From d58e24f6a97bc80ab911aedcfd78c11dd27e6252 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Nils=20O=2E=20Sel=C3=A5sdal?= <nos@utel.tech>
Date: Tue, 21 Apr 2026 23:01:22 +0200
Subject: [PATCH] Minor cleanup

---
 include/ucore/slot_allocator.h | 11 ++++++-----
 src/spool.c                    |  5 +----
 2 files changed, 7 insertions(+), 9 deletions(-)

diff --git a/include/ucore/slot_allocator.h b/include/ucore/slot_allocator.h
index 417df05..b7ca13f 100644
--- a/include/ucore/slot_allocator.h
+++ b/include/ucore/slot_allocator.h
@@ -5,9 +5,10 @@
 #include <assert.h>
 
 //Free memory is reused to build a linked list of slots
-typedef struct UCSlot UCSlot;
-struct UCSlot {
-    UCSlot *next;
+typedef union  UCSlot  UCSlot;
+union UCSlot {
+    UCSlot *next;       // next free block (when not allocated)
+    uint8_t data[0];   // data when allocated
 };
 
 typedef struct UCSlotArena UCSlotArena;
@@ -71,7 +72,7 @@ static inline void *uc_slot_alloc(UCSlotArena *arena)
 #endif
     }
 
-    return slot;
+    return &slot->data[0];
 }
 /**
  * Free a slot.
@@ -84,7 +85,7 @@ static inline void uc_slot_free(UCSlotArena *arena, void *memory)
 #ifdef DEBUG
         for (const UCSlot *slot = arena->free_list ; slot = slot->next) {
             if (slot == mem) {
-                assert("Double free detected");
+                assert(0 && "Double free detected");
             }
         }
 #endif
diff --git a/src/spool.c b/src/spool.c
index c40116e..decb58f 100644
--- a/src/spool.c
+++ b/src/spool.c
@@ -41,7 +41,7 @@ void uc_pool_init(UCPool *pool, void *buffer, size_t buffer_size, size_t block_s
             p->next = next;
             p = next;
         }
-        ((UCPoolBlock *)p)->next = NULL; // last element
+        p->next = NULL; // last element
         pool->free_list = (UCPoolBlock *)first_addr;
     }
 
@@ -65,8 +65,6 @@ void *uc_pool_alloc(UCPool *pool)
 #endif
     return block->data;
 }
-#include <stdio.h>
-
 void uc_pool_free(UCPool *pool, void *p)
 {
     if (p == NULL) {
@@ -92,7 +90,6 @@ void uc_pool_free(UCPool *pool, void *p)
     pool->free_list = p;
 }
 
-
 void uc_pool_reset(UCPool *pool)
 {
    if (pool->capacity == 0)