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; $Id: U8LS-x86-32.asm $
;; @file
; BS3Kit - 32-bit Watcom C/C++, 64-bit integer left shift.
;
;
; Copyright (C) 2007-2023 Oracle and/or its affiliates.
;
; This file is part of VirtualBox base platform packages, as
; available from https://www.virtualbox.org.
;
; This program is free software; you can redistribute it and/or
; modify it under the terms of the GNU General Public License
; as published by the Free Software Foundation, in version 3 of the
; License.
;
; This program is distributed in the hope that it will be useful, but
; WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
; General Public License for more details.
;
; You should have received a copy of the GNU General Public License
; along with this program; if not, see <https://www.gnu.org/licenses>.
;
; The contents of this file may alternatively be used under the terms
; of the Common Development and Distribution License Version 1.0
; (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
; in the VirtualBox 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.
;
; SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
;
%include "iprt/asmdefs.mac"
BEGINCODE
;;
; 64-bit integer left 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 __U8LS
__U8LS:
global __I8LS
__I8LS:
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.
shld edx, eax, cl
shl eax, cl
.return:
pop ecx
ret
.big_shift:
; Shifting 32 or more.
mov edx, eax
shl edx, cl ; Only uses lower 5 bits.
xor eax, eax
jmp .return
|
