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// Copyright 2017 Alex Ong<the.onga@gmail.com>
// Copyright 2021 Simon Arlott
// SPDX-License-Identifier: GPL-2.0-or-later
//
// Basic per-row algorithm. Uses an 8-bit counter per key.
// After pressing a key, it immediately changes state, and sets a counter.
// No further inputs are accepted until DEBOUNCE milliseconds have occurred.
#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 matrix_need_update;
static bool cooked_changed;
static inline void update_debounce_counters(uint8_t elapsed_time);
static inline void transfer_matrix_values(matrix_row_t raw[], matrix_row_t cooked[]);
void debounce_init(uint8_t num_rows) {}
bool debounce(matrix_row_t raw[], matrix_row_t cooked[], uint8_t num_rows, 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(MIN(elapsed_time, UINT8_MAX));
}
}
if (changed || matrix_need_update) {
if (!updated_last) {
last_time = timer_read_fast();
}
transfer_matrix_values(raw, cooked);
}
return cooked_changed;
}
/**
* @brief Updates per-row debounce counters and determines if matrix needs updating.
*
* Iterates through each row in the matrix and checks its debounce counter. If the debounce
* period has elapsed, the counter is reset and the matrix is marked for update. Otherwise,
* the counter is decremented by the elapsed time and marked for further updates if needed.
*
* @param elapsed_time The time elapsed since the last debounce update, in milliseconds.
*/
static inline void update_debounce_counters(uint8_t elapsed_time) {
counters_need_update = false;
matrix_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;
matrix_need_update = true;
} else {
debounce_counters[row] -= elapsed_time;
counters_need_update = true;
}
}
}
}
/**
* @brief Transfers debounced key states from the raw matrix to the cooked matrix.
*
* For each row in the matrix, this function checks if its state has changed and if its
* debounce counter has elapsed. If so, the debounce counter is reset, the cooked matrix
* is updated to reflect the new state, and the matrix is marked for further updates.
*
* @param raw The current raw key state matrix.
* @param cooked The debounced key state matrix
*/
static inline void transfer_matrix_values(matrix_row_t raw[], matrix_row_t cooked[]) {
matrix_need_update = false;
for (uint8_t row = 0; row < MATRIX_ROWS_PER_HAND; row++) {
matrix_row_t existing_row = cooked[row];
matrix_row_t raw_row = raw[row];
// determine new value basd on debounce pointer + raw value
if (existing_row != raw_row) {
if (debounce_counters[row] == DEBOUNCE_ELAPSED) {
debounce_counters[row] = DEBOUNCE;
cooked_changed |= cooked[row] ^ raw_row;
cooked[row] = raw_row;
counters_need_update = true;
}
}
}
}
#else
# include "none.c"
#endif
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