Refactor EGL device enumeration code

glest.cabal

@@ -80,7 +80,6 @@ library
     unix,
     unordered-containers,
     utf8-string,
-    vector,
     xml,
   extra-libraries: EGL, GLESv2
   hs-source-dirs:

src/Glest/Egl.hs

@@ -10,7 +10,6 @@ import Control.Exception
 import Data.Foldable (elem)
 import Data.Set (Set)
 import qualified Data.Set as Set
-import Data.Vector.Storable.Mutable qualified as V
 import Foreign
 import Foreign.C.Error
 import Foreign.C.String
@@ -55,63 +54,27 @@ instance Show EglException where
   show (EglException 0x300e) = "EGL_CONTEXT_LOST"
   show _ = "Invalid EGL error number"
 
-loadEglExtensionFunctions :: IO ()
-loadEglExtensionFunctions =
-  [CU.block|
-    void {
-      eglQueryDevicesEXT = (PFNEGLQUERYDEVICESEXTPROC)eglGetProcAddress("eglQueryDevicesEXT");
-      eglQueryDeviceStringEXT = (PFNEGLQUERYDEVICESTRINGEXTPROC)eglGetProcAddress("eglQueryDeviceStringEXT");
-      // if (eglQueryDevicesEXT == NULL) {
-      //   return NULL;
-      // }
-    }
-  |]
-
 eglGetError :: IO EglException
 eglGetError = EglException <$> [CU.exp| EGLint { eglGetError() } |]
 
 initializeEgl :: IO ()
 initializeEgl = do
-  loadEglExtensionFunctions
+  clientExtensionsString <-
+    eglQueryString
+      [CU.pure|EGLDisplay { EGL_NO_DISPLAY }|]
+      [CU.pure|EGLint { EGL_EXTENSIONS }|]
 
-  deviceCount <- throwErrnoIfMinus1 "eglQueryDevicesEXT"
-    [CU.block|
-      EGLint {
-        EGLint count;
-        EGLBoolean result = eglQueryDevicesEXT(0, NULL, &count);
-        if (!result) {
-          return -1;
-        }
-        return count;
-      }
-    |]
-  traceIO $ "Available EGL devices: " <> show deviceCount
+  traceIO $ mconcat ["EGL client extensions: ", clientExtensionsString]
 
-  devices :: V.IOVector EGLDeviceEXT <- V.new (fromIntegral deviceCount)
-  V.unsafeWith devices \devicesPtr ->
-    throwErrnoIf_ (== 0) "eglQueryDevicesEXT"
-      [CU.block|
-        EGLBoolean {
-          EGLint count;
-          EGLBoolean result = eglQueryDevicesEXT($(EGLint deviceCount), $(EGLDeviceEXT* devicesPtr), &count);
-          if (count < $(EGLint deviceCount)) {
-            return EGL_FALSE;
-          }
-          return result;
-        }
-      |]
+  let clientExtensions = Set.fromList (words clientExtensionsString)
 
-  V.iforM_ devices \i device -> do
-    vendor <- eglQueryDeviceString device [CU.pure|EGLint { EGL_EXTENSIONS }|]
-    traceIO $ mconcat ["Device ", show i, ": ", vendor]
-    renderNode <- eglTryQueryDeviceString device [CU.pure|EGLint { EGL_DRM_RENDER_NODE_FILE_EXT }|]
-    traceIO $ mconcat ["Device ", show i, ": ", show renderNode]
+  unless ("EGL_EXT_device_enumeration" `elem` clientExtensions && "EGL_EXT_device_query" `elem` clientExtensions) do
+    fail "Missing extensions for device enumeration"
+  display <- getEglDisplayDevice
 
-  traceIO "Using device 0"
-  device <- V.read devices 0
-
-  display <- throwErrnoIfNull "eglGetPlatformDisplay"
-    [CU.exp|EGLDisplay { eglGetPlatformDisplay(EGL_PLATFORM_DEVICE_EXT, $(EGLDeviceEXT device), NULL) }|]
+  --when ("EGL_MESA_platform_surfaceless" `elem` clientExtensions) do
+  --  traceIO "Surfaceless platform available"
+  --display <- getEglDisplaySurfaceless
 
   (major :: EGLint, minor :: EGLint) <- C.withPtrs_ \(majorPtr, minorPtr) ->
     throwErrnoIf_ (== 0) "eglInitialize"
@@ -161,6 +124,64 @@ initializeEgl = do
     [CU.exp|EGLBoolean { eglMakeCurrent($(EGLDisplay display), EGL_NO_SURFACE, EGL_NO_SURFACE, $(EGLContext context)) }|]
 
 
+getEglDisplayDevice :: IO EGLDisplay
+getEglDisplayDevice = do
+  -- Requires EGL_EXT_device_enumeration and EGL_EXT_device_query
+  [CU.block|
+    void {
+      eglQueryDevicesEXT = (PFNEGLQUERYDEVICESEXTPROC)eglGetProcAddress("eglQueryDevicesEXT");
+      eglQueryDeviceStringEXT = (PFNEGLQUERYDEVICESTRINGEXTPROC)eglGetProcAddress("eglQueryDeviceStringEXT");
+    }
+  |]
+
+  deviceCount <- throwErrnoIfMinus1 "eglQueryDevicesEXT"
+    [CU.block|
+      EGLint {
+        EGLint count;
+        EGLBoolean result = eglQueryDevicesEXT(0, NULL, &count);
+        if (!result) {
+          return -1;
+        }
+        return count;
+      }
+    |]
+  traceIO $ "Available EGL devices: " <> show deviceCount
+
+  (devices :: [EGLDeviceEXT]) <- allocaArray (fromIntegral deviceCount) \ptr -> do
+    throwErrnoIf_ (== 0) "eglQueryDevicesEXT"
+      [CU.block|
+        EGLBoolean {
+          EGLint count;
+          EGLBoolean result = eglQueryDevicesEXT($(EGLint deviceCount), $(EGLDeviceEXT* ptr), &count);
+          if (count < $(EGLint deviceCount)) {
+            return EGL_FALSE;
+          }
+          return result;
+        }
+      |]
+    peekArray (fromIntegral deviceCount) ptr
+
+  forM_ (zip [0,1..] devices) \(i, device) -> do
+    vendor <- eglQueryDeviceString device [CU.pure|EGLint { EGL_EXTENSIONS }|]
+    traceIO $ mconcat ["Device ", show i, ": ", vendor]
+    deviceNode <- eglTryQueryDeviceString device [CU.pure|EGLint { EGL_DRM_DEVICE_FILE_EXT }|]
+    traceIO $ mconcat ["Device ", show i, ": ", show deviceNode]
+    renderNode <- eglTryQueryDeviceString device [CU.pure|EGLint { EGL_DRM_RENDER_NODE_FILE_EXT }|]
+    traceIO $ mconcat ["Device ", show i, ": ", show renderNode]
+
+  traceIO "Using device 0"
+  (device:_) <- pure devices
+
+  throwErrnoIfNull "eglGetPlatformDisplay"
+    [CU.exp|EGLDisplay { eglGetPlatformDisplay(EGL_PLATFORM_DEVICE_EXT, $(EGLDeviceEXT device), NULL) }|]
+
+--getEglDisplaySurfaceless :: IO EGLDisplay
+--getEglDisplaySurfaceless = do
+--  -- Requires EGL_MESA_platform_surfaceless
+--  throwErrnoIfNull "eglGetPlatformDisplay"
+--    [CU.exp|EGLDisplay { eglGetPlatformDisplay(EGL_PLATFORM_SURFACELESS_MESA, EGL_DEFAULT_DISPLAY, NULL) }|]
+
+
 eglQueryString :: EGLDisplay -> EGLint -> IO String
 eglQueryString display name =
   peekCString =<< throwErrnoIfNull "eglQueryString"