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; $Id: bs3-wc32-U8RS.asm $
;; @file
; BS3Kit - 32-bit Watcom C/C++, 64-bit unsigned integer right shift.
;
;
; Copyright (C) 2007-2019 Oracle Corporation
;
; This file is part of VirtualBox Open Source Edition (OSE), as
; available from http://www.virtualbox.org. This file is free software;
; you can redistribute it and/or modify it under the terms of the GNU
; General Public License (GPL) as published by the Free Software
; Foundation, in version 2 as it comes in the "COPYING" file of the
; VirtualBox OSE distribution. VirtualBox OSE is distributed in the
; hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
;
; The contents of this file may alternatively be used under the terms
; of the Common Development and Distribution License Version 1.0
; (CDDL) only, as it comes in the "COPYING.CDDL" file of the
; VirtualBox OSE distribution, in which case the provisions of the
; CDDL are applicable instead of those of the GPL.
;
; You may elect to license modified versions of this file under the
; terms and conditions of either the GPL or the CDDL or both.
;
%include "bs3kit-template-header.mac"
;;
; 64-bit unsigned integer right shift.
;
; @returns EDX:EAX
; @param EDX:EAX Value to shift.
; @param BL Shift count (it's specified as ECX:EBX, but we only use BL).
;
global $??U8RS
$??U8RS:
push ecx ; We're allowed to trash ECX, but why bother.
mov cl, bl
and cl, 3fh
test cl, 20h
jnz .big_shift
; Shifting less than 32.
shrd eax, edx, cl
shr edx, cl
.return:
pop ecx
ret
.big_shift:
; Shifting 32 or more.
mov eax, edx
shr eax, cl ; Only uses lower 5 bits.
xor edx, edx
jmp .return
|
