic("TODO: Implement I/O Register", .{});
         }
     };
 };