VideoCommon: Add texture decoding shader generators

Source/Core/VideoCommon/TextureConversionShader.h

@@ -4,6 +4,9 @@
 
 #pragma once
 
+#include <string>
+#include <utility>
+
 #include "Common/CommonTypes.h"
 
 enum class APIType;
@@ -13,4 +16,40 @@ namespace TextureConversionShader
 u16 GetEncodedSampleCount(u32 format);
 
 const char* GenerateEncodingShader(u32 format, APIType ApiType);
-}
+
+// View format of the input data to the texture decoding shader.
+enum BufferFormat
+{
+  BUFFER_FORMAT_R8_UINT,
+  BUFFER_FORMAT_R16_UINT,
+  BUFFER_FORMAT_R32G32_UINT,
+  BUFFER_FORMAT_COUNT
+};
+
+// Information required to compile and dispatch a texture decoding shader.
+struct DecodingShaderInfo
+{
+  BufferFormat buffer_format;
+  u32 palette_size;
+  u32 group_size_x;
+  u32 group_size_y;
+  bool group_flatten;
+  const char* shader_body;
+};
+
+// Obtain shader information for the specified texture format.
+// If this format does not have a shader written for it, returns nullptr.
+const DecodingShaderInfo* GetDecodingShaderInfo(u32 format);
+
+// Determine how many bytes there are in each element of the texel buffer.
+// Needed for alignment and stride calculations.
+u32 GetBytesPerBufferElement(BufferFormat buffer_format);
+
+// Determine how many thread groups should be dispatched for an image of the specified width/height.
+// First is the number of X groups, second is the number of Y groups, Z is always one.
+std::pair<u32, u32> GetDispatchCount(const DecodingShaderInfo* info, u32 width, u32 height);
+
+// Returns the GLSL string containing the texture decoding shader for the specified format.
+std::string GenerateDecodingShader(u32 format, u32 palette_format, APIType api_type);
+
+}  // namespace TextureConversionShader