/*
* 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.
*/
/** @addtogroup genericmm
* @{
*/
/**
* @file
* @brief Buddy allocator framework.
*
* This file contains buddy system allocator framework.
* Specialized functions are needed for this abstract framework to be useful.
*/
#include <mm/buddy.h>
#include <mm/frame.h>
#include <arch/types.h>
#include <debug.h>
#include <print.h>
#include <macros.h>
/** Return size needed for the buddy configuration data. */
size_t buddy_conf_size(size_t max_order)
{
return sizeof(buddy_system_t) + (max_order + 1) * sizeof(link_t);
}
/** Create buddy system.
*
* Allocate memory for and initialize new buddy system.
*
* @param b Preallocated buddy system control data.
* @param max_order The biggest allocable size will be 2^max_order.
* @param op Operations for new buddy system.
* @param data Pointer to be used by implementation.
*
* @return New buddy system.
*/
void
buddy_system_create(buddy_system_t *b, uint8_t max_order,
buddy_system_operations_t *op, void *data)
{
int i;
ASSERT(max_order < BUDDY_SYSTEM_INNER_BLOCK);
ASSERT(op->find_buddy);
ASSERT(op->set_order);
ASSERT(op->get_order);
ASSERT(op->bisect);
ASSERT(op->coalesce);
ASSERT(op->mark_busy);
/*
* Use memory after our own structure.
*/
b->order = (link_t *) (&b[1]);
for (i = 0; i <= max_order; i++)
list_initialize(&b->order[i]);
b->max_order = max_order;
b->op = op;
b->data = data;
}
/** Check if buddy system can allocate block.
*
* @param b Buddy system pointer.
* @param i Size of the block (2^i).
*
* @return True if block can be allocated.
*/
bool buddy_system_can_alloc(buddy_system_t *b, uint8_t i)
{
uint8_t k;
/*
* If requested block is greater then maximal block
* we know immediatly that we cannot satisfy the request.
*/
if (i > b->max_order)
return false;
/*
* Check if any bigger or equal order has free elements
*/
for (k = i; k <= b->max_order; k++) {
if (!list_empty(&b->order[k])) {
return true;
}
}
return false;
}
/** Allocate PARTICULAR block from buddy system.
*
* @return Block of data or NULL if no such block was found.
*/
link_t *buddy_system_alloc_block(buddy_system_t *b, link_t *block)
{
link_t *left,*right, *tmp;
uint8_t order;
left = b->op->find_block(b, block, BUDDY_SYSTEM_INNER_BLOCK);
ASSERT(left);
list_remove(left);
while (1) {
if (!b->op->get_order(b, left)) {
b->op->mark_busy(b, left);
return left;
}
order = b->op->get_order(b, left);
right = b->op->bisect(b, left);
b->op->set_order(b, left, order - 1);
b->op->set_order(b, right, order - 1);
tmp = b->op->find_block(b, block, BUDDY_SYSTEM_INNER_BLOCK);
if (tmp == right) {
right = left;
left = tmp;
}
ASSERT(tmp == left);
b->op->mark_busy(b, left);
buddy_system_free(b, right);
b->op->mark_available(b, left);
}
}
/** 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, uint8_t 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);
b->op->mark_busy(b, res);
return res;
}
/*
* If order i is already the maximal order,
* the request cannot be satisfied.
*/
if (i == b->max_order)
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(b, res);
b->op->set_order(b, res, i);
b->op->set_order(b, hlp, i);
/*
* Return the other half to buddy system. Mark the first part
* full, so that it won't coalesce again.
*/
b->op->mark_busy(b, res);
buddy_system_free(b, hlp);
return res;
}
/** 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;
uint8_t i;
/*
* Determine block's order.
*/
i = b->op->get_order(b, block);
ASSERT(i <= b->max_order);
if (i != b->max_order) {
/*
* See if there is any buddy in the list of order i.
*/
buddy = b->op->find_buddy(b, block);
if (buddy) {
ASSERT(b->op->get_order(b, buddy) == i);
/*
* Remove buddy from the list of order i.
*/
list_remove(buddy);
/*
* Invalidate order of both block and buddy.
*/
b->op->set_order(b, block, BUDDY_SYSTEM_INNER_BLOCK);
b->op->set_order(b, buddy, BUDDY_SYSTEM_INNER_BLOCK);
/*
* Coalesce block and buddy into one block.
*/
hlp = b->op->coalesce(b, block, buddy);
/*
* Set order of the coalesced block to i + 1.
*/
b->op->set_order(b, hlp, i + 1);
/*
* Recursively add the coalesced block to the list of
* order i + 1.
*/
buddy_system_free(b, hlp);
return;
}
}
/*
* Insert block into the list of order i.
*/
list_append(block, &b->order[i]);
}
/** @}
*/