1 files changed, 81 insertions, 0 deletions
diff --git a/src/VBox/Runtime/common/asm/ASMAtomicReadU64.asm b/src/VBox/Runtime/common/asm/ASMAtomicReadU64.asm
new file mode 100644
index 00000000..e665b6e0
--- /dev/null
+++ b/src/VBox/Runtime/common/asm/ASMAtomicReadU64.asm
@@ -0,0 +1,81 @@
+; $Id: ASMAtomicReadU64.asm $
+;; @file
+; IPRT - ASMAtomicReadU64().
+;
+
+;
+; Copyright (C) 2006-2022 Oracle and/or its affiliates.
+;
+; This file is part of VirtualBox base platform packages, as
+; available from https://www.virtualbox.org.
+;
+; This program is free software; you can redistribute it and/or
+; modify it under the terms of the GNU General Public License
+; as published by the Free Software Foundation, in version 3 of the
+; License.
+;
+; This program is distributed in the hope that it will be useful, but
+; WITHOUT ANY WARRANTY; without even the implied warranty of
+; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+; General Public License for more details.
+;
+; You should have received a copy of the GNU General Public License
+; along with this program; if not, see <https://www.gnu.org/licenses>.
+;
+; The contents of this file may alternatively be used under the terms
+; of the Common Development and Distribution License Version 1.0
+; (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
+; in the VirtualBox 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.
+;
+; SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
+;
+
+;*******************************************************************************
+;* Header Files                                                                *
+;*******************************************************************************
+%include "iprt/asmdefs.mac"
+
+BEGINCODE
+
+;;
+; Atomically reads 64-bit value.
+;
+; @param   pu64     x86:ebp+8
+;
+; @returns The current value. (x86:eax+edx)
+;
+;
+RT_BEGINPROC ASMAtomicReadU64
+%ifdef RT_ARCH_AMD64
+        mfence                          ; ASSUME its present.
+ %ifdef ASM_CALL64_MSC
+        mov     rax, [rcx]
+ %else
+        mov     rax, [rdi]
+ %endif
+        ret
+%endif
+%ifdef RT_ARCH_X86
+        push    ebp
+        mov     ebp, esp
+        push    ebx
+        push    edi
+
+        xor     eax, eax
+        xor     edx, edx
+        mov     edi, [ebp+08h]
+        xor     ecx, ecx
+        xor     ebx, ebx
+        lock cmpxchg8b [edi]
+
+        pop     edi
+        pop     ebx
+        leave
+        ret
+%endif
+ENDPROC ASMAtomicReadU64
+