1 files changed, 62 insertions, 0 deletions
diff --git a/MdePkg/Library/BaseMemoryLibOptPei/Ia32/CopyMem.S b/MdePkg/Library/BaseMemoryLibOptPei/Ia32/CopyMem.S
new file mode 100644
index 0000000000000..12006753d89f9
--- /dev/null
+++ b/MdePkg/Library/BaseMemoryLibOptPei/Ia32/CopyMem.S
@@ -0,0 +1,62 @@
+#------------------------------------------------------------------------------
+#
+# 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.
+#
+# Module Name:
+#
+#   CopyMem.S
+#
+# Abstract:
+#
+#   CopyMem function
+#
+# Notes:
+#
+#------------------------------------------------------------------------------
+
+ASM_GLOBAL ASM_PFX(InternalMemCopyMem)
+
+#------------------------------------------------------------------------------
+#  VOID *
+#  EFIAPI
+#  InternalMemCopyMem (
+#    IN VOID   *Destination,
+#    IN VOID   *Source,
+#    IN UINTN  Count
+#    );
+#------------------------------------------------------------------------------
+ASM_PFX(InternalMemCopyMem):
+    push    %esi
+    push    %edi
+    movl    16(%esp), %esi              # esi <- Source
+    movl    12(%esp), %edi              # edi <- Destination
+    movl    20(%esp), %edx              # edx <- Count
+    cmpl    %esi, %edi
+    je      L_CopyDone
+    cmpl    $0, %edx
+    je      L_CopyDone
+    leal    -1(%esi, %edx), %eax        # eax <- End of Source
+    cmpl    %edi, %esi
+    jae     L_CopyBytes
+    cmpl    %edi, %eax
+    jb      L_CopyBytes                 # Copy backward if overlapped
+    movl    %eax, %esi                  # esi <- End of Source
+    leal    -1(%edi, %edx), %edi        # edi <- End of Destination
+    std
+L_CopyBytes:
+    movl    %edx, %ecx
+    rep
+    movsb                               # Copy bytes backward
+    cld
+L_CopyDone:
+    movl    12(%esp), %eax              # eax <- Destination as return value
+    pop     %edi
+    pop     %esi
+    ret