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#include <stdlib.h>
#include "pool.h"
#define PAGE_SIZE 4096
typedef struct header_t {
struct header_t *next;
} header_t;
struct opcut_pool_t {
hat_allocator_t *a;
size_t item_size;
header_t *blocks;
header_t *items;
};
static void allocate_block(opcut_pool_t *pool) {
size_t items_per_block =
(PAGE_SIZE - sizeof(header_t)) / (sizeof(header_t) + pool->item_size);
if (items_per_block < 1)
items_per_block = 1;
header_t *block = hat_allocator_alloc(
pool->a,
sizeof(header_t) +
items_per_block * (sizeof(header_t) + pool->item_size),
NULL);
if (!block)
return;
block->next = pool->blocks;
pool->blocks = block;
for (size_t i = 0; i < items_per_block; ++i) {
header_t *header = (void *)block + sizeof(header_t) +
i * (sizeof(header_t) + pool->item_size);
header->next = pool->items;
pool->items = header;
}
}
opcut_pool_t *opcut_pool_create(hat_allocator_t *a, size_t item_size) {
opcut_pool_t *pool = hat_allocator_alloc(a, sizeof(opcut_pool_t), NULL);
if (!pool)
return NULL;
if (item_size % sizeof(void *) != 0)
item_size += sizeof(void *) - (item_size % sizeof(void *));
pool->a = a;
pool->item_size = item_size;
pool->blocks = NULL;
pool->items = NULL;
return pool;
}
void opcut_pool_destroy(opcut_pool_t *pool) {
while (pool->blocks) {
header_t *block = pool->blocks;
pool->blocks = block->next;
hat_allocator_free(pool->a, block);
}
hat_allocator_free(pool->a, pool);
}
void *opcut_pool_alloc(opcut_pool_t *pool) {
if (!pool->items)
allocate_block(pool);
if (!pool->items)
return NULL;
header_t *header = pool->items;
pool->items = header->next;
return header + 1;
}
void opcut_pool_free(opcut_pool_t *pool, void *item) {
header_t *header = (header_t *)item - 1;
header->next = pool->items;
pool->items = header;
}
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