text: /*
   * Copyright (c) 2005 Sergey Bondari
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * - Redistributions of source code must retain the above copyright
   *   notice, this list of conditions and the following disclaimer.
   * - Redistributions in binary form must reproduce the above copyright
   *   notice, this list of conditions and the following disclaimer in the
   *   documentation and/or other materials provided with the distribution.
   * - The name of the author may not be used to endorse or promote products
   *   derived from this software without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  /** @addtogroup generic
   * @{
   */
  
  /**
   * @file
   * @brief Sorting functions.
   *
   * This files contains functions implementing several sorting
   * algorithms (e.g. quick sort and gnome sort).
   *
   */
  
  #include <mm/slab.h>
  #include <memstr.h>
  #include <sort.h>
  
  /** Immediate buffer size.
   *
   * For small buffer sizes avoid doing malloc()
   * and use the stack.
   *
   */
  #define IBUF_SIZE  32
  
  /** Array accessor.
   *
   */
  #define INDEX(buf, i, elem_size)  ((buf) + (i) * (elem_size))
  
  /** Gnome sort
   *
   * Apply generic gnome sort algorithm on supplied data,
   * using pre-allocated buffer.
   *
   * @param data      Pointer to data to be sorted.
   * @param cnt       Number of elements to be sorted.
   * @param elem_size Size of one element.
   * @param cmp       Comparator function.
   * @param arg       3rd argument passed to cmp.
   * @param slot      Pointer to scratch memory buffer
   *                  elem_size bytes long.
   *
   */
  static void _gsort(void *data, size_t cnt, size_t elem_size, sort_cmp_t cmp,
      void *arg, void *slot)
  {
  	size_t i = 0;
  	
  	while (i < cnt) {
  		if ((i > 0) &&
  		    (cmp(INDEX(data, i, elem_size),
  		    INDEX(data, i - 1, elem_size), arg) == -1)) {
  			memcpy(slot, INDEX(data, i, elem_size), elem_size);
  			memcpy(INDEX(data, i, elem_size), INDEX(data, i - 1, elem_size),
  			    elem_size);
  			memcpy(INDEX(data, i - 1, elem_size), slot, elem_size);
  			i--;
  		} else
  			i++;
  	}
  }
  
  /** Quicksort
   *
   * Apply generic quicksort algorithm on supplied data,
   * using pre-allocated buffers.
   *
   * @param data      Pointer to data to be sorted.
   * @param cnt       Number of elements to be sorted.
   * @param elem_size Size of one element.
   * @param cmp       Comparator function.
   * @param arg       3rd argument passed to cmp.
   * @param slot      Pointer to scratch memory buffer
   *                  elem_size bytes long.
   * @param pivot     Pointer to scratch memory buffer
   *                  elem_size bytes long.
   *
   */
  static void _qsort(void *data, size_t cnt, size_t elem_size, sort_cmp_t cmp,
      void *arg, void *slot, void *pivot)
  {
  	if (cnt > 4) {
  		size_t i = 0;
  		size_t j = cnt - 1;
  		
  		memcpy(pivot, data, elem_size);
  		
  		while (true) {
  			while ((cmp(INDEX(data, i, elem_size), pivot, arg) < 0) && (i < cnt))
  				i++;
  			
  			while ((cmp(INDEX(data, j, elem_size), pivot, arg) >= 0) && (j > 0))
  				j--;
  			
  			if (i < j) {
  				memcpy(slot, INDEX(data, i, elem_size), elem_size);
  				memcpy(INDEX(data, i, elem_size), INDEX(data, j, elem_size),
  				    elem_size);
  				memcpy(INDEX(data, j, elem_size), slot, elem_size);
  			} else
  				break;
  		}
  		
  		_qsort(data, j + 1, elem_size, cmp, arg, slot, pivot);
  		_qsort(INDEX(data, j + 1, elem_size), cnt - j - 1, elem_size,
  		    cmp, arg, slot, pivot);
  	} else
  		_gsort(data, cnt, elem_size, cmp, arg, slot);
  }
  
  /** Gnome sort wrapper
   *
   * This is only a wrapper that takes care of memory
   * allocations for storing the slot element for generic
   * gnome sort algorithm.
   *
   * This function can sleep.
   *
   * @param data      Pointer to data to be sorted.
   * @param cnt       Number of elements to be sorted.
   * @param elem_size Size of one element.
   * @param cmp       Comparator function.
   * @param arg       3rd argument passed to cmp.
   *
   * @return True if sorting succeeded.
   *
   */
  bool gsort(void *data, size_t cnt, size_t elem_size, sort_cmp_t cmp, void *arg)
  {
  	uint8_t ibuf_slot[IBUF_SIZE];
  	void *slot;
  	
  	if (elem_size > IBUF_SIZE) {
  		slot = (void *) malloc(elem_size, 0);
  		if (!slot)
  			return false;
  	} else
  		slot = (void *) ibuf_slot;
  	
  	_gsort(data, cnt, elem_size, cmp, arg, slot);
  	
  	if (elem_size > IBUF_SIZE)
  		free(slot);
  	
  	return true;
  }
  
  /** Quicksort wrapper
   *
   * This is only a wrapper that takes care of memory
   * allocations for storing the pivot and temporary elements
   * for generic quicksort algorithm.
   *
   * This function can sleep.
   *
   * @param data      Pointer to data to be sorted.
   * @param cnt       Number of elements to be sorted.
   * @param elem_size Size of one element.
   * @param cmp       Comparator function.
   * @param arg       3rd argument passed to cmp.
   *
   * @return True if sorting succeeded.
   *
   */
  bool qsort(void *data, size_t cnt, size_t elem_size, sort_cmp_t cmp, void *arg)
  {
  	uint8_t ibuf_slot[IBUF_SIZE];
  	uint8_t ibuf_pivot[IBUF_SIZE];
  	void *slot;
  	void *pivot;
  	
  	if (elem_size > IBUF_SIZE) {
  		slot = (void *) malloc(elem_size, 0);
  		if (!slot)
  			return false;
  		
  		pivot = (void *) malloc(elem_size, 0);
  		if (!pivot) {
  			free(slot);
  			return false;
  		}
  	} else {
  		slot = (void *) ibuf_slot;
  		pivot = (void *) ibuf_pivot;
  	}
  	
  	_qsort(data, cnt, elem_size, cmp, arg, slot, pivot);
  	
  	if (elem_size > IBUF_SIZE) {
  		free(pivot);
  		free(slot);
  	}
  	
  	return true;
  }
  
  /** @}
   */
  