MdePkg/BaseSynchronizationLib: Add InterlockedCompareExchange16

This implements the function InterlockedCompareExchange16 () for all
architectures, using architecture and toolchain specific intrinsics
or primitive assembler instructions.

Contributed-under: TianoCore Contribution Agreement 1.0
Reviewed-by: Olivier Martin <olivier.martin@arm.com>
Acked-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Michael Kinney <michael.d.kinney@intel.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16966 6f19259b-4bc3-4df7-8a09-765794883524

MdePkg/Library/BaseSynchronizationLib/Ipf/InterlockedCompareExchange16.s

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+/// @file
+///   Contains an implementation of InterlockedCompareExchange16 on Itanium-
+///   based architecture.
+///
+/// Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>
+/// Copyright (c) 2015, Linaro Ltd. All rights reserved.<BR>
+/// 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:  InterlockedCompareExchange16.s
+///
+///
+
+.auto
+.text
+
+.proc   InternalSyncCompareExchange16
+.type   InternalSyncCompareExchange16, @function
+InternalSyncCompareExchange16::
+        zxt2                r33 = r33
+        mov                 ar.ccv = r33
+        cmpxchg2.rel        r8  = [r32], r34
+        mf
+        br.ret.sptk.many    b0
+.endp   InternalSyncCompareExchange16