text: /**
   * \file
   *
   * \brief Events implementation.
   *
   * Copyright (c) 2015-2018 Microchip Technology Inc. and its subsidiaries.
   *
   * \asf_license_start
   *
   * \page License
   *
   * Subject to your compliance with these terms, you may use Microchip
   * software and any derivatives exclusively with Microchip products.
   * It is your responsibility to comply with third party license terms applicable
   * to your use of third party software (including open source software) that
   * may accompany Microchip software.
   *
   * THIS SOFTWARE IS SUPPLIED BY MICROCHIP "AS IS". NO WARRANTIES,
   * WHETHER EXPRESS, IMPLIED OR STATUTORY, APPLY TO THIS SOFTWARE,
   * INCLUDING ANY IMPLIED WARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY,
   * AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT WILL MICROCHIP BE
   * LIABLE FOR ANY INDIRECT, SPECIAL, PUNITIVE, INCIDENTAL OR CONSEQUENTIAL
   * LOSS, DAMAGE, COST OR EXPENSE OF ANY KIND WHATSOEVER RELATED TO THE
   * SOFTWARE, HOWEVER CAUSED, EVEN IF MICROCHIP HAS BEEN ADVISED OF THE
   * POSSIBILITY OR THE DAMAGES ARE FORESEEABLE.  TO THE FULLEST EXTENT
   * ALLOWED BY LAW, MICROCHIP'S TOTAL LIABILITY ON ALL CLAIMS IN ANY WAY
   * RELATED TO THIS SOFTWARE WILL NOT EXCEED THE AMOUNT OF FEES, IF ANY,
   * THAT YOU HAVE PAID DIRECTLY TO MICROCHIP FOR THIS SOFTWARE.
   *
   * \asf_license_stop
   *
   */
  
  #include <utils_event.h>
  #include <utils_assert.h>
  #include <string.h>
  
  #define EVENT_WORD_BITS (sizeof(event_word_t) * 8)
  
  static struct list_descriptor events;
  static uint8_t                subscribed[EVENT_MASK_SIZE];
  
  int32_t event_subscribe(struct event *const event, const event_id_t id, event_cb_t cb)
  {
  	/* get byte and bit number of the given event in the event mask */
  	const uint8_t position = id >> 3;
  	const uint8_t mask     = 1 << (id & 0x7);
  
  	ASSERT(event && cb && (id < EVENT_MAX_AMOUNT));
  
  	if (event->mask[position] & mask) {
  		return ERR_NO_CHANGE; /* Already subscribed */
  	}
  
  	if (!is_list_element(&events, event)) {
  		memset(event->mask, 0, EVENT_MASK_SIZE);
  		list_insert_as_head(&events, event);
  	}
  	event->cb = cb;
  	event->mask[position] |= mask;
  
  	subscribed[position] |= mask;
  
  	return ERR_NONE;
  }
  
  int32_t event_unsubscribe(struct event *const event, const event_id_t id)
  {
  	/* get byte and bit number of the given event in the event mask */
  	const uint8_t       position = id >> 3;
  	const uint8_t       mask     = 1 << (id & 0x7);
  	const struct event *current;
  	uint8_t             i;
  
  	ASSERT(event && (id < EVENT_MAX_AMOUNT));
  
  	if (!(event->mask[position] & mask)) {
  		return ERR_NO_CHANGE; /* Already unsubscribed */
  	}
  
  	event->mask[position] &= ~mask;
  
  	/* Check if there are more subscribers */
  	for ((current = (const struct event *)list_get_head(&events)); current;
  	     current = (const struct event *)list_get_next_element(current)) {
  		if (current->mask[position] & mask) {
  			break;
  		}
  	}
  	if (!current) {
  		subscribed[position] &= ~mask;
  	}
  
  	/* Remove event from the list. Can be unsave, document it! */
  	for (i = 0; i < ARRAY_SIZE(event->mask); i++) {
  		if (event->mask[i]) {
  			return ERR_NONE;
  		}
  	}
  	list_delete_element(&events, event);
  
  	return ERR_NONE;
  }
  
  void event_post(const event_id_t id, const event_data_t data)
  {
  	/* get byte and bit number of the given event in the event mask */
  	const uint8_t       position = id >> 3;
  	const uint8_t       mask     = 1 << (id & 0x7);
  	const struct event *current;
  
  	ASSERT((id < EVENT_MAX_AMOUNT));
  
  	if (!(subscribed[position] & mask)) {
  		return; /* No subscribers */
  	}
  
  	/* Find all subscribers */
  	for ((current = (const struct event *)list_get_head(&events)); current;
  	     current = (const struct event *)list_get_next_element(current)) {
  		if (current->mask[position] & mask) {
  			current->cb(id, data);
  		}
  	}
  }
  