ladybird/LibC/qsort.cpp

78 lines
3.0 KiB
C++

/*-
* Copyright (c) 1980, 1983, 1990 The Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
*/
#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)qsort.c 5.9 (Berkeley) 2/23/91";
#endif /* LIBC_SCCS and not lint */
#include <sys/types.h>
#include <stdlib.h>
static void insertion_sort(void* bot, size_t nmemb, size_t size, int (*compar)(const void *, const void *));
void qsort(void* bot, size_t nmemb, size_t size, int (*compar)(const void *, const void *))
{
if (nmemb <= 1)
return;
insertion_sort(bot, nmemb, size, compar);
}
void insertion_sort(void* bot, size_t nmemb, size_t size, int (*compar)(const void *, const void *))
{
int cnt;
unsigned char ch;
char *s1, *s2, *t1, *t2, *top;
/*
* A simple insertion sort (see Knuth, Vol. 3, page 81, Algorithm
* S). Insertion sort has the same worst case as most simple sorts
* (O N^2). It gets used here because it is (O N) in the case of
* sorted data.
*/
top = (char*)bot + nmemb * size;
for (t1 = (char*)bot + size; t1 < top;) {
for (t2 = t1; (t2 -= size) >= bot && compar(t1, t2) < 0;);
if (t1 != (t2 += size)) {
/* Bubble bytes up through each element. */
for (cnt = size; cnt--; ++t1) {
ch = *t1;
for (s1 = s2 = t1; (s2 -= size) >= t2; s1 = s2)
*s1 = *s2;
*s1 = ch;
}
} else
t1 += size;
}
}