/* An alternative to qsort, with an identical interface.
This file is part of the GNU C Library.
Copyright (C) 1992-2018 Free Software Foundation, Inc.
Written by Mike Haertel, September 1988.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <alloca.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <memcopy.h>
#include <errno.h>
#include <atomic.h>
struct msort_param
{
size_t s;
size_t var;
__compar_d_fn_t cmp;
void *arg;
char *t;
};
static void msort_with_tmp (const struct msort_param *p, void *b, size_t n);
static void
msort_with_tmp (const struct msort_param *p, void *b, size_t n)
{
char *b1, *b2;
size_t n1, n2;
if (n <= 1)
return;
n1 = n / 2;
n2 = n - n1;
b1 = b;
b2 = (char *) b + (n1 * p->s);
msort_with_tmp (p, b1, n1);
msort_with_tmp (p, b2, n2);
char *tmp = p->t;
const size_t s = p->s;
__compar_d_fn_t cmp = p->cmp;
void *arg = p->arg;
switch (p->var)
{
case 0:
while (n1 > 0 && n2 > 0)
{
if ((*cmp) (b1, b2, arg) <= 0)
{
*(uint32_t *) tmp = *(uint32_t *) b1;
b1 += sizeof (uint32_t);
--n1;
}
else
{
*(uint32_t *) tmp = *(uint32_t *) b2;
b2 += sizeof (uint32_t);
--n2;
}
tmp += sizeof (uint32_t);
}
break;
case 1:
while (n1 > 0 && n2 > 0)
{
if ((*cmp) (b1, b2, arg) <= 0)
{
*(uint64_t *) tmp = *(uint64_t *) b1;
b1 += sizeof (uint64_t);
--n1;
}
else
{
*(uint64_t *) tmp = *(uint64_t *) b2;
b2 += sizeof (uint64_t);
--n2;
}
tmp += sizeof (uint64_t);
}
break;
case 2:
while (n1 > 0 && n2 > 0)
{
unsigned long *tmpl = (unsigned long *) tmp;
unsigned long *bl;
tmp += s;
if ((*cmp) (b1, b2, arg) <= 0)
{
bl = (unsigned long *) b1;
b1 += s;
--n1;
}
else
{
bl = (unsigned long *) b2;
b2 += s;
--n2;
}
while (tmpl < (unsigned long *) tmp)
*tmpl++ = *bl++;
}
break;
case 3:
while (n1 > 0 && n2 > 0)
{
if ((*cmp) (*(const void **) b1, *(const void **) b2, arg) <= 0)
{
*(void **) tmp = *(void **) b1;
b1 += sizeof (void *);
--n1;
}
else
{
*(void **) tmp = *(void **) b2;
b2 += sizeof (void *);
--n2;
}
tmp += sizeof (void *);
}
break;
default:
while (n1 > 0 && n2 > 0)
{
if ((*cmp) (b1, b2, arg) <= 0)
{
tmp = (char *) __mempcpy (tmp, b1, s);
b1 += s;
--n1;
}
else
{
tmp = (char *) __mempcpy (tmp, b2, s);
b2 += s;
--n2;
}
}
break;
}
if (n1 > 0)
memcpy (tmp, b1, n1 * s);
memcpy (b, p->t, (n - n2) * s);
}
void
__qsort_r (void *b, size_t n, size_t s, __compar_d_fn_t cmp, void *arg)
{
size_t size = n * s;
char *tmp = NULL;
struct msort_param p;
/* For large object sizes use indirect sorting. */
if (s > 32)
size = 2 * n * sizeof (void *) + s;
if (size < 1024)
/* The temporary array is small, so put it on the stack. */
p.t = __alloca (size);
else
{
/* We should avoid allocating too much memory since this might
have to be backed up by swap space. */
static long int phys_pages;
static int pagesize;
if (pagesize == 0)
{
phys_pages = __sysconf (_SC_PHYS_PAGES);
if (phys_pages == -1)
/* Error while determining the memory size. So let's
assume there is enough memory. Otherwise the
implementer should provide a complete implementation of
the `sysconf' function. */
phys_pages = (long int) (~0ul >> 1);
/* The following determines that we will never use more than
a quarter of the physical memory. */
phys_pages /= 4;
/* Make sure phys_pages is written to memory. */
atomic_write_barrier ();
pagesize = __sysconf (_SC_PAGESIZE);
}
/* Just a comment here. We cannot compute
phys_pages * pagesize
and compare the needed amount of memory against this value.
The problem is that some systems might have more physical
memory then can be represented with a `size_t' value (when
measured in bytes. */
/* If the memory requirements are too high don't allocate memory. */
if (size / pagesize > (size_t) phys_pages)
{
_quicksort (b, n, s, cmp, arg);
return;
}
/* It's somewhat large, so malloc it. */
int save = errno;
tmp = malloc (size);
__set_errno (save);
if (tmp == NULL)
{
/* Couldn't get space, so use the slower algorithm
that doesn't need a temporary array. */
_quicksort (b, n, s, cmp, arg);
return;
}
p.t = tmp;
}
p.s = s;
p.var = 4;
p.cmp = cmp;
p.arg = arg;
if (s > 32)
{
/* Indirect sorting. */
char *ip = (char *) b;
void **tp = (void **) (p.t + n * sizeof (void *));
void **t = tp;
void *tmp_storage = (void *) (tp + n);
while ((void *) t < tmp_storage)
{
*t++ = ip;
ip += s;
}
p.s = sizeof (void *);
p.var = 3;
msort_with_tmp (&p, p.t + n * sizeof (void *), n);
/* tp[0] .. tp[n - 1] is now sorted, copy around entries of
the original array. Knuth vol. 3 (2nd ed.) exercise 5.2-10. */
char *kp;
size_t i;
for (i = 0, ip = (char *) b; i < n; i++, ip += s)
if ((kp = tp[i]) != ip)
{
size_t j = i;
char *jp = ip;
memcpy (tmp_storage, ip, s);
do
{
size_t k = (kp - (char *) b) / s;
tp[j] = jp;
memcpy (jp, kp, s);
j = k;
jp = kp;
kp = tp[k];
}
while (kp != ip);
tp[j] = jp;
memcpy (jp, tmp_storage, s);
}
}
else
{
if ((s & (sizeof (uint32_t) - 1)) == 0
&& ((char *) b - (char *) 0) % __alignof__ (uint32_t) == 0)
{
if (s == sizeof (uint32_t))
p.var = 0;
else if (s == sizeof (uint64_t)
&& ((char *) b - (char *) 0) % __alignof__ (uint64_t) == 0)
p.var = 1;
else if ((s & (sizeof (unsigned long) - 1)) == 0
&& ((char *) b - (char *) 0)
% __alignof__ (unsigned long) == 0)
p.var = 2;
}
msort_with_tmp (&p, b, n);
}
free (tmp);
}
libc_hidden_def (__qsort_r)
weak_alias (__qsort_r, qsort_r)
void
qsort (void *b, size_t n, size_t s, __compar_fn_t cmp)
{
return __qsort_r (b, n, s, (__compar_d_fn_t) cmp, NULL);
}
libc_hidden_def (qsort)