1 files changed, 55 insertions, 0 deletions
diff --git a/MdePkg/Library/BaseMemoryLibOptDxe/X64/IsZeroBuffer.nasm b/MdePkg/Library/BaseMemoryLibOptDxe/X64/IsZeroBuffer.nasm
new file mode 100644
index 0000000000..00b1067eee
--- /dev/null
+++ b/MdePkg/Library/BaseMemoryLibOptDxe/X64/IsZeroBuffer.nasm
@@ -0,0 +1,55 @@
+;------------------------------------------------------------------------------
+;
+; Copyright (c) 2016, 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:
+;
+;   IsZeroBuffer.nasm
+;
+; Abstract:
+;
+;   IsZeroBuffer function
+;
+; Notes:
+;
+;------------------------------------------------------------------------------
+
+    DEFAULT REL
+    SECTION .text
+
+;------------------------------------------------------------------------------
+;  BOOLEAN
+;  EFIAPI
+;  InternalMemIsZeroBuffer (
+;    IN CONST VOID  *Buffer,
+;    IN UINTN       Length
+;    );
+;------------------------------------------------------------------------------
+global ASM_PFX(InternalMemIsZeroBuffer)
+ASM_PFX(InternalMemIsZeroBuffer):
+    push    rdi
+    mov     rdi, rcx                   ; rdi <- Buffer
+    mov     rcx, rdx                   ; rcx <- Length
+    shr     rcx, 3                     ; rcx <- number of qwords
+    and     rdx, 7                     ; rdx <- number of trailing bytes
+    xor     rax, rax                   ; rax <- 0, also set ZF
+    repe    scasq
+    jnz     @ReturnFalse               ; ZF=0 means non-zero element found
+    mov     rcx, rdx
+    repe    scasb
+    jnz     @ReturnFalse
+    pop     rdi
+    mov     rax, 1                     ; return TRUE
+    ret
+@ReturnFalse:
+    pop     rdi
+    xor     rax, rax
+    ret                                ; return FALSE
+