/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2013 Blender Foundation
 * All rights reserved.
 *
 * The Original Code is: all of this file.
 *
 * Contributor(s): Benoit Bolsee,
 *                 Sergey Sharybin.
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/** \file blender/blenlib/intern/sort.c
 *  \ingroup bli
 */

#include <stdlib.h>

#if defined(__GLIBC__) && (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 8))
/* do nothing! */
#else

#include "BLI_utildefines.h"

#include "BLI_sort.h"

#ifdef min  /* for msvc */
#  undef min
#endif

/**
 * qsort, copied from FreeBSD source.
 * with only very minor edits, see:
 * http://github.com/freebsd/freebsd/blob/master/sys/libkern/qsort.c
 *
 * \note modified to use glibc arg order for callbacks.
 */
BLI_INLINE char	*med3(char *, char *, char *, BLI_sort_cmp_t, void *);
BLI_INLINE void	 swapfunc(char *, char *, int, int);

#define min(a, b)	(a) < (b) ? (a) : (b)
#define swapcode(TYPE, parmi, parmj, n)		\
{											\
	long i = (n) / sizeof(TYPE); 			\
	TYPE *pi = (TYPE *) (parmi); 			\
	TYPE *pj = (TYPE *) (parmj); 			\
	do { 									\
		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;

BLI_INLINE void swapfunc(char *a, char *b, int n, 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)
#define	CMP(t, x, y) (cmp((x), (y), (t)))

BLI_INLINE char *med3(char *a, char *b, char *c, BLI_sort_cmp_t cmp, void *thunk)
{
	return  CMP(thunk, a, b) < 0 ?
	       (CMP(thunk, b, c) < 0 ? b : (CMP(thunk, a, c) < 0 ? c : a )) :
	       (CMP(thunk, b, c) > 0 ? b : (CMP(thunk, a, c) < 0 ? a : c ));
}

/**
 * Quick sort reentrant.
 */
void BLI_qsort_r(void *a, size_t n, size_t es, BLI_sort_cmp_t cmp, void *thunk)
{
	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(thunk, pl - es, pl) > 0;
			     pl -= es)
			{
				swap(pl, pl - es);
			}
		}
		return;
	}
	pm = (char *)a + (n / 2) * es;
	if (n > 7) {
		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, thunk);
			pm = med3(pm - d, pm, pm + d, cmp, thunk);
			pn = med3(pn - 2 * d, pn - d, pn, cmp, thunk);
		}
		pm = med3(pl, pm, pn, cmp, thunk);
	}
	swap((char *)a, pm);
	pa = pb = (char *)a + es;

	pc = pd = (char *)a + (n - 1) * es;
	for (;;) {
		while (pb <= pc && (r = CMP(thunk, pb, a)) <= 0) {
			if (r == 0) {
				swap_cnt = 1;
				swap(pa, pb);
				pa += es;
			}
			pb += es;
		}
		while (pb <= pc && (r = CMP(thunk, 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(thunk, pl - es, pl) > 0;
			     pl -= es)
			{
				swap(pl, pl - es);
			}
		}
		return;
	}

	pn = (char *)a + n * es;
	r = min(pa - (char *)a, pb - pa);
	vecswap((char *)a, pb - r, r);
	r = min(pd - pc, pn - pd - es);
	vecswap(pb, pn - r, r);
	if ((r = pb - pa) > es)
		BLI_qsort_r(a, r / es, es, cmp, thunk);
	if ((r = pd - pc) > es) {
		/* Iterate rather than recurse to save stack space */
		a = pn - r;
		n = r / es;
		goto loop;
	}
}

#endif  /* __GLIBC__ */
