/*
 * VBMouse - BIOS data area access routines
 * 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 BDA_H
#define BDA_H

#include "utils.h"

#define BIOS_DATA_AREA_SEGMENT 0x40

static inline uint32_t bda_get_dword(unsigned int offset) {
	uint32_t __far *p = MK_FP(BIOS_DATA_AREA_SEGMENT, offset);
	return *p;
}

static inline uint16_t bda_get_word(unsigned int offset) {
	uint16_t __far *p = MK_FP(BIOS_DATA_AREA_SEGMENT, offset);
	return *p;
}

static inline uint8_t bda_get_byte(unsigned int offset) {
	uint8_t __far *p = MK_FP(BIOS_DATA_AREA_SEGMENT, offset);
	return *p;
}

#define bda_get_ebda_segment()    bda_get_word(0x0e)

#define bda_get_equipment()       bda_get_word(0x10)

#define bda_get_video_mode()      bda_get_byte(0x49)
#define bda_get_num_columns()     bda_get_word(0x4a)
#define bda_get_video_page_size() bda_get_word(0x4c)
#define bda_get_cur_video_page()  bda_get_word(0x62)
#define bda_get_last_row()        bda_get_byte(0x84)
#define bda_get_char_height()     bda_get_word(0x85)

#define bda_get_tick_count()      bda_get_dword(0x6c)
#define bda_get_tick_count_lo()   bda_get_word(0x6c)

static inline void bda_wait_tick() {
	uint16_t cur_ticks = bda_get_tick_count_lo();
	do {
		pause();
	} while (cur_ticks == bda_get_tick_count_lo());
}

static inline void bda_wait_ticks(unsigned int ticks) {
	for (; ticks > 0; ticks--) {
		bda_wait_tick();
	}
}

#endif // BDA_H