gpu: implement Interface.reference, Interface.release

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

gpu/src/Interface.zig

@@ -2,16 +2,24 @@
 //!
 //! Like std.mem.Allocator, but representing a WebGPU implementation.
 
-// The type erased pointer to the Device implementation
+const Interface = @This();
+
+/// The type erased pointer to the Interface implementation
 ptr: *anyopaque,
 vtable: *const VTable,
 
 pub const VTable = struct {
-    // TODO(gpu): make these *const fn once stage2 is released.
-    deinit: fn (ptr: *anyopaque) void,
+    reference: fn (ptr: *anyopaque) void,
+    release: fn (ptr: *anyopaque) void,
 };
 
+pub inline fn reference(interface: Interface) void {
+    interface.vtable.reference(interface.ptr);
+}
+
+pub inline fn release(interface: Interface) void {
+    interface.vtable.release(interface.ptr);
+}
+
 // TODO:
 // WGPU_EXPORT void wgpuInstanceRequestAdapter(WGPUInstance instance, WGPURequestAdapterOptions const * options, WGPURequestAdapterCallback callback, void * userdata);
-// WGPU_EXPORT void wgpuInstanceReference(WGPUInstance instance);
-// WGPU_EXPORT void wgpuInstanceRelease(WGPUInstance instance);

gpu/src/NativeInstance.zig

@@ -8,26 +8,32 @@ const NativeInstance = @This();
 /// The WGPUInstance that is wrapped by this native instance.
 instance: c.WGPUInstance,
 
-vtable: Interface.VTable,
-
 /// Wraps a native WGPUInstance to provide an implementation of the gpu.Interface.
 pub fn wrap(instance: *anyopaque) NativeInstance {
-    return .{
-        .instance = @ptrCast(c.WGPUInstance, instance),
-        .vtable = undefined, // TODO
-    };
+    return .{ .instance = @ptrCast(c.WGPUInstance, instance) };
 }
 
+const interface_vtable = Interface.VTable{
+    .reference = (struct {
+        pub fn reference(ptr: *anyopaque) void {
+            const native = @ptrCast(*NativeInstance, @alignCast(@alignOf(*NativeInstance), ptr));
+            c.wgpuInstanceReference(native.instance);
+        }
+    }).reference,
+    .release = (struct {
+        pub fn release(ptr: *anyopaque) void {
+            const native = @ptrCast(*NativeInstance, @alignCast(@alignOf(*NativeInstance), ptr));
+            c.wgpuInstanceRelease(native.instance);
+        }
+    }).release,
+};
+
 /// Returns the gpu.Interface for interacting with this native instance.
 pub fn interface(native: *NativeInstance) Interface {
     return .{
         .ptr = native,
-        .vtable = &native.vtable,
+        .vtable = &interface_vtable,
     };
-    // TODO: implement Interface
-    // WGPU_EXPORT void wgpuInstanceReference(WGPUInstance instance);
-    // WGPU_EXPORT void wgpuInstanceRelease(WGPUInstance instance);
-
     // TODO: implement Device interface
 
     // TODO: implement Adapter interface: