queue.c

/*******************************************************************************
 * This file is part of SWIFT.
 * Copyright (c) 2012 Pedro Gonnet (pedro.gonnet@durham.ac.uk)
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser 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 Lesser General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 ******************************************************************************/

/* Config parameters. */
#include "../config.h"

/* Some standard headers. */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/* MPI headers. */
#ifdef WITH_MPI
#include <mpi.h>
#endif

/* This object's header. */
#include "queue.h"

/* Local headers. */
#include "atomic.h"
#include "error.h"
#include "memswap.h"

/**
 * @brief Push the task at the given index up the heap until it is either at the
 * top or smaller than its parent.
 *
 * @param q The task #queue.
 * @param ind The index of the task to be sifted-down in the queue.
 *
 * @return The new index of the entry.
 */
int queue_bubble_up(struct queue *q, int ind) {
  /* Set some pointers we will use often. */
  struct queue_entry *entries = q->entries;
  const float w = entries[ind].weight;

  /* While we are not yet at the top of the heap... */
  while (ind > 0) {
    /* Check if the parent is larger and bail if not.. */
    const int parent = (ind - 1) / 2;
    if (w < entries[parent].weight) break;

    /* Parent is not larger, so swap. */
    memswap(&entries[ind], &entries[parent], sizeof(struct queue_entry));
    ind = parent;
  }

  return ind;
}

/**
 * @brief Push the task at the given index down the heap until both its children