From 39eaa57a77f64b7433df476abff3ce038224e54c Mon Sep 17 00:00:00 2001
From: Dzmitry Malyshau <kvarkus@gmail.com>
Date: Sun, 18 Jul 2021 02:15:02 -0400
Subject: [PATCH] hlsl-out: implement constant buffer support

---
 src/back/hlsl/writer.rs     | 27 ++++++++++++++++++---------
 tests/out/hlsl/globals.hlsl |  2 +-
 tests/out/hlsl/shadow.hlsl  |  2 +-
 tests/out/hlsl/skybox.hlsl  |  2 +-
 4 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/src/back/hlsl/writer.rs b/src/back/hlsl/writer.rs
index 245fb78e74..64055a698e 100644
--- a/src/back/hlsl/writer.rs
+++ b/src/back/hlsl/writer.rs
@@ -344,7 +344,7 @@ impl<'a, W: Write> Writer<'a, W> {
             crate::StorageClass::Function => unreachable!("Function storage class"),
             crate::StorageClass::Private => ("static ", ""),
             crate::StorageClass::WorkGroup => ("groupshared ", ""),
-            crate::StorageClass::Uniform => ("", "b"),
+            crate::StorageClass::Uniform => ("cbuffer", "b"),
             crate::StorageClass::Storage | crate::StorageClass::Handle => {
                 if let TypeInner::Sampler { .. } = *inner {
                     ("", "s")
@@ -358,12 +358,13 @@ impl<'a, W: Write> Writer<'a, W> {
         };
 
         write!(self.out, "{}", storage)?;
-        self.write_type(module, global.ty)?;
-        write!(
-            self.out,
-            " {}",
-            &self.names[&NameKey::GlobalVariable(handle)]
-        )?;
+        // constant buffer declarations are expected to be inlined, e.g.
+        // cbuffer foo: register(b0) { field1: type1; };
+        if global.class != crate::StorageClass::Uniform {
+            self.write_type(module, global.ty)?;
+        }
+        let name = &self.names[&NameKey::GlobalVariable(handle)];
+        write!(self.out, " {}", name)?;
         if let TypeInner::Array { size, .. } = module.types[global.ty].inner {
             self.write_array_size(module, size)?;
         }
@@ -375,14 +376,22 @@ impl<'a, W: Write> Writer<'a, W> {
             if self.options.shader_model > super::ShaderModel::V5_0 {
                 write!(self.out, ", space{}", bt.space)?;
             }
-            writeln!(self.out, ");")?;
-        } else {
+            write!(self.out, ")")?;
+        } else if global.class == crate::StorageClass::Private {
             write!(self.out, " = ")?;
             if let Some(init) = global.init {
                 self.write_constant(module, init)?;
             } else {
                 self.write_default_init(module, global.ty)?;
             }
+        }
+
+        if global.class == crate::StorageClass::Uniform {
+            write!(self.out, " {{ ")?;
+            self.write_type(module, global.ty)?;
+            let name = &self.names[&NameKey::GlobalVariable(handle)];
+            writeln!(self.out, " {}; }}", name)?;
+        } else {
             writeln!(self.out, ";")?;
         }
 
diff --git a/tests/out/hlsl/globals.hlsl b/tests/out/hlsl/globals.hlsl
index 9ae4325888..0236e18272 100644
--- a/tests/out/hlsl/globals.hlsl
+++ b/tests/out/hlsl/globals.hlsl
@@ -1,6 +1,6 @@
 static const bool Foo = true;
 
-groupshared float wg[10] = (float[10])0;
+groupshared float wg[10];
 
 [numthreads(1, 1, 1)]
 void main()
diff --git a/tests/out/hlsl/shadow.hlsl b/tests/out/hlsl/shadow.hlsl
index e123bebdd7..bcce7a0fd1 100644
--- a/tests/out/hlsl/shadow.hlsl
+++ b/tests/out/hlsl/shadow.hlsl
@@ -16,7 +16,7 @@ struct Lights {
     Light data[1];
 };
 
-Globals u_globals : register(b0);
+cbuffer u_globals : register(b0) { Globals u_globals; }
 Lights s_lights : register(t1);
 Texture2DArray t_shadow : register(t2);
 SamplerComparisonState sampler_shadow : register(s3);
diff --git a/tests/out/hlsl/skybox.hlsl b/tests/out/hlsl/skybox.hlsl
index 283ab73b88..6886185b6c 100644
--- a/tests/out/hlsl/skybox.hlsl
+++ b/tests/out/hlsl/skybox.hlsl
@@ -8,7 +8,7 @@ struct Data {
     float4x4 view;
 };
 
-Data r_data : register(b0, space0);
+cbuffer r_data : register(b0, space0) { Data r_data; }
 TextureCube<float4> r_texture : register(t0, space0);
 SamplerState r_sampler : register(s0, space1);