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/*
* Copyright (c) 2021 The ZMK Contributors
*
* SPDX-License-Identifier: MIT
*/
#include "debounce.h"
static uint32_t get_threshold(const struct debounce_state *state,
const struct debounce_config *config) {
return state->pressed ? config->debounce_release_ms : config->debounce_press_ms;
}
static void increment_counter(struct debounce_state *state, const int elapsed_ms) {
if (state->counter + elapsed_ms > DEBOUNCE_COUNTER_MAX) {
state->counter = DEBOUNCE_COUNTER_MAX;
} else {
state->counter += elapsed_ms;
}
}
static void decrement_counter(struct debounce_state *state, const int elapsed_ms) {
if (state->counter < elapsed_ms) {
state->counter = 0;
} else {
state->counter -= elapsed_ms;
}
}
void debounce_update(struct debounce_state *state, const bool active, const int elapsed_ms,
const struct debounce_config *config) {
// This uses a variation of the integrator debouncing described at
// https://www.kennethkuhn.com/electronics/debounce.c
// Every update where "active" does not match the current state, we increment
// a counter, otherwise we decrement it. When the counter reaches a
// threshold, the state flips and we reset the counter.
state->changed = false;
if (active == state->pressed) {
decrement_counter(state, elapsed_ms);
return;
}
const uint32_t flip_threshold = get_threshold(state, config);
if (state->counter < flip_threshold) {
increment_counter(state, elapsed_ms);
return;
}
state->pressed = !state->pressed;
state->counter = 0;
state->changed = true;
}
bool debounce_is_active(const struct debounce_state *state) {
return state->pressed || state->counter > 0;
}
bool debounce_is_pressed(const struct debounce_state *state) { return state->pressed; }
bool debounce_get_changed(const struct debounce_state *state) { return state->changed; }
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