README: Fix image path for display in gitweb

[tattlekey] / client / tattlekey.c

/* tattlekey: A one-key UDP keyboard
 * Copyright (C) 2023  Scott Worley <scottworley@scottworley.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

#include "pico/cyw43_arch.h"
#include "pico/stdlib.h"
#include "pico/util/pheap.h"
#include "pico/util/queue.h"

#include "blink.h"
#include "button.h"
#include "config.h"
#include "net.h"
#include "press.h"

enum event_type { NEW_BUTTON_PRESS, RESEND_TIME };
typedef struct {
  enum event_type type;
  union {
    struct {
      uint32_t timestamp;
    } buttonpress;
  };
} event_t;

queue_t queue;

uint32_t time_s() { return time_us_64() / 1000000ul; }

/* Often we don't bother checking for failure (full queue) because
 *   1. The best thing to do in this unfortunate situation is to blithely
 *      continue, dropping some events; continuing is better than stopping.
 *   2. Neither interrupt context nor queue-processing context can block
 *      until space is available, or even sit around & blink the LED to
 *      signal a problem.
 * (We also get a bit of type safety by taking event_t* rather than void*.) */
static void queue_try_add_ignoring_errors(queue_t *q, event_t *e) {
  queue_try_add(q, e);
}

static void button_pressed() {
  /* This runs in interrupt context; don't linger.  */
  static uint64_t last_button_press_time = 0;
  uint32_t now = time_s();
  uint32_t time_since_last_press = now - last_button_press_time;
  if (time_since_last_press >= config_minimum_seconds_between_button_presses) {
    last_button_press_time = now;
    event_t e;
    e.type = NEW_BUTTON_PRESS;
    e.buttonpress.timestamp = now;
    queue_try_add_ignoring_errors(&queue, &e);
  }
}

static void time_to_send(uint _) {
  /* This runs in interrupt context; don't linger.  */
  event_t e;
  e.type = RESEND_TIME;
  queue_try_add_ignoring_errors(&queue, &e);
}

void set_resend_alarm(int alarm, uint32_t now, uint32_t next_act_time) {
  uint32_t sleep_duration = next_act_time - now;
  if (hardware_alarm_set_target(alarm,
                                make_timeout_time_ms(sleep_duration * 1000)))
    signal_error_by_blinking();
}

void service_sleeps(int alarm, press_pile_t *pp) {
  hardware_alarm_cancel(alarm);

  while (1) {
    uint32_t now = time_s();
    int32_t act_time = next_scheduled_send(pp);
    if (act_time == -1)
      return;
    if (act_time > now) {
      set_resend_alarm(alarm, now, act_time);
      return;
    }
    press_t press;
    if (!get_press_due_for_resend(pp, now, &press))
      signal_error_by_blinking();
    u32_t ago = now - press.timestamp;
    send_report_packet(press.seq, ago);
    press.send_count++;
    if (press.send_count < config_resend_count) {
      add_press(pp, &press);
    }
  }
}

void service_queue() {
  int alarm = hardware_alarm_claim_unused(true);
  if (alarm == -1)
    signal_error_by_blinking();
  hardware_alarm_set_callback(alarm, time_to_send);

  press_pile_t *pp = create_press_pile();
  u16_t seq = 0;
  while (1) {
    service_sleeps(alarm, pp);

    event_t e;
    queue_remove_blocking(&queue, &e);
    switch (e.type) {
    case NEW_BUTTON_PRESS: {
      add_press(pp, &(press_t){e.buttonpress.timestamp, seq++, 0});
      if (seq == 0)
        new_epoch();
    } break;
    case RESEND_TIME: {
      /* OK, we're awake. Cool. Thanks! (We actually do the sends in the
       * service_sleeps() call at the top of the loop.)  */
    } break;
    default:
      signal_error_by_blinking();
    }
  }
}

int main() {
  stdio_init_all();
  if (cyw43_arch_init_with_country(CYW43_COUNTRY_USA))
    signal_error_by_blinking();
  cyw43_arch_enable_sta_mode();
  signal(3, 100);
  if (cyw43_arch_wifi_connect_timeout_ms(config_wifi_ssid, config_wifi_pass,
                                         CYW43_AUTH_WPA2_AES_PSK, 90000))
    signal_error_by_blinking();
  signal(2, 300);

  queue_init(&queue, sizeof(event_t), 99);

  begin_listening_for_button_press(button_pressed);

  service_queue();
}