nuclear@0: /*
nuclear@0: DOS interrupt-based keyboard driver.
nuclear@0: Copyright (C) 2013  John Tsiombikas <nuclear@member.fsf.org>
nuclear@0: 
nuclear@0: This program is free software: you can redistribute it and/or modify
nuclear@0: it under the terms of the GNU General Public License as published by
nuclear@0: the Free Software Foundation, either version 3 of the License, or
nuclear@0: (at your option) any later version.
nuclear@0: 
nuclear@0: This program is distributed in the hope that it will be useful,
nuclear@0: but WITHOUT ANY WARRANTY; without even the implied warranty of
nuclear@0: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
nuclear@0: GNU General Public License  for more details.
nuclear@0: 
nuclear@0: You should have received a copy of the GNU General Public License
nuclear@0: along with the program. If not, see <http://www.gnu.org/licenses/>
nuclear@0: */
nuclear@0: #define KEYB_C_
nuclear@0: 
nuclear@0: #include <stdio.h>
nuclear@0: #include <stdlib.h>
nuclear@0: #include <string.h>
nuclear@0: #include <conio.h>
nuclear@0: #include <dos.h>
nuclear@0: #include <i86.h>
nuclear@0: #include "keyb.h"
nuclear@0: #include "scancode.h"
nuclear@0: 
nuclear@0: #define KB_INTR		0x9
nuclear@0: #define KB_PORT		0x60
nuclear@0: 
nuclear@0: #define PIC1_CMD_PORT	0x20
nuclear@0: #define OCW2_EOI		(1 << 5)
nuclear@0: 
nuclear@0: #define DONE_INIT	(prev_handler)
nuclear@0: 
nuclear@0: static void __interrupt __far kbintr();
nuclear@0: 
nuclear@0: static void (__interrupt __far *prev_handler)();
nuclear@0: 
nuclear@0: static int *buffer;
nuclear@0: static int buffer_size, buf_ridx, buf_widx;
nuclear@0: static int last_key;
nuclear@0: 
nuclear@0: static unsigned int num_pressed;
nuclear@0: static unsigned char keystate[256];
nuclear@0: 
nuclear@0: #define ADVANCE(x)	((x) = ((x) + 1) % buffer_size)
nuclear@0: 
nuclear@0: int kb_init(int bufsz)
nuclear@0: {
nuclear@0: 	if(DONE_INIT) {
nuclear@0: 		fprintf(stderr, "keyboard driver already initialized!\n");
nuclear@0: 		return 0;
nuclear@0: 	}
nuclear@0: 
nuclear@0: 	buffer_size = bufsz;
nuclear@0: 	if(buffer_size && !(buffer = malloc(buffer_size * sizeof *buffer))) {
nuclear@0: 		fprintf(stderr, "failed to allocate input buffer, continuing without\n");
nuclear@0: 		buffer_size = 0;
nuclear@0: 	}
nuclear@0: 	buf_ridx = buf_widx = 0;
nuclear@0: 	last_key = -1;
nuclear@0: 
nuclear@0: 	memset(keystate, 0, sizeof keystate);
nuclear@0: 	num_pressed = 0;
nuclear@0: 
nuclear@0: 	/* set our interrupt handler */
nuclear@0: 	_disable();
nuclear@0: 	prev_handler = _dos_getvect(KB_INTR);
nuclear@0: 	_dos_setvect(KB_INTR, kbintr);
nuclear@0: 	_enable();
nuclear@0: 
nuclear@0: 	return 0;
nuclear@0: }
nuclear@0: 
nuclear@0: void kb_shutdown(void)
nuclear@0: {
nuclear@0: 	if(!DONE_INIT) {
nuclear@0: 		return;
nuclear@0: 	}
nuclear@0: 
nuclear@0: 	/* restore the original interrupt handler */
nuclear@0: 	_disable();
nuclear@0: 	_dos_setvect(KB_INTR, prev_handler);
nuclear@0: 	_enable();
nuclear@0: 
nuclear@0: 	free(buffer);
nuclear@0: }
nuclear@0: 
nuclear@0: int kb_isdown(int key)
nuclear@0: {
nuclear@0: 	if(key == KB_ANY) {
nuclear@0: 		return num_pressed;
nuclear@0: 	}
nuclear@0: 	return (int)keystate[key];
nuclear@0: }
nuclear@0: 
nuclear@0: void kb_wait(void)
nuclear@0: {
nuclear@0: 	int key;
nuclear@0: 	while((key = kb_getkey()) == -1) {
nuclear@0: 		/* put the processor to sleep while waiting for keypresses, but first
nuclear@0: 		 * make sure interrupts are enabled, or we'll sleep forever
nuclear@0: 		 */
nuclear@0: 		__asm {
nuclear@0: 			sti
nuclear@0: 			hlt
nuclear@0: 		}
nuclear@0: 	}
nuclear@0: 	kb_putback(key);
nuclear@0: }
nuclear@0: 
nuclear@0: int kb_getkey(void)
nuclear@0: {
nuclear@0: 	int res;
nuclear@0: 
nuclear@0: 	if(buffer) {
nuclear@0: 		if(buf_ridx == buf_widx) {
nuclear@0: 			return -1;
nuclear@0: 		}
nuclear@0: 		res = buffer[buf_ridx];
nuclear@0: 		ADVANCE(buf_ridx);
nuclear@0: 	} else {
nuclear@0: 		res = last_key;
nuclear@0: 		last_key = -1;
nuclear@0: 	}
nuclear@0: 	return res;
nuclear@0: }
nuclear@0: 
nuclear@0: void kb_putback(int key)
nuclear@0: {
nuclear@0: 	if(buffer) {
nuclear@0: 		/* go back a place */
nuclear@0: 		if(--buf_ridx < 0) {
nuclear@0: 			buf_ridx += buffer_size;
nuclear@0: 		}
nuclear@0: 
nuclear@0: 		/* if the write end hasn't caught up with us, go back one place
nuclear@0: 		 * and put it there, otherwise just overwrite the oldest key which
nuclear@0: 		 * is right where we were.
nuclear@0: 		 */
nuclear@0: 		if(buf_ridx == buf_widx) {
nuclear@0: 			ADVANCE(buf_ridx);
nuclear@0: 		}
nuclear@0: 
nuclear@0: 		buffer[buf_ridx] = key;
nuclear@0: 	} else {
nuclear@0: 		last_key = key;
nuclear@0: 	}
nuclear@0: }
nuclear@0: 
nuclear@0: static void __interrupt __far kbintr()
nuclear@0: {
nuclear@0: 	unsigned char code;
nuclear@0: 	int key, press;
nuclear@0: 
nuclear@0: 	code = inp(KB_PORT);
nuclear@0: 
nuclear@0: 	if(code >= 128) {
nuclear@0: 		press = 0;
nuclear@0: 		code -= 128;
nuclear@0: 
nuclear@0: 		if(num_pressed > 0) {
nuclear@0: 			num_pressed--;
nuclear@0: 		}
nuclear@0: 	} else {
nuclear@0: 		press = 1;
nuclear@0: 
nuclear@0: 		num_pressed++;
nuclear@0: 	}
nuclear@0: 
nuclear@0: 	key = scantbl[code];
nuclear@0: 
nuclear@0: 	if(press) {
nuclear@0: 		/* append to buffer */
nuclear@0: 		last_key = key;
nuclear@0: 		if(buffer_size > 0) {
nuclear@0: 			buffer[buf_widx] = key;
nuclear@0: 			ADVANCE(buf_widx);
nuclear@0: 			/* if the write end overtook the read end, advance the read end
nuclear@0: 			 * too, to discard the oldest keypress from the buffer
nuclear@0: 			 */
nuclear@0: 			if(buf_widx == buf_ridx) {
nuclear@0: 				ADVANCE(buf_ridx);
nuclear@0: 			}
nuclear@0: 		}
nuclear@0: 	}
nuclear@0: 
nuclear@0: 	/* and update keystate table */
nuclear@0: 	keystate[key] = press;
nuclear@0: 
nuclear@0: 	outp(PIC1_CMD_PORT, OCW2_EOI);	/* send end-of-interrupt */
nuclear@0: }