Subversion Repositories or1k

/*

FUNCTION

<<qsort>>---sort an array

INDEX

        qsort

ANSI_SYNOPSIS

        #include <stdlib.h>

        void qsort(void *<[base]>, size_t <[nmemb]>, size_t <[size]>,

                   int (*<[compar]>)(const void *, const void *) );

TRAD_SYNOPSIS

        #include <stdlib.h>

        qsort(<[base]>, <[nmemb]>, <[size]>, <[compar]> )

        char *<[base]>;

        size_t <[nmemb]>;

        size_t <[size]>;

        int (*<[compar]>)();

DESCRIPTION

<<qsort>> sorts an array (beginning at <[base]>) of <[nmemb]> objects.

<[size]> describes the size of each element of the array.

You must supply a pointer to a comparison function, using the argument

shown as <[compar]>.  (This permits sorting objects of unknown

properties.)  Define the comparison function to accept two arguments,

each a pointer to an element of the array starting at <[base]>.  The

result of <<(*<[compar]>)>> must be negative if the first argument is

less than the second, zero if the two arguments match, and positive if

the first argument is greater than the second (where ``less than'' and

``greater than'' refer to whatever arbitrary ordering is appropriate).

The array is sorted in place; that is, when <<qsort>> returns, the

array elements beginning at <[base]> have been reordered.

RETURNS

<<qsort>> does not return a result.

PORTABILITY

<<qsort>> is required by ANSI (without specifying the sorting algorithm).

*/

/*-

 * 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.

 */

#include <_ansi.h>

#include <stdlib.h>

#ifndef __GNUC__

#define inline

#endif

static inline char      *med3 _PARAMS((char *, char *, char *, int (*)()));

static inline void       swapfunc _PARAMS((char *, char *, int, int));

#define min(a, b)       (a) < (b) ? a : b

/*

 * Qsort routine from Bentley & McIlroy's "Engineering a Sort Function".

 */

#define swapcode(TYPE, parmi, parmj, n) {               \

        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);                               \

}

#define SWAPINIT(a, es) swaptype = ((char *)a - (char *)0) % sizeof(long) || \

        es % sizeof(long) ? 2 : es == sizeof(long)? 0 : 1;

static inline void

_DEFUN(swapfunc, (a, b, n, swaptype),

        char *a _AND

        char *b _AND

        int n _AND

        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 *

_DEFUN(med3, (a, b, c, cmp),

        char *a _AND

        char *b _AND

        char *c _AND

        int (*cmp)())

{

        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

_DEFUN(qsort, (a, n, es, cmp),

        void *a _AND

        size_t n _AND

        size_t es _AND

        int (*cmp)())

{

        char *pa, *pb, *pc, *pd, *pl, *pm, *pn;

        int d, r, swaptype, swap_cnt;

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 = 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 && (r = cmp(pb, a)) <= 0) {

                        if (r == 0) {

                                swap_cnt = 1;

                                swap(pa, pb);

                                pa += es;

                        }

                        pb += es;

                }

                while (pb <= pc && (r = cmp(pc, a)) >= 0) {

                        if (r == 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);*/

}