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/*
Copyright 2021 Chad Austin <chad@chadaustin.me>
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, see <http://www.gnu.org/licenses/>.
*/
/*
Symmetric per-row debounce algorithm. Changes only apply when
DEBOUNCE milliseconds have elapsed since the last change.
*/
#include "debounce.h"
#include "timer.h"
#include <stdlib.h>
#ifndef DEBOUNCE
# define DEBOUNCE 5
#endif
static uint16_t last_time;
// [row] milliseconds until key's state is considered debounced.
static uint8_t* countdowns;
// [row]
static matrix_row_t* last_raw;
void debounce_init(uint8_t num_rows) {
countdowns = (uint8_t*)calloc(num_rows, sizeof(uint8_t));
last_raw = (matrix_row_t*)calloc(num_rows, sizeof(matrix_row_t));
last_time = timer_read();
}
void debounce_free(void) {
free(countdowns);
countdowns = NULL;
free(last_raw);
last_raw = NULL;
}
bool debounce(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, bool changed) {
uint16_t now = timer_read();
uint16_t elapsed16 = TIMER_DIFF_16(now, last_time);
last_time = now;
uint8_t elapsed = (elapsed16 > 255) ? 255 : elapsed16;
bool cooked_changed = false;
uint8_t* countdown = countdowns;
for (uint8_t row = 0; row < num_rows; ++row, ++countdown) {
matrix_row_t raw_row = raw[row];
if (raw_row != last_raw[row]) {
*countdown = DEBOUNCE;
last_raw[row] = raw_row;
} else if (*countdown > elapsed) {
*countdown -= elapsed;
} else if (*countdown) {
cooked_changed |= cooked[row] ^ raw_row;
cooked[row] = raw_row;
*countdown = 0;
}
}
return cooked_changed;
}
bool debounce_active(void) {
return true;
}
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