1 files changed, 49 insertions, 0 deletions
diff --git a/src/VBox/Devices/EFI/Firmware/MdePkg/Library/BaseMemoryLibOptDxe/Ia32/IsZeroBuffer.nasm b/src/VBox/Devices/EFI/Firmware/MdePkg/Library/BaseMemoryLibOptDxe/Ia32/IsZeroBuffer.nasm
new file mode 100644
index 00000000..a329ceca
--- /dev/null
+++ b/src/VBox/Devices/EFI/Firmware/MdePkg/Library/BaseMemoryLibOptDxe/Ia32/IsZeroBuffer.nasm
@@ -0,0 +1,49 @@
+;------------------------------------------------------------------------------
+;
+; Copyright (c) 2016, Intel Corporation. All rights reserved.<BR>
+; SPDX-License-Identifier: BSD-2-Clause-Patent
+;
+; Module Name:
+;
+;   IsZeroBuffer.nasm
+;
+; Abstract:
+;
+;   IsZeroBuffer function
+;
+; Notes:
+;
+;------------------------------------------------------------------------------
+
+    SECTION .text
+
+;------------------------------------------------------------------------------
+;  BOOLEAN
+;  EFIAPI
+;  InternalMemIsZeroBuffer (
+;    IN CONST VOID  *Buffer,
+;    IN UINTN       Length
+;    );
+;------------------------------------------------------------------------------
+global ASM_PFX(InternalMemIsZeroBuffer)
+ASM_PFX(InternalMemIsZeroBuffer):
+    push    edi
+    mov     edi, [esp + 8]             ; edi <- Buffer
+    mov     ecx, [esp + 12]            ; ecx <- Length
+    mov     edx, ecx                   ; edx <- ecx
+    shr     ecx, 2                     ; ecx <- number of dwords
+    and     edx, 3                     ; edx <- number of trailing bytes
+    xor     eax, eax                   ; eax <- 0, also set ZF
+    repe    scasd
+    jnz     @ReturnFalse               ; ZF=0 means non-zero element found
+    mov     ecx, edx
+    repe    scasb
+    jnz     @ReturnFalse
+    pop     edi
+    mov     eax, 1                     ; return TRUE
+    ret
+@ReturnFalse:
+    pop     edi
+    xor     eax, eax
+    ret                                ; return FALSE
+