1 files changed, 44 insertions, 0 deletions
diff --git a/src/VBox/Runtime/win/amd64/ASMAtomicBitClear.asm b/src/VBox/Runtime/win/amd64/ASMAtomicBitClear.asm
new file mode 100644
index 00000000..fadc734e
--- /dev/null
+++ b/src/VBox/Runtime/win/amd64/ASMAtomicBitClear.asm
@@ -0,0 +1,44 @@
+;; @file
+; IPRT - ASMAtomicBitClear().
+;
+
+;
+; Copyright (C) 2006-2020 Oracle Corporation
+;
+; This file is part of VirtualBox Open Source Edition (OSE), as
+; available from http://www.virtualbox.org. This file is free software;
+; you can redistribute it and/or modify it under the terms of the GNU
+; General Public License (GPL) as published by the Free Software
+; Foundation, in version 2 as it comes in the "COPYING" file of the
+; VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+; hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+;
+; The contents of this file may alternatively be used under the terms
+; of the Common Development and Distribution License Version 1.0
+; (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+; VirtualBox OSE distribution, in which case the provisions of the
+; CDDL are applicable instead of those of the GPL.
+;
+; You may elect to license modified versions of this file under the
+; terms and conditions of either the GPL or the CDDL or both.
+;
+
+;*******************************************************************************
+;* Header Files                                                                *
+;*******************************************************************************
+%include "iprt/asmdefs.mac"
+
+BEGINCODE
+
+;;
+; Atomically clears a bit in a bitmap.
+;
+; @param   rcx  pvBitmap    Pointer to the bitmap.
+; @param   edx  iBit        The bit to toggle set.
+; @remark  No memory barrier, take care on smp.
+;
+BEGINPROC_EXPORTED ASMAtomicBitClear
+        lock btr [rcx], edx
+        ret
+ENDPROC ASMAtomicBitClear
+