client: Interleave accepting new button presses & re-sends

[tattlekey] / client / tattlekey.c

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

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

enum event_type { BUTTONPRESS, SEND };
typedef struct {
  enum event_type type;
  union {
    struct {
      uint32_t timestamp;
    } buttonpress;
    struct {
      uint32_t timestamp;
      u16_t seq;
      u8_t send_count;
    } send;
  };
} 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 = BUTTONPRESS;
    e.buttonpress.timestamp = now;
    queue_try_add_ignoring_errors(&queue, &e);
  }
}

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);

  u16_t seq = 0;
  while (1) {
    event_t e;
    queue_remove_blocking(&queue, &e);
    switch (e.type) {
    case BUTTONPRESS: {
      event_t send_e;
      send_e.type = SEND;
      send_e.send.timestamp = e.buttonpress.timestamp;
      send_e.send.seq = seq++;
      send_e.send.send_count = 0;
      queue_try_add_ignoring_errors(&queue, &send_e);
    } break;
    case SEND: {
      uint32_t now = time_s();
      uint32_t ago = now - e.send.timestamp;
      send_report(e.send.seq, ago);
      e.send.send_count++;
      if (e.send.send_count < config_resend_count)
        queue_try_add_ignoring_errors(&queue, &e);
      /* TODO: Sleep elsewhere. */
      signal(e.send.send_count == 1 ? 2 : 1, 100);
      sleep_ms(config_resend_interval_ms);
    } break;
    default:
      signal_error_by_blinking();
    }
  }
}