From 03a9cbab9a1835b3c42925b8710c01921c58ef8f Mon Sep 17 00:00:00 2001
From: Stephen Gutekanst <stephen@hexops.com>
Date: Tue, 16 Aug 2022 17:35:18 -0700
Subject: [PATCH] gpu: add Device.Descriptor.init slice helper

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>
---
 gpu/README.md      |  1 +
 gpu/src/device.zig | 18 +++++++++++++++++-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/gpu/README.md b/gpu/README.md
index 9e45b701..27012675 100644
--- a/gpu/README.md
+++ b/gpu/README.md
@@ -169,6 +169,7 @@ And, to initialize data structures with slices in them, the following helpers ar
 * `BindGroup.Descriptor.init`
 * `InstanceDescriptor.init`
 * `TogglesDeviceDescriptor.init`
+* `Device.Descriptor.init`
 
 ### Typed callbacks
 
diff --git a/gpu/src/device.zig b/gpu/src/device.zig
index 21f8d4f2..782a951f 100644
--- a/gpu/src/device.zig
+++ b/gpu/src/device.zig
@@ -44,11 +44,27 @@ pub const Device = opaque {
     pub const Descriptor = extern struct {
         next_in_chain: ?*const ChainedStruct = null,
         label: ?[*:0]const u8 = null,
-        // TODO: slice helper
         required_features_count: u32 = 0,
         required_features: ?[*]const FeatureName = null,
         required_limits: ?*const RequiredLimits = null,
         default_queue: Queue.Descriptor = Queue.Descriptor{},
+
+        /// Provides a slightly friendlier Zig API to initialize this structure.
+        pub inline fn init(v: struct {
+            next_in_chain: ?*const ChainedStruct = null,
+            label: ?[*:0]const u8 = null,
+            required_features: ?[]const FeatureName = null,
+            required_limits: ?*const RequiredLimits = null,
+            default_queue: Queue.Descriptor = Queue.Descriptor{},
+        }) Descriptor {
+            return .{
+                .next_in_chain = v.next_in_chain,
+                .label = v.label,
+                .required_features_count = if (v.required_features) |e| @intCast(u32, e.len) else 0,
+                .required_features = if (v.required_features) |e| e.ptr else null,
+                .default_queue = v.default_queue,
+            };
+        }
     };
 
     pub inline fn createBindGroup(device: *Device, descriptor: *const BindGroup.Descriptor) *BindGroup {