doskeyb

annotate keyb.c @ 0:c2b210a70ce9

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initial DOS keyboard driver commit
author John Tsiombikas <nuclear@member.fsf.org>
date Mon, 23 Sep 2013 03:42:39 +0300
parents
children da4c014bb055
rev   line source
nuclear@0 1 /*
nuclear@0 2 DOS interrupt-based keyboard driver.
nuclear@0 3 Copyright (C) 2013 John Tsiombikas <nuclear@member.fsf.org>
nuclear@0 4
nuclear@0 5 This program is free software: you can redistribute it and/or modify
nuclear@0 6 it under the terms of the GNU General Public License as published by
nuclear@0 7 the Free Software Foundation, either version 3 of the License, or
nuclear@0 8 (at your option) any later version.
nuclear@0 9
nuclear@0 10 This program is distributed in the hope that it will be useful,
nuclear@0 11 but WITHOUT ANY WARRANTY; without even the implied warranty of
nuclear@0 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
nuclear@0 13 GNU General Public License for more details.
nuclear@0 14
nuclear@0 15 You should have received a copy of the GNU General Public License
nuclear@0 16 along with the program. If not, see <http://www.gnu.org/licenses/>
nuclear@0 17 */
nuclear@0 18 #define KEYB_C_
nuclear@0 19
nuclear@0 20 #include <stdio.h>
nuclear@0 21 #include <stdlib.h>
nuclear@0 22 #include <string.h>
nuclear@0 23 #include <conio.h>
nuclear@0 24 #include <dos.h>
nuclear@0 25 #include <i86.h>
nuclear@0 26 #include "keyb.h"
nuclear@0 27 #include "scancode.h"
nuclear@0 28
nuclear@0 29 #define KB_INTR 0x9
nuclear@0 30 #define KB_PORT 0x60
nuclear@0 31
nuclear@0 32 #define PIC1_CMD_PORT 0x20
nuclear@0 33 #define OCW2_EOI (1 << 5)
nuclear@0 34
nuclear@0 35 #define DONE_INIT (prev_handler)
nuclear@0 36
nuclear@0 37 static void __interrupt __far kbintr();
nuclear@0 38
nuclear@0 39 static void (__interrupt __far *prev_handler)();
nuclear@0 40
nuclear@0 41 static int *buffer;
nuclear@0 42 static int buffer_size, buf_ridx, buf_widx;
nuclear@0 43 static int last_key;
nuclear@0 44
nuclear@0 45 static unsigned char keystate[256];
nuclear@0 46
nuclear@0 47 #define ADVANCE(x) ((x) = ((x) + 1) % buffer_size)
nuclear@0 48
nuclear@0 49 int kb_init(int bufsz)
nuclear@0 50 {
nuclear@0 51 if(DONE_INIT) {
nuclear@0 52 fprintf(stderr, "keyboard driver already initialized!\n");
nuclear@0 53 return 0;
nuclear@0 54 }
nuclear@0 55
nuclear@0 56 buffer_size = bufsz;
nuclear@0 57 if(buffer_size && !(buffer = malloc(buffer_size * sizeof *buffer))) {
nuclear@0 58 fprintf(stderr, "failed to allocate input buffer, continuing without\n");
nuclear@0 59 buffer_size = 0;
nuclear@0 60 }
nuclear@0 61 buf_ridx = buf_widx = 0;
nuclear@0 62 last_key = -1;
nuclear@0 63
nuclear@0 64 memset(keystate, 0, sizeof keystate);
nuclear@0 65
nuclear@0 66 /* set our interrupt handler */
nuclear@0 67 _disable();
nuclear@0 68 prev_handler = _dos_getvect(KB_INTR);
nuclear@0 69 _dos_setvect(KB_INTR, kbintr);
nuclear@0 70 _enable();
nuclear@0 71
nuclear@0 72 return 0;
nuclear@0 73 }
nuclear@0 74
nuclear@0 75 void kb_shutdown(void)
nuclear@0 76 {
nuclear@0 77 if(!DONE_INIT) {
nuclear@0 78 return;
nuclear@0 79 }
nuclear@0 80
nuclear@0 81 /* restore the original interrupt handler */
nuclear@0 82 _disable();
nuclear@0 83 _dos_setvect(KB_INTR, prev_handler);
nuclear@0 84 _enable();
nuclear@0 85
nuclear@0 86 free(buffer);
nuclear@0 87 }
nuclear@0 88
nuclear@0 89 int kb_isdown(int key)
nuclear@0 90 {
nuclear@0 91 return (int)keystate[key];
nuclear@0 92 }
nuclear@0 93
nuclear@0 94 void kb_wait(void)
nuclear@0 95 {
nuclear@0 96 int key;
nuclear@0 97 while((key = kb_getkey()) == -1) {
nuclear@0 98 /* put the processor to sleep while waiting for keypresses, but first
nuclear@0 99 * make sure interrupts are enabled, or we'll sleep forever
nuclear@0 100 */
nuclear@0 101 __asm {
nuclear@0 102 sti
nuclear@0 103 hlt
nuclear@0 104 }
nuclear@0 105 }
nuclear@0 106 kb_putback(key);
nuclear@0 107 }
nuclear@0 108
nuclear@0 109 int kb_getkey(void)
nuclear@0 110 {
nuclear@0 111 int res;
nuclear@0 112
nuclear@0 113 if(buffer) {
nuclear@0 114 if(buf_ridx == buf_widx) {
nuclear@0 115 return -1;
nuclear@0 116 }
nuclear@0 117 res = buffer[buf_ridx];
nuclear@0 118 ADVANCE(buf_ridx);
nuclear@0 119 } else {
nuclear@0 120 res = last_key;
nuclear@0 121 last_key = -1;
nuclear@0 122 }
nuclear@0 123 return res;
nuclear@0 124 }
nuclear@0 125
nuclear@0 126 void kb_putback(int key)
nuclear@0 127 {
nuclear@0 128 if(buffer) {
nuclear@0 129 /* go back a place */
nuclear@0 130 if(--buf_ridx < 0) {
nuclear@0 131 buf_ridx += buffer_size;
nuclear@0 132 }
nuclear@0 133
nuclear@0 134 /* if the write end hasn't caught up with us, go back one place
nuclear@0 135 * and put it there, otherwise just overwrite the oldest key which
nuclear@0 136 * is right where we were.
nuclear@0 137 */
nuclear@0 138 if(buf_ridx == buf_widx) {
nuclear@0 139 ADVANCE(buf_ridx);
nuclear@0 140 }
nuclear@0 141
nuclear@0 142 buffer[buf_ridx] = key;
nuclear@0 143 } else {
nuclear@0 144 last_key = key;
nuclear@0 145 }
nuclear@0 146 }
nuclear@0 147
nuclear@0 148 static void __interrupt __far kbintr()
nuclear@0 149 {
nuclear@0 150 unsigned char code;
nuclear@0 151 int key, press;
nuclear@0 152
nuclear@0 153 code = inp(KB_PORT);
nuclear@0 154
nuclear@0 155 if(code >= 128) {
nuclear@0 156 press = 0;
nuclear@0 157 code -= 128;
nuclear@0 158 } else {
nuclear@0 159 press = 1;
nuclear@0 160 }
nuclear@0 161
nuclear@0 162 key = scantbl[code];
nuclear@0 163
nuclear@0 164 if(press) {
nuclear@0 165 /* append to buffer */
nuclear@0 166 last_key = key;
nuclear@0 167 if(buffer_size > 0) {
nuclear@0 168 buffer[buf_widx] = key;
nuclear@0 169 ADVANCE(buf_widx);
nuclear@0 170 /* if the write end overtook the read end, advance the read end
nuclear@0 171 * too, to discard the oldest keypress from the buffer
nuclear@0 172 */
nuclear@0 173 if(buf_widx == buf_ridx) {
nuclear@0 174 ADVANCE(buf_ridx);
nuclear@0 175 }
nuclear@0 176 }
nuclear@0 177 }
nuclear@0 178
nuclear@0 179 /* and update keystate table */
nuclear@0 180 keystate[key] = press;
nuclear@0 181
nuclear@0 182 outp(PIC1_CMD_PORT, OCW2_EOI); /* send end-of-interrupt */
nuclear@0 183 }