fix: implement Ace Lightning (2002) obscure behaviour

Reviewed-on: #7

.github/workflows/main.yml

@@ -24,8 +24,8 @@ jobs:
       - name: prepare-linux
         if: runner.os == 'Linux'
         run: |
-            sudo apt-get update
+            sudo apt update
-            sudo apt-get install libsdl2-dev
+            sudo apt install libgtk-3-dev libsdl2-dev
       - name: prepare-windows
         if: runner.os == 'Windows'
         run: |

README.md

@@ -2,6 +2,8 @@
 
 A Game Boy Advance Emulator written in Zig ⚡!
 
+![ZBA running リズム天国](assets/screenshot.png)
+
 ## Scope
 
 I'm hardly the first to write a Game Boy Advance Emulator nor will I be the last. This project isn't going to compete with the GOATs like [mGBA](https://github.com/mgba-emu) or [NanoBoyAdvance](https://github.com/nba-emu/NanoBoyAdvance). There aren't any interesting ideas either like in [DSHBA](https://github.com/DenSinH/DSHBA).
@@ -13,14 +15,13 @@ This is a simple (read: incomplete) for-fun long-term project. I hope to get "mo
 - [x] Affine Sprites
 - [ ] Windowing (see [this branch](https://git.musuka.dev/paoda/zba/src/branch/window))
 - [ ] Audio Resampler (Having issues with SDL2's)
-- [x] Immediate Mode GUI (see [this branch](https://git.musuka.dev/paoda/zba/src/branch/imgui))
 - [ ] Refactoring for easy-ish perf boosts
 
 ## Usage
 
 As it currently exists, ZBA is run from the terminal. In your console of choice, type `./zba --help` to see what you can do.
 
-I typically find myself typing `./zba -b ./bin/bios.bin ./bin/test/suite.gba` to see how badly my "cool new feature" broke everything else.
+I typically find myself typing `./zba -b ./bin/bios.bin` and then going to File -> Insert ROM to load the title of my choice.
 
 Need a BIOS? Why not try using the open-source [Cult-Of-GBA BIOS](https://github.com/Cult-of-GBA/BIOS) written by [fleroviux](https://github.com/fleroviux) and [DenSinH](https://github.com/DenSinH)?
 
@@ -77,7 +78,7 @@ arm7wrestler GBA Fixed | [destoer](https://github.com/destoer)
 
 ## Compiling
 
-Most recently built on Zig [v0.11.0-dev.1580+a5b34a61a](https://github.com/ziglang/zig/tree/a5b34a61a)
+Most recently built on Zig [v0.11.0-dev.2168+322ace70f](https://github.com/ziglang/zig/tree/322ace70f)
 
 ### Dependencies
 

build.zig

@@ -6,9 +6,9 @@ const gdbstub = @import("lib/zba-gdbstub/build.zig");
 const zgui = @import("lib/zgui/build.zig");
 const nfd = @import("lib/nfd-zig/build.zig");
 
-pub fn build(b: *std.build.Builder) void {
+pub fn build(b: *std.Build) void {
     // Minimum Zig Version
-    const min_ver = std.SemanticVersion.parse("0.11.0-dev.1580+a5b34a61a") catch return; // https://github.com/ziglang/zig/commit/a5b34a61a
+    const min_ver = std.SemanticVersion.parse("0.11.0-dev.2168+322ace70f") catch return; // https://github.com/ziglang/zig/commit/322ace70f
     if (builtin.zig_version.order(min_ver).compare(.lt)) {
         std.log.err("{s}", .{b.fmt("Zig v{} does not meet the minimum version requirement. (Zig v{})", .{ builtin.zig_version, min_ver })});
         std.os.exit(1);
@@ -48,7 +48,8 @@ pub fn build(b: *std.build.Builder) void {
     exe.addAnonymousModule("zba-util", .{ .source_file = .{ .path = "lib/zba-util/src/lib.zig" } });
 
     // gdbstub
-    gdbstub.link(exe);
+    exe.addModule("gdbstub", gdbstub.getModule(b));
+
     // NativeFileDialog(ue) Bindings
     exe.linkLibrary(nfd.makeLib(b, target, optimize));
     exe.addModule("nfd", nfd.getModule(b));
@@ -59,9 +60,10 @@ pub fn build(b: *std.build.Builder) void {
     exe.addModule("sdl2", sdk.getNativeModule());
 
     // Dear ImGui bindings
-    const zgui_pkg = zgui.package(b, .{ .options = .{ .backend = .sdl2_opengl3 } });
+
-    exe.addModule("zgui", zgui_pkg.module);
+    // .shared option should stay in sync with SDL.zig call above where true == .dynamic, and false == .static
-    zgui.link(exe, zgui_pkg.options);
+    const zgui_pkg = zgui.package(b, target, optimize, .{ .options = .{ .backend = .sdl2_opengl3, .shared = true } });
+    zgui_pkg.link(exe);
 
     exe.install();
 

src/core/bus/GamePak.zig

@@ -179,23 +179,30 @@ pub fn write(self: *Self, comptime T: type, word_count: u16, address: u32, value
     }
 }
 
-pub fn init(allocator: Allocator, cpu: *Arm7tdmi, rom_path: []const u8, save_path: ?[]const u8) !Self {
+pub fn init(allocator: Allocator, cpu: *Arm7tdmi, maybe_rom: ?[]const u8, maybe_save: ?[]const u8) !Self {
-    const file = try std.fs.cwd().openFile(rom_path, .{});
+    const Device = Gpio.Device;
-    defer file.close();
 
-    const file_buf = try file.readToEndAlloc(allocator, try file.getEndPos());
+    const items: struct { []u8, [12]u8, Backup.Kind, Device.Kind } = if (maybe_rom) |file_path| blk: {
-    const title = file_buf[0xA0..0xAC].*;
+        const file = try std.fs.cwd().openFile(file_path, .{});
-    const kind = Backup.guess(file_buf);
+        defer file.close();
-    const device = if (config.config().guest.force_rtc) .Rtc else guessDevice(file_buf);
 
-    logHeader(file_buf, title);
+        const buffer = try file.readToEndAlloc(allocator, try file.getEndPos());
+        const title = buffer[0xA0..0xAC];
+        logHeader(buffer, title);
+
+        const device_kind = if (config.config().guest.force_rtc) .Rtc else guessDevice(buffer);
+
+        break :blk .{ buffer, title.*, Backup.guess(buffer), device_kind };
+    } else .{ try allocator.alloc(u8, 0), [_]u8{0} ** 12, .None, .None };
+
+    const title = items[1];
 
     return .{
-        .buf = file_buf,
+        .buf = items[0],
         .allocator = allocator,
         .title = title,
-        .backup = try Backup.init(allocator, kind, title, save_path),
+        .backup = try Backup.init(allocator, items[2], title, maybe_save),
-        .gpio = try Gpio.init(allocator, cpu, device),
+        .gpio = try Gpio.init(allocator, cpu, items[3]),
     };
 }
 
@@ -223,11 +230,11 @@ fn guessDevice(buf: []const u8) Gpio.Device.Kind {
     return .None;
 }
 
-fn logHeader(buf: []const u8, title: [12]u8) void {
+fn logHeader(buf: []const u8, title: *const [12]u8) void {
-    const ver = buf[0xBC];
+    const version = buf[0xBC];
 
     log.info("Title: {s}", .{title});
-    if (ver != 0) log.info("Version: {}", .{ver});
+    if (version != 0) log.info("Version: {}", .{version});
 
     log.info("Game Code: {s}", .{buf[0xAC..0xB0]});
     log.info("Maker Code: {s}", .{buf[0xB0..0xB2]});

src/core/bus/backup.zig

@@ -32,7 +32,7 @@ pub const Backup = struct {
     flash: Flash,
     eeprom: Eeprom,
 
-    const Kind = enum {
+    pub const Kind = enum {
         Eeprom,
         Sram,
         Flash,
@@ -205,6 +205,10 @@ pub const Backup = struct {
         const file_path = try self.savePath(allocator, path);
         defer allocator.free(file_path);
 
+        // FIXME: communicate edge case to the user?
+        if (std.mem.eql(u8, &self.title, "ACE LIGHTNIN"))
+            return;
+
         switch (self.kind) {
             .Sram, .Flash, .Flash1M, .Eeprom => {
                 const file = try std.fs.createFileAbsolute(file_path, .{});

src/imgui.zig

@@ -21,30 +21,27 @@ const gba_height = @import("core/ppu.zig").height;
 
 const log = std.log.scoped(.Imgui);
 
-// TODO: Document how I decided on this value (I forgot 😅)
+// two seconds worth of fps values into the past
-const histogram_len = 0x400;
+const histogram_len = 0x80;
 
 /// Immediate-Mode GUI State
 pub const State = struct {
-    title: [:0]const u8,
+    title: [12:0]u8,
 
     fps_hist: RingBuffer(u32),
     should_quit: bool = false,
 
-    pub fn init(allocator: Allocator, title: [12]u8) !@This() {
+    /// if zba is initialized with a ROM already provided, this initializer should be called
+    /// with `title_opt` being non-null
+    pub fn init(allocator: Allocator, title_opt: ?*const [12]u8) !@This() {
         const history = try allocator.alloc(u32, histogram_len);
-        const without_null = std.mem.sliceTo(&title, 0);
 
-        return .{
+        const title: [12:0]u8 = if (title_opt) |t| t.* ++ [_:0]u8{} else "[No Title]\x00\x00".*;
-            .title = try allocator.dupeZ(u8, without_null),
+        return .{ .title = title, .fps_hist = RingBuffer(u32).init(history) };
-            .fps_hist = RingBuffer(u32).init(history),
-        };
     }
 
     pub fn deinit(self: *@This(), allocator: Allocator) void {
-        allocator.free(self.title);
         allocator.free(self.fps_hist.buf);
-
         self.* = undefined;
     }
 };
@@ -60,21 +57,26 @@ pub fn draw(state: *State, tex_id: GLuint, cpu: *Arm7tdmi) void {
             defer zgui.endMenu();
 
             if (zgui.menuItem("Quit", .{})) state.should_quit = true;
+
             if (zgui.menuItem("Insert ROM", .{})) blk: {
                 const maybe_path = nfd.openFileDialog("gba", null) catch |e| {
-                    log.err("failed to open file dialog: {?}", .{e});
+                    log.err("failed to open file dialog: {}", .{e});
                     break :blk;
                 };
 
-                if (maybe_path) |file_path| {
+                const file_path = maybe_path orelse {
-                    defer nfd.freePath(file_path);
+                    log.warn("did not receive a file path", .{});
-                    log.info("user chose: \"{s}\"", .{file_path});
+                    break :blk;
+                };
+                defer nfd.freePath(file_path);
 
-                    emu.replaceGamepak(cpu, file_path) catch |e| {
+                log.info("user chose: \"{s}\"", .{file_path});
-                        log.err("failed to replace GamePak: {}", .{e});
+                emu.replaceGamepak(cpu, file_path) catch |e| {
-                        break :blk;
+                    log.err("failed to replace GamePak: {}", .{e});
-                    };
+                    break :blk;
-                }
+                };
+
+                state.title = cpu.bus.pak.title ++ [_:0]u8{};
             }
         }
 
@@ -91,7 +93,7 @@ pub fn draw(state: *State, tex_id: GLuint, cpu: *Arm7tdmi) void {
         const w = @intToFloat(f32, gba_width * win_scale);
         const h = @intToFloat(f32, gba_height * win_scale);
 
-        const window_title = if (state.title.len != 0) state.title else "[No Title]";
+        const window_title = std.mem.sliceTo(&state.title, 0);
         _ = zgui.begin(window_title, .{ .flags = .{ .no_resize = true, .always_auto_resize = true } });
         defer zgui.end();
 
@@ -127,7 +129,7 @@ pub fn draw(state: *State, tex_id: GLuint, cpu: *Arm7tdmi) void {
         defer zgui.end();
 
         const tmp = blk: {
-            var buf: [0x400]u32 = undefined;
+            var buf: [histogram_len]u32 = undefined;
             const len = state.fps_hist.copy(&buf);
 
             break :blk .{ buf, len };

src/main.zig

@@ -90,8 +90,10 @@ pub fn main() void {
         cpu.fastBoot();
     }
 
+    const title_ptr = if (paths.rom != null) &bus.pak.title else null;
+
     // TODO: Just copy the title instead of grabbing a pointer to it
-    var gui = Gui.init(allocator, bus.pak.title, &bus.apu) catch |e| exitln("failed to init gui: {}", .{e});
+    var gui = Gui.init(allocator, &bus.apu, title_ptr) catch |e| exitln("failed to init gui: {}", .{e});
     defer gui.deinit();
 
     var quit = std.atomic.Atomic(bool).init(false);
@@ -139,7 +141,7 @@ pub fn main() void {
 
 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});
+    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.warn("No BIOS provided", .{});
@@ -188,10 +190,10 @@ fn ensureConfigDirExists(config_path: []const u8) !void {
     try dir.makePath("zba");
 }
 
-fn romPath(result: *const clap.Result(clap.Help, &params, clap.parsers.default)) []const u8 {
+fn romPath(result: *const clap.Result(clap.Help, &params, clap.parsers.default)) ?[]const u8 {
     return switch (result.positionals.len) {
+        0 => null,
         1 => result.positionals[0],
-        0 => exitln("ZBA requires a path to a GamePak ROM", .{}),
         else => exitln("ZBA received too many positional arguments.", .{}),
     };
 }

src/platform.zig

@@ -57,7 +57,7 @@ pub const Gui = struct {
     allocator: Allocator,
     program_id: gl.GLuint,
 
-    pub fn init(allocator: Allocator, title: [12]u8, apu: *Apu) !Self {
+    pub fn init(allocator: Allocator, apu: *Apu, title_opt: ?*const [12]u8) !Self {
         if (SDL.SDL_Init(SDL.SDL_INIT_VIDEO | SDL.SDL_INIT_EVENTS | SDL.SDL_INIT_AUDIO) < 0) panic();
         if (SDL.SDL_GL_SetAttribute(SDL.SDL_GL_CONTEXT_PROFILE_MASK, SDL.SDL_GL_CONTEXT_PROFILE_CORE) < 0) panic();
         if (SDL.SDL_GL_SetAttribute(SDL.SDL_GL_CONTEXT_MAJOR_VERSION, 3) < 0) panic();
@@ -91,7 +91,7 @@ pub const Gui = struct {
             .audio = Audio.init(apu),
 
             .allocator = allocator,
-            .state = try imgui.State.init(allocator, title),
+            .state = try imgui.State.init(allocator, title_opt),
         };
     }
 

src/util.zig

@@ -50,7 +50,7 @@ pub fn escape(title: [12]u8) [12]u8 {
 }
 
 pub const FilePaths = struct {
-    rom: []const u8,
+    rom: ?[]const u8,
     bios: ?[]const u8,
     save: ?[]const u8,
 };