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/*
* Copyright (c) 2012 William Pitcock <nenolod@dereferenced.org>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice is present in all copies.
*
* 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 "mowgli.h"
static mowgli_list_t allocator_list;
static mowgli_heap_t *allocator_heap;
/*
* Our slice allocation engine.
*/
typedef struct
{
size_t size;
mowgli_heap_t *heap;
mowgli_node_t node;
} slice_alloc_t;
/*
* Allocation tag.
*/
typedef struct
{
slice_alloc_t *owner;
} slice_tag_t;
/*
* Given a size_t, determine the closest power-of-two, which is larger.
*/
static inline size_t
nexthigher(size_t k)
{
size_t i;
k--;
for (i = 1; i < sizeof(k) * 8; i <<= 1)
k |= k >> i;
return k + 1;
}
/*
* Set up an allocator.
*/
static inline slice_alloc_t *
create_allocator(size_t k)
{
slice_alloc_t *a;
a = mowgli_heap_alloc(allocator_heap);
mowgli_node_add(a, &a->node, &allocator_list);
a->size = k;
a->heap = mowgli_heap_create(k, 16, BH_LAZY);
return a;
}
/*
* Find an allocator which fits the requested allocation size.
*/
static inline slice_alloc_t *
find_or_create_allocator(size_t i)
{
size_t k;
mowgli_node_t *n;
k = nexthigher(i);
MOWGLI_ITER_FOREACH(n, allocator_list.head)
{
slice_alloc_t *a = n->data;
if (a->size == k)
return a;
}
return create_allocator(k);
}
/*
* Allocate a slice of memory.
*/
static void *
memslice_alloc(size_t i)
{
void *ptr;
slice_alloc_t *alloc;
size_t adj_size;
adj_size = i + sizeof(slice_tag_t);
alloc = find_or_create_allocator(adj_size);
ptr = mowgli_heap_alloc(alloc->heap);
((slice_tag_t *) ptr)->owner = alloc;
return (char *) ptr + sizeof(slice_tag_t);
}
/*
* Free a slice of memory.
*/
static void
memslice_free(void *ptr)
{
slice_tag_t *tag;
return_if_fail(ptr != NULL);
tag = (void *) ((char *) ptr - sizeof(slice_tag_t));
mowgli_heap_free(tag->owner->heap, tag);
}
/*
* Initialize memslice.
*/
static mowgli_allocation_policy_t *memslice = NULL;
void
mowgli_memslice_bootstrap(void)
{
allocator_heap = mowgli_heap_create(sizeof(slice_alloc_t), 16, BH_NOW);
memslice = mowgli_allocation_policy_create("memslice", memslice_alloc, memslice_free);
}
mowgli_allocation_policy_t *
mowgli_memslice_get_policy(void)
{
return memslice;
}
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