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