1 files changed, 33 insertions, 0 deletions
diff --git a/src/VBox/Devices/EFI/Firmware/MdePkg/Library/BaseSynchronizationLib/X64/InterlockedDecrement.nasm b/src/VBox/Devices/EFI/Firmware/MdePkg/Library/BaseSynchronizationLib/X64/InterlockedDecrement.nasm
new file mode 100644
index 00000000..d36d9b00
--- /dev/null
+++ b/src/VBox/Devices/EFI/Firmware/MdePkg/Library/BaseSynchronizationLib/X64/InterlockedDecrement.nasm
@@ -0,0 +1,33 @@
+;------------------------------------------------------------------------------
+;
+; Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
+; SPDX-License-Identifier: BSD-2-Clause-Patent
+;
+; Module Name:
+;
+;   InterlockedDecrement.Asm
+;
+; Abstract:
+;
+;   InterlockedDecrement function
+;
+; Notes:
+;
+;------------------------------------------------------------------------------
+
+    DEFAULT REL
+    SECTION .text
+
+;------------------------------------------------------------------------------
+; UINT32
+; EFIAPI
+; InternalSyncDecrement (
+;   IN      volatile UINT32           *Value
+;   );
+;------------------------------------------------------------------------------
+global ASM_PFX(InternalSyncDecrement)
+ASM_PFX(InternalSyncDecrement):
+    mov       eax, 0FFFFFFFFh
+    lock xadd dword [rcx], eax
+    dec       eax
+    ret