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/*
* VBMouse - Interface to some DOS int 21h services
* Copyright (C) 2022 Javier S. Pedro
*
* 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; either version 2
* of the License, or (at your option) any later version.
* 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, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#ifndef INT21DOS_H
#define INT21DOS_H
#include <stdbool.h>
#include <dos.h>
#define DOS_PSP_SIZE 256
enum dos_allocation_strategy {
DOS_FIT_FIRST = 0,
DOS_FIT_BEST = 1,
DOS_FIT_LAST = 2,
DOS_FIT_HIGH = 0x80,
DOS_FIT_HIGHONLY = 0x40,
};
static unsigned dos_query_allocation_strategy(void);
#pragma aux dos_query_allocation_strategy = \
"mov ax, 0x5800" \
"int 0x21" \
__value [ax]
static int dos_set_allocation_strategy(unsigned strategy);
#pragma aux dos_set_allocation_strategy = \
"clc" \
"mov ax, 0x5801" \
"int 0x21" \
"jc end" \
"mov ax, 0" \
"end:" \
__parm [bx] \
__value [ax]
static bool dos_query_umb_link_state(void);
#pragma aux dos_query_umb_link_state = \
"mov ax, 0x5802" \
"int 0x21" \
__value [al]
static int dos_set_umb_link_state(bool state);
#pragma aux dos_set_umb_link_state = \
"clc" \
"mov ax, 0x5803" \
"int 0x21" \
"jc end" \
"mov ax, 0" \
"end:" \
__parm [bx] \
__value [ax]
/** Allocates a new DOS segment.
* @returns either the allocated segment or 0 if any error. */
static __segment dos_alloc(unsigned paragraphs);
#pragma aux dos_alloc = \
"clc" \
"mov ah, 0x48" \
"int 0x21" \
"jnc end" \
"mov ax, 0xB" \
"end:" \
__parm [bx] \
__value [ax]
/** Frees DOS segment. */
static void dos_free(_segment segment);
#pragma aux dos_free = \
"mov ah, 0x49" \
"int 0x21" \
__parm [es] \
__modify [ax]
/** Sets a given PSP as the current active process. */
static void dos_set_psp(_segment psp);
#pragma aux dos_set_psp = \
"mov ah, 0x50" \
"int 0x21" \
__parm [bx] \
__modify [ax]
#endif // INT21DOS_H
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