; $Id: ASMAtomicXchgU16.asm 106061 2024-09-16 14:03:52Z vboxsync $
;; @file
; IPRT - ASMAtomicXchgU16().
;

;
; Copyright (C) 2006-2024 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
;

;*******************************************************************************
;* Header Files                                                                *
;*******************************************************************************
%include "iprt/asmdefs.mac"

BEGINCODE

;;
; Atomically Exchange an unsigned 16-bit value, ordered.
;
; @param    pu16     x86:ebp+8   gcc:rdi  msc:rcx
; @param    u16New   x86:ebp+c   gcc:si   msc:dx
;
; @returns Current (i.e. old) *pu16 value (AX).
;
RT_BEGINPROC ASMAtomicXchgU16
%ifdef RT_ARCH_AMD64
 %ifdef ASM_CALL64_MSC
        mov     ax, dx
        xchg    [rcx], ax
 %else
        mov     ax, si
        xchg    [rdi], ax
 %endif
%elifdef RT_ARCH_X86
        mov     ecx, [esp+04h]
        mov     ax, [esp+08h]
        xchg    [ecx], ax
%else
 %error "Unsupport arch."
%endif
        ret
ENDPROC ASMAtomicXchgU16

