1/*
2** License Applicability. Except to the extent portions of this file are
3** made subject to an alternative license as permitted in the SGI Free
4** Software License B, Version 1.1 (the "License"), the contents of this
5** file are subject only to the provisions of the License. You may not use
6** this file except in compliance with the License. You may obtain a copy
7** of the License at Silicon Graphics, Inc., attn: Legal Services, 1600
8** Amphitheatre Parkway, Mountain View, CA 94043-1351, or at:
9**
10** http://oss.sgi.com/projects/FreeB
11**
12** Note that, as provided in the License, the Software is distributed on an
13** "AS IS" basis, with ALL EXPRESS AND IMPLIED WARRANTIES AND CONDITIONS
14** DISCLAIMED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES AND
15** CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A
16** PARTICULAR PURPOSE, AND NON-INFRINGEMENT.
17**
18** Original Code. The Original Code is: OpenGL Sample Implementation,
19** Version 1.2.1, released January 26, 2000, developed by Silicon Graphics,
20** Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc.
21** Copyright in any portions created by third parties is as indicated
22** elsewhere herein. All Rights Reserved.
23**
24** Additional Notice Provisions: The application programming interfaces
25** established by SGI in conjunction with the Original Code are The
26** OpenGL(R) Graphics System: A Specification (Version 1.2.1), released
27** April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version
28** 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X
29** Window System(R) (Version 1.3), released October 19, 1998. This software
30** was created using the OpenGL(R) version 1.2.1 Sample Implementation
31** published by SGI, but has not been independently verified as being
32** compliant with the OpenGL(R) version 1.2.1 Specification.
33**
34*/
35/*
36*/
37
38#include <stdlib.h>
39#include <stdio.h>
40
41
42static void swap(void *v[], int i, int j)
43{
44  void *temp;
45  temp = v[i];
46  v[i] = v[j];
47  v[j] = temp;
48}
49
50/*as an example to use this function to
51 *sort integers, you need to supply the function
52 *int comp(int *i1, int *i2)
53 *{
54 *  if( *i1 < * i2) return -1;
55 *  else return 1;
56 *}
57 *and an array of pointers to integers:
58 * int *v[100] (allocate space for where  each v[i] points to).
59 *then you can call:
60 * quicksort( (void**)v, left, right, (int (*)(void *, void *))comp)
61 */
62void quicksort(void *v[], int left, int right,
63	       int (*comp) (void *, void *))
64{
65  int i, last;
66  if(left >= right) /*do nothing if array contains */
67    return;         /*fewer than two elements*/
68
69  swap(v, left, (left+right)/2);
70  last = left;
71  for(i=left+1; i<=right; i++)
72    if((*comp)(v[i], v[left])<0)
73      swap(v, ++last, i);
74  swap(v, left, last);
75  quicksort(v, left, last-1, comp);
76  quicksort(v, last+1, right, comp);
77}
78