Got ecs and assets imported

assets/assets-template

@@ -0,0 +1,8 @@
+{{#sprites}}
+// {{name}}
+pub const {{name}}_width = {{width}};
+pub const {{name}}_height = {{height}};
+pub const {{name}}_flags = {{flags}}; // {{flagsHumanReadable}}
+pub const {{name}} = [{{length}}]u8{ {{bytes}} };
+
+{{/sprites}}

assets/assets.zig

@@ -0,0 +1,2 @@
+// pub const tiles = @import("tiles.zig");
+pub usingnamespace @import("sprites.zig");

build-assets.sh

@@ -0,0 +1,4 @@
+#!/usr/bin/env bash
+
+w4 png2src --template assets/assets-template --zig assets/tiles.png -o assets/tiles.zig
+w4 png2src --template assets/assets-template --zig assets/sprites.png -o assets/sprites.zig

build.zig

@@ -45,9 +45,15 @@ test "stack version check" {
 }
 
 pub fn build(b: *std.build.Builder) !void {
+    const assets = std.build.Pkg{
+        .name = "assets",
+        .path = .{ .path = "assets/assets.zig" },
+    };
+
     const zig_version = @import("builtin").zig_version;
     const mode = b.standardReleaseOptions();
     const lib = b.addSharedLibrary("cart", "src/main.zig", .unversioned);
+    lib.addPackage(assets);
     lib.setBuildMode(mode);
     lib.setTarget(.{ .cpu_arch = .wasm32, .os_tag = .freestanding });
     lib.import_memory = true;

src/ecs.zig

@@ -0,0 +1,169 @@
+const std = @import("std");
+const ArgsTuple = std.meta.Tuple;
+const Tuple = std.meta.Tuple;
+
+pub fn World(comptime ComponentBase: type) type {
+    // Build a component type at comptime based off of ComponentBase. It makes all the fields
+    // nullable so they are easy to pull out of the store.
+    const Component = componentConstructor: {
+        var fields = std.meta.fields(ComponentBase);
+        var newFields: [fields.len]std.builtin.TypeInfo.StructField = undefined;
+        inline for (fields) |field, i| {
+            const T = field.field_type;
+            const default: ?T = null;
+            newFields[i] = std.builtin.TypeInfo.StructField{
+                .name = field.name,
+                .field_type = ?T,
+                .default_value = default,
+                .is_comptime = false,
+                .alignment = if (@sizeOf(T) > 0) @alignOf(T) else 0,
+            };
+        }
+        break :componentConstructor @Type(.{ .Struct = .{
+            .layout = .Auto,
+            .fields = &newFields,
+            .decls = &[_]std.builtin.TypeInfo.Declaration{},
+            .is_tuple = false,
+        } });
+    };
+    return struct {
+        components: ComponentPool,
+        alloc: std.mem.Allocator,
+        pub const Query = ComponentQuery;
+
+        const ComponentPool = std.MultiArrayList(Component);
+        const ComponentEnum = std.meta.FieldEnum(Component);
+        const ComponentSet = std.EnumSet(ComponentEnum);
+        const ComponentQuery = struct {
+            required: ComponentSet = ComponentSet.init(.{}),
+            excluded: ComponentSet = ComponentSet.init(.{}),
+
+            pub fn init() @This() {
+                return @This(){};
+            }
+
+            pub fn query(require_set: []const ComponentEnum, exclude_set: []const ComponentEnum) @This() {
+                var this = @This(){};
+                for (require_set) |f| {
+                    this.required.insert(f);
+                }
+                for (exclude_set) |f| {
+                    this.excluded.insert(f);
+                }
+                return this;
+            }
+
+            pub fn require(set: []const ComponentEnum) @This() {
+                var this = @This(){};
+                for (set) |f| {
+                    this.required.insert(f);
+                }
+                return this;
+            }
+
+            pub fn exclude(set: []const ComponentEnum) @This() {
+                var this = @This(){};
+                for (set) |f| {
+                    this.excluded.insert(f);
+                }
+                return this;
+            }
+        };
+
+        const fields = std.meta.fields(Component);
+
+        pub fn init(alloc: std.mem.Allocator) @This() {
+            return @This(){
+                .components = ComponentPool{},
+                .alloc = alloc,
+            };
+        }
+
+        pub fn create(this: *@This(), component: Component) usize {
+            const len = this.components.len;
+            this.components.append(this.alloc, component) catch unreachable;
+            return len;
+        }
+
+        pub fn destroy(this: *@This(), entity: usize) void {
+            // TODO
+            _ = this;
+            _ = entity;
+            @compileError("unimplemented");
+        }
+
+        pub fn get(this: *@This(), entity: usize, component: ComponentEnum) *Component {
+            return this.components.items(component)[entity];
+        }
+
+        fn enum2type(comptime enumList: []const ComponentEnum) []type {
+            var t: [enumList.len]type = undefined;
+            inline for (enumList) |e, i| {
+                const field_type = @typeInfo(fields[@enumToInt(e)].field_type);
+                t[i] = *field_type.Optional.child;
+            }
+            return &t;
+        }
+
+        pub fn process(this: *@This(), dt: f32, comptime comp: []const ComponentEnum, func: anytype) void {
+            const Args = Tuple([_]type{f32} ++ enum2type(comp));
+            var i = this.iter(Query.require(comp));
+            while (i.next()) |e| {
+                var args: Args = undefined;
+                args[0] = dt;
+                inline for (comp) |f, j| {
+                    args[j + 1] = &(@field(e, @tagName(f)).?);
+                }
+                @call(.{}, func, args);
+            }
+        }
+
+        pub fn iterAll(this: *@This()) Iterator {
+            return Iterator.init(this, ComponentQuery{});
+        }
+
+        pub fn iter(this: *@This(), query: ComponentQuery) Iterator {
+            return Iterator.init(this, query);
+        }
+
+        const Self = @This();
+        const Iterator = struct {
+            world: *Self,
+            lastComponent: ?Component,
+            index: usize,
+            query: ComponentQuery,
+
+            pub fn init(w: *Self, q: ComponentQuery) @This() {
+                return @This(){
+                    .world = w,
+                    .lastComponent = null,
+                    .index = 0,
+                    .query = q,
+                };
+            }
+
+            pub fn next(this: *@This()) ?*Component {
+                if (this.lastComponent) |e| this.world.components.set(this.index - 1, e);
+                if (this.index == this.world.components.len) return null;
+                var match = false;
+                while (!match) {
+                    if (this.index == this.world.components.len) return null;
+                    this.lastComponent = this.world.components.get(this.index);
+                    match = true;
+                    inline for (fields) |f| {
+                        const fenum = std.meta.stringToEnum(ComponentEnum, f.name) orelse unreachable;
+                        const required = this.query.required.contains(fenum);
+                        const excluded = this.query.excluded.contains(fenum);
+                        const has = @field(this.lastComponent.?, f.name) != null;
+                        if ((required and !has) or (excluded and has)) {
+                            match = false;
+                            break;
+                        }
+                    }
+                    this.index += 1;
+                }
+                return &this.lastComponent.?;
+            }
+        };
+    };
+}

src/main.zig

@@ -1,25 +1,52 @@
+const std = @import("std");
 const w4 = @import("wasm4.zig");
+const ecs = @import("ecs.zig");
+const assets = @import("assets");
 
-const smiley = [8]u8{
+const Vec2f = std.meta.Vector(2, f32);
-    0b11000011,
+const Pos = Vec2f;
-    0b10000001,
+const Control = enum { player };
-    0b00100100,
+const Component = struct {
-    0b00100100,
+    pos: Pos,
-    0b00000000,
+    control: Control,
-    0b00100100,
-    0b10011001,
-    0b11000011,
 };
+const World = ecs.World(Component);
+
+const KB = 1024;
+var heap: [1 * KB]u8 = undefined;
+var fba = std.heap.FixedBufferAllocator.init(&heap);
+var world: World = World.init(fba.allocator());
+
+export fn start() void {
+    _ = world.create(.{ .pos = .{ 76, 76 }, .control = .player });
+}
 
 export fn update() void {
     w4.DRAW_COLORS.* = 2;
-    w4.text("Hello from Zig!", 10, 10);
+    w4.text("Hello from Zig!", .{ 10, 10 });
 
-    const gamepad = w4.GAMEPAD1.*;
+    if (w4.GAMEPAD1.button_1) {
-    if (gamepad & w4.BUTTON_1 != 0) {
         w4.DRAW_COLORS.* = 4;
     }
 
-    w4.blit(&smiley, 76, 76, 8, 8, w4.BLIT_1BPP);
+    world.process(1, &.{ .pos, .control }, controlProcess);
-    w4.text("Press X to blink", 16, 90);
+    world.process(1, &.{.pos}, drawProcess);
+
+    w4.DRAW_COLORS.* = 2;
+    // w4.blit(&smiley, .{ 76, 76 }, .{ 8, 8 }, .{ .bpp = .b1 });
+    w4.text("Press X to blink", .{ 16, 90 });
+}
+
+fn drawProcess(_: f32, pos: *Pos) void {
+    w4.DRAW_COLORS.* = 0x0030;
+    w4.externs.blitSub(&assets.sprites, @floatToInt(i32, pos.*[0]), @floatToInt(i32, pos.*[1]), 8, 8, 0, 0, 128, assets.sprites_flags);
+}
+
+fn controlProcess(_: f32, pos: *Pos, control: *Control) void {
+    _ = control;
+    if (w4.GAMEPAD1.button_up) pos.*[1] -= 1;
+    if (w4.GAMEPAD1.button_down) pos.*[1] += 1;
+    if (w4.GAMEPAD1.button_left) pos.*[0] -= 1;
+    if (w4.GAMEPAD1.button_right) pos.*[0] += 1;
+    // w4.trace("here", .{});
 }

src/wasm4.zig

@@ -1,13 +1,102 @@
-//
+//! Stolen from pfgithub's wasm4-zig repo
-// WASM-4: https://wasm4.org/docs
+//! https://github.com/pfgithub/wasm4-zig
 
-// ┌───────────────────────────────────────────────────────────────────────────┐
+const w4 = @This();
-// │                                                                           │
+const std = @import("std");
-// │ Platform Constants                                                        │
-// │                                                                           │
-// └───────────────────────────────────────────────────────────────────────────┘
 
-pub const CANVAS_SIZE: u32 = 160;
+/// PLATFORM CONSTANTS
+pub const CANVAS_SIZE = 160;
+
+/// Helpers
+pub const Vec2 = @import("std").meta.Vector(2, i32);
+pub const x = 0;
+pub const y = 1;
+
+pub fn texLen(size: Vec2) usize {
+    return @intCast(usize, std.math.divCeil(i32, size[x] * size[y] * 2, 8) catch unreachable);
+}
+
+pub const Mbl = enum { mut, cons };
+pub fn Tex(comptime mbl: Mbl) type {
+    return struct {
+        // oh that's really annoying…
+        // ideally there would be a way to have a readonly Tex and a mutable Tex
+        // and the mutable should implicit cast to readonly
+        data: switch (mbl) {
+            .mut => [*]u8,
+            .cons => [*]const u8,
+        },
+        size: Vec2,
+
+        pub fn wrapSlice(slice: switch (mbl) {
+            .mut => []u8,
+            .cons => []const u8,
+        }, size: Vec2) Tex(mbl) {
+            if (slice.len != texLen(size)) {
+                unreachable;
+            }
+            return .{
+                .data = slice.ptr,
+                .size = size,
+            };
+        }
+
+        pub fn cons(tex: Tex(.mut)) Tex(.cons) {
+            return .{
+                .data = tex.data,
+                .size = tex.size,
+            };
+        }
+
+        pub fn blit(dest: Tex(.mut), dest_ul: Vec2, src: Tex(.cons), src_ul: Vec2, src_wh: Vec2, remap_colors: [4]u3, scale: Vec2) void {
+            for (range(@intCast(usize, src_wh[y]))) |_, y_usz| {
+                const yp = @intCast(i32, y_usz);
+                for (range(@intCast(usize, src_wh[x]))) |_, x_usz| {
+                    const xp = @intCast(i32, x_usz);
+                    const pos = Vec2{ xp, yp };
+
+                    const value = remap_colors[src.get(src_ul + pos)];
+                    if (value <= std.math.maxInt(u2)) {
+                        dest.rect(pos * scale + dest_ul, scale, @intCast(u2, value));
+                    }
+                }
+            }
+        }
+        pub fn rect(dest: Tex(.mut), ul: Vec2, wh: Vec2, color: u2) void {
+            for (range(std.math.lossyCast(usize, wh[y]))) |_, y_usz| {
+                const yp = @intCast(i32, y_usz);
+                for (range(std.math.lossyCast(usize, wh[x]))) |_, x_usz| {
+                    const xp = @intCast(i32, x_usz);
+
+                    dest.set(ul + Vec2{ xp, yp }, color);
+                }
+            }
+        }
+        pub fn get(tex: Tex(mbl), pos: Vec2) u2 {
+            if (@reduce(.Or, pos < w4.Vec2{ 0, 0 })) return 0;
+            if (@reduce(.Or, pos >= tex.size)) return 0;
+            const index_unscaled = pos[w4.x] + (pos[w4.y] * tex.size[w4.x]);
+            const index = @intCast(usize, @divFloor(index_unscaled, 4));
+            const byte_idx = @intCast(u3, (@mod(index_unscaled, 4)) * 2);
+            return @truncate(u2, tex.data[index] >> byte_idx);
+        }
+        pub fn set(tex: Tex(.mut), pos: Vec2, value: u2) void {
+            if (@reduce(.Or, pos < w4.Vec2{ 0, 0 })) return;
+            if (@reduce(.Or, pos >= tex.size)) return;
+            const index_unscaled = pos[w4.x] + (pos[w4.y] * tex.size[w4.x]);
+            const index = @intCast(usize, @divFloor(index_unscaled, 4));
+            const byte_idx = @intCast(u3, (@mod(index_unscaled, 4)) * 2);
+            tex.data[index] &= ~(@as(u8, 0b11) << byte_idx);
+            tex.data[index] |= @as(u8, value) << byte_idx;
+        }
+    };
+}
+
+pub fn range(len: usize) []const void {
+    return @as([*]const void, &[_]void{})[0..len];
+}
+
+// pub const Tex1BPP = struct {…};
 
 // ┌───────────────────────────────────────────────────────────────────────────┐
 // │                                                                           │
@@ -17,26 +106,71 @@ pub const CANVAS_SIZE: u32 = 160;
 
 pub const PALETTE: *[4]u32 = @intToPtr(*[4]u32, 0x04);
 pub const DRAW_COLORS: *u16 = @intToPtr(*u16, 0x14);
-pub const GAMEPAD1: *const u8 = @intToPtr(*const u8, 0x16);
+pub const GAMEPAD1: *const Gamepad = @intToPtr(*const Gamepad, 0x16);
-pub const GAMEPAD2: *const u8 = @intToPtr(*const u8, 0x17);
+pub const GAMEPAD2: *const Gamepad = @intToPtr(*const Gamepad, 0x17);
-pub const GAMEPAD3: *const u8 = @intToPtr(*const u8, 0x18);
+pub const GAMEPAD3: *const Gamepad = @intToPtr(*const Gamepad, 0x18);
-pub const GAMEPAD4: *const u8 = @intToPtr(*const u8, 0x19);
+pub const GAMEPAD4: *const Gamepad = @intToPtr(*const Gamepad, 0x19);
-pub const MOUSE_X: *const i16 = @intToPtr(*const i16, 0x1a);
-pub const MOUSE_Y: *const i16 = @intToPtr(*const i16, 0x1c);
-pub const MOUSE_BUTTONS: *const u8 = @intToPtr(*const u8, 0x1e);
-pub const SYSTEM_FLAGS: *u8 = @intToPtr(*u8, 0x1f);
-pub const FRAMEBUFFER: *[6400]u8 = @intToPtr(*[6400]u8, 0xA0);
 
-pub const BUTTON_1: u8 = 1;
+pub const MOUSE: *const Mouse = @intToPtr(*const Mouse, 0x1a);
-pub const BUTTON_2: u8 = 2;
+pub const SYSTEM_FLAGS: *SystemFlags = @intToPtr(*SystemFlags, 0x1f);
-pub const BUTTON_LEFT: u8 = 16;
+pub const FRAMEBUFFER: *[CANVAS_SIZE * CANVAS_SIZE / 4]u8 = @intToPtr(*[6400]u8, 0xA0);
-pub const BUTTON_RIGHT: u8 = 32;
+pub const ctx = Tex(.mut){
-pub const BUTTON_UP: u8 = 64;
+    .data = @intToPtr([*]u8, 0xA0), // apparently casting *[N]u8 to [*]u8 at comptime causes a compiler crash
-pub const BUTTON_DOWN: u8 = 128;
+    .size = .{ CANVAS_SIZE, CANVAS_SIZE },
+};
 
-pub const MOUSE_LEFT: u8 = 1;
+pub const Gamepad = packed struct {
-pub const MOUSE_RIGHT: u8 = 2;
+    button_1: bool,
-pub const MOUSE_MIDDLE: u8 = 4;
+    button_2: bool,
+    _: u2 = 0,
+    button_left: bool,
+    button_right: bool,
+    button_up: bool,
+    button_down: bool,
+    comptime {
+        if (@sizeOf(@This()) != @sizeOf(u8)) unreachable;
+    }
+
+    pub fn format(value: @This(), comptime _: []const u8, _: @import("std").fmt.FormatOptions, writer: anytype) !void {
+        if (value.button_1) try writer.writeAll("1");
+        if (value.button_2) try writer.writeAll("2");
+        if (value.button_left) try writer.writeAll("<"); //"←");
+        if (value.button_right) try writer.writeAll(">");
+        if (value.button_up) try writer.writeAll("^");
+        if (value.button_down) try writer.writeAll("v");
+    }
+};
+
+pub const Mouse = packed struct {
+    x: i16,
+    y: i16,
+    buttons: MouseButtons,
+    pub fn pos(mouse: Mouse) Vec2 {
+        return .{ mouse.x, mouse.y };
+    }
+    comptime {
+        if (@sizeOf(@This()) != 5) unreachable;
+    }
+};
+
+pub const MouseButtons = packed struct {
+    left: bool,
+    right: bool,
+    middle: bool,
+    _: u5 = 0,
+    comptime {
+        if (@sizeOf(@This()) != @sizeOf(u8)) unreachable;
+    }
+};
+
+pub const SystemFlags = packed struct {
+    preserve_framebuffer: bool,
+    hide_gamepad_overlay: bool,
+    _: u6 = 0,
+    comptime {
+        if (@sizeOf(@This()) != @sizeOf(u8)) unreachable;
+    }
+};
 
 pub const SYSTEM_PRESERVE_FRAMEBUFFER: u8 = 1;
 pub const SYSTEM_HIDE_GAMEPAD_OVERLAY: u8 = 2;
@@ -47,38 +181,68 @@ pub const SYSTEM_HIDE_GAMEPAD_OVERLAY: u8 = 2;
 // │                                                                           │
 // └───────────────────────────────────────────────────────────────────────────┘
 
-/// Copies pixels to the framebuffer.
+pub const externs = struct {
     pub extern fn blit(sprite: [*]const u8, x: i32, y: i32, width: i32, height: i32, flags: u32) void;
-
+    pub extern fn blitSub(sprite: [*]const u8, x: i32, y: i32, width: i32, height: i32, src_x: u32, src_y: u32, strie: i32, flags: u32) void;
-/// Copies a subregion within a larger sprite atlas to the framebuffer.
-pub extern fn blitSub(sprite: [*]const u8, x: i32, y: i32, width: i32, height: i32, src_x: u32, src_y: u32, stride: i32, flags: u32) void;
-
-pub const BLIT_2BPP: u32 = 1;
-pub const BLIT_1BPP: u32 = 0;
-pub const BLIT_FLIP_X: u32 = 2;
-pub const BLIT_FLIP_Y: u32 = 4;
-pub const BLIT_ROTATE: u32 = 8;
-
-/// Draws a line between two points.
     pub extern fn line(x1: i32, y1: i32, x2: i32, y2: i32) void;
-
-/// Draws an oval (or circle).
     pub extern fn oval(x: i32, y: i32, width: i32, height: i32) void;
-
+    pub extern fn rect(x: i32, y: i32, width: i32, height: i32) void;
-/// Draws a rectangle.
+    pub extern fn textUtf8(strPtr: [*]const u8, strLen: usize, x: i32, y: i32) void;
-pub extern fn rect(x: i32, y: i32, width: u32, height: u32) void;
-
-/// Draws text using the built-in system font.
-pub fn text(str: []const u8, x: i32, y: i32) void {
-    textUtf8(str.ptr, str.len, x, y);
-}
-extern fn textUtf8(strPtr: [*]const u8, strLen: usize, x: i32, y: i32) void;
 
     /// Draws a vertical line
-pub extern fn vline(x: i32, y: i32, len: u32) void;
+    extern fn vline(x: i32, y: i32, len: u32) void;
 
     /// Draws a horizontal line
-pub extern fn hline(x: i32, y: i32, len: u32) void;
+    extern fn hline(x: i32, y: i32, len: u32) void;
+
+    pub extern fn tone(frequency: u32, duration: u32, volume: u32, flags: u32) void;
+};
+
+/// Copies pixels to the framebuffer.
+pub fn blit(sprite: []const u8, pos: Vec2, size: Vec2, flags: BlitFlags) void {
+    if (sprite.len * 8 != size[x] * size[y]) unreachable;
+    externs.blit(sprite.ptr, pos[x], pos[y], size[x], size[y], @bitCast(u32, flags));
+}
+
+/// Copies a subregion within a larger sprite atlas to the framebuffer.
+pub fn blitSub(sprite: []const u8, pos: Vec2, size: Vec2, src: Vec2, strie: i32, flags: BlitFlags) void {
+    if (sprite.len * 8 >= size[x] * size[y]) trace("Sprite not large enough {}", .{sprite.len});
+    externs.blitSub(sprite.ptr, pos[x], pos[y], size[x], size[y], @intCast(u32, src[x]), @intCast(u32, src[y]), strie, @bitCast(u32, flags));
+}
+
+pub const BlitFlags = packed struct {
+    bpp: enum(u1) {
+        b1,
+        b2,
+    },
+    flip_x: bool = false,
+    flip_y: bool = false,
+    rotate: bool = false,
+    _: u28 = 0,
+    comptime {
+        if (@sizeOf(@This()) != @sizeOf(u32)) unreachable;
+    }
+};
+
+/// Draws a line between two points.
+pub fn line(pos1: Vec2, pos2: Vec2) void {
+    externs.line(pos1[x], pos1[y], pos2[x], pos2[y]);
+}
+
+/// Draws an oval (or circle).
+pub fn oval(ul: Vec2, size: Vec2) void {
+    externs.oval(ul[x], ul[y], size[x], size[y]);
+}
+
+/// Draws a rectangle.
+pub fn rect(ul: Vec2, size: Vec2) void {
+    externs.rect(ul[x], ul[y], size[x], size[y]);
+}
+
+/// Draws text using the built-in system font.
+pub fn text(str: []const u8, pos: Vec2) void {
+    externs.textUtf8(str.ptr, str.len, pos[x], pos[y]);
+}
 
 // ┌───────────────────────────────────────────────────────────────────────────┐
 // │                                                                           │
@@ -87,16 +251,51 @@ pub extern fn hline(x: i32, y: i32, len: u32) void;
 // └───────────────────────────────────────────────────────────────────────────┘
 
 /// Plays a sound tone.
-pub extern fn tone(frequency: u32, duration: u32, volume: u32, flags: u32) void;
+pub fn tone(frequency: ToneFrequency, duration: ToneDuration, volume: u32, flags: ToneFlags) void {
+    return externs.tone(@bitCast(u32, frequency), @bitCast(u32, duration), volume, @bitCast(u8, flags));
+}
+pub const ToneFrequency = packed struct {
+    start: u16,
+    end: u16 = 0,
 
-pub const TONE_PULSE1: u32 = 0;
+    comptime {
-pub const TONE_PULSE2: u32 = 1;
+        if (@sizeOf(@This()) != @sizeOf(u32)) unreachable;
-pub const TONE_TRIANGLE: u32 = 2;
+    }
-pub const TONE_NOISE: u32 = 3;
+};
-pub const TONE_MODE1: u32 = 0;
+
-pub const TONE_MODE2: u32 = 4;
+pub const ToneDuration = packed struct {
-pub const TONE_MODE3: u32 = 8;
+    sustain: u8 = 0,
-pub const TONE_MODE4: u32 = 12;
+    release: u8 = 0,
+    decay: u8 = 0,
+    attack: u8 = 0,
+
+    comptime {
+        if (@sizeOf(@This()) != @sizeOf(u32)) unreachable;
+    }
+};
+
+pub const ToneFlags = packed struct {
+    pub const Channel = enum(u2) {
+        pulse1,
+        pulse2,
+        triangle,
+        noise,
+    };
+    pub const Mode = enum(u2) {
+        p12_5,
+        p25,
+        p50,
+        p75,
+    };
+
+    channel: Channel,
+    mode: Mode = .p12_5,
+    _: u4 = 0,
+
+    comptime {
+        if (@sizeOf(@This()) != @sizeOf(u8)) unreachable;
+    }
+};
 
 // ┌───────────────────────────────────────────────────────────────────────────┐
 // │                                                                           │
@@ -117,10 +316,25 @@ pub extern fn diskw(src: [*]const u8, size: u32) u32;
 // └───────────────────────────────────────────────────────────────────────────┘
 
 /// Prints a message to the debug console.
-pub fn trace(x: []const u8) void {
+/// Disabled in release builds.
-    traceUtf8(x.ptr, x.len);
+pub fn trace(comptime fmt: []const u8, args: anytype) void {
+    if (@import("builtin").mode != .Debug) @compileError("trace not allowed in release builds.");
+
+    // stack size is [8192]u8
+    var buffer: [100]u8 = undefined;
+    var fbs = std.io.fixedBufferStream(&buffer);
+    const writer = fbs.writer();
+    writer.print(fmt, args) catch {
+        const err_msg = switch (@import("builtin").mode) {
+            .Debug => "[trace err] " ++ fmt,
+            else => "[trace err]", // max 100 bytes in trace message.
+        };
+        return traceUtf8(err_msg, err_msg.len);
+    };
+
+    traceUtf8(&buffer, fbs.pos);
 }
-extern fn traceUtf8(strPtr: [*]const u8, strLen: usize) void;
+extern fn traceUtf8(str_ptr: [*]const u8, str_len: usize) void;
 
 /// Use with caution, as there's no compile-time type checking.
 ///