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; $Id: bs3-cmn-SwitchHlpConvRealModeRetfPopBpDecBpAndReturn.asm $
;; @file
; BS3Kit - SwitchHlpConvRealModeRetfPopBpDecBpAndReturn
;
;
; 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 "bs3kit-template-header.mac"
BS3_EXTERN_CMN Bs3SelFar32ToFlat32
;;
; SwitchToXxx helper that converts a 16-bit real mode far return
; into something suitable for the current mode and performs the return.
;
; The caller jmps to this routine. The stack holds an incremented BP (odd is
; far indicator) and a 16-bit far return address.
;
; @uses Nothing.
; @remarks 16-bit ASSUMES we're returning to protected mode!!
;
%if TMPL_BITS == 16
BS3_BEGIN_TEXT16_FARSTUBS
%endif
BS3_PROC_BEGIN_CMN Bs3SwitchHlpConvRealModeRetfPopBpDecBpAndReturn, BS3_PBC_NEAR
%if TMPL_BITS == 16
; Convert the selector of the 16:16 real mode return address to the
; corresponding 16-bit protected mode selector.
push ax
mov ax, [bp + 2 + 2]
push ax
BS3_EXTERN_CMN Bs3SelRealModeCodeToProtMode
call Bs3SelRealModeCodeToProtMode ; This doesn't trash any registers (except AX).
add sp, 2
mov [bp + 2 + 2], ax
pop ax
pop bp
dec bp
retf
%elif TMPL_BITS == 32
push xAX
push xDX
movzx eax, word [xSP + xCB*2 + 2 + 2] ; return segment
movzx edx, word [xSP + xCB*2 + 2] ; return offset
shl eax, 4
add eax, edx
mov [xSP + xCB*2 + 2], eax
pop xDX
pop xAX
pop bp
dec bp
ret
%else
sub rsp, 2h
push xAX
push xDX
movzx eax, word [xSP + xCB*2 + 4 + 2] ; return segment
movzx edx, word [xSP + xCB*2 + 4] ; return offset
shl eax, 4
add eax, edx
mov bp, [xSP + xCB*2 + 2]
dec bp
mov [xSP + xCB*2], rax
pop xDX
pop xAX
ret
%endif
BS3_PROC_END_CMN Bs3SwitchHlpConvRealModeRetfPopBpDecBpAndReturn
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