From cf019fef472ea52d5342a9ea35f23d3c6f1b438f Mon Sep 17 00:00:00 2001
From: valentinbreiz <valentinbreiz@gmail.com>
Date: Mon, 6 Jul 2020 05:31:17 +0200
Subject: [PATCH] check if VBE is available with multiboot

---
 source/Cosmos.Core/Multiboot.cs               | 19 +++++++++++++++++++
 .../Graphics/FullScreenCanvas.cs              |  4 ++--
 source/Cosmos.System2/Graphics/VBECanvas.cs   |  6 ++++++
 3 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/source/Cosmos.Core/Multiboot.cs b/source/Cosmos.Core/Multiboot.cs
index bb61cbf04..97de17c68 100644
--- a/source/Cosmos.Core/Multiboot.cs
+++ b/source/Cosmos.Core/Multiboot.cs
@@ -64,6 +64,25 @@ namespace Cosmos.Core
     public unsafe static class VBE
     {
 
+        static uint VBEINFO_PRESENT = (1 << 11);
+
+        public static bool IsAvailable()
+        {
+            if ((Bootstrap.header->Flags & VBEINFO_PRESENT) == 0)
+            {
+                return false;
+            }
+            else
+            {
+                return true;
+            }
+        }
+
+        public static ModeInfo getModeInfo()
+        {
+            return *Bootstrap.modeinfo;
+        }
+
         [StructLayout(LayoutKind.Explicit, Size = 36)]
         public struct ControllerInfo
         {
diff --git a/source/Cosmos.System2/Graphics/FullScreenCanvas.cs b/source/Cosmos.System2/Graphics/FullScreenCanvas.cs
index 4beffad0c..2395c13d6 100644
--- a/source/Cosmos.System2/Graphics/FullScreenCanvas.cs
+++ b/source/Cosmos.System2/Graphics/FullScreenCanvas.cs
@@ -66,7 +66,7 @@ namespace Cosmos.System.Graphics
             {
                 return new SVGAIICanvas();
             }
-            else if (BGAExists() || PCI.GetDevice((VendorID)0x80EE, (DeviceID)0xBEEF) != null)
+            else if (BGAExists() || PCI.GetDevice((VendorID)0x80EE, (DeviceID)0xBEEF) != null || Core.VBE.IsAvailable())
             {
                 return new VBECanvas();
             }
@@ -88,7 +88,7 @@ namespace Cosmos.System.Graphics
             {
                 return new SVGAIICanvas(mode);
             }
-            else if (BGAExists() || PCI.GetDevice((VendorID)0x80EE, (DeviceID)0xBEEF) != null)
+            else if (BGAExists() || PCI.GetDevice((VendorID)0x80EE, (DeviceID)0xBEEF) != null || Core.VBE.IsAvailable())
             {
                 return new VBECanvas(mode);
             }
diff --git a/source/Cosmos.System2/Graphics/VBECanvas.cs b/source/Cosmos.System2/Graphics/VBECanvas.cs
index a38d5a735..4bc6a5a33 100644
--- a/source/Cosmos.System2/Graphics/VBECanvas.cs
+++ b/source/Cosmos.System2/Graphics/VBECanvas.cs
@@ -44,6 +44,12 @@ namespace Cosmos.System.Graphics
         {
             Global.mDebugger.SendInternal($"Creating new VBEScreen() with mode {aMode.Columns}x{aMode.Rows}x{(uint)aMode.ColorDepth}");
 
+            if (Core.VBE.IsAvailable())
+            {
+                Core.VBE.ModeInfo ModeInfo = Core.VBE.getModeInfo();
+                aMode = new Mode(ModeInfo.width, ModeInfo.height, (ColorDepth)ModeInfo.bpp);
+            }
+
             ThrowIfModeIsNotValid(aMode);
 
             _VBEDriver = new VBEDriver((ushort)aMode.Columns, (ushort)aMode.Rows, (ushort)aMode.ColorDepth);