port: EterImageLib Image/TGAImage/DXTCImage verbatim (+ d3d.h ddraw shim)

-fno-strict-aliasing on the port targets: 40250 relies on MSVC's lack of
type-based alias analysis (DXTCImage reads Color8888 through DWORD*).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/port/CMakeLists.txt

@@ -43,6 +43,9 @@ endif()
 set(MT_PORT_WARNING_FLAGS)
 if(NOT MSVC)
     set(MT_PORT_WARNING_FLAGS -Wno-unknown-pragmas -Wno-format-security)
+    # MSVC does no type-based alias analysis and 40250 relies on it (DXTCImage reads a Color8888 through a
+    # DWORD*; clang -O2 then loads the colour before it is written).
+    list(APPEND MT_PORT_WARNING_FLAGS -fno-strict-aliasing)
 endif()
 target_compile_options(port_logic PUBLIC ${MT_PORT_WARNING_FLAGS})
 # 40250 headers keep `#pragma comment(lib, "d3d8.lib")` etc. verbatim; clang turns them into ELF
@@ -208,6 +211,9 @@ if(BUILD_TESTING AND CMAKE_SYSTEM_NAME STREQUAL CMAKE_HOST_SYSTEM_NAME)
     add_executable(port_input_test ${PROJECT_SOURCE_DIR}/tests/port/port_input_test.cpp)
     target_link_libraries(port_input_test PRIVATE port_platform)
     add_test(NAME port.input COMMAND $<TARGET_FILE:port_input_test>)
+    add_executable(port_eter_image_test ${PROJECT_SOURCE_DIR}/tests/port/port_eter_image_test.cpp)
+    target_link_libraries(port_eter_image_test PRIVATE port_platform)
+    add_test(NAME port.eter_image COMMAND $<TARGET_FILE:port_eter_image_test>)
 
     # MilesLib: the 40250 sound managers over the Miles emulation (platform/MilesLib/MilesAil.cpp).
     add_executable(port_miles_test ${PROJECT_SOURCE_DIR}/tests/port/port_miles_test.cpp)

src/port/common/shim/sdk/d3d.h

@@ -0,0 +1,122 @@
+#pragma once
+// Shim for the DirectX 7 <d3d.h> on non-Windows targets: the <ddraw.h> surface description 40250
+// EterImageLib/DXTCImage.cpp copies straight out of a .dds file (the 124 bytes after the "DDS " magic).
+//
+// PORT: lpSurface is a pointer in <ddraw.h>, 4 bytes in the 32-bit client; it is a DWORD here so the
+// structure keeps the on-disk layout on 64-bit targets.
+#include "../win32/windows.h"
+
+#define DDSD_CAPS 0x00000001l
+#define DDSD_HEIGHT 0x00000002l
+#define DDSD_WIDTH 0x00000004l
+#define DDSD_PITCH 0x00000008l
+#define DDSD_PIXELFORMAT 0x00001000l
+#define DDSD_MIPMAPCOUNT 0x00020000l
+#define DDSD_LINEARSIZE 0x00080000l
+
+#define DDPF_ALPHAPIXELS 0x00000001l
+#define DDPF_FOURCC 0x00000004l
+#define DDPF_RGB 0x00000040l
+#define DDPF_ALPHAPREMULT 0x00008000l
+
+typedef struct _DDCOLORKEY
+{
+	DWORD dwColorSpaceLowValue;
+	DWORD dwColorSpaceHighValue;
+} DDCOLORKEY;
+
+typedef struct _DDPIXELFORMAT
+{
+	DWORD dwSize;
+	DWORD dwFlags;
+	DWORD dwFourCC;
+	union
+	{
+		DWORD dwRGBBitCount;
+		DWORD dwYUVBitCount;
+		DWORD dwZBufferBitDepth;
+		DWORD dwAlphaBitDepth;
+		DWORD dwLuminanceBitCount;
+		DWORD dwBumpBitCount;
+		DWORD dwPrivateFormatBitCount;
+	};
+	union
+	{
+		DWORD dwRBitMask;
+		DWORD dwYBitMask;
+		DWORD dwStencilBitDepth;
+		DWORD dwLuminanceBitMask;
+		DWORD dwBumpDuBitMask;
+		DWORD dwOperations;
+	};
+	union
+	{
+		DWORD dwGBitMask;
+		DWORD dwUBitMask;
+		DWORD dwZBitMask;
+		DWORD dwBumpDvBitMask;
+	};
+	union
+	{
+		DWORD dwBBitMask;
+		DWORD dwVBitMask;
+		DWORD dwStencilBitMask;
+		DWORD dwBumpLuminanceBitMask;
+	};
+	union
+	{
+		DWORD dwRGBAlphaBitMask;
+		DWORD dwYUVAlphaBitMask;
+		DWORD dwLuminanceAlphaBitMask;
+		DWORD dwRGBZBitMask;
+		DWORD dwYUVZBitMask;
+	};
+} DDPIXELFORMAT;
+
+typedef struct _DDSCAPS2
+{
+	DWORD dwCaps;
+	DWORD dwCaps2;
+	DWORD dwCaps3;
+	DWORD dwCaps4;
+} DDSCAPS2;
+
+typedef struct _DDSURFACEDESC2
+{
+	DWORD dwSize;
+	DWORD dwFlags;
+	DWORD dwHeight;
+	DWORD dwWidth;
+	union
+	{
+		LONG lPitch;
+		DWORD dwLinearSize;
+	};
+	union
+	{
+		DWORD dwBackBufferCount;
+		DWORD dwDepth;
+	};
+	union
+	{
+		DWORD dwMipMapCount;
+		DWORD dwRefreshRate;
+		DWORD dwSrcVBHandle;
+	};
+	DWORD dwAlphaBitDepth;
+	DWORD dwReserved;
+	DWORD lpSurface;
+	union
+	{
+		DDCOLORKEY ddckCKDestOverlay;
+		DWORD dwEmptyFaceColor;
+	};
+	DDCOLORKEY ddckCKDestBlt;
+	DDCOLORKEY ddckCKSrcOverlay;
+	DDCOLORKEY ddckCKSrcBlt;
+	DDPIXELFORMAT ddpfPixelFormat;
+	DDSCAPS2 ddsCaps;
+	DWORD dwTextureStage;
+} DDSURFACEDESC2, *LPDDSURFACEDESC2;
+
+static_assert(sizeof(DDPIXELFORMAT) == 32 && sizeof(DDSURFACEDESC2) == 124, "the .dds header layout");