circuitpython/shared-module/keypad/KeyMatrix.c

/*
 * This file is part of the Micro Python project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2021 Dan Halbert for Adafruit Industries
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "py/gc.h"
#include "py/runtime.h"
#include "shared-bindings/keypad/Event.h"
#include "shared-bindings/keypad/KeyMatrix.h"
#include "shared-bindings/digitalio/DigitalInOut.h"
#include "shared-bindings/util.h"
#include "supervisor/port.h"
#include "supervisor/shared/lock.h"
#include "supervisor/shared/tick.h"

static supervisor_lock_t keypad_keymatrix_linked_list_lock;

#define DEBOUNCE_TICKS (20)

// Top bit of 16-bit event indicates pressed or released. Rest is key_num.
#define EVENT_PRESSED (1 << 15)
#define EVENT_RELEASED (0)
#define EVENT_KEY_NUM_MASK (~EVENT_PRESSED)

static mp_uint_t row_col_to_key_num(keypad_keymatrix_obj_t *self, mp_uint_t row, mp_uint_t col) {
    return row * self->col_digitalinouts->len + col;
}

void common_hal_keypad_keymatrix_construct(keypad_keymatrix_obj_t *self, mp_uint_t num_row_pins, mcu_pin_obj_t *row_pins[], mp_uint_t num_col_pins, mcu_pin_obj_t *col_pins[], size_t max_events) {

    mp_obj_t row_dios[num_row_pins];
    for (size_t row = 0; row < num_row_pins; row++) {
        digitalio_digitalinout_obj_t *dio = m_new_obj(digitalio_digitalinout_obj_t);
        dio->base.type = &digitalio_digitalinout_type;
        common_hal_digitalio_digitalinout_construct(dio, row_pins[row]);
        common_hal_digitalio_digitalinout_switch_to_input(dio, PULL_UP);
        row_dios[row] = dio;
    }
    self->row_digitalinouts = mp_obj_new_tuple(num_row_pins, row_dios);

    mp_obj_t col_dios[num_col_pins];
    for (size_t col = 0; col < num_col_pins; col++) {
        digitalio_digitalinout_obj_t *dio = m_new_obj(digitalio_digitalinout_obj_t);
        dio->base.type = &digitalio_digitalinout_type;
        common_hal_digitalio_digitalinout_construct(dio, col_pins[col]);
        common_hal_digitalio_digitalinout_switch_to_input(dio, PULL_UP);
        col_dios[col] = dio;
    }
    self->col_digitalinouts = mp_obj_new_tuple(num_col_pins, col_dios);

    self->currently_pressed = (bool *)gc_alloc(sizeof(bool) * num_row_pins * num_col_pins, false, false);
    self->previously_pressed = (bool *)gc_alloc(sizeof(bool) * num_row_pins * num_col_pins, false, false);

    // Event queue is 16-bit values.
    ringbuf_alloc(&self->encoded_events, max_events * 2, false);

    // Add self to the list of active Keys objects.

    supervisor_acquire_lock(&keypad_keymatrix_linked_list_lock);
    self->next = MP_STATE_VM(keypad_keymatrix_linked_list);
    MP_STATE_VM(keypad_keymatrix_linked_list) = self;
    supervisor_release_lock(&keypad_keymatrix_linked_list_lock);

    supervisor_enable_tick();
}

void common_hal_keypad_keymatrix_deinit(keypad_keymatrix_obj_t *self) {
    if (common_hal_keypad_keymatrix_deinited(self)) {
        return;
    }

    for (size_t row = 0; row < common_hal_keypad_keymatrix_num_rows(self); row++) {
        common_hal_digitalio_digitalinout_deinit(self->row_digitalinouts->items[row]);
    }
    self->row_digitalinouts = MP_ROM_NONE;

    for (size_t col = 0; col < common_hal_keypad_keymatrix_num_cols(self); col++) {
        common_hal_digitalio_digitalinout_deinit(self->col_digitalinouts->items[col]);
    }
    self->col_digitalinouts = MP_ROM_NONE;

    // Remove self from the list of active KeyMatrix objects.

    supervisor_acquire_lock(&keypad_keymatrix_linked_list_lock);
    if (MP_STATE_VM(keypad_keymatrix_linked_list) == self) {
        // I'm at the front; splice myself out.
        MP_STATE_VM(keypad_keymatrix_linked_list) = self->next;
    } else {
        keypad_keymatrix_obj_t *current = MP_STATE_VM(keypad_keymatrix_linked_list);
        while (current) {
            if (current->next == self) {
                // Splice myself out.
                current->next = self->next;
                break;
            }
            current = current->next;
        }
    }
    supervisor_release_lock(&keypad_keymatrix_linked_list_lock);
}

bool common_hal_keypad_keymatrix_deinited(keypad_keymatrix_obj_t *self) {
    return self->row_digitalinouts == MP_ROM_NONE;
}

size_t common_hal_keypad_keymatrix_num_keys(keypad_keymatrix_obj_t *self) {
    return common_hal_keypad_keymatrix_num_rows(self) * common_hal_keypad_keymatrix_num_cols(self);
}

size_t common_hal_keypad_keymatrix_num_rows(keypad_keymatrix_obj_t *self) {
    return self->row_digitalinouts->len;
}

size_t common_hal_keypad_keymatrix_num_cols(keypad_keymatrix_obj_t *self) {
    return self->col_digitalinouts->len;
}

bool common_hal_keypad_keymatrix_pressed(keypad_keymatrix_obj_t *self, mp_uint_t key_num) {
    return self->currently_pressed[key_num];
}

mp_obj_t common_hal_keypad_keymatrix_next_event(keypad_keymatrix_obj_t *self) {
    int encoded_event = ringbuf_get16(&self->encoded_events);
    if (encoded_event == -1) {
        return MP_ROM_NONE;
    }

    keypad_event_obj_t *event = m_new_obj(keypad_event_obj_t);
    event->base.type = &keypad_event_type;
    common_hal_keypad_event_construct(event, encoded_event & EVENT_KEY_NUM_MASK, encoded_event & EVENT_PRESSED);
    return MP_OBJ_FROM_PTR(event);
}

void common_hal_keypad_keymatrix_clear_events(keypad_keymatrix_obj_t *self) {
    ringbuf_clear(&self->encoded_events);
}

mp_uint_t common_hal_keypad_keymatrix_key_num(keypad_keymatrix_obj_t *self, mp_uint_t row, mp_uint_t col) {
    return row_col_to_key_num(self, row, col);
}

static void keypad_keymatrix_scan(keypad_keymatrix_obj_t *self) {
    uint64_t now = port_get_raw_ticks(NULL);
    if (now - self->last_scan_ticks < DEBOUNCE_TICKS) {
        // Too soon. Wait longer to debounce.
        return;
    }

    self->last_scan_ticks = now;

    // On entry, all pins are set to inputs with a pull-up.
    for (size_t row = 0; row < common_hal_keypad_keymatrix_num_rows(self); row++) {
        // Switch this row to an output and set to low.
        common_hal_digitalio_digitalinout_switch_to_output(
            self->row_digitalinouts->items[row], false, DRIVE_MODE_PUSH_PULL);

        for (size_t col = 0; col < common_hal_keypad_keymatrix_num_cols(self); col++) {
            mp_uint_t key_num = row_col_to_key_num(self, row, col);
            const bool previous = self->currently_pressed[key_num];
            self->previously_pressed[key_num] = previous;

            // Get the current state, by reading whether the col got pulled down or not.
            // If low, the key is pressed.
            const bool current =
                !common_hal_digitalio_digitalinout_get_value(self->col_digitalinouts->items[col]);
            self->currently_pressed[key_num] = current;

            // Record any transitions.
            if (previous != current) {
                if (ringbuf_num_empty(&self->encoded_events) == 0) {
                    // Discard oldest if full.
                    ringbuf_get16(&self->encoded_events);
                }
                ringbuf_put16(&self->encoded_events, key_num | (current ? EVENT_PRESSED : EVENT_RELEASED));
            }

        }

        // Switch the row back to an input, pulled up.
        common_hal_digitalio_digitalinout_switch_to_input(self->row_digitalinouts->items[row], PULL_UP);
    }
}

void keypad_keymatrix_tick(void) {
    // Fast path.
    if (!MP_STATE_VM(keypad_keymatrix_linked_list)) {
        return;
    }

    if (supervisor_try_lock(&keypad_keymatrix_linked_list_lock)) {
        keypad_keymatrix_obj_t *keypad_keymatrix = MP_STATE_VM(keypad_keymatrix_linked_list);
        while (keypad_keymatrix) {
            keypad_keymatrix_scan(keypad_keymatrix);
            keypad_keymatrix = keypad_keymatrix->next;
        }
        supervisor_release_lock(&keypad_keymatrix_linked_list_lock);
    }
}

void keypad_keymatrix_reset(void) {
    if (MP_STATE_VM(keypad_keymatrix_linked_list)) {
        supervisor_disable_tick();
    }

    MP_STATE_VM(keypad_keys_linked_list) = NULL;
    keypad_keymatrix_linked_list_lock = false;
}