diff options
| author |   Angelos Mouzakitis <a.mouzakitis@virtualopensystems.com> | 2023-10-10 14:33:42 +0000 |
|---|---|---|
| committer | Angelos Mouzakitis <a.mouzakitis@virtualopensystems.com> | 2023-10-10 14:33:42 +0000 |
| commit | af1a266670d040d2f4083ff309d732d648afba2a (patch) | |
| tree | 2fc46203448ddcc6f81546d379abfaeb323575e9 /roms/edk2/MdePkg/Library/BaseMemoryLibOptDxe/X64/IsZeroBuffer.nasm | |
| parent | e02cda008591317b1625707ff8e115a4841aa889 (diff) | |
Change-Id: Iaf8d18082d3991dec7c0ebbea540f092188eb4ec
Diffstat (limited to 'roms/edk2/MdePkg/Library/BaseMemoryLibOptDxe/X64/IsZeroBuffer.nasm')
| -rw-r--r-- | roms/edk2/MdePkg/Library/BaseMemoryLibOptDxe/X64/IsZeroBuffer.nasm | 49 |
1 files changed, 49 insertions, 0 deletions
diff --git a/roms/edk2/MdePkg/Library/BaseMemoryLibOptDxe/X64/IsZeroBuffer.nasm b/roms/edk2/MdePkg/Library/BaseMemoryLibOptDxe/X64/IsZeroBuffer.nasm new file mode 100644 index 000000000..a6e1d817f --- /dev/null +++ b/roms/edk2/MdePkg/Library/BaseMemoryLibOptDxe/X64/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:
+;
+;------------------------------------------------------------------------------
+
+ 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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