////////////////////////////////////////////////////////////////////////////////
// Mercury and Colyseus Software Distribution 
// 
// Copyright (C) 2004-2005 Ashwin Bharambe (ashu@cs.cmu.edu)
//               2004-2005 Jeffrey Pang    (jeffpang@cs.cmu.edu)
//                    2004 Mukesh Agrawal  (mukesh@cs.cmu.edu)
// 
// 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, 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307
// USA
////////////////////////////////////////////////////////////////////////////////
/*-
 * Copyright 1997-2003 John-Mark Gurney.
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
 *
 *	$Id: fib.cpp 2382 2005-11-03 22:54:59Z ashu $
 *
 */

#include "fib.h"
#include "fibpriv.h"

#include <limits.h>
#include <stdlib.h>

#include "Benchmark.h"

#define swap(type, a, b)		\
do {			\
    type c;		\
	c = a;		\
	a = b;		\
	b = c;		\
} while (0)		\

#define INT_BITS        (sizeof(int) * 8)
static inline int
ceillog2(unsigned int a)
{
    int oa;
    int i;
    int b;

    oa = a;
    b = INT_BITS / 2;
    i = 0;
    while (b) {
	i = (i << 1);
	if (a >= (unsigned int)(1 << b)) {
	    a /= (1 << b);
	    i = i | 1;
	} else
	    a &= (1 << b) - 1;
	b /= 2;
    }
    if ((1 << i) == oa)
	return i;
    else
	return i + 1;
}

/*
 * Private Heap Functions
 */
static void
fh_deleteel(struct fibheap *h, struct fibheap_el *x)
{
    void *data;
    int key;

    data = x->fhe_data;
    key = x->fhe_key;

    if (!h->fh_keys)
	fh_replacedata(h, x, h->fh_neginf);
    else
	fh_replacekey(h, x, INT_MIN);
    if (fh_extractminel(h) != x) {
	/*
	 * XXX - This should never happen as fh_replace should set it
	 * to min.
	 */
	abort();
    }

    x->fhe_data = data;
    x->fhe_key = key;
}

static void
fh_initheap(struct fibheap *newh)
{
    newh->fh_cmp_fnct = NULL;
    newh->fh_neginf = NULL;
    newh->fh_n = 0;
    newh->fh_Dl = -1;
    newh->fh_cons = NULL;
    newh->fh_min = NULL;
    newh->fh_root = NULL;
    newh->fh_keys = 0;
#ifdef FH_STATS
    newh->fh_maxn = 0;
    newh->fh_ninserts = 0;
    newh->fh_nextracts = 0;
#endif
}

static void
fh_destroyheap(struct fibheap *h)
{
    h->fh_cmp_fnct = NULL;
    h->fh_neginf = NULL;
    if (h->fh_cons != NULL)
	free(h->fh_cons);
    h->fh_cons = NULL;
    free(h);
}

/*
 * Public Heap Functions
 */
struct fibheap *
fh_makekeyheap()
{
    struct fibheap *n;

    if ((n = (struct fibheap *)malloc(sizeof *n)) == NULL)
	return NULL;

    fh_initheap(n);
    n->fh_keys = 1;

    return n;
}

struct fibheap *
fh_makeheap()
{
    struct fibheap *n;

    if ((n = (struct fibheap *)malloc(sizeof *n)) == NULL)
	return NULL;

    fh_initheap(n);

    return n;
}

voidcmp
fh_setcmp(struct fibheap *h, voidcmp fnct)
{
    voidcmp oldfnct;

    oldfnct = h->fh_cmp_fnct;
    h->fh_cmp_fnct = fnct;

    return oldfnct;
}

void *
fh_setneginf(struct fibheap *h, void *data)
{
    void *old;

    old = h->fh_neginf;
    h->fh_neginf = data;

    return old;
}

struct fibheap *
fh_union(struct fibheap *ha, struct fibheap *hb)
{
    struct fibheap_el *x;

    if (ha->fh_root == NULL || hb->fh_root == NULL) {
	/* either one or both are empty */
	if (ha->fh_root == NULL) {
	    fh_destroyheap(ha);
	    return hb;
	} else {
	    fh_destroyheap(hb);
	    return ha;
	}
    }
    ha->fh_root->fhe_left->fhe_right = hb->fh_root;
    hb->fh_root->fhe_left->fhe_right = ha->fh_root;
    x = ha->fh_root->fhe_left;
    ha->fh_root->fhe_left = hb->fh_root->fhe_left;
    hb->fh_root->fhe_left = x;
    ha->fh_n += hb->fh_n;
    /*
     * we probably should also keep stats on number of unions
     */

    /* set fh_min if necessary */
    if (fh_compare(ha, hb->fh_min, ha->fh_min) < 0)
	ha->fh_min = hb->fh_min;

    fh_destroyheap(hb);
    return ha;
}

void
fh_deleteheap(struct fibheap *h)
{
    /*
     * We could do this even faster by walking each binomial tree, but
     * this is simpler to code.
     */
    while (h->fh_min != NULL)
	fhe_destroy(fh_extractminel(h));

    fh_destroyheap(h);
}

/*
 * Public Key Heap Functions
 */
struct fibheap_el *
fh_insertkey(struct fibheap *h, int key, void *data)
{
    struct fibheap_el *x;

    if ((x = fhe_newelem()) == NULL)
	return NULL;

    /* just insert on root list, and make sure it's not the new min */
    x->fhe_data = data;
    x->fhe_key = key;

    fh_insertel(h, x);

    return x;
}

int
fh_minkey(struct fibheap *h)
{
    if (h->fh_min == NULL)
	return INT_MIN;
    return h->fh_min->fhe_key;
}

int
fh_replacekey(struct fibheap *h, struct fibheap_el *x, int key)
{
    int ret;

    ret = x->fhe_key;
    (void)fh_replacekeydata(h, x, key, x->fhe_data);

    return ret;
}

void *
fh_replacekeydata(struct fibheap *h, struct fibheap_el *x, int key, void *data)
{
    void *odata;
    int okey;
    struct fibheap_el *y;
    int r;

    odata = x->fhe_data;
    okey = x->fhe_key;

    /*
     * we can increase a key by deleting and reinserting, that
     * requires O(lgn) time.
     */
    if ((r = fh_comparedata(h, key, data, x)) > 0) {
	/* XXX - bad code! */
	abort();
	fh_deleteel(h, x);

	x->fhe_data = data;
	x->fhe_key = key;

	fh_insertel(h, x);

	return odata;
    }

    x->fhe_data = data;
    x->fhe_key = key;

    /* because they are equal, we don't have to do anything */
    if (r == 0)
	return odata;

    y = x->fhe_p;

    if (h->fh_keys && okey == key)
	return odata;

    if (y != NULL && fh_compare(h, x, y) <= 0) {
	fh_cut(h, x, y);
	fh_cascading_cut(h, y);
    }

    /*
     * the = is so that the call from fh_delete will delete the proper
     * element.
     */
    if (fh_compare(h, x, h->fh_min) <= 0)
	h->fh_min = x;

    return odata;
}

/*
 * Public void * Heap Functions
 */
/*
 * this will return these values:
 *	NULL	failed for some reason
 *	ptr	token to use for manipulation of data
 */
struct fibheap_el *
fh_insert(struct fibheap *h, void *data)
{
    struct fibheap_el *x;

    if ((x = fhe_newelem()) == NULL)
	return NULL;

    /* just insert on root list, and make sure it's not the new min */
    x->fhe_data = data;

    fh_insertel(h, x);

    return x;
}

void *
fh_min(struct fibheap *h)
{
    if (h->fh_min == NULL)
	return NULL;
    return h->fh_min->fhe_data;
}

void *
fh_extractmin(struct fibheap *h)
{
    struct fibheap_el *z;
    void *ret;

    ret = NULL;

    START(temp::fh_extractmin);
    if (h->fh_min != NULL) {
	z = fh_extractminel(h);
	ret = z->fhe_data;
#ifndef NO_FREE
	fhe_destroy(z);
#endif

    }
    STOP(temp::fh_extractmin);

    return ret;
}

void *
fh_replacedata(struct fibheap *h, struct fibheap_el *x, void *data)
{
    return fh_replacekeydata(h, x, x->fhe_key, data);
}

void *
fh_delete(struct fibheap *h, struct fibheap_el *x)
{
    void *k;

    k = x->fhe_data;
    if (!h->fh_keys)
	fh_replacedata(h, x, h->fh_neginf);
    else
	fh_replacekey(h, x, INT_MIN);
    fh_extractmin(h);

    return k;
}

/*
 * Statistics Functions
 */
#ifdef FH_STATS
int
fh_maxn(struct fibheap *h)
{
    return h->fh_maxn;
}

int
fh_ninserts(struct fibheap *h)
{
    return h->fh_ninserts;
}

int
fh_nextracts(struct fibheap *h)
{
    return h->fh_nextracts;
}
#endif

/*
 * begin of private element fuctions
 */
static struct fibheap_el *
fh_extractminel(struct fibheap *h)
{
    struct fibheap_el *ret;
    struct fibheap_el *x, *y, *orig;

    ret = h->fh_min;

    orig = NULL;
    /* put all the children on the root list */
    /* for true consistancy, we should use fhe_remove */
    for(x = ret->fhe_child; x != orig && x != NULL;) {
	if (orig == NULL)
	    orig = x;
	y = x->fhe_right;
	x->fhe_p = NULL;
	fh_insertrootlist(h, x);
	x = y;
    }
    /* remove minimum from root list */
    fh_removerootlist(h, ret);
    h->fh_n--;

    /* if we aren't empty, consolidate the heap */
    if (h->fh_n == 0)
	h->fh_min = NULL;
    else {
	h->fh_min = ret->fhe_right;
	fh_consolidate(h);
    }

#ifdef FH_STATS
    h->fh_nextracts++;
#endif

    return ret;
}

static void
fh_insertrootlist(struct fibheap *h, struct fibheap_el *x)
{
    if (h->fh_root == NULL) {
	h->fh_root = x;
	x->fhe_left = x;
	x->fhe_right = x;
	return;
    }

    fhe_insertafter(h->fh_root, x);
}

static void
fh_removerootlist(struct fibheap *h, struct fibheap_el *x)
{
    if (x->fhe_left == x)
	h->fh_root = NULL;
    else
	h->fh_root = fhe_remove(x);
}

static void
fh_consolidate(struct fibheap *h)
{
    struct fibheap_el **a;
    struct fibheap_el *w;
    struct fibheap_el *y;
    struct fibheap_el *x;
    int i;
    int d;
    int D;

    fh_checkcons(h);

    /* assign a the value of h->fh_cons so I don't have to rewrite code */
    D = h->fh_Dl + 1;
    a = h->fh_cons;

    for (i = 0; i < D; i++)
	a[i] = NULL;

    while ((w = h->fh_root) != NULL) {
	x = w;
	fh_removerootlist(h, w);
	d = x->fhe_degree;
	/* XXX - assert that d < D */
	while(a[d] != NULL) {
	    y = a[d];
	    if (fh_compare(h, x, y) > 0)
		swap(struct fibheap_el *, x, y);
	    fh_heaplink(h, y, x);
	    a[d] = NULL;
	    d++;
	}
	a[d] = x;
    }
    h->fh_min = NULL;
    for (i = 0; i < D; i++)
	if (a[i] != NULL) {
	    fh_insertrootlist(h, a[i]);
	    if (h->fh_min == NULL || fh_compare(h, a[i],
						h->fh_min) < 0)
		h->fh_min = a[i];
	}
}

static void
fh_heaplink(struct fibheap *h, struct fibheap_el *y, struct fibheap_el *x)
{
    /* make y a child of x */
    if (x->fhe_child == NULL)
	x->fhe_child = y;
    else
	fhe_insertbefore(x->fhe_child, y);
    y->fhe_p = x;
    x->fhe_degree++;
    y->fhe_mark = 0;
}

static void
fh_cut(struct fibheap *h, struct fibheap_el *x, struct fibheap_el *y)
{
    fhe_remove(x);
    y->fhe_degree--;
    fh_insertrootlist(h, x);
    x->fhe_p = NULL;
    x->fhe_mark = 0;
}

static void
fh_cascading_cut(struct fibheap *h, struct fibheap_el *y)
{
    struct fibheap_el *z;

    while ((z = y->fhe_p) != NULL) {
	if (y->fhe_mark == 0) {
	    y->fhe_mark = 1;
	    return;
	} else {
	    fh_cut(h, y, z);
	    y = z;
	}
    }
}

/*
 * begining of handling elements of fibheap
 */
static struct fibheap_el *
fhe_newelem()
{
    struct fibheap_el *e;

    if ((e = (struct fibheap_el *)malloc(sizeof *e)) == NULL)
	return NULL;

    fhe_initelem(e);

    return e;
}

static void
fhe_initelem(struct fibheap_el *e)
{
    e->fhe_degree = 0;
    e->fhe_mark = 0;
    e->fhe_p = NULL;
    e->fhe_child = NULL;
    e->fhe_left = e;
    e->fhe_right = e;
    e->fhe_data = NULL;
}

static void
fhe_insertafter(struct fibheap_el *a, struct fibheap_el *b)
{
    if (a == a->fhe_right) {
	a->fhe_right = b;
	a->fhe_left = b;
	b->fhe_right = a;
	b->fhe_left = a;
    } else {
	b->fhe_right = a->fhe_right;
	a->fhe_right->fhe_left = b;
	a->fhe_right = b;
	b->fhe_left = a;
    }
}

static inline void
fhe_insertbefore(struct fibheap_el *a, struct fibheap_el *b)
{
    fhe_insertafter(a->fhe_left, b);
}

static struct fibheap_el *
fhe_remove(struct fibheap_el *x)
{
    struct fibheap_el *ret;

    if (x == x->fhe_left)
	ret = NULL;
    else
	ret = x->fhe_left;

    /* fix the parent pointer */
    if (x->fhe_p != NULL && x->fhe_p->fhe_child == x)
	x->fhe_p->fhe_child = ret;

    x->fhe_right->fhe_left = x->fhe_left;
    x->fhe_left->fhe_right = x->fhe_right;

    /* clear out hanging pointers */
    x->fhe_p = NULL;
    x->fhe_left = x;
    x->fhe_right = x;

    return ret;
}

static void
fh_checkcons(struct fibheap *h)
{
    int oDl;

    /* make sure we have enough memory allocated to "reorganize" */
    if (h->fh_Dl == -1 || h->fh_n > (1 << h->fh_Dl)) {
	oDl = h->fh_Dl;
	if ((h->fh_Dl = ceillog2(h->fh_n) + 1) < 8)
	    h->fh_Dl = 8;
	if (oDl != h->fh_Dl)
	    h->fh_cons = (struct fibheap_el **)realloc(h->fh_cons,
						       sizeof *h->fh_cons * (h->fh_Dl + 1));
	if (h->fh_cons == NULL)
	    abort();
    }
}

static int
fh_compare(struct fibheap *h, struct fibheap_el *a, struct fibheap_el *b)
{
    if (h->fh_keys) {
	if (a->fhe_key < b->fhe_key)
	    return -1;
	if (a->fhe_key == b->fhe_key)
	    return 0;
	return 1;
    } else
	return h->fh_cmp_fnct(a->fhe_data, b->fhe_data);
}

static int
fh_comparedata(struct fibheap *h, int key, void *data, struct fibheap_el *b)
{
    struct fibheap_el a;

    a.fhe_key = key;
    a.fhe_data = data;

    return fh_compare(h, &a, b);
}

static void
fh_insertel(struct fibheap *h, struct fibheap_el *x)
{
    fh_insertrootlist(h, x);

    if (h->fh_min == NULL || (h->fh_keys ? x->fhe_key < h->fh_min->fhe_key
			      : h->fh_cmp_fnct(x->fhe_data, h->fh_min->fhe_data) < 0))
	h->fh_min = x;

    h->fh_n++;

#ifdef FH_STATS
    if (h->fh_n > h->fh_maxn)
	h->fh_maxn = h->fh_n;
    h->fh_ninserts++;
#endif

}
// vim: set sw=4 sts=4 ts=8 noet: 
// Local Variables:
// Mode: c++
// c-basic-offset: 4
// tab-width: 8
// indent-tabs-mode: t
// End:
