1 files changed, 44 insertions, 0 deletions
diff --git a/Core/MdePkg/Library/BaseLib/Ia32/Mwait.c b/Core/MdePkg/Library/BaseLib/Ia32/Mwait.c
new file mode 100644
index 0000000000..e9ecb2cecd
--- /dev/null
+++ b/Core/MdePkg/Library/BaseLib/Ia32/Mwait.c
@@ -0,0 +1,44 @@
+/** @file
+  AsmMwait function
+
+  Copyright (c) 2006 - 2008, Intel Corporation. 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.
+
+**/
+
+/**
+  Executes an MWAIT instruction.
+
+  Executes an MWAIT instruction with the register state specified by Eax and
+  Ecx. Returns Eax. This function is only available on IA-32 and x64.
+
+  @param  RegisterEax The value to load into EAX or RAX before executing the MONITOR
+                      instruction.
+  @param  RegisterEcx The value to load into ECX or RCX before executing the MONITOR
+                      instruction.
+
+  @return RegisterEax
+
+**/
+UINTN
+EFIAPI
+AsmMwait (
+  IN      UINTN                     RegisterEax,
+  IN      UINTN                     RegisterEcx
+  )
+{
+  _asm {
+    mov     eax, RegisterEax
+    mov     ecx, RegisterEcx
+    _emit   0x0f              // mwait
+    _emit   0x01
+    _emit   0xC9
+  }
+}
+