/*
 *    Modifications from vanilla NetBSD source:
 *        Add do ... while() macro fix
 *        Remove __inline, _DIAGASSERTs, __P
 *
 *      $PostgreSQL: pgsql/src/port/qsort.c,v 1.5 2004/10/05 00:12:49 neilc Exp $
 */

/*      $NetBSD: qsort.c,v 1.13 2003/08/07 16:43:42 agc Exp $   */

/*-
 * 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. 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 <stdlib.h>
#include <assert.h>

static void     qsortOK(void *a, size_t n, size_t es, int (*cmp) (const void *, const void *));
static void     qsortWORST(void *a, size_t n, size_t es, int (*cmp) (const void *, const void *));
static void     qsortBEST(void *a, size_t n, size_t es, int (*cmp) (const void *, const void *));

#define CROSSOVER_POINT 15

#undef WORST
#undef OK
#undef BEST

#define WORST (2)
#define OK (1)
#define BEST (0)

static void     invert(void *arr, size_t n, size_t es, void (*swap) (char *a, char *b, size_t es))
{
	char *a = arr;
	char *b = a + (n-1) * es;
	while(b > a)
	{
		swap(a,b, es);
		a += es;
		b -= es;
	}
}


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

static void     swapFast(char *a, char *b, size_t n)
{
    do {
        size_t          i = (n) / sizeof(long);
        long           *pi = (long *) (void *) (a);
        long           *pj = (long *) (void *) (b);
        do {
            long            t = *pi;
            *pi++ = *pj;
            *pj++ = t;
        } while (--i > 0);
    } while (0);
}

static void     swapWORST(char *a, char *b, size_t n)
{
    do {
        size_t          i = (n);/* sizeof char is 1 by definition */
        char           *pi = (char *) (void *) (a);
        char           *pj = (char *) (void *) (b);
        do {
            char            t = *pi;
            *pi++ = *pj;
            *pj++ = t;
        } while (--i > 0);
    } while (0);
}

static 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));
}

static int     sorted(void *arr, size_t count, size_t stride, int (*cmp) (const void *, const void *))
{
    int             i;
	char *p = arr;
	char *thisp = p;
	char *nextp = p + stride;
    for (i = 0; i < count-1; i++)
	{
        if (cmp(thisp, nextp) > 0) {
            return 0;
        }
		thisp = nextp;
		nextp += stride;
	}
	return 1;
}

static int     reversed(void *arr, size_t count, size_t stride, int (*cmp) (const void *, const void *))
{
    int             i;
	char *p = arr;
	char *thisp = p;
	char *nextp = p + stride;
    for (i = 0; i < count-1; i++)
	{
        if (cmp(thisp, nextp) < 0) {
            return 0;
        }
		thisp = nextp;
		nextp += stride;
	}
	return 1;
}


void            qsortPDQ(void *a, size_t n, size_t es, int (*cmp) (const void *, const void *))
{
    int             swaptype = WORST;
    swaptype = ((char *) a - (char *) 0) % sizeof(long) || es % sizeof(long) ? 2 : es == sizeof(long) ? 0 : 1;
    switch (swaptype) {
    case BEST:
        qsortBEST(a, n, es, cmp);
        break;
    case OK:
        qsortOK(a, n, es, cmp);
        break;
    case WORST:
        qsortWORST(a, n, es, cmp);
        break;
    default:
        assert(0);
        exit(EXIT_FAILURE);
    }
}


static void     qsortWORST(void *a, size_t n, size_t es, int (*cmp) (const void *, const void *))
{
    char           *pa,
                   *pb,
                   *pc,
                   *pd,
                   *pl,
                   *pm,
                   *pn;
    int             d,
                    r,
                    swap_cnt;


loop:
    swap_cnt = 0;
    /* Insertion sort tiny partitions */
    if (n <= CROSSOVER_POINT) {
		if (reversed(a, n, es, cmp))
		{
			invert(a, n, es, swapFast);
			return;
		}
        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)
                swapWORST(pl, pl - es, es);

        return;
    }
	if (sorted(a, n, es, cmp)) return;
    pm = (char *) a + (n / 2) * es;
    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);
    swapWORST(a, pm, es);
    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;
                swapWORST(pa, pb, es);
                pa += es;
            }
            pb += es;
        }
        while (pb <= pc && (r = cmp(pc, a)) >= 0) {
            if (r == 0) {
                swap_cnt = 1;
                swapWORST(pc, pd, es);
                pd -= es;
            }
            pc -= es;
        }
        if (pb > pc)
            break;
        swapWORST(pb, pc, es);
        swap_cnt = 1;
        pb += es;
        pc -= es;
    }
    if (swap_cnt == 0) {
        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)
                swapWORST(pl, pl - es, es);
        return;
    }
    pn = (char *) a + n * es;
    r = ((pa - (char *) a) < (pb - pa) ? (pa - (char *) a) : (pb - pa));
    if ((r) > 0)
        swapWORST((a), (pb - r), (size_t) (r));
    r = ((pd - pc) < (pn - pd - es) ? (pd - pc) : (pn - pd - es));
    if ((r) > 0)
        swapWORST((pb), (pn - r), (size_t) (r));
    if ((r = pb - pa) > es)
        qsortWORST(a, r / es, es, cmp);
    if ((r = pd - pc) > es) {

        a = pn - r;
        n = r / es;
        goto loop;
    }
}

static void     qsortOK(void *a, size_t n, size_t es, int (*cmp) (const void *, const void *))
{
    char           *pa,
                   *pb,
                   *pc,
                   *pd,
                   *pl,
                   *pm,
                   *pn;
    int             d,
                    r,
                    swap_cnt;

loop:
    swap_cnt = 0;
    /* Insertion sort tiny partitions */
    if (n <= CROSSOVER_POINT) {
		if (reversed(a, n, es, cmp))
		{
			invert(a, n, es, swapFast);
			return;
		}
        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)
                swapFast(pl, pl - es, es);

        return;
    }
	if (sorted(a, n, es, cmp)) return;
    pm = (char *) a + (n / 2) * es;
    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);
    swapFast(a, pm, es);
    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;
                swapFast(pa, pb, es);
                pa += es;
            }
            pb += es;
        }
        while (pb <= pc && (r = cmp(pc, a)) >= 0) {
            if (r == 0) {
                swap_cnt = 1;
                swapFast(pc, pd, es);
                pd -= es;
            }
            pc -= es;
        }
        if (pb > pc)
            break;
        swapFast(pb, pc, es);
        swap_cnt = 1;
        pb += es;
        pc -= es;
    }
    if (swap_cnt == 0) {
        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)
                swapFast(pl, pl - es, es);
        return;
    }
    pn = (char *) a + n * es;
    r = ((pa - (char *) a) < (pb - pa) ? (pa - (char *) a) : (pb - pa));
    if ((r) > 0)
        swapFast((a), (pb - r), (size_t) (r));
    r = ((pd - pc) < (pn - pd - es) ? (pd - pc) : (pn - pd - es));
    if ((r) > 0)
        swapFast((pb), (pn - r), (size_t) (r));
    if ((r = pb - pa) > es)
        qsortOK(a, r / es, es, cmp);
    if ((r = pd - pc) > es) {

        a = pn - r;
        n = r / es;
        goto loop;
    }
}


static void     qsortBEST(void *a, size_t n, size_t es, int (*cmp) (const void *, const void *))
{
    char           *pa,
                   *pb,
                   *pc,
                   *pd,
                   *pl,
                   *pm,
                   *pn;
    int             d,
                    r,
                    swap_cnt;
    long            t;
loop:
    swap_cnt = 0;
    if (n <= CROSSOVER_POINT) {
		if (reversed(a, n, es, cmp))
		{
			invert(a, n, es, swapFast);
			return;
		}
        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) {
                t = *(long *) (void *) (pl);
                *(long *) (void *) (pl) = *(long *) (void *) (pl - es);
                *(long *) (void *) (pl - es) = t;
            }
        return;
    }
	if (sorted(a, n, es, cmp)) return;
    pm = (char *) a + (n / 2) * es;
    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);
    t = *(long *) (void *) (a);
    *(long *) (void *) (a) = *(long *) (void *) (pm);
    *(long *) (void *) (pm) = t;
    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;
                t = *(long *) (void *) (pa);
                *(long *) (void *) (pa) = *(long *) (void *) (pb);
                *(long *) (void *) (pb) = t;
                pa += es;
            }
            pb += es;
        }
        while (pb <= pc && (r = cmp(pc, a)) >= 0) {
            if (r == 0) {
                swap_cnt = 1;
                t = *(long *) (void *) (pc);
                *(long *) (void *) (pc) = *(long *) (void *) (pd);
                *(long *) (void *) (pd) = t;
                pd -= es;
            }
            pc -= es;
        }
        if (pb > pc)
            break;
        {
            t = *(long *) (void *) (pb);
            *(long *) (void *) (pb) = *(long *) (void *) (pc);
            *(long *) (void *) (pc) = t;
        }
        swap_cnt = 1;
        pb += es;
        pc -= es;
    }
    if (swap_cnt == 0) {
        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) {
                t = *(long *) (void *) (pl);
                *(long *) (void *) (pl) = *(long *) (void *) (pl - es);
                *(long *) (void *) (pl - es) = t;
            }
        return;
    }
    pn = (char *) a + n * es;
    r = ((pa - (char *) a) < (pb - pa) ? (pa - (char *) a) : (pb - pa));
    if ((r) > 0)
        swapFast((a), (pb - r), (size_t) (r));
    r = ((pd - pc) < (pn - pd - es) ? (pd - pc) : (pn - pd - es));
    if ((r) > 0)
        swapFast((pb), (pn - r), (size_t) (r));
    if ((r = pb - pa) > es)
        qsortBEST(a, r / es, es, cmp);
    if ((r = pd - pc) > es) {
        a = pn - r;
        n = r / es;
        goto loop;
    }
}