Initial port to x86_64 gnu assembly.

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@1959 6f19259b-4bc3-4df7-8a09-765794883524

MdePkg/Library/BaseLib/X64/WriteMsr64.S

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+#------------------------------------------------------------------------------
+#
+# Copyright (c) 2006, Intel Corporation
+# All rights reserved. This program and the accompanying materials
+# are licensed and made available under the terms and conditions of the BSD License
+# which accompanies this distribution.  The full text of the license may be found at
+# http://opensource.org/licenses/bsd-license.php
+#
+# THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+# WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+#
+# Module Name:
+#
+#   WriteMsr64.S
+#
+# Abstract:
+#
+#   AsmWriteMsr64 function
+#
+# Notes:
+#
+#------------------------------------------------------------------------------
+
+
+#------------------------------------------------------------------------------
+# UINT64
+# EFIAPI
+# AsmWriteMsr64 (
+#   IN UINT32  Index,
+#   IN UINT64  Value
+#   );
+# TODO:
+#------------------------------------------------------------------------------
+.global _AsmWriteMsr64;
+.align 16;
+_AsmWriteMsr64:
+    mov	%rdx, %rax
+    shr $0x20, %rdx
+    wrmsr
+    ret