| 1 | ; $Id: bs3-mode-SwitchToPPV86.asm 60019 2016-03-14 11:33:59Z vboxsync $
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| 2 | ;; @file
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| 3 | ; BS3Kit - Bs3SwitchToPPV86
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| 4 | ;
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| 5 |
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| 6 | ;
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| 7 | ; Copyright (C) 2007-2016 Oracle Corporation
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| 8 | ;
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| 9 | ; This file is part of VirtualBox Open Source Edition (OSE), as
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| 10 | ; available from http://www.virtualbox.org. This file is free software;
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| 11 | ; you can redistribute it and/or modify it under the terms of the GNU
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| 12 | ; General Public License (GPL) as published by the Free Software
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| 13 | ; Foundation, in version 2 as it comes in the "COPYING" file of the
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| 14 | ; VirtualBox OSE distribution. VirtualBox OSE is distributed in the
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| 15 | ; hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
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| 16 | ;
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| 17 | ; The contents of this file may alternatively be used under the terms
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| 18 | ; of the Common Development and Distribution License Version 1.0
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| 19 | ; (CDDL) only, as it comes in the "COPYING.CDDL" file of the
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| 20 | ; VirtualBox OSE distribution, in which case the provisions of the
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| 21 | ; CDDL are applicable instead of those of the GPL.
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| 22 | ;
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| 23 | ; You may elect to license modified versions of this file under the
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| 24 | ; terms and conditions of either the GPL or the CDDL or both.
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| 25 | ;
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| 26 |
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| 27 | %include "bs3kit-template-header.mac"
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| 28 |
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| 29 |
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| 30 | ;;
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| 31 | ; Switch to 16-bit v8086 paged protected mode with 32-bit sys+tss from any other mode.
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| 32 | ;
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| 33 | ; @cproto BS3_DECL(void) Bs3SwitchToPPV86(void);
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| 34 | ;
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| 35 | ; @uses Nothing (except high 32-bit register parts).
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| 36 | ;
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| 37 | ; @remarks Obviously returns to 16-bit v8086 mode, even if the caller was
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| 38 | ; in 32-bit or 64-bit mode.
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| 39 | ;
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| 40 | ; @remarks Does not require 20h of parameter scratch space in 64-bit mode.
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| 41 | ;
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| 42 | BS3_PROC_BEGIN_MODE Bs3SwitchToPPV86
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| 43 | %if TMPL_MODE == BS3_MODE_PPV86
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| 44 | ret
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| 45 |
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| 46 | %else
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| 47 | ;
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| 48 | ; Switch to 32-bit PP32 and from there to V8086.
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| 49 | ;
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| 50 | extern TMPL_NM(Bs3SwitchToPP32)
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| 51 | call TMPL_NM(Bs3SwitchToPP32)
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| 52 | BS3_SET_BITS 32
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| 53 |
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| 54 | ;
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| 55 | ; Switch to v8086 mode after adjusting the return address.
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| 56 | ;
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| 57 | %if TMPL_BITS == 16
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| 58 | push word [esp]
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| 59 | mov word [esp + 2], 0
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| 60 | %elif TMPL_BITS == 64
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| 61 | pop dword [esp + 4]
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| 62 | %endif
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| 63 | extern _Bs3SwitchTo16BitV86_c32
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| 64 | jmp _Bs3SwitchTo16BitV86_c32
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| 65 | %endif
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| 66 | BS3_PROC_END_MODE Bs3SwitchToPPV86
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| 67 |
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