[BOOT] Add EFI headers and entry point

BOOT/ENVIRON/LIB/EFI/efistatus.c

@@ -0,0 +1,84 @@
+/*++
+
+Copyright (c) 2024, the LibreXP developers.
+Provided under the BSD 3-Clause license.
+
+Module Name:
+
+   efistatus.c
+
+Abstract:
+
+   Provides EFI status code utilities.
+
+--*/
+
+#include "bootmgr.h"
+
+EFI_STATUS
+EfiGetEfiStatusCode (
+    IN NTSTATUS Status
+    )
+
+/*++
+
+Routine Description:
+
+    Converts an NT status code into an EFI status code.
+
+Arguments:
+
+    Status - The NT status code to be converted.
+
+Return Value:
+
+    The EFI status code.
+
+--*/
+
+{
+    switch (Status) {
+    case STATUS_SUCCESS:
+        return EFI_SUCCESS;
+    case STATUS_DRIVER_UNABLE_TO_LOAD:
+        return EFI_LOAD_ERROR;
+    case STATUS_INVALID_PARAMETER:
+        return EFI_INVALID_PARAMETER;
+    case STATUS_NOT_SUPPORTED:
+        return EFI_UNSUPPORTED;
+    case STATUS_INVALID_BUFFER_SIZE:
+        return EFI_BAD_BUFFER_SIZE;
+    case STATUS_BUFFER_TOO_SMALL:
+        return EFI_BUFFER_TOO_SMALL;
+    case STATUS_IO_DEVICE_ERROR:
+        return EFI_DEVICE_ERROR;
+    case STATUS_MEDIA_WRITE_PROTECTED:
+        return EFI_WRITE_PROTECTED;
+    case STATUS_INSUFFICIENT_RESOURCES:
+        return EFI_OUT_OF_RESOURCES;
+    case STATUS_DISK_CORRUPT_ERROR:
+        return EFI_VOLUME_CORRUPTED;
+    case STATUS_DISK_FULL:
+        return EFI_VOLUME_FULL;
+    case STATUS_NO_MEDIA:
+        return EFI_NO_MEDIA;
+    case STATUS_MEDIA_CHANGED:
+        return EFI_MEDIA_CHANGED;
+    case STATUS_NOT_FOUND:
+        return EFI_NOT_FOUND;
+    case STATUS_ACCESS_DENIED:
+        return EFI_ACCESS_DENIED;
+    case STATUS_NO_MATCH:
+        return EFI_NO_MAPPING;
+    case STATUS_TIMEOUT:
+        return EFI_TIMEOUT;
+    case STATUS_DEVICE_NOT_READY:
+        return EFI_NOT_STARTED;
+    case STATUS_DEVICE_ALREADY_ATTACHED:
+        return EFI_ALREADY_STARTED;
+    case STATUS_REQUEST_ABORTED:
+        return EFI_ABORTED;
+    default:
+        return EFI_NO_MAPPING;
+    }
+}