spool: Clean up with gcc/clang specific features

include/ucore/spool.h

@@ -1,5 +1,5 @@
 #ifndef UC_SPOOL_H_
-#define UC_SPOOL_H
+#define UC_SPOOL_H_
 
 #include <stddef.h>
 #include <stdint.h>
@@ -7,6 +7,11 @@
 extern "C" {
 #endif
 
+typedef union UCPoolBlock UCPoolBlock;
+union UCPoolBlock {
+   UCPoolBlock *next; // next free block (when not allocated)
+   unsigned char data[]; // data when allocated
+};
 /** @file
  * Static pool allocator.
  *
@@ -23,12 +28,12 @@ extern "C" {
 */
 typedef struct UCPool UCPool;
 struct UCPool {
-   unsigned char *free_list;   // intrusive free list
+   UCPoolBlock *free_list;   // 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
+   UCPoolBlock *start;       // start of user buffer
+   UCPoolBlock *end;         // one past end of user buffer
 };
 
 /** Initialize the pool.
@@ -47,6 +52,7 @@ void uc_pool_init(UCPool *pool,
                size_t alignment);
 
 // Allocate a block from the pool. Returns NULL if no more space
+[[gnu::assume_aligned(_Alignof(UCPoolBlock))]]
 void *uc_pool_alloc(UCPool *pool);
 
 // Free @p . Returns memory to the pool