Add pool allocator

include/ucore/spool.h

@@ -0,0 +1,60 @@
+#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