yaffs_qsort.c
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/*
* Copyright (c) 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include "yportenv.h"
/* #include <linux/string.h> */
/*
* Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".
*/
#define swapcode(TYPE, parmi, parmj, n) do { \
long i = (n) / sizeof(TYPE); \
register TYPE *pi = (TYPE *) (parmi); \
register TYPE *pj = (TYPE *) (parmj); \
do { \
register TYPE t = *pi; \
*pi++ = *pj; \
*pj++ = t; \
} while (--i > 0); \
} while (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, int n, int swaptype)
{
if (swaptype <= 1)
swapcode(long, a, b, n);
else
swapcode(char, a, b, n);
}
#define yswap(a, b) do { \
if (swaptype == 0) { \
long t = *(long *)(a); \
*(long *)(a) = *(long *)(b); \
*(long *)(b) = t; \
} else \
swapfunc(a, b, es, swaptype); \
} while (0)
#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));
}
#ifndef min
#define min(a, b) (((a) < (b)) ? (a) : (b))
#endif
void
yaffs_qsort(void *aa, size_t n, size_t es,
int (*cmp)(const void *, const void *))
{
char *pa, *pb, *pc, *pd, *pl, *pm, *pn;
int d, r, swaptype, swap_cnt;
register char *a = 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)
yswap(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);
}
yswap(a, pm);
pa = pb = (char *)a + es;
pc = pd = (char *)a + (n - 1) * es;
for (;;) {
while (pb <= pc && (r = cmp(pb, a)) <= 0) {
if (r == 0) {
swap_cnt = 1;
yswap(pa, pb);
pa += es;
}
pb += es;
}
while (pb <= pc && (r = cmp(pc, a)) >= 0) {
if (r == 0) {
swap_cnt = 1;
yswap(pc, pd);
pd -= es;
}
pc -= es;
}
if (pb > pc)
break;
yswap(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)
yswap(pl, pl - es);
return;
}
pn = (char *)a + n * es;
r = min(pa - (char *)a, pb - pa);
vecswap(a, pb - r, r);
r = min((long)(pd - pc), (long)(pn - pd - es));
vecswap(pb, pn - r, r);
r = pb - pa;
if (r > es)
yaffs_qsort(a, r / es, es, cmp);
r = pd - pc;
if (r > es) {
/* Iterate rather than recurse to save stack space */
a = pn - r;
n = r / es;
goto loop;
}
/* yaffs_qsort(pn - r, r / es, es, cmp);*/
}