1 files changed, 104 insertions, 0 deletions
diff --git a/UefiLessonsPkg/SaveBGRT/SaveBGRT.c b/UefiLessonsPkg/SaveBGRT/SaveBGRT.c
new file mode 100644
index 0000000..2fda8d8
--- /dev/null
+++ b/UefiLessonsPkg/SaveBGRT/SaveBGRT.c
@@ -0,0 +1,104 @@
+#include <Library/UefiBootServicesTableLib.h>
+#include <Library/UefiLib.h>
+
+#include <Protocol/AcpiSystemDescriptionTable.h>
+#include <Library/ShellLib.h>
+#include <IndustryStandard/Bmp.h>
+
+EFI_STATUS WriteFile(CHAR16* FileName, VOID* Data, UINTN* Size)
+{
+  SHELL_FILE_HANDLE FileHandle;
+  EFI_STATUS Status = ShellOpenFileByName(
+    FileName,
+    &FileHandle,
+    EFI_FILE_MODE_CREATE | EFI_FILE_MODE_WRITE | EFI_FILE_MODE_READ,
+    0
+  );
+  if (!EFI_ERROR(Status)) {
+    Print(L"Save it to %s\n", FileName);
+    UINTN ToWrite = *Size;
+    Status = ShellWriteFile(
+      FileHandle,
+      Size,
+      Data
+    );
+    if (EFI_ERROR(Status)) {
+      Print(L"Can't write file: %r\n", Status);
+    }
+    if (*Size != ToWrite) {
+      Print(L"Error! Not all data was written\n");
+    }
+    Status = ShellCloseFile(
+      &FileHandle
+    );
+    if (EFI_ERROR(Status)) {
+      Print(L"Can't close file: %r\n", Status);
+    }
+  } else {
+    Print(L"Can't open file: %r\n", Status);
+  }
+  return Status;
+}
+
+EFI_STATUS
+EFIAPI
+UefiMain (
+  IN EFI_HANDLE        ImageHandle,
+  IN EFI_SYSTEM_TABLE  *SystemTable
+  )
+{
+  EFI_ACPI_SDT_PROTOCOL* AcpiSdtProtocol;
+  EFI_STATUS Status = gBS->LocateProtocol (
+                  &gEfiAcpiSdtProtocolGuid,
+                  NULL,
+                  (VOID**)&AcpiSdtProtocol
+                  );
+  if (EFI_ERROR (Status)) {
+    return Status;
+  }
+
+  BOOLEAN BGRT_found = FALSE;
+  UINTN Index = 0;
+  EFI_ACPI_SDT_HEADER* Table;
+  EFI_ACPI_TABLE_VERSION Version;
+  UINTN TableKey;
+  while (TRUE) {
+    Status = AcpiSdtProtocol->GetAcpiTable(Index,
+      &Table,
+      &Version,
+      &TableKey
+    );
+    if (EFI_ERROR(Status)) {
+      break;
+    }
+    if (((CHAR8)((Table->Signature >>  0) & 0xFF) == 'B') &&
+        ((CHAR8)((Table->Signature >>  8) & 0xFF) == 'G') &&
+        ((CHAR8)((Table->Signature >> 16) & 0xFF) == 'R') &&
+        ((CHAR8)((Table->Signature >> 24) & 0xFF) == 'T')) {
+      BGRT_found = TRUE;
+      break;
+    }
+    Index++;
+  }
+  if (!BGRT_found) {
+    Print(L"BGRT table is not present in the system\n");
+    return EFI_UNSUPPORTED;
+  }
+
+  EFI_ACPI_6_3_BOOT_GRAPHICS_RESOURCE_TABLE* BGRT = (EFI_ACPI_6_3_BOOT_GRAPHICS_RESOURCE_TABLE*)Table;
+  if (BGRT->ImageType == 0) {
+    BMP_IMAGE_HEADER* BMP = (BMP_IMAGE_HEADER*)(BGRT->ImageAddress);
+
+    if ((BMP->CharB != 'B') || (BMP->CharM != 'M')) {
+      Print(L"BMP image has wrong signature!\n");
+      return EFI_UNSUPPORTED;
+    }
+    Print(L"BGRT conatins BMP image with %dx%d resolution\n", BMP->PixelWidth, BMP->PixelHeight);
+    UINTN Size = BMP->Size;
+    Status = WriteFile(L"BGRT.bmp", BMP, &Size);
+    if (EFI_ERROR(Status)) {
+      Print(L"Error! Can't write BGRT.bmp file\n");
+    }
+  }
+  return Status;
+}