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; $Id: bs3-cmn-RegSetDr0.asm $
;; @file
; BS3Kit - Bs3RegSetDr0
;
;
; 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"
BS3_EXTERN_CMN Bs3Syscall
%if TMPL_BITS == 16
BS3_EXTERN_DATA16 g_bBs3CurrentMode
%endif
TMPL_BEGIN_TEXT
;;
; @cproto BS3_CMN_PROTO_STUB(void, Bs3RegSetDr0,(RTCCUINTXREG uValue));
;
; @param uValue The value to set.
; @remarks Does not require 20h of parameter scratch space in 64-bit mode.
;
; @uses No GPRs.
;
BS3_PROC_BEGIN_CMN Bs3RegSetDr0, BS3_PBC_HYBRID_SAFE
BS3_CALL_CONV_PROLOG 1
push xBP
mov xBP, xSP
push sSI
%if TMPL_BITS == 16
; If V8086 mode we have to go thru a syscall.
test byte [BS3_DATA16_WRT(g_bBs3CurrentMode)], BS3_MODE_CODE_V86
jnz .via_system_call
cmp byte [BS3_DATA16_WRT(g_bBs3CurrentMode)], BS3_MODE_RM
je .direct_access
%endif
; If not in ring-0, we have to make a system call.
mov si, ss
and si, X86_SEL_RPL
jnz .via_system_call
.direct_access:
mov sSI, [xBP + xCB + cbCurRetAddr]
mov dr0, sSI
jmp .return
.via_system_call:
push xDX
push xAX
mov sSI, [xBP + xCB + cbCurRetAddr]
mov xAX, BS3_SYSCALL_SET_DRX
mov dl, 0
call Bs3Syscall
pop xAX
pop xDX
.return:
pop sSI
pop xBP
BS3_CALL_CONV_EPILOG 1
BS3_HYBRID_RET
BS3_PROC_END_CMN Bs3RegSetDr0
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