--- /dev/null
+;------------------------------------------------------------------------------\r
+;\r
+; Copyright (c) 2006, Intel Corporation. All rights reserved.<BR>\r
+; This program and the accompanying materials\r
+; are licensed and made available under the terms and conditions of the BSD License\r
+; which accompanies this distribution. The full text of the license may be found at\r
+; http://opensource.org/licenses/bsd-license.php.\r
+;\r
+; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
+; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
+;\r
+; Module Name:\r
+;\r
+; CopyMem.Asm\r
+;\r
+; Abstract:\r
+;\r
+; CopyMem function\r
+;\r
+; Notes:\r
+;\r
+;------------------------------------------------------------------------------\r
+\r
+ SECTION .text\r
+\r
+;------------------------------------------------------------------------------\r
+; VOID *\r
+; InternalMemCopyMem (\r
+; IN VOID *Destination,\r
+; IN VOID *Source,\r
+; IN UINTN Count\r
+; )\r
+;------------------------------------------------------------------------------\r
+global ASM_PFX(InternalMemCopyMem)\r
+ASM_PFX(InternalMemCopyMem):\r
+ push esi\r
+ push edi\r
+ mov esi, [esp + 16] ; esi <- Source\r
+ mov edi, [esp + 12] ; edi <- Destination\r
+ mov edx, [esp + 20] ; edx <- Count\r
+ lea eax, [esi + edx - 1] ; eax <- End of Source\r
+ cmp esi, edi\r
+ jae .0\r
+ cmp eax, edi\r
+ jae @CopyBackward ; Copy backward if overlapped\r
+.0:\r
+ mov ecx, edx\r
+ and edx, 3\r
+ shr ecx, 2\r
+ rep movsd ; Copy as many Dwords as possible\r
+ jmp @CopyBytes\r
+@CopyBackward:\r
+ mov esi, eax ; esi <- End of Source\r
+ lea edi, [edi + edx - 1] ; edi <- End of Destination\r
+ std\r
+@CopyBytes:\r
+ mov ecx, edx\r
+ rep movsb ; Copy bytes backward\r
+ cld\r
+ mov eax, [esp + 12] ; eax <- Destination as return value\r
+ pop edi\r
+ pop esi\r
+ ret\r
+\r