Permalink
Cannot retrieve contributors at this time
Name already in use
A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?
glibc/stdlib/msort.c
Go to fileThis commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
156 lines (136 sloc)
3.95 KB
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
/* An alternative to qsort, with an identical interface. | |
This file is part of the GNU C Library. | |
Copyright (C) 1992,95-97,99,2000,01,02 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, write to the Free | |
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA | |
02111-1307 USA. */ | |
#include <alloca.h> | |
#include <stdlib.h> | |
#include <string.h> | |
#include <unistd.h> | |
#include <memcopy.h> | |
#include <errno.h> | |
static void msort_with_tmp (void *b, size_t n, size_t s, | |
__compar_fn_t cmp, char *t); | |
static void | |
msort_with_tmp (void *b, size_t n, size_t s, __compar_fn_t cmp, | |
char *t) | |
{ | |
char *tmp; | |
char *b1, *b2; | |
size_t n1, n2; | |
if (n <= 1) | |
return; | |
n1 = n / 2; | |
n2 = n - n1; | |
b1 = b; | |
b2 = (char *) b + (n1 * s); | |
msort_with_tmp (b1, n1, s, cmp, t); | |
msort_with_tmp (b2, n2, s, cmp, t); | |
tmp = t; | |
if (s == OPSIZ && (b1 - (char *) 0) % OPSIZ == 0) | |
/* We are operating on aligned words. Use direct word stores. */ | |
while (n1 > 0 && n2 > 0) | |
{ | |
if ((*cmp) (b1, b2) <= 0) | |
{ | |
--n1; | |
*((op_t *) tmp)++ = *((op_t *) b1)++; | |
} | |
else | |
{ | |
--n2; | |
*((op_t *) tmp)++ = *((op_t *) b2)++; | |
} | |
} | |
else | |
while (n1 > 0 && n2 > 0) | |
{ | |
if ((*cmp) (b1, b2) <= 0) | |
{ | |
tmp = (char *) __mempcpy (tmp, b1, s); | |
b1 += s; | |
--n1; | |
} | |
else | |
{ | |
tmp = (char *) __mempcpy (tmp, b2, s); | |
b2 += s; | |
--n2; | |
} | |
} | |
if (n1 > 0) | |
memcpy (tmp, b1, n1 * s); | |
memcpy (b, t, (n - n2) * s); | |
} | |
void | |
qsort (void *b, size_t n, size_t s, __compar_fn_t cmp) | |
{ | |
const size_t size = n * s; | |
if (size < 1024) | |
{ | |
void *buf = __alloca (size); | |
/* The temporary array is small, so put it on the stack. */ | |
msort_with_tmp (b, n, s, cmp, buf); | |
} | |
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 (phys_pages == 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; | |
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); | |
else | |
{ | |
/* It's somewhat large, so malloc it. */ | |
int save = errno; | |
char *tmp = malloc (size); | |
if (tmp == NULL) | |
{ | |
/* Couldn't get space, so use the slower algorithm | |
that doesn't need a temporary array. */ | |
__set_errno (save); | |
_quicksort (b, n, s, cmp); | |
} | |
else | |
{ | |
__set_errno (save); | |
msort_with_tmp (b, n, s, cmp, tmp); | |
free (tmp); | |
} | |
} | |
} | |
} | |
libc_hidden_def (qsort) |