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/*
 * Project: S.Ha.R.K.
 *
 * Coordinators:
 *   Giorgio Buttazzo    <giorgio@sssup.it>
 *   Paolo Gai           <pj@gandalf.sssup.it>
 *
 * Authors     :
 *   Paolo Gai           <pj@gandalf.sssup.it>
 *   (see the web pages for full authors list)
 *
 * ReTiS Lab (Scuola Superiore S.Anna - Pisa - Italy)
 *
 * http://www.sssup.it
 * http://retis.sssup.it
 * http://shark.sssup.it
 */

/**
 ------------
 CVS :        $Id: free.c,v 1.1.1.1 2002-03-29 14:12:52 pj Exp $

 File:        $File$
 Revision:    $Revision: 1.1.1.1 $
 Last update: $Date: 2002-03-29 14:12:52 $
 ------------

this code is from:
List-based Memory Management, from OsKit.

**/

/*
 * Copyright (C) 2000 Paolo Gai
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */
/*
 * Copyright (c) 1995, 1998-1999 University of Utah and the Flux Group.
 * All rights reserved.
 *
 * This file is part of the Flux OSKit.  The OSKit is free software, also known
 * as "open source;" you can redistribute it and/or modify it under the terms
 * of the GNU General Public License (GPL), version 2, as published by the Free
 * Software Foundation (FSF).  To explore alternate licensing terms, contact
 * the University of Utah at csl-dist@cs.utah.edu or +1-801-585-3271.
 *
 * The OSKit 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 GPL for more details.  You should have
 * received a copy of the GPL along with the OSKit; see the file COPYING.  If
 * not, write to the FSF, 59 Temple Place #330, Boston, MA 02111-1307, USA.
 */

#include <kernel/lmm.h>
#define assert(test) assertk(test)

void lmm_free(lmm_t *lmm, void *block, size_t size)
{
        struct lmm_region *reg;
        struct lmm_node *node = (struct lmm_node*)
                                ((DWORD)block & ~ALIGN_MASK);
        struct lmm_node *prevnode, *nextnode;

        assert(lmm != 0);
        assert(block != 0);
        assert(size > 0);

        size = (((DWORD)block & ALIGN_MASK) + size + ALIGN_MASK)
                & ~ALIGN_MASK;

        /* First find the region to add this block to.  */
        for (reg = lmm->regions; ; reg = reg->next)
        {
                assert(reg != 0);
                CHECKREGPTR(reg);

                if (((DWORD)node >= reg->min)
                    && ((DWORD)node < reg->max))
                        break;
        }

        /* Record the newly freed space in the region's free space counter.  */
        reg->free += size;
        assert(reg->free <= reg->max - reg->min);

        /* Now find the location in that region's free list
           at which to add the node.  */
        for (prevnode = 0, nextnode = reg->nodes;
             (nextnode != 0) && (nextnode < node);
             prevnode = nextnode, nextnode = nextnode->next);

        /* Coalesce the new free chunk into the previous chunk if possible.  */
        if ((prevnode) &&
            ((DWORD)prevnode + prevnode->size >= (DWORD)node))
        {
                assert((DWORD)prevnode + prevnode->size
                       == (DWORD)node);

                /* Coalesce prevnode with nextnode if possible.  */
                if (((DWORD)nextnode)
                    && ((DWORD)node + size >= (DWORD)nextnode))
                {
                        assert((DWORD)node + size
                               == (DWORD)nextnode);

                        prevnode->size += size + nextnode->size;
                        prevnode->next = nextnode->next;
                }
                else
                {
                        /* Not possible -
                           just grow prevnode around newly freed memory.  */
                        prevnode->size += size;
                }
        }
        else
        {
                /* Insert the new node into the free list.  */
                if (prevnode)
                        prevnode->next = node;
                else
                        reg->nodes = node;

                /* Try coalescing the new node with the nextnode.  */
                if ((nextnode) &&
                    (DWORD)node + size >= (DWORD)nextnode)
                {
                        node->size = size + nextnode->size;
                        node->next = nextnode->next;
                }
                else
                {
                        node->size = size;
                        node->next = nextnode;
                }
        }
}