From 60496259b2cbc09c377569307ca34d19cdbcab5a Mon Sep 17 00:00:00 2001
From: Stephen Gutekanst <stephen@hexops.com>
Date: Sun, 24 Jul 2022 19:11:26 -0700
Subject: [PATCH] gpu: add Adapter.enumerateFeatures

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
---
 gpu/TODO-webgpu.h     |  1 -
 gpu/src/adapter.zig   |  6 ++++++
 gpu/src/interface.zig | 12 ++++++++++++
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/gpu/TODO-webgpu.h b/gpu/TODO-webgpu.h
index 0bc9c4c3..38e45a34 100644
--- a/gpu/TODO-webgpu.h
+++ b/gpu/TODO-webgpu.h
@@ -10,7 +10,6 @@ typedef void (*WGPURequestAdapterCallback)(WGPURequestAdapterStatus status, WGPU
 typedef void (*WGPURequestDeviceCallback)(WGPURequestDeviceStatus status, WGPUDevice device, char const * message, void * userdata);
 
 // Methods of Adapter
-WGPU_EXPORT size_t wgpuAdapterEnumerateFeatures(WGPUAdapter adapter, WGPUFeatureName * features);
 WGPU_EXPORT bool wgpuAdapterGetLimits(WGPUAdapter adapter, WGPUSupportedLimits * limits);
 WGPU_EXPORT void wgpuAdapterGetProperties(WGPUAdapter adapter, WGPUAdapterProperties * properties);
 WGPU_EXPORT bool wgpuAdapterHasFeature(WGPUAdapter adapter, WGPUFeatureName feature);
diff --git a/gpu/src/adapter.zig b/gpu/src/adapter.zig
index e13044f2..6e6a78dc 100644
--- a/gpu/src/adapter.zig
+++ b/gpu/src/adapter.zig
@@ -2,12 +2,18 @@ const testing = @import("std").testing;
 const ChainedStructOut = @import("types.zig").ChainedStructOut;
 const Device = @import("device.zig").Device;
 const DeviceDescriptor = @import("device.zig").DeviceDescriptor;
+const FeatureName = @import("types.zig").FeatureName;
 const impl = @import("interface.zig").impl;
 
 pub const Adapter = *opaque {
     pub inline fn createDevice(adapter: Adapter, descriptor: ?*const DeviceDescriptor) ?Device {
         return impl.createDevice(adapter, descriptor);
     }
+
+    /// Call once with null to determine the array length, and again to fetch the feature list.
+    pub inline fn enumerateFeatures(adapter: Adapter, features: ?[*]FeatureName) usize {
+        return impl.adapterEnumerateFeatures(adapter, features);
+    }
 };
 
 pub const AdapterType = enum(u32) {
diff --git a/gpu/src/interface.zig b/gpu/src/interface.zig
index 6c3885fb..bea0c7c4 100644
--- a/gpu/src/interface.zig
+++ b/gpu/src/interface.zig
@@ -20,6 +20,7 @@ pub fn Interface(comptime Impl: type) type {
     assertDecl(Impl, "createInstance", fn (descriptor: *const InstanceDescriptor) callconv(.Inline) ?Instance);
     assertDecl(Impl, "getProcAddress", fn (device: gpu.Device, proc_name: [*:0]const u8) callconv(.Inline) ?gpu.Proc);
     assertDecl(Impl, "adapterCreateDevice", fn (adapter: gpu.Adapter, descriptor: ?*const gpu.DeviceDescriptor) callconv(.Inline) ?gpu.Device);
+    assertDecl(Impl, "adapterEnumerateFeatures", fn (adapter: gpu.Adapter, features: ?[*]gpu.FeatureName) callconv(.Inline) usize);
     return Impl;
 }
 
@@ -47,6 +48,11 @@ pub fn Export(comptime Impl: type) type {
         export fn wgpuAdapterCreateDevice(adapter: gpu.Adapter, descriptor: ?*const gpu.DeviceDescriptor) ?gpu.Device {
             return Impl.adapterCreateDevice(adapter, descriptor);
         }
+
+        // WGPU_EXPORT size_t wgpuAdapterEnumerateFeatures(WGPUAdapter adapter, WGPUFeatureName * features);
+        export fn wgpuAdapterEnumerateFeatures(adapter: gpu.Adapter, features: ?[*]gpu.FeatureName) usize {
+            return Impl.adapterEnumerateFeatures(adapter, features);
+        }
     };
 }
 
@@ -68,6 +74,12 @@ pub const NullInterface = Interface(struct {
         _ = descriptor;
         return null;
     }
+
+    pub inline fn adapterEnumerateFeatures(adapter: gpu.Adapter, features: ?[*]gpu.FeatureName) usize {
+        _ = adapter;
+        _ = features;
+        return 0;
+    }
 });
 
 test "null" {