client: Calculate 'ago' with a clock

[tattlekey] / client / button.c

#include "button.h"
#include "config.h"

#include "hardware/gpio.h"

#include "pico/stdlib.h"

static callback_t button_callback = NULL;

static void respond_to_gpio_interrupt(uint gpio, uint32_t event_mask) {
  if (gpio == button_pin && event_mask & GPIO_IRQ_EDGE_FALL &&
      button_callback) {
    button_callback();
  }
}

void begin_listening_for_button_press(callback_t callback) {
  button_callback = callback;

  gpio_set_pulls(button_pin, 1, 0);

  /* Allow some time for the pull-up to take effect.
   * I'm not sure if this is necessary.
   * https://datasheets.raspberrypi.com/pico/raspberry-pi-pico-c-sdk.pdf says
   * the internal GPIO pull-up resistors are 50k. */
  sleep_ms(100);

  gpio_set_irq_enabled_with_callback(button_pin, GPIO_IRQ_EDGE_FALL, 1,
                                     respond_to_gpio_interrupt);
}