mirror of
https://github.com/CloverHackyColor/CloverBootloader.git
synced 2024-11-24 11:45:27 +01:00
54 lines
1.5 KiB
NASM
54 lines
1.5 KiB
NASM
|
;------------------------------------------------------------------------------
|
||
|
|
; @file
|
||
|
|
; Copyright (C) 2020, vit9696. All rights reserved.
|
||
|
|
;
|
||
|
|
; All rights reserved.
|
||
|
|
;
|
||
|
|
; 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.
|
||
|
|
;------------------------------------------------------------------------------
|
||
|
|
|
||
|
|
BITS 64
|
||
|
|
DEFAULT REL
|
||
|
|
|
||
|
|
SECTION .text
|
||
|
|
|
||
|
|
;------------------------------------------------------------------------------
|
||
|
|
; UINT64
|
||
|
|
; EFIAPI
|
||
|
|
; AsmAddRngJitter (
|
||
|
|
; IN UINT64 Value
|
||
|
|
; );
|
||
|
|
;------------------------------------------------------------------------------
|
||
|
|
align 8
|
||
|
|
global ASM_PFX(AsmAddRngJitter)
|
||
|
|
ASM_PFX(AsmAddRngJitter):
|
||
|
|
; This assembly code corresponds to Hamming Weight implementation for targets
|
||
|
|
; with fast multiplication.
|
||
|
|
; REF: https://en.wikipedia.org/wiki/Hamming_weight#Efficient_implementation
|
||
|
|
mov rax, rcx
|
||
|
|
shr rax, 1
|
||
|
|
mov rdx, 5555555555555555h
|
||
|
|
and rdx, rax
|
||
|
|
sub rcx, rdx
|
||
|
|
mov rax, 3333333333333333h
|
||
|
|
mov rdx, rcx
|
||
|
|
and rdx, rax
|
||
|
|
shr rcx, 2
|
||
|
|
and rcx, rax
|
||
|
|
add rcx, rdx
|
||
|
|
mov rax, rcx
|
||
|
|
shr rax, 4
|
||
|
|
lea rax, [rax+rcx]
|
||
|
|
mov rcx, 0F0F0F0F0F0F0F0Fh
|
||
|
|
and rcx, rax
|
||
|
|
mov rax, 101010101010101h
|
||
|
|
imul rax, rcx
|
||
|
|
shr rax, 38h
|
||
|
|
ret
|