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// Copyright 2017 Alex Ong<the.onga@gmail.com>
// Copyright 2020 Andrei Purdea<andrei@purdea.ro>
// Copyright 2021 Simon Arlott
// Copyright @filterpaper
// SPDX-License-Identifier: GPL-2.0-or-later
//
// Basic symmetric per-row algorithm. Uses an 8-bit counter per row.
// When no state changes have occured for DEBOUNCE milliseconds, we push the state.
#include "debounce.h"
#include "timer.h"
#include "util.h"
#ifndef DEBOUNCE
# define DEBOUNCE 5
#endif
// Maximum debounce: 255ms
#if DEBOUNCE > UINT8_MAX
# undef DEBOUNCE
# define DEBOUNCE UINT8_MAX
#endif
#define DEBOUNCE_ELAPSED 0
#if DEBOUNCE > 0
typedef uint8_t debounce_counter_t;
// Uses MATRIX_ROWS_PER_HAND instead of MATRIX_ROWS to support split keyboards
static debounce_counter_t debounce_counters[MATRIX_ROWS_PER_HAND] = {DEBOUNCE_ELAPSED};
static bool counters_need_update;
static bool cooked_changed;
static inline void update_debounce_counters_and_transfer_if_expired(matrix_row_t raw[], matrix_row_t cooked[], uint8_t elapsed_time);
static inline void start_debounce_counters(matrix_row_t raw[], matrix_row_t cooked[]);
void debounce_init(void) {}
bool debounce(matrix_row_t raw[], matrix_row_t cooked[], bool changed) {
static fast_timer_t last_time;
bool updated_last = false;
cooked_changed = false;
if (counters_need_update) {
fast_timer_t now = timer_read_fast();
fast_timer_t elapsed_time = TIMER_DIFF_FAST(now, last_time);
last_time = now;
updated_last = true;
if (elapsed_time > 0) {
// Update debounce counters with elapsed timer clamped to UINT8_MAX
update_debounce_counters_and_transfer_if_expired(raw, cooked, MIN(elapsed_time, UINT8_MAX));
}
}
if (changed) {
if (!updated_last) {
last_time = timer_read_fast();
}
start_debounce_counters(raw, cooked);
}
return cooked_changed;
}
/**
* @brief Updates debounce counters and transfers debounced row states if the debounce period has expired.
*
* Iterates through each row in the matrix and checks its debounce counter. If the debounce period has expired
* for a row, the debounced state is updated to match the raw state. Otherwise, the debounce counter is decremented
* by the elapsed time and marked for further updates.
*
* @param raw The current raw key state matrix.
* @param cooked The debounced key state matrix to be updated.
* @param elapsed_time The time elapsed since the last debounce update, in milliseconds.
*/
static inline void update_debounce_counters_and_transfer_if_expired(matrix_row_t raw[], matrix_row_t cooked[], uint8_t elapsed_time) {
counters_need_update = false;
for (uint8_t row = 0; row < MATRIX_ROWS_PER_HAND; row++) {
if (debounce_counters[row] != DEBOUNCE_ELAPSED) {
if (debounce_counters[row] <= elapsed_time) {
debounce_counters[row] = DEBOUNCE_ELAPSED;
cooked_changed |= cooked[row] ^ raw[row];
cooked[row] = raw[row];
} else {
debounce_counters[row] -= elapsed_time;
counters_need_update = true;
}
}
}
}
/**
* @brief Initializes debounce counters for rows with changed states.
*
* For each row in the matrix, this function checks if the raw state differs from the debounced state.
* If a change is detected and the debounce counter has elapsed, the counter is set to the debounce period
* and marked for update. Otherwise, the counter is cleared.
*
* @param raw The current raw key state matrix.
* @param cooked The debounced key state matrix.
*/
static inline void start_debounce_counters(matrix_row_t raw[], matrix_row_t cooked[]) {
for (uint8_t row = 0; row < MATRIX_ROWS_PER_HAND; row++) {
if (raw[row] != cooked[row]) {
debounce_counters[row] = DEBOUNCE;
counters_need_update = true;
} else {
debounce_counters[row] = DEBOUNCE_ELAPSED;
}
}
}
#else
# include "none.c"
#endif
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