1 files changed, 85 insertions, 0 deletions
diff --git a/src_c/pool.c b/src_c/pool.c
new file mode 100644
index 0000000..619a97d
--- /dev/null
+++ b/src_c/pool.c
@@ -0,0 +1,85 @@
+#include <stdlib.h>
+#include "pool.h"
+
+
+#define PAGE_SIZE 4096
+
+
+typedef struct header_t {
+    struct header_t *next;
+} header_t;
+
+
+struct opcut_pool_t {
+    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 =
+        malloc(sizeof(header_t) +
+               items_per_block * (sizeof(header_t) + pool->item_size));
+    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(size_t item_size) {
+    opcut_pool_t *pool = malloc(sizeof(opcut_pool_t));
+    if (!pool)
+        return NULL;
+
+    if (item_size % sizeof(void *) != 0)
+        item_size += sizeof(void *) - (item_size % sizeof(void *));
+
+    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;
+        free(block);
+    }
+    free(pool);
+}
+
+
+void *opcut_pool_get(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_return(opcut_pool_t *pool, void *item) {
+    header_t *header = (header_t *)item - 1;
+    header->next = pool->items;
+    pool->items = header;
+}