core: add mach.Core module API

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

src/Core.zig

@@ -0,0 +1,67 @@
+const std = @import("std");
+const mach = @import("main.zig");
+
+pub const name = .mach_core;
+
+pub const Mod = mach.Mod(@This());
+
+pub const global_events = .{
+    .init = .{ .handler = fn () void },
+    .deinit = .{ .handler = fn () void },
+    .tick = .{ .handler = fn () void },
+};
+
+pub const local_events = .{
+    .init = .{ .handler = init },
+
+    // TODO(important): need some way to tie event execution to a specific thread once we have a
+    // multithreaded dispatch implementation
+    .main_thread_tick = .{ .handler = mainThreadTick },
+    .main_thread_tick_done = .{ .handler = fn () void },
+    .deinit = .{ .handler = deinit },
+    .exit = .{ .handler = exit },
+};
+
+var gpa = std.heap.GeneralPurposeAllocator(.{}){};
+
+device: *mach.gpu.Device,
+queue: *mach.gpu.Queue,
+should_exit: bool = false,
+
+fn init(core: *Mod) !void {
+    // Initialize GPU implementation
+    if (comptime mach.core.options.use_wgpu) try mach.core.wgpu.Impl.init(mach.core.allocator, .{});
+    if (comptime mach.core.options.use_sysgpu) try mach.core.sysgpu.Impl.init(mach.core.allocator, .{});
+
+    mach.core.allocator = gpa.allocator(); // TODO: banish this global allocator
+    try mach.core.init(.{});
+
+    core.init(.{
+        .device = mach.core.device,
+        .queue = mach.core.device.getQueue(),
+    });
+
+    core.sendGlobal(.init, .{});
+}
+
+fn deinit(core: *Mod) void {
+    core.state().queue.release();
+    // TODO: this triggers a device loss error, which we should handle correctly
+    // core.state().device.release();
+    mach.core.deinit();
+    _ = gpa.deinit();
+}
+
+fn mainThreadTick(core: *Mod) !void {
+    _ = try mach.core.update(null);
+
+    // Send .tick to anyone interested
+    core.sendGlobal(.tick, .{});
+
+    // Signal that mainThreadTick is done
+    core.send(.main_thread_tick_done, .{});
+}
+
+fn exit(core: *Mod) void {
+    core.state().should_exit = true;
+}