Bite the bullet and flip the video buffer in software.

Until a better solution is found.

Signed-off-by: Andrea Odetti <mariofutire@gmail.com>

linux.md

@@ -91,7 +91,11 @@ See [sa2](source/frontends/sa2/README.md).
 
 ### ra2
 
-There is an initial [libretro](https://docs.libretro.com/development/cores/developing-cores/) core, with minimal keyboard support and upside down video.
+There is an initial [libretro](https://docs.libretro.com/development/cores/developing-cores/) core.
+
+Keyboard works, but a lot of keys overlap with RetroArch shortcuts.
+
+Video works, but the vertical flip is done in software.
 
 Must be manually configured:
 ``cmake -DLIBRETRO_PATH=/path/to/libretro-common``

source/frontends/retro/game.cpp

@@ -112,7 +112,10 @@ namespace
 
 }
 
-Game::Game() : mySpeed(true)
+Game::Game()
+  : mySpeed(true)
+  , myWidth(GetFrameBufferWidth())
+  , myHeight(GetFrameBufferHeight())
 {
   EmulatorOptions options;
   options.memclear = g_nMemoryClearType;
@@ -125,6 +128,9 @@ Game::Game() : mySpeed(true)
 
   InitializeRegistry(options);
   initialiseEmulator();
+
+  const size_t size = myWidth * myHeight * sizeof(bgra_t);
+  myVideoBuffer.resize(size);
 }
 
 Game::~Game()
@@ -270,8 +276,18 @@ void Game::processKeyUp(unsigned keycode, uint32_t character, uint16_t key_modif
 
 void Game::drawVideoBuffer()
 {
-  const size_t pitch = GetFrameBufferWidth() * 4;
+  const size_t pitch = myWidth * sizeof(bgra_t);
-  video_cb(g_pFramebufferbits, GetFrameBufferWidth(), GetFrameBufferHeight(), pitch);
+  // this should not be necessary
+  // either libretro handles it
+  // or we should change AW
+  // but for now, there is no alternative
+  for (size_t row = 0; row < myHeight; ++row)
+  {
+    const uint8_t * src = g_pFramebufferbits + row * pitch;
+    uint8_t * dst = myVideoBuffer.data() + (myHeight - row - 1) * pitch;
+    memcpy(dst, src, pitch);
+  }
+  video_cb(myVideoBuffer.data(), myWidth, myHeight, pitch);
 }
 
 bool Game::loadGame(const char * path)

source/frontends/retro/game.h

@@ -20,7 +20,11 @@ public:
 private:
   Speed mySpeed;  // fixed speed
 
+  const size_t myHeight;
+  const size_t myWidth;
+
   static void processKeyDown(unsigned keycode, uint32_t character, uint16_t key_modifiers);
   static void processKeyUp(unsigned keycode, uint32_t character, uint16_t key_modifiers);
 
+  std::vector<uint8_t> myVideoBuffer;
 };