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/* darkstat 3
* copyright (c) 2001-2006 Emil Mikulic.
*
* hosts_sort.c: quicksort a table of buckets.
*
* You may use, modify and redistribute this file under the terms of the
* GNU General Public License version 2. (see COPYING.GPL)
*/
#include "darkstat.h"
#include "hosts_db.h"
#include "err.h"
/* ---------------------------------------------------------------------------
* comparator for sorting (biggest first)
*/
static int
cmp(const struct bucket * const *x, const struct bucket * const *y,
const enum sort_dir dir)
{
uint64_t a, b;
switch (dir) {
case IN:
a = (*x)->in;
b = (*y)->in;
break;
case OUT:
a = (*x)->out;
b = (*y)->out;
break;
case TOTAL:
a = (*x)->total;
b = (*y)->total;
break;
default:
errx(1, "cmp: unknown direction: %d", dir);
}
if (a < b) return (1);
else if (a > b) return (-1);
else return (0);
}
/*
* The quicksort code is derived from FreeBSD's
* src/lib/libc/stdlib/qsort.c v1.12
*/
/*-
* Copyright (c) 1992, 1993
* 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.
*/
static void
vecswap(const struct bucket **pi, const struct bucket **pj, int n)
{
if (n <= 0)
return;
do {
const struct bucket *t = *pi;
*pi++ = *pj;
*pj++ = t;
} while (--n > 0);
}
#define swap(a, b) { \
const struct bucket *t = *(const struct bucket **)(a); \
*(const struct bucket **)(a) = *(const struct bucket **)(b); \
*(const struct bucket **)(b) = t; \
}
static const struct bucket **
med3(const struct bucket **a,
const struct bucket **b,
const struct bucket **c,
const enum sort_dir dir)
{
return (cmp(a, b, dir) < 0)
? (cmp(b, c, dir) < 0 ? b : (cmp(a, c, dir) < 0 ? c : a ))
: (cmp(b, c, dir) > 0 ? b : (cmp(a, c, dir) < 0 ? a : c ));
}
/* Partial sort - only sort elements in the range [left:right] */
void
qsort_buckets(const struct bucket **a, size_t n,
size_t left, size_t right,
const enum sort_dir dir)
{
const struct bucket **pa, **pb, **pc, **pd, **pl, **pm, **pn;
int d, r, swap_cnt;
loop:
swap_cnt = 0;
if (n < 7) {
for (pm = a+1; pm < a+n; pm++)
for (pl = pm;
(pl > a) && (cmp(pl-1, pl, dir) > 0);
pl--)
swap(pl, pl-1);
return;
}
pm = a + (n / 2);
if (n > 7) {
pl = a;
pn = a + (n - 1);
if (n > 40) {
d = (n / 8);
pl = med3(pl, pl + d, pl + 2 * d, dir);
pm = med3(pm - d, pm, pm + d, dir);
pn = med3(pn - 2 * d, pn - d, pn, dir);
}
pm = med3(pl, pm, pn, dir);
}
swap(a, pm);
pa = pb = a + 1;
pc = pd = a + (n - 1);
for (;;) {
while (pb <= pc && (r = cmp(pb, a, dir)) <= 0) {
if (r == 0) {
swap_cnt = 1;
swap(pa, pb);
pa++;
}
pb++;
}
while (pb <= pc && (r = cmp(pc, a, dir)) >= 0) {
if (r == 0) {
swap_cnt = 1;
swap(pc, pd);
pd--;
}
pc--;
}
if (pb > pc)
break;
swap(pb, pc);
swap_cnt = 1;
pb++;
pc--;
}
if (swap_cnt == 0) { /* Switch to insertion sort */
for (pm = a + 1; pm < a+n; pm++)
for (pl = pm;
(pl > a) && (cmp(pl-1, pl, dir) > 0);
pl--)
swap(pl, pl-1);
return;
}
pn = a + n;
r = min(pa - a, pb - pa);
vecswap(a, pb - r, r);
r = min(pd - pc, pn - pd - 1);
vecswap(pb, pn - r, r);
if (((r = pb - pa) > 1) && ((unsigned)r >= left))
qsort_buckets(a, r, left, right, dir);
if (((r = pd - pc) > 1) && (n - r <= right)) {
/* Iterate rather than recurse to save stack space */
if (n - r > left)
left = 0;
else
left -= n - r;
right -= n - r;
a += n - r;
n = r;
goto loop;
}
/* qsort(pn - r, r, cmp);*/
}
/* vim:set ts=3 sw=3 tw=78 expandtab: */
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