2000-05-06 21:34:20 +02:00
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; File:
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; apisupt.asm
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; Description:
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; Assembly support routines for stack manipulation, etc.
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;
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; Copyright (c) 1995, 1998
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; Pasquale J. Villani
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; All Rights Reserved
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;
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; This file is part of DOS-C.
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;
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; DOS-C is free software; you can redistribute it and/or
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; modify it under the terms of the GNU General Public License
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; as published by the Free Software Foundation; either version
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; 2, or (at your option) any later version.
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;
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; DOS-C is distributed in the hope that it will be useful, but
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; WITHOUT ANY WARRANTY; without even the implied warranty of
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; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
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; the GNU General Public License for more details.
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;
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; You should have received a copy of the GNU General Public
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; License along with DOS-C; see the file COPYING. If not,
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; write to the Free Software Foundation, 675 Mass Ave,
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; Cambridge, MA 02139, USA.
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;
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; $Id$
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;
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; $Log$
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2001-03-21 03:56:26 +01:00
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; Revision 1.4 2001/03/21 02:56:25 bartoldeman
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; See history.txt for changes. Bug fixes and HMA support are the main ones.
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;
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2000-05-25 22:56:23 +02:00
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; Revision 1.3 2000/05/25 20:56:21 jimtabor
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; Fixed project history
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;
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2000-05-08 06:30:00 +02:00
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; Revision 1.2 2000/05/08 04:29:59 jimtabor
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; Update CVS to 2020
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2000-05-06 21:34:20 +02:00
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;
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2000-05-25 22:56:23 +02:00
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; Revision 1.1.1.1 2000/05/06 19:34:53 jhall1
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; The FreeDOS Kernel. A DOS kernel that aims to be 100% compatible with
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; MS-DOS. Distributed under the GNU GPL.
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;
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2000-05-06 21:34:20 +02:00
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; Revision 1.2 1999/08/10 17:57:12 jprice
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; ror4 2011-02 patch
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;
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; Revision 1.1.1.1 1999/03/29 15:40:38 jprice
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; New version without IPL.SYS
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;
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; Revision 1.4 1999/02/08 05:55:57 jprice
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; Added Pat's 1937 kernel patches
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;
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; Revision 1.3 1999/02/01 01:48:41 jprice
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; Clean up; Now you can use hex numbers in config.sys. added config.sys screen function to change screen mode (28 or 43/50 lines)
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;
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; Revision 1.2 1999/01/22 04:13:25 jprice
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; Formating
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;
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; Revision 1.1.1.1 1999/01/20 05:51:01 jprice
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; Imported sources
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;
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; Rev 1.4 06 Dec 1998 8:47:02 patv
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;Expanded due to new I/O subsystem.
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;
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; Rev 1.3 16 Jan 1997 12:46:44 patv
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;pre-Release 0.92 feature additions
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;
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; Rev 1.2 29 May 1996 21:03:38 patv
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;bug fixes for v0.91a
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;
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; Rev 1.1 01 Sep 1995 17:54:26 patv
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;First GPL release.
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;
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; Rev 1.0 02 Jul 1995 9:04:50 patv
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;Initial revision.
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; $EndLog$
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;
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%include "segs.inc"
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extern _api_sp:wrt DGROUP ; api stacks - for context
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extern _api_ss:wrt DGROUP ; switching
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extern _usr_sp:wrt DGROUP ; user stacks
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extern _usr_ss:wrt DGROUP
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2001-03-21 03:56:26 +01:00
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segment HMA_TEXT
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2000-05-06 21:34:20 +02:00
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global _set_stack
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;
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; void far set_stack(void) -
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; save current stack and setup our local stack
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;
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_set_stack:
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; save foreground stack
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; we need to get the return values from the stack
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; since the current stack will change
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pop ax ;get return offset
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pop bx ;get return segment
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; Save the flags so that we can restore correct interrupt
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; state later. We need to disable interrupts so that we
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; don't trash memory with new sp-old ss combination
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pushf
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pop dx
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cli
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; save bp
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push bp
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mov cx, sp
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neg cx
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; save away foreground process' stack
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push word [_usr_ss]
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push word [_usr_sp]
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mov word [_usr_ss],ss
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mov word [_usr_sp],sp
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; setup our local stack
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mov ss,word [_api_ss]
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mov sp,word [_api_sp]
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add cx, sp
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add bp, cx
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; setup for ret
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push bx
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push ax
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; now restore interrupt state
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push dx
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popf
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retf
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;
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; void far restore_stack(void) -
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; restore foreground stack, throw ours away
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;
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global _restore_stack
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_restore_stack:
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; we need to get the return values from the stack
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; since the current stack will change
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pop cx ;get return offset
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pop bx ;get return segment
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; Save the flags so that we can restore correct interrupt
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; state later. We need to disable interrupts so that we
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; don't trash memory with new sp-old ss combination
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pushf
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pop dx
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cli
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; save background stack
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mov word [_api_ss],ss
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mov word [_api_sp],sp
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; restore foreground stack here
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mov ss,word [_usr_ss]
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mov sp,word [_usr_sp]
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pop word [_usr_sp]
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pop word [_usr_ss]
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; make bp relative to our stack frame
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pop bp
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;mov bp,sp
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; setup for ret
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push bx
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push cx
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; now restore interrupt state
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push dx
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popf
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retf
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