/*
* Copyright (C) 2005 Jakub Jermar
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - 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.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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.
*/
#include <mm/buddy.h>
#include <mm/frame.h>
#include <mm/heap.h>
#include <arch/types.h>
#include <typedefs.h>
#include <list.h>
#include <debug.h>
/** Create buddy system
*
* Allocate memory for and initialize new buddy system.
*
* @param max_order The biggest allocable size will be 2^max_order.
* @param op Operations for new buddy system.
*
* @return New buddy system.
*/
buddy_system_t *buddy_system_create(__u8 max_order, buddy_operations_t *op)
{
buddy_system_t *b;
int i;
ASSERT(op->find_buddy);
ASSERT(op->set_order);
ASSERT(op->get_order);
ASSERT(op->bisect);
ASSERT(op->coalesce);
/*
* Allocate memory for structure describing the whole buddy system.
*/
b = (buddy_system_t *) early_malloc(sizeof(buddy_system_t));
if (b) {
/*
* Allocate memory for all orders this buddy system will work with.
*/
b->order = (link_t *) early_malloc(max_order * sizeof(link_t));
if (!b->order) {
early_free(b);
return NULL;
}
for (i = 0; i < max_order; i++)
list_initialize(&b->order[i]);
b->max_order = max_order;
b->op = op;
}
return b;
}
/** Allocate block from buddy system.
*
* Allocate block from buddy system.
*
* @param b Buddy system pointer.
* @param i Returned block will be 2^i big.
*
* @return Block of data represented by link_t.
*/
link_t *buddy_system_alloc(buddy_system_t *b, __u8 i)
{
link_t *res, *hlp;
ASSERT(i < b->max_order);
/*
* If the list of order i is not empty,
* the request can be immediatelly satisfied.
*/
if (!list_empty(&b->order[i])) {
res = b->order[i].next;
list_remove(res);
return res;
}
/*
* If order i is already the maximal order,
* the request cannot be satisfied.
*/
if (i == b->max_order - 1)
return NULL;
/*
* Try to recursively satisfy the request from higher order lists.
*/
hlp = buddy_system_alloc(b, i + 1);
/*
* The request could not be satisfied
* from higher order lists.
*/
if (!hlp)
return NULL;
res = hlp;
/*
* Bisect the block and set order of both of its parts to i.
*/
hlp = b->op->bisect(res);
b->op->set_order(res, i);
b->op->set_order(hlp, i);
/*
* Return the other half to buddy system.
*/
buddy_system_free(b, hlp);
return res;
}
/** Return block to buddy system.
*
* Return block to buddy system.
*
* @param b Buddy system pointer.
* @param block Block to return.
*/
void buddy_system_free(buddy_system_t *b, link_t *block)
{
link_t *buddy, *hlp;
__u8 i;
/*
* Determine block's order.
*/
i = b->op->get_order(block);
ASSERT(i < b->max_order);
/*
* See if there is any buddy in the list of order i.
*/
buddy = b->op->find_buddy(block);
if (buddy && i != b->max_order - 1) {
/*
* Remove buddy from the list of order i.
*/
list_remove(buddy);
/*
* Coalesce block and buddy into one block.
*/
hlp = b->op->coalesce(block, buddy);
/*
* Set order of the coalesced block to i + 1.
*/
b->op->set_order(hlp, i + 1);
/*
* Recursively add the coalesced block to the list of order i + 1.
*/
buddy_system_free(b, hlp);
}
else {
/*
* Insert block into the list of order i.
*/
list_append(block, &b->order[i]);
}
}