From aff9f1c25f0fac6f91099d51a8cfcc666bff38cf Mon Sep 17 00:00:00 2001
From: Connor McLaughlin <stenzek@gmail.com>
Date: Fri, 30 Jul 2021 00:40:51 +1000
Subject: [PATCH] D3D12: Add helper for offsetting descriptors

---
 src/common/d3d12/descriptor_heap_manager.cpp | 32 ++++++++++++++------
 src/common/d3d12/descriptor_heap_manager.h   | 24 ++++++++++++---
 2 files changed, 42 insertions(+), 14 deletions(-)

diff --git a/src/common/d3d12/descriptor_heap_manager.cpp b/src/common/d3d12/descriptor_heap_manager.cpp
index 573e47514..5fbe7d78f 100644
--- a/src/common/d3d12/descriptor_heap_manager.cpp
+++ b/src/common/d3d12/descriptor_heap_manager.cpp
@@ -51,7 +51,7 @@ void DescriptorHeapManager::Destroy()
   m_free_slots.clear();
 }
 
-bool DescriptorHeapManager::Allocate(DescriptorHandle* handle)
+bool DescriptorHeapManager::Allocate(DescriptorHandle* handle, u32 count /* = 1 */)
 {
   // Start past the temporary slots, no point in searching those.
   for (u32 group = 0; group < m_free_slots.size(); group++)
@@ -64,11 +64,22 @@ bool DescriptorHeapManager::Allocate(DescriptorHandle* handle)
     for (; bit < BITSET_SIZE; bit++)
     {
       if (bs[bit])
-        break;
+      {
+        u32 offset;
+        for (offset = 0; offset < count; offset++)
+        {
+          if (!bs[bit + offset])
+            break;
+        }
+
+        if (offset == count)
+          break;
+      }
     }
 
     u32 index = group * BITSET_SIZE + bit;
-    bs[bit] = false;
+    for (u32 offset = 0; offset < count; offset++)
+      bs[bit + offset] = false;
 
     handle->index = index;
     handle->cpu_handle.ptr = m_heap_base_cpu.ptr + index * m_descriptor_increment_size;
@@ -80,21 +91,24 @@ bool DescriptorHeapManager::Allocate(DescriptorHandle* handle)
   return false;
 }
 
-void DescriptorHeapManager::Free(u32 index)
+void DescriptorHeapManager::Free(u32 index, u32 count /* = 1 */)
 {
   Assert(index < m_num_descriptors);
 
-  u32 group = index / BITSET_SIZE;
-  u32 bit = index % BITSET_SIZE;
-  m_free_slots[group][bit] = true;
+  for (u32 i = 0; i < count; i++, index++)
+  {
+    u32 group = index / BITSET_SIZE;
+    u32 bit = index % BITSET_SIZE;
+    m_free_slots[group][bit] = true;
+  }
 }
 
-void DescriptorHeapManager::Free(DescriptorHandle* handle)
+void DescriptorHeapManager::Free(DescriptorHandle* handle, u32 count /* = 1 */)
 {
   if (handle->index == DescriptorHandle::INVALID_INDEX)
     return;
 
-  Free(handle->index);
+  Free(handle->index, count);
   handle->Clear();
 }
 
diff --git a/src/common/d3d12/descriptor_heap_manager.h b/src/common/d3d12/descriptor_heap_manager.h
index 4be5144ed..8cd80c98f 100644
--- a/src/common/d3d12/descriptor_heap_manager.h
+++ b/src/common/d3d12/descriptor_heap_manager.h
@@ -44,15 +44,29 @@ public:
   DescriptorHeapManager();
   ~DescriptorHeapManager();
 
-  ID3D12DescriptorHeap* GetDescriptorHeap() const { return m_descriptor_heap.Get(); }
-  u32 GetDescriptorIncrementSize() const { return m_descriptor_increment_size; }
+  ALWAYS_INLINE ID3D12DescriptorHeap* GetDescriptorHeap() const { return m_descriptor_heap.Get(); }
+  ALWAYS_INLINE u32 GetDescriptorIncrementSize() const { return m_descriptor_increment_size; }
+
+  ALWAYS_INLINE D3D12_CPU_DESCRIPTOR_HANDLE OffsetCPUHandle(D3D12_CPU_DESCRIPTOR_HANDLE handle, u32 count) const
+  {
+    D3D12_CPU_DESCRIPTOR_HANDLE ret;
+    ret.ptr = handle.ptr + m_descriptor_increment_size * count;
+    return ret;
+  }
+
+  ALWAYS_INLINE D3D12_GPU_DESCRIPTOR_HANDLE OffsetGPUHandle(D3D12_GPU_DESCRIPTOR_HANDLE handle, u32 count) const
+  {
+    D3D12_GPU_DESCRIPTOR_HANDLE ret;
+    ret.ptr = handle.ptr + m_descriptor_increment_size * count;
+    return ret;
+  }
 
   bool Create(ID3D12Device* device, D3D12_DESCRIPTOR_HEAP_TYPE type, u32 num_descriptors, bool shader_visible);
   void Destroy();
 
-  bool Allocate(DescriptorHandle* handle);
-  void Free(DescriptorHandle* handle);
-  void Free(u32 index);
+  bool Allocate(DescriptorHandle* handle, u32 count = 1);
+  void Free(DescriptorHandle* handle, u32 count = 1);
+  void Free(u32 index, u32 count = 1);
 
 private:
   Microsoft::WRL::ComPtr<ID3D12DescriptorHeap> m_descriptor_heap;