#ifndef UC_SPOOL_H_
#define UC_SPOOL_H

#include <stddef.h>
#include <stdint.h>
#ifdef __cplusplus
extern "C" {
#endif

/** @file
 * Static pool allocator.
 *
 *  An UCPool allocates fixed size memory chunks from a provided buffer,
 *  and memory allocations can be free'd in any order.
 *
 * The backing array should be suitable aligned to the types
 * that will be allocated from it. Use .e.g
 * @code
 * _Alignas(16) char mem[1024];
 * @endcode
 * as the backing buffer.
 *
*/
typedef struct UCPool UCPool;
struct UCPool {
   unsigned char *free_list;   // intrusive free list
   size_t block_size; // aligned size of each block
   size_t capacity;   // number of blocks
   size_t align;      // alignment
   unsigned char *start;       // start of user buffer
   unsigned char *end;         // one past end of user buffer
};

/** Initialize the pool.
 *
 * Block size will be rounded up by alignment, or to size of a pointer
 *
 * @param buffer      backing buffer for the pool
 * @param buffer_size size of @buffer
 * @param block_size  size of each allocation.
 * @param alignment   alignment of each block (must be power of 2)
 */
void uc_pool_init(UCPool *pool,
               void *buffer,
               size_t buffer_size,
               size_t block_size,
               size_t alignment);

// Allocate a block from the pool. Returns NULL if no more space
void *uc_pool_alloc(UCPool *pool);

// Free @p . Returns memory to the pool
void uc_pool_free(UCPool *pool, void *p);
void uc_pool_reset(UCPool *pool);

#ifdef __cplusplus
}
#endif

#endif