Minor update to enable 'white box' testing of some internal functions (#284)

Audio/SoundCommon.h

@@ -55,31 +55,31 @@ namespace DirectX
 
 
     // Helper for validating wave format structure
-    bool IsValid(_In_ const WAVEFORMATEX* wfx) noexcept;
+    bool __cdecl IsValid(_In_ const WAVEFORMATEX* wfx) noexcept;
 
 
     // Helper for getting a default channel mask from channels
-    uint32_t GetDefaultChannelMask(int channels) noexcept;
+    uint32_t __cdecl GetDefaultChannelMask(int channels) noexcept;
 
 
     // Helpers for creating various wave format structures
-    void CreateIntegerPCM(_Out_ WAVEFORMATEX* wfx,
+    void __cdecl CreateIntegerPCM(_Out_ WAVEFORMATEX* wfx,
         int sampleRate, int channels, int sampleBits) noexcept;
-    void CreateFloatPCM(_Out_ WAVEFORMATEX* wfx,
+    void __cdecl CreateFloatPCM(_Out_ WAVEFORMATEX* wfx,
         int sampleRate, int channels) noexcept;
-    void CreateADPCM(_Out_writes_bytes_(wfxSize) WAVEFORMATEX* wfx, size_t wfxSize,
+    void __cdecl CreateADPCM(_Out_writes_bytes_(wfxSize) WAVEFORMATEX* wfx, size_t wfxSize,
         int sampleRate, int channels, int samplesPerBlock) noexcept(false);
 #ifdef DIRECTX_ENABLE_XWMA
-    void CreateXWMA(_Out_ WAVEFORMATEX* wfx,
+    void __cdecl CreateXWMA(_Out_ WAVEFORMATEX* wfx,
         int sampleRate, int channels, int blockAlign, int avgBytes, bool wma3) noexcept;
 #endif
 #ifdef DIRECTX_ENABLE_XMA2
-    void CreateXMA2(_Out_writes_bytes_(wfxSize) WAVEFORMATEX* wfx, size_t wfxSize,
+    void __cdecl CreateXMA2(_Out_writes_bytes_(wfxSize) WAVEFORMATEX* wfx, size_t wfxSize,
         int sampleRate, int channels, int bytesPerBlock, int blockCount, int samplesEncoded) noexcept(false);
 #endif
 
     // Helper for computing pan volume matrix
-    bool ComputePan(float pan, unsigned int channels, _Out_writes_(16) float* matrix) noexcept;
+    bool __cdecl ComputePan(float pan, unsigned int channels, _Out_writes_(16) float* matrix) noexcept;
 
     // Helper class for implementing SoundEffectInstance
     class SoundEffectInstanceBase

Src/LoaderHelpers.h

@@ -523,6 +523,9 @@ namespace DirectX
             size_t bpe = 0;
             switch (fmt)
             {
+            case DXGI_FORMAT_UNKNOWN:
+                return E_INVALIDARG;
+
             case DXGI_FORMAT_BC1_TYPELESS:
             case DXGI_FORMAT_BC1_UNORM:
             case DXGI_FORMAT_BC1_UNORM_SRGB: