From be3d902be5895a13b34b88c7521ba6106e806cba Mon Sep 17 00:00:00 2001
From: Imbus <>
Date: Mon, 8 Sep 2025 07:43:15 +0200
Subject: [PATCH 1/4] freelist: Move align macro fiddling into header

---
 freelist/freelist.c | 13 -------------
 freelist/freelist.h | 13 +++++++++++++
 2 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/freelist/freelist.c b/freelist/freelist.c
index 9b47a8d..7fd946e 100644
--- a/freelist/freelist.c
+++ b/freelist/freelist.c
@@ -5,19 +5,6 @@
 #include <stdio.h>
 #include <stdlib.h>
 
-/* Fiddle these around according to your need. */
-#ifdef FREELIST_NOALIGN
-#define ALIGN(x) (x)
-#else // FREELIST_NOALIGN
-
-/* Align to nearest multiple of sizeof(void*) */
-static inline size_t align_up(size_t n) {
-    return (n + sizeof(void *) - 1) & ~(sizeof(void *) - 1);
-}
-
-#define ALIGN(x) (align_up(x))
-#endif // FREELIST_NOALIGN
-
 /* Initialize the FreeList */
 int fl_init(FreeList *fl, uintptr_t start, uintptr_t end, size_t itemsize) {
     size_t size = ALIGN(itemsize + sizeof(FreeListBlock));
diff --git a/freelist/freelist.h b/freelist/freelist.h
index de12d5d..f0e8ed4 100644
--- a/freelist/freelist.h
+++ b/freelist/freelist.h
@@ -5,6 +5,19 @@
 #include <stdint.h>
 #include <stdlib.h>
 
+/* Fiddle these around according to your need. Delete or check makefile */
+#ifdef FREELIST_NOALIGN
+#define ALIGN(x) (x)
+#else // FREELIST_NOALIGN
+
+/* Align to nearest multiple of sizeof(void*) */
+static inline size_t align_up(size_t n) {
+    return (n + sizeof(void *) - 1) & ~(sizeof(void *) - 1);
+}
+
+#define ALIGN(x) (align_up(x))
+#endif // FREELIST_NOALIGN
+
 #define FL_FREE ((uint8_t)0x00)
 #define FL_USED ((uint8_t)0x01)
 

From 8f41b0873dc565e5159b583fff950fa436e1b8cb Mon Sep 17 00:00:00 2001
From: Imbus <>
Date: Mon, 8 Sep 2025 07:43:22 +0200
Subject: [PATCH 2/4] Disable align in makefile

---
 freelist/Makefile | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/freelist/Makefile b/freelist/Makefile
index 7f6d8a6..9d85953 100644
--- a/freelist/Makefile
+++ b/freelist/Makefile
@@ -1,6 +1,8 @@
 CC = gcc
 CFLAGS = -Wall -O2
 
+CFLAGS += -DFREELIST_NOALIGN
+
 TARGET = main.elf
 SRC = main.c freelist.c
 

From 13a0d42514836a580d61b882962c044dd5bd094d Mon Sep 17 00:00:00 2001
From: Imbus <>
Date: Mon, 8 Sep 2025 07:52:41 +0200
Subject: [PATCH 3/4] Remove block header from allocated blocks entirely

---
 freelist/freelist.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/freelist/freelist.c b/freelist/freelist.c
index 7fd946e..380010f 100644
--- a/freelist/freelist.c
+++ b/freelist/freelist.c
@@ -4,10 +4,11 @@
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 
 /* Initialize the FreeList */
 int fl_init(FreeList *fl, uintptr_t start, uintptr_t end, size_t itemsize) {
-    size_t size = ALIGN(itemsize + sizeof(FreeListBlock));
+    size_t size = ALIGN(itemsize);
 
     if (!fl || end <= start)
         return EXIT_FAILURE;
@@ -39,7 +40,8 @@ void *fl_alloc(FreeList *fl) {
     fl->free = fl->free->next;
     fl->allocated++;
 
-    return ((void *)m) + sizeof(FreeListBlock);
+    memset((void *)m, 0, sizeof(FreeListBlock));
+    return ((void *)m);
 }
 
 /* Return some memory to the FreeList */
@@ -48,7 +50,7 @@ int fl_free(FreeList *fl, void *ptr) {
         return EXIT_FAILURE; /* We cant free memory we do not own */
     }
 
-    FreeListBlock *block = (FreeListBlock *)((uintptr_t)ptr - sizeof(FreeListBlock));
+    FreeListBlock *block = (FreeListBlock *)(uintptr_t)ptr;
 
     block->next = fl->free;
     fl->free = block;

From a8b7fc75e3a68e6cef133a1f4c371f15e2b5a689 Mon Sep 17 00:00:00 2001
From: Imbus <>
Date: Mon, 8 Sep 2025 07:52:54 +0200
Subject: [PATCH 4/4] Some more info in demo main

---
 freelist/main.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/freelist/main.c b/freelist/main.c
index 0841d2e..49aa19b 100644
--- a/freelist/main.c
+++ b/freelist/main.c
@@ -17,16 +17,21 @@ void printvec(const Vec3 *v) {
     printf("Vec3: (%d, %d, %d)\n", v->x, v->y, v->z);
 }
 
+#define BUFFER_SIZE (4096)
+
 int main() {
-    FreeList fl;
-    char    *mem = malloc(4096);
+    FreeList    fl;
+    const char *mem = malloc(BUFFER_SIZE);
+
+    fl_init(&fl, (uintptr_t)mem, (uintptr_t)mem + BUFFER_SIZE, sizeof(Vec3));
+    const size_t cap = fl_capacity(&fl);
+
+    printf("Item size: %lu\n", sizeof(Vec3));
+    printf("Buffer size: %d\n", BUFFER_SIZE);
+    printf("Space utilization internal: %.2f%%\n", 100.0 * fl_utilization(&fl, sizeof(Vec3)));
 
-    fl_init(&fl, (uintptr_t)mem, (uintptr_t)mem + 4096, sizeof(Vec3));
-    size_t cap = fl_capacity(&fl);
     assert(fl_available(&fl) == cap);
 
-    printf("Space utilization: %.2f%%\n", 100.0 * fl_utilization(&fl, sizeof(Vec3)));
-
     Vec3 *a = fl_alloc(&fl);
     Vec3 *b = fl_alloc(&fl);
     Vec3 *c = fl_alloc(&fl);