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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: alloc_ge.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) 1995-1996, 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_alloc_gen(lmm_t *lmm, size_t size, lmm_flags_t flags,
                    int align_bits, DWORD align_ofs,
                    DWORD in_min, size_t in_size)
{
        DWORD in_max = in_min + in_size;
        struct lmm_region *reg;

#if 0
        kern_printf("lmm_alloc_gen %08x\n", size);
        lmm_dump(lmm);
#endif

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

        for (reg = lmm->regions; reg; reg = reg->next)
        {
                struct lmm_node **nodep, *node;

                CHECKREGPTR(reg);

                /* First trivially reject the entire region if possible.  */
                if ((flags & ~reg->flags)
                    || (reg->min >= in_max)
                    || (reg->max <= in_min))
                        continue;

                for (nodep = &reg->nodes;
                     (node = *nodep) != 0;
                     nodep = &node->next)
                {
                        DWORD addr;
                        struct lmm_node *anode;
                        int i;

                        assert(((DWORD)node & ALIGN_MASK) == 0);
                        assert(((DWORD)node->size & ALIGN_MASK) == 0);
                        assert((node->next == 0) || (node->next > node));
                        assert((DWORD)node < reg->max);

                        /* Now make a first-cut trivial elimination check
                           to skip chunks that are _definitely_ too small.  */
                        if (node->size < size)
                                continue;

                        /* Now compute the address at which
                           the allocated chunk would have to start.  */
                        addr = (DWORD)node;
                        if (addr < in_min)
                                addr = in_min;
                        for (i = 0; i < align_bits; i++)
                        {
                                DWORD bit = (DWORD)1 << i;
                                if ((addr ^ align_ofs) & bit)
                                        addr += bit;
                        }

                        /* See if the block at the adjusted address
                           is still entirely within the node.  */
                        if ((addr - (DWORD)node + size) > node->size)
                                continue;

                        /* If the block extends past the range constraint,
                           then all of the rest of the nodes in this region
                           will extend past it too, so stop here. */
                        if (addr + size > in_max)
                                break;

                        /* OK, we can allocate the block from this node.  */

                        /* If the allocation leaves at least ALIGN_SIZE
                           space before it, then split the node.  */
                        anode = (struct lmm_node*)(addr & ~ALIGN_MASK);
                        assert(anode >= node);
                        if (anode > node)
                        {
                                size_t split_size = (DWORD)anode
                                                  - (DWORD)node;
                                assert((split_size & ALIGN_MASK) == 0);
                                anode->next = node->next;
                                anode->size = node->size - split_size;
                                node->size = split_size;
                                nodep = &node->next;
                        }

                        /* Now use the first part of the anode
                           to satisfy the allocation,
                           splitting off the tail end if necessary.  */
                        size = ((addr & ALIGN_MASK) + size + ALIGN_MASK)
                                & ~ALIGN_MASK;
                        if (anode->size > size)
                        {
                                struct lmm_node *newnode;

                                /* Split the node and return its head.  */
                                newnode = (struct lmm_node*)
                                                ((void*)anode + size);
                                newnode->next = anode->next;
                                newnode->size = anode->size - size;
                                *nodep = newnode;
                        }
                        else
                        {
                                /* Remove and return the entire node.  */
                                *nodep = anode->next;
                        }

                        /* Adjust the region's free memory counter.  */
                        assert(reg->free >= size);
                        reg->free -= size;

#if 0
                        kern_printf("lmm_alloc_gen returning %08x\n", addr);
                        lmm_dump(lmm);
#endif

                        return (void*)addr;
                }
        }

#if 0
        kern_printf("lmm_alloc_gen failed\n");
#endif

        return 0;
}