1 files changed, 57 insertions, 0 deletions
diff --git a/MdePkg/Library/BaseMemoryLibOptDxe/X64/SetMem.S b/MdePkg/Library/BaseMemoryLibOptDxe/X64/SetMem.S
new file mode 100644
index 000000000000..41558f610563
--- /dev/null
+++ b/MdePkg/Library/BaseMemoryLibOptDxe/X64/SetMem.S
@@ -0,0 +1,57 @@
+#------------------------------------------------------------------------------
+#
+# Copyright (c) 2006 - 2009, 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:
+#
+#   SetMem.S
+#
+# Abstract:
+#
+#   SetMem function
+#
+# Notes:
+#
+#------------------------------------------------------------------------------
+#------------------------------------------------------------------------------
+#  VOID *
+#  EFIAPI
+#  InternalMemSetMem (
+#    IN VOID   *Buffer,
+#    IN UINTN  Count,
+#    IN UINT8  Value
+#    )
+#------------------------------------------------------------------------------
+ASM_GLOBAL ASM_PFX(InternalMemSetMem)
+ASM_PFX(InternalMemSetMem):
+    pushq   %rdi
+    pushq   %rbx
+    pushq   %rcx        # push Buffer
+    movq    %r8, %rax   # rax = Value
+    andq    $0xff, %rax # rax = lower 8 bits of r8, upper 56 bits are 0
+    movb    %al, %ah    # ah  = al
+    movw    %ax, %bx    # bx  = ax
+    shlq    $0x10, %rax # rax = ax << 16
+    movw    %bx,  %ax   # ax  = bx
+    movq    %rax, %rbx  # ebx = eax
+    shlq    $0x20, %rax # rax = rax << 32
+    orq     %rbx, %rax  # eax = ebx
+    movq    %rcx, %rdi  # rdi = Buffer
+    movq    %rdx, %rcx  # rcx = Count
+    shrq    $3, %rcx    # rcx = rcx / 8
+    cld
+    rep     stosq 
+    movq    %rdx, %rcx  # rcx = rdx
+    andq    $7, %rcx    # rcx = rcx & 7
+    rep     stosb 
+    popq    %rax        # rax = Buffer
+    popq    %rbx
+    popq    %rdi
+    ret