/* median-3 variant of quicksort - coded by John Garnett.
using this quicksort rather than the builtin one because most
builtin implementations choke on non-deterministic compare functions
(and we can't control what compare function is used since it is at
the mudlib level). Based on algorithm appearing in _Data Structures and
Algorithm Analysis_ by Cawnthorpe.
*/
#include "std.h"
#include "qsort.h"
#define LEN sizeof(svalue_t)
#define MAX_LEN 1000
INLINE_STATIC void doSwap (char *, char *, int);
static void qSort (void *, int, int, int, int, int (*) ());
INLINE_STATIC void doSwap (register char * one, register char * two,
register int size)
{
register char t;
while (size--) {
t = *one;
*(one++) = *two;
*(two++) = t;
}
}
/* qsort adapted from page 87 of K&R 2nd edition */
static void qSort(void *v, int left, int right, int size, int rightmost, int (*compar) (void *, void *))
{
int i, last, szleft;
if ((left >= right) || (left < 0) || (right > rightmost) || (right < 0)) {
return;
}
szleft = size * left;
doSwap((char *) v + szleft, (char *) v + (size * ((left + right) / 2)), size);
last = left;
for (i = left + 1; i <= right; i++) {
if ((*compar) ((char *) v + (size * i), (char *) v + szleft) < 0) {
doSwap((char *) v + (size * ++last), (char *) v + (size * i), size);
}
}
doSwap((char *) v + szleft, (char *) v + (size * last), size);
qSort(v, left, last - 1, size, rightmost, compar);
qSort(v, last + 1, right, size, rightmost, compar);
}
void quickSort(void *a, int nmemb, int size, int (*compar) (void *, void *))
{
if (nmemb < 2) {
return;
}
qSort(a, 0, nmemb - 1, size, nmemb - 1, compar);
}
