openmv/lib/imlib/qsort.c
iabdalkader daf2bb30da misc: Restructure repo.
Signed-off-by: iabdalkader <i.abdalkader@gmail.com>
2025-04-13 08:28:34 +02:00

158 lines
5.3 KiB
C

/*
* Copyright (c) 1992, 1993 The Regents of the University of California.
*
* 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. 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.
*
* Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
*/
#include <stdlib.h>
#define min(a, b) (a) < (b) ? a : b
#define swapcode(TYPE, parmi, parmj, n) { \
size_t i = (n) / sizeof(TYPE); \
TYPE *pi = (TYPE *) (parmi); \
TYPE *pj = (TYPE *) (parmj); \
do { \
TYPE t = *pi; \
*pi++ = *pj; \
*pj++ = t; \
} while (--i > 0); \
}
#define SWAPINIT(a, es) swaptype = ((char *) a - (char *) 0) % sizeof(long) || \
es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;
static __inline void swapfunc(char *a, char *b, size_t n, int swaptype) {
if (swaptype <= 1) {
swapcode(long, a, b, n);
} else {
swapcode(char, a, b, n);
}
}
#define swap(a, b) \
if (swaptype == 0) { \
long t = *(long *) (a); \
*(long *) (a) = *(long *) (b); \
*(long *) (b) = t; \
} \
else \
swapfunc(a, b, es, swaptype)
#define vecswap(a, b, n) if ((n) > 0) swapfunc(a, b, n, swaptype)
static __inline char *med3(char *a, char *b, char *c, int (*cmp) (const void *, const void *)) {
return cmp(a, b) < 0 ?
(cmp(b, c) < 0 ? b : (cmp(a, c) < 0 ? c : a))
:(cmp(b, c) > 0 ? b : (cmp(a, c) < 0 ? a : c));
}
void qsort(void *aa, size_t n, size_t es, int (*cmp) (const void *, const void *)) {
char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
int cmp_result, swaptype, swap_cnt;
size_t d, r;
char *a = (char *) aa;
loop:
SWAPINIT(a, es);
swap_cnt = 0;
if (n < 7) {
for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) {
for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
pl -= es) {
swap(pl, pl - es);
}
}
return;
}
pm = (char *) a + (n / 2) * es;
if (n > 7) {
pl = (char *) a;
pn = (char *) a + (n - 1) * es;
if (n > 40) {
d = (n / 8) * es;
pl = med3(pl, pl + d, pl + 2 * d, cmp);
pm = med3(pm - d, pm, pm + d, cmp);
pn = med3(pn - 2 * d, pn - d, pn, cmp);
}
pm = med3(pl, pm, pn, cmp);
}
swap(a, pm);
pa = pb = (char *) a + es;
pc = pd = (char *) a + (n - 1) * es;
for (;;) {
while (pb <= pc && (cmp_result = cmp(pb, a)) <= 0) {
if (cmp_result == 0) {
swap_cnt = 1;
swap(pa, pb);
pa += es;
}
pb += es;
}
while (pb <= pc && (cmp_result = cmp(pc, a)) >= 0) {
if (cmp_result == 0) {
swap_cnt = 1;
swap(pc, pd);
pd -= es;
}
pc -= es;
}
if (pb > pc) {
break;
}
swap(pb, pc);
swap_cnt = 1;
pb += es;
pc -= es;
}
if (swap_cnt == 0) {
/* Switch to insertion sort */
for (pm = (char *) a + es; pm < (char *) a + n * es; pm += es) {
for (pl = pm; pl > (char *) a && cmp(pl - es, pl) > 0;
pl -= es) {
swap(pl, pl - es);
}
}
return;
}
pn = (char *) a + n * es;
r = min(pa - (char *) a, pb - pa);
vecswap(a, pb - r, r);
r = min(pd - pc, pn - pd - es);
vecswap(pb, pn - r, r);
if ((r = pb - pa) > es) {
qsort(a, r / es, es, cmp);
}
if ((r = pd - pc) > es) {
/* Iterate rather than recurse to save stack space */
a = pn - r;
n = r / es;
goto loop;
}
/* qsort(pn - r, r / es, es, cmp); */
}