add double buffering

2 files changed, 29 insertions, 2 deletions

diff --git a/UefiMonitorTest/UefiMonitorTest.c b/UefiMonitorTest/UefiMonitorTest.c
index 2d27013..8dda9b7 100644
--- a/UefiMonitorTest/UefiMonitorTest.c
+++ b/UefiMonitorTest/UefiMonitorTest.c
@@ -23,7 +23,10 @@ PrepareGraphicsInfo (
   ASSERT (Gop != NULL);
 
   Graphics->Gop         = Gop;
-  Graphics->Base        = (UINT8 *)Gop->Mode->FrameBufferBase;
+  Graphics->FrontBuffer = (UINT8 *)Gop->Mode->FrameBufferBase;
+  Graphics->BufferSize  = Gop->Mode->FrameBufferSize;
+  Graphics->BackBuffer  = AllocateCopyPool (Graphics->BufferSize, Graphics->FrontBuffer);
+  ASSERT (Graphics->BackBuffer != NULL);
   Graphics->Width       = Gop->Mode->Info->HorizontalResolution;
   Graphics->Height      = Gop->Mode->Info->VerticalResolution;
   Graphics->PixelWidth  = 4; // A pixel is 32-bits
@@ -44,6 +47,18 @@ PrepareGraphicsInfo (
 }
 
 STATIC
+VOID
+ForgetGraphicsInfo (
+  IN GRAPHICS_CONTEXT *Graphics
+  )
+{
+  ASSERT (Graphics != NULL);
+
+  // Should we zero all the data structure?
+
+  FreePool (Graphics->BackBuffer);
+}
+
 EFI_GRAPHICS_OUTPUT_PROTOCOL *
 GetGraphicsOutputProtocol (
   VOID
@@ -100,5 +115,9 @@ UefiMain (
 
   PrepareGraphicsInfo (&Graphics, Gop);
 
+  
+
+  ForgetGraphicsInfo (&Graphics);
+
   return EFI_SUCCESS;
 }
diff --git a/UefiMonitorTest/UefiMonitorTest.h b/UefiMonitorTest/UefiMonitorTest.h
index d6306bc..97ada85 100644
--- a/UefiMonitorTest/UefiMonitorTest.h
+++ b/UefiMonitorTest/UefiMonitorTest.h
@@ -10,7 +10,15 @@ typedef struct {
   /// Base address of graphics linear frame buffer.
   /// Starts from the upper left pixel.
   ///
-  UINT8                                   *Base;
+  UINT8                                   *FrontBuffer;
+  ///
+  /// Pointer to allocated memory. Secondary linear buffer.
+  ///
+  UINT8                                   *BackBuffer;
+  ///
+  /// Amount of frame buffer needed to support the active mode.
+  ///
+  UINTN                                   BufferSize;
   ///
   /// The size of video screen in pixels in the X dimension.
   ///