diff options
Diffstat (limited to 'MdePkg/Library/BaseMemoryLibSse2/X64/IsZeroBuffer.nasm')
| -rw-r--r-- | MdePkg/Library/BaseMemoryLibSse2/X64/IsZeroBuffer.nasm | 76 |
1 files changed, 76 insertions, 0 deletions
diff --git a/MdePkg/Library/BaseMemoryLibSse2/X64/IsZeroBuffer.nasm b/MdePkg/Library/BaseMemoryLibSse2/X64/IsZeroBuffer.nasm new file mode 100644 index 000000000000..3d5b6a128104 --- /dev/null +++ b/MdePkg/Library/BaseMemoryLibSse2/X64/IsZeroBuffer.nasm @@ -0,0 +1,76 @@ +;------------------------------------------------------------------------------ +; +; 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 + xor rcx, rcx ; rcx <- 0 + sub rcx, rdi + and rcx, 15 ; rcx + rdi aligns on 16-byte boundary + jz @Is16BytesZero + cmp rcx, rdx ; Length already in rdx + cmova rcx, rdx ; bytes before the 16-byte boundary + sub rdx, rcx + xor rax, rax ; rax <- 0, also set ZF + repe scasb + jnz @ReturnFalse ; ZF=0 means non-zero element found +@Is16BytesZero: + mov rcx, rdx + and rdx, 15 + shr rcx, 4 + jz @IsBytesZero +.0: + pxor xmm0, xmm0 ; xmm0 <- 0 + pcmpeqb xmm0, [rdi] ; check zero for 16 bytes + pmovmskb eax, xmm0 ; eax <- compare results + ; nasm doesn't support 64-bit destination + ; for pmovmskb + cmp eax, 0xffff + jnz @ReturnFalse + add rdi, 16 + loop .0 +@IsBytesZero: + mov rcx, rdx + xor rax, rax ; rax <- 0, also set ZF + repe scasb + jnz @ReturnFalse ; ZF=0 means non-zero element found + pop rdi + mov rax, 1 ; return TRUE + ret +@ReturnFalse: + pop rdi + xor rax, rax + ret ; return FALSE + |