1 files changed, 144 insertions, 0 deletions
diff --git a/third_party/rust/wgpu-hal/src/dx11/library.rs b/third_party/rust/wgpu-hal/src/dx11/library.rs
new file mode 100644
index 0000000000..ea597abd56
--- /dev/null
+++ b/third_party/rust/wgpu-hal/src/dx11/library.rs
@@ -0,0 +1,144 @@
+use std::ptr;
+
+use winapi::{
+    shared::{
+        dxgi,
+        minwindef::{HMODULE, UINT},
+        winerror,
+    },
+    um::{d3d11, d3d11_1, d3d11_2, d3dcommon},
+};
+
+use crate::auxil::dxgi::result::HResult;
+
+type D3D11CreateDeviceFun = unsafe extern "system" fn(
+    *mut dxgi::IDXGIAdapter,
+    d3dcommon::D3D_DRIVER_TYPE,
+    HMODULE,
+    UINT,
+    *const d3dcommon::D3D_FEATURE_LEVEL,
+    UINT,
+    UINT,
+    *mut *mut d3d11::ID3D11Device,
+    *mut d3dcommon::D3D_FEATURE_LEVEL,
+    *mut *mut d3d11::ID3D11DeviceContext,
+) -> d3d12::HRESULT;
+
+pub(super) struct D3D11Lib {
+    // We use the os specific symbol to drop the lifetime parameter.
+    //
+    // SAFETY: we must ensure this outlives the Library.
+    d3d11_create_device: libloading::os::windows::Symbol<D3D11CreateDeviceFun>,
+
+    lib: libloading::Library,
+}
+impl D3D11Lib {
+    pub fn new() -> Option<Self> {
+        unsafe {
+            let lib = libloading::Library::new("d3d11.dll").ok()?;
+
+            let d3d11_create_device = lib
+                .get::<D3D11CreateDeviceFun>(b"D3D11CreateDevice")
+                .ok()?
+                .into_raw();
+
+            Some(Self {
+                lib,
+                d3d11_create_device,
+            })
+        }
+    }
+
+    pub fn create_device(
+        &self,
+        adapter: d3d12::DxgiAdapter,
+    ) -> Option<(super::D3D11Device, d3dcommon::D3D_FEATURE_LEVEL)> {
+        let feature_levels = [
+            d3dcommon::D3D_FEATURE_LEVEL_11_1,
+            d3dcommon::D3D_FEATURE_LEVEL_11_0,
+            d3dcommon::D3D_FEATURE_LEVEL_10_1,
+            d3dcommon::D3D_FEATURE_LEVEL_10_0,
+            d3dcommon::D3D_FEATURE_LEVEL_9_3,
+            d3dcommon::D3D_FEATURE_LEVEL_9_2,
+            d3dcommon::D3D_FEATURE_LEVEL_9_1,
+        ];
+
+        let mut device = d3d12::WeakPtr::<d3d11::ID3D11Device>::null();
+        let mut feature_level: d3dcommon::D3D_FEATURE_LEVEL = 0;
+
+        // We need to try this twice. If the first time fails due to E_INVALIDARG
+        // we are running on a machine without a D3D11.1 runtime, and need to
+        // retry without the feature level 11_1 feature level.
+        //
+        // Why they thought this was a good API, who knows.
+
+        let mut hr = unsafe {
+            (self.d3d11_create_device)(
+                adapter.as_mut_ptr() as *mut _,
+                d3dcommon::D3D_DRIVER_TYPE_UNKNOWN,
+                ptr::null_mut(), // software implementation DLL???
+                0,               // flags
+                feature_levels.as_ptr(),
+                feature_levels.len() as u32,
+                d3d11::D3D11_SDK_VERSION,
+                device.mut_self(),
+                &mut feature_level,
+                ptr::null_mut(), // device context
+            )
+        };
+
+        // Try again without FL11_1
+        if hr == winerror::E_INVALIDARG {
+            hr = unsafe {
+                (self.d3d11_create_device)(
+                    adapter.as_mut_ptr() as *mut _,
+                    d3dcommon::D3D_DRIVER_TYPE_UNKNOWN,
+                    ptr::null_mut(), // software implementation DLL???
+                    0,               // flags
+                    feature_levels[1..].as_ptr(),
+                    feature_levels[1..].len() as u32,
+                    d3d11::D3D11_SDK_VERSION,
+                    device.mut_self(),
+                    &mut feature_level,
+                    ptr::null_mut(), // device context
+                )
+            };
+        }
+
+        // Any errors here are real and we should complain about
+        if let Err(err) = hr.into_result() {
+            log::error!("Failed to make a D3D11 device: {}", err);
+            return None;
+        }
+
+        // We always try to upcast in highest -> lowest order
+
+        // Device -> Device2
+        unsafe {
+            match device.cast::<d3d11_2::ID3D11Device2>().into_result() {
+                Ok(device2) => {
+                    device.destroy();
+                    return Some((super::D3D11Device::Device2(device2), feature_level));
+                }
+                Err(hr) => {
+                    log::info!("Failed to cast device to ID3D11Device2: {}", hr)
+                }
+            }
+        }
+
+        // Device -> Device1
+        unsafe {
+            match device.cast::<d3d11_1::ID3D11Device1>().into_result() {
+                Ok(device1) => {
+                    device.destroy();
+                    return Some((super::D3D11Device::Device1(device1), feature_level));
+                }
+                Err(hr) => {
+                    log::info!("Failed to cast device to ID3D11Device1: {}", hr)
+                }
+            }
+        }
+
+        Some((super::D3D11Device::Device(device), feature_level))
+    }
+}