diff options
Diffstat (limited to 'Core/MdePkg/Library/BaseMemoryLibOptDxe/X64/IsZeroBuffer.nasm')
-rw-r--r-- | Core/MdePkg/Library/BaseMemoryLibOptDxe/X64/IsZeroBuffer.nasm | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/Core/MdePkg/Library/BaseMemoryLibOptDxe/X64/IsZeroBuffer.nasm b/Core/MdePkg/Library/BaseMemoryLibOptDxe/X64/IsZeroBuffer.nasm new file mode 100644 index 0000000000..00b1067eee --- /dev/null +++ b/Core/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
+
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