keys.c

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/***
 * This file is part of OpenHome, an open source home automation system.
 * Copyright (C) 2003 Jan Klötzke
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <avr/io.h>
#include <avr/interrupt.h>
#include <inttypes.h>
#include "main/keys.h"

#define KEY_PRESS       5
#define KEY_REPEAT      96
#define KEY_DELAY       12

static uint8_t cycle = 0;
static uint8_t leds, status;
static uint8_t key_counter[8];
static uint8_t key_buffer[8];
static uint8_t key_repeat_mask = 0;
static volatile uint8_t kbd_rd, kbd_wr = 0;

void keys_sense_keys(void)
{
        uint8_t key, mask, stat;
        
        // drive led's and capture key stats
        cycle++;
        if (cycle & 0x01) {
                // ch2
                cbi(PORTD, PD5);
                PORTC = (PORTC & 0xf0) | (leds >> 4);
                sbi(PORTD, PD4);
                asm volatile ("nop");
                status = (status & 0x0f) | (PINF & 0xf0);
        } else {
                // ch1
                cbi(PORTD, PD4);
                PORTC = (PORTC & 0xf0) | (leds & 0x0f);
                sbi(PORTD, PD5);
                asm volatile ("nop");
                status = (status & 0xf0) | (PINF >> 4);
        }
        
        // scan for keypress every 8ms
        if (cycle < 8) return;
        cycle = 0;
        stat = status;
        mask = key_repeat_mask;
        for (key=0; key<8; key++) {
                if (stat & 1) {
                        key_counter[key]++;     // key pressed
                } else {
                        key_counter[key] = 0;   // key released
                }

                if (key_counter[key] > KEY_REPEAT) {
                        key_counter[key] -= KEY_DELAY;
                        if ((mask & 1) == 0) goto skip;
                } else {
                        if (key_counter[key] != KEY_PRESS) goto skip;
                }
                key_buffer[kbd_wr++] = key+1;
                kbd_wr &= 7;

        skip:
                mask >>= 1;
                stat >>= 1;
        }
}

uint8_t keys_key_pressed(void)
{
        return kbd_rd != kbd_wr;
}

uint8_t keys_get_key(void)
{
        uint8_t result;
        
        while (kbd_rd == kbd_wr);
        result = key_buffer[kbd_rd++];
        kbd_rd &= 7;
        return result;
}

void keys_set_leds(uint8_t mask)
{
        leds = ~mask;
}

void keys_set_repeat_mask(uint8_t mask)
{
        key_repeat_mask = mask;
}

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