Add `etcpak` library for faster ETC/ETC2/S3TC imports.

- `etc` module was renamed to `etcpak` and modified to use the new library.
- PKM importer is removed in the process, it's obsolete.
- Old library `etc2comp` is removed.
- S3TC compression no longer done via `squish` (but decompression still is).
- Slight modifications to etcpak sources for MinGW compatibility,
  to fix LLVM `-Wc++11-narrowing` errors, and to allow using vendored or
  system libpng.

Co-authored-by: Rémi Verschelde <rverschelde@gmail.com>

1 files changed, 56 insertions, 0 deletions

diff --git a/thirdparty/etcpak/BlockData.hpp b/thirdparty/etcpak/BlockData.hpp
new file mode 100644
index 0000000000..209e35b4e6
--- /dev/null
+++ b/thirdparty/etcpak/BlockData.hpp
@@ -0,0 +1,56 @@
+#ifndef __BLOCKDATA_HPP__
+#define __BLOCKDATA_HPP__
+
+#include <condition_variable>
+#include <future>
+#include <memory>
+#include <mutex>
+#include <stdint.h>
+#include <stdio.h>
+#include <vector>
+
+#include "Bitmap.hpp"
+#include "ForceInline.hpp"
+#include "Vector.hpp"
+
+class BlockData
+{
+public:
+    enum Type
+    {
+        Etc1,
+        Etc2_RGB,
+        Etc2_RGBA,
+        Dxt1,
+        Dxt5
+    };
+
+    BlockData( const char* fn );
+    BlockData( const char* fn, const v2i& size, bool mipmap, Type type );
+    BlockData( const v2i& size, bool mipmap, Type type );
+    ~BlockData();
+
+    BitmapPtr Decode();
+
+    void Process( const uint32_t* src, uint32_t blocks, size_t offset, size_t width, Channels type, bool dither );
+    void ProcessRGBA( const uint32_t* src, uint32_t blocks, size_t offset, size_t width );
+
+    const v2i& Size() const { return m_size; }
+
+private:
+    etcpak_no_inline BitmapPtr DecodeRGB();
+    etcpak_no_inline BitmapPtr DecodeRGBA();
+    etcpak_no_inline BitmapPtr DecodeDxt1();
+    etcpak_no_inline BitmapPtr DecodeDxt5();
+
+    uint8_t* m_data;
+    v2i m_size;
+    size_t m_dataOffset;
+    FILE* m_file;
+    size_t m_maplen;
+    Type m_type;
+};
+
+typedef std::shared_ptr<BlockData> BlockDataPtr;
+
+#endif