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/*
* Simple memory pool for variable-length allocations.
*
* Copyright (c) 2009 Marko Kreen
*
* 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 appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <usual/mempool.h>
/*
* Allows allocation of several variable-sized objects,
* freeing them all together.
*
* ToDo: make it more 'obstack'-like (???)
* - free_last
* - resize_last
* - append
*/
struct MemPool {
struct MemPool *prev;
unsigned size;
unsigned used;
};
void *mempool_alloc(struct MemPool **pool, unsigned size)
{
struct MemPool *cur = *pool;
void *ptr;
unsigned nsize;
size = ALIGN(size);
if (cur && cur->used + size <= cur->size) {
ptr = (char *)(cur + 1) + cur->used;
cur->used += size;
return ptr;
} else {
nsize = cur ? (2 * cur->size) : 512;
while (nsize < size)
nsize *= 2;
cur = calloc(1, sizeof(*cur) + nsize);
if (cur == NULL)
return NULL;
cur->used = size;
cur->size = nsize;
cur->prev = *pool;
*pool = cur;
return (char *)(cur + 1);
}
}
void mempool_destroy(struct MemPool **pool)
{
struct MemPool *cur, *tmp;
if (!pool)
return;
for (cur = *pool, *pool = NULL; cur; ) {
tmp = cur->prev;
free(cur);
cur = tmp;
}
}
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