1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/src/keyb.c	Mon Sep 23 04:34:43 2013 +0300
     1.3 @@ -0,0 +1,194 @@
     1.4 +/*
     1.5 +DOS interrupt-based keyboard driver.
     1.6 +Copyright (C) 2013  John Tsiombikas <nuclear@member.fsf.org>
     1.7 +
     1.8 +This program is free software: you can redistribute it and/or modify
     1.9 +it under the terms of the GNU General Public License as published by
    1.10 +the Free Software Foundation, either version 3 of the License, or
    1.11 +(at your option) any later version.
    1.12 +
    1.13 +This program is distributed in the hope that it will be useful,
    1.14 +but WITHOUT ANY WARRANTY; without even the implied warranty of
    1.15 +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    1.16 +GNU General Public License  for more details.
    1.17 +
    1.18 +You should have received a copy of the GNU General Public License
    1.19 +along with the program. If not, see <http://www.gnu.org/licenses/>
    1.20 +*/
    1.21 +#define KEYB_C_
    1.22 +
    1.23 +#include <stdio.h>
    1.24 +#include <stdlib.h>
    1.25 +#include <string.h>
    1.26 +#include <conio.h>
    1.27 +#include <dos.h>
    1.28 +#include <i86.h>
    1.29 +#include "keyb.h"
    1.30 +#include "scancode.h"
    1.31 +
    1.32 +#define KB_INTR		0x9
    1.33 +#define KB_PORT		0x60
    1.34 +
    1.35 +#define PIC1_CMD_PORT	0x20
    1.36 +#define OCW2_EOI		(1 << 5)
    1.37 +
    1.38 +#define DONE_INIT	(prev_handler)
    1.39 +
    1.40 +static void __interrupt __far kbintr();
    1.41 +
    1.42 +static void (__interrupt __far *prev_handler)();
    1.43 +
    1.44 +static int *buffer;
    1.45 +static int buffer_size, buf_ridx, buf_widx;
    1.46 +static int last_key;
    1.47 +
    1.48 +static unsigned int num_pressed;
    1.49 +static unsigned char keystate[256];
    1.50 +
    1.51 +#define ADVANCE(x)	((x) = ((x) + 1) % buffer_size)
    1.52 +
    1.53 +int kb_init(int bufsz)
    1.54 +{
    1.55 +	if(DONE_INIT) {
    1.56 +		fprintf(stderr, "keyboard driver already initialized!\n");
    1.57 +		return 0;
    1.58 +	}
    1.59 +
    1.60 +	buffer_size = bufsz;
    1.61 +	if(buffer_size && !(buffer = malloc(buffer_size * sizeof *buffer))) {
    1.62 +		fprintf(stderr, "failed to allocate input buffer, continuing without\n");
    1.63 +		buffer_size = 0;
    1.64 +	}
    1.65 +	buf_ridx = buf_widx = 0;
    1.66 +	last_key = -1;
    1.67 +
    1.68 +	memset(keystate, 0, sizeof keystate);
    1.69 +	num_pressed = 0;
    1.70 +
    1.71 +	/* set our interrupt handler */
    1.72 +	_disable();
    1.73 +	prev_handler = _dos_getvect(KB_INTR);
    1.74 +	_dos_setvect(KB_INTR, kbintr);
    1.75 +	_enable();
    1.76 +
    1.77 +	return 0;
    1.78 +}
    1.79 +
    1.80 +void kb_shutdown(void)
    1.81 +{
    1.82 +	if(!DONE_INIT) {
    1.83 +		return;
    1.84 +	}
    1.85 +
    1.86 +	/* restore the original interrupt handler */
    1.87 +	_disable();
    1.88 +	_dos_setvect(KB_INTR, prev_handler);
    1.89 +	_enable();
    1.90 +
    1.91 +	free(buffer);
    1.92 +}
    1.93 +
    1.94 +int kb_isdown(int key)
    1.95 +{
    1.96 +	if(key == KB_ANY) {
    1.97 +		return num_pressed;
    1.98 +	}
    1.99 +	return (int)keystate[key];
   1.100 +}
   1.101 +
   1.102 +void kb_wait(void)
   1.103 +{
   1.104 +	int key;
   1.105 +	while((key = kb_getkey()) == -1) {
   1.106 +		/* put the processor to sleep while waiting for keypresses, but first
   1.107 +		 * make sure interrupts are enabled, or we'll sleep forever
   1.108 +		 */
   1.109 +		__asm {
   1.110 +			sti
   1.111 +			hlt
   1.112 +		}
   1.113 +	}
   1.114 +	kb_putback(key);
   1.115 +}
   1.116 +
   1.117 +int kb_getkey(void)
   1.118 +{
   1.119 +	int res;
   1.120 +
   1.121 +	if(buffer) {
   1.122 +		if(buf_ridx == buf_widx) {
   1.123 +			return -1;
   1.124 +		}
   1.125 +		res = buffer[buf_ridx];
   1.126 +		ADVANCE(buf_ridx);
   1.127 +	} else {
   1.128 +		res = last_key;
   1.129 +		last_key = -1;
   1.130 +	}
   1.131 +	return res;
   1.132 +}
   1.133 +
   1.134 +void kb_putback(int key)
   1.135 +{
   1.136 +	if(buffer) {
   1.137 +		/* go back a place */
   1.138 +		if(--buf_ridx < 0) {
   1.139 +			buf_ridx += buffer_size;
   1.140 +		}
   1.141 +
   1.142 +		/* if the write end hasn't caught up with us, go back one place
   1.143 +		 * and put it there, otherwise just overwrite the oldest key which
   1.144 +		 * is right where we were.
   1.145 +		 */
   1.146 +		if(buf_ridx == buf_widx) {
   1.147 +			ADVANCE(buf_ridx);
   1.148 +		}
   1.149 +
   1.150 +		buffer[buf_ridx] = key;
   1.151 +	} else {
   1.152 +		last_key = key;
   1.153 +	}
   1.154 +}
   1.155 +
   1.156 +static void __interrupt __far kbintr()
   1.157 +{
   1.158 +	unsigned char code;
   1.159 +	int key, press;
   1.160 +
   1.161 +	code = inp(KB_PORT);
   1.162 +
   1.163 +	if(code >= 128) {
   1.164 +		press = 0;
   1.165 +		code -= 128;
   1.166 +
   1.167 +		if(num_pressed > 0) {
   1.168 +			num_pressed--;
   1.169 +		}
   1.170 +	} else {
   1.171 +		press = 1;
   1.172 +
   1.173 +		num_pressed++;
   1.174 +	}
   1.175 +
   1.176 +	key = scantbl[code];
   1.177 +
   1.178 +	if(press) {
   1.179 +		/* append to buffer */
   1.180 +		last_key = key;
   1.181 +		if(buffer_size > 0) {
   1.182 +			buffer[buf_widx] = key;
   1.183 +			ADVANCE(buf_widx);
   1.184 +			/* if the write end overtook the read end, advance the read end
   1.185 +			 * too, to discard the oldest keypress from the buffer
   1.186 +			 */
   1.187 +			if(buf_widx == buf_ridx) {
   1.188 +				ADVANCE(buf_ridx);
   1.189 +			}
   1.190 +		}
   1.191 +	}
   1.192 +
   1.193 +	/* and update keystate table */
   1.194 +	keystate[key] = press;
   1.195 +
   1.196 +	outp(PIC1_CMD_PORT, OCW2_EOI);	/* send end-of-interrupt */
   1.197 +}