/* GLIB - Library of useful routines for C programming

 * Copyright (C) 1991, 1992, 1996, 1997,1999,2004 Free Software Foundation, Inc.

 * Copyright (C) 2000 Eazel, Inc.

 * Copyright (C) 1995-1997  Peter Mattis, Spencer Kimball and Josh MacDonald

 *

 * This 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.

 *

 * This 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 this library; if not, see <http://www.gnu.org/licenses/>.

 */

#include "config.h"

#include <limits.h>

#include <stdlib.h>

#include <string.h>

#include "galloca.h"

#include "gmem.h"

#include "gqsort.h"

#include "gtestutils.h"

/* This file was originally from stdlib/msort.c in gnu libc, just changed

   to build inside glib and to not fall back to an unstable quicksort

   for large arrays. */

/* An alternative to qsort, with an identical interface.

   This file is part of the GNU C Library.

   Copyright (C) 1992,95-97,99,2000,01,02,04,07 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/>.  */

struct msort_param

{

  size_t s;

  size_t var;

  GCompareDataFunc 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;

  char *tmp = p->t;

  const size_t s = p->s;

  GCompareDataFunc cmp = p->cmp;

  void *arg = p->arg;

  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);

  switch (p->var)

    {

    case 0:

      while (n1 > 0 && n2 > 0)

	{

	  if ((*cmp) (b1, b2, arg) <= 0)

	    {

	      *(guint32 *) tmp = *(guint32 *) b1;

	      b1 += sizeof (guint32);

	      --n1;

	    }

	  else

	    {

	      *(guint32 *) tmp = *(guint32 *) b2;

	      b2 += sizeof (guint32);

	      --n2;

	    }

	  tmp += sizeof (guint32);

	}

      break;

    case 1:

      while (n1 > 0 && n2 > 0)

	{

	  if ((*cmp) (b1, b2, arg) <= 0)

	    {

	      *(guint64 *) tmp = *(guint64 *) b1;

	      b1 += sizeof (guint64);

	      --n1;

	    }

	  else

	    {

	      *(guint64 *) tmp = *(guint64 *) b2;

	      b2 += sizeof (guint64);

	      --n2;

	    }

	  tmp += sizeof (guint64);

	}

      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)

	    {

	      memcpy (tmp, b1, s);

	      tmp += s;

	      b1 += s;

	      --n1;

	    }

	  else

	    {

	      memcpy (tmp, b2, s);

	      tmp += s;

	      b2 += s;

	      --n2;

	    }

	}

      break;

    }

  if (n1 > 0)

    memcpy (tmp, b1, n1 * s);

  memcpy (b, p->t, (n - n2) * s);

}

static void

msort_r (void *b, size_t n, size_t s, GCompareDataFunc 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 = g_alloca (size);

  else

    {

      /* It's large, so malloc it.  */

      tmp = g_malloc (size);

      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);

      char *kp;

      size_t i;

      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.  */

      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 (guint32) - 1)) == 0

	  && ((char *) b - (char *) 0) % ALIGNOF_GUINT32 == 0)

	{

	  if (s == sizeof (guint32))

	    p.var = 0;

	  else if (s == sizeof (guint64)

		   && ((char *) b - (char *) 0) % ALIGNOF_GUINT64 == 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);

    }

  g_free (tmp);

}

/**

 * g_qsort_with_data:

 * @pbase: (not nullable): start of array to sort

 * @total_elems: elements in the array

 * @size: size of each element

 * @compare_func: function to compare elements

 * @user_data: data to pass to @compare_func

 *

 * This is just like the standard C qsort() function, but

 * the comparison routine accepts a user data argument.

 *

 * This is guaranteed to be a stable sort since version 2.32.

 */

void

g_qsort_with_data (gconstpointer    pbase,

                   gint             total_elems,

                   gsize            size,

                   GCompareDataFunc compare_func,

                   gpointer         user_data)

{

  msort_r ((gpointer)pbase, total_elems, size, compare_func, user_data);

}