v1.0.2 release

arena.h

@@ -1,15 +1,33 @@
-// arena.h - v1.0.1 - MIT License - https://github.com/seajee/arena.h
+// arena.h - v1.0.2 - MIT License - https://github.com/seajee/arena.h
 // single header library for region-based memory management.
 //
-// License and changelog:
+// [License and changelog]
 //
 //     See end of file.
 //
-// Compile-time options:
+// [Single header library usage]
+//
+//     Including this header file as such does what you normally expect.
+//
+//     If you also need to include all of the function implementations you
+//     need to #define ARENA_IMPLEMENTATION before including the header file
+//     like this:
+//
+//         #define ARENA_IMPLEMENTATION
+//         #include "arena.h"
+//
+// [Compile-time options]
 //
 //     Note: every compile-time option listed here should be configured before
 //           the #include "arena.h"
 //
+//     #define ARENA_NO_ASSERT
+//
+//         This macro disables assertions that happen when a reallocation
+//         fails. The disabled assertions will be replaced with a simple
+//         condition that returns NULL when it fails. Note that ARENA_ASSERT
+//         is only used in arena_alloc().
+//
 //     #define ARENA_REGION_CAPACITY new_region_capacity_in_bytes (4096)
 //
 //         This macro defines the default capacity for arena regions.
@@ -17,7 +35,8 @@
 //     #define ARENA_ASSERT my_assert
 //
 //         This macro defines an alternative function for assertions. In this
-//         library, ARENA_ASSERT is only used when ARENA_REALLOC fails.
+//         library, ARENA_ASSERT is only used when arena_alloc() fails. Will
+//         be overwritten if ARENA_NO_ASSERT is defined.
 //
 //     #define ARENA_REALLOC my_realloc
 //     #define ARENA_FREE my_free
@@ -26,7 +45,7 @@
 //         and deallocation on the heap. They are only used for managing
 //         Arena_Region structures.
 //
-// Function documentation:
+// [Function documentation]
 //
 // In this library, arenas are implemented as linked lists of regions. Each
 // region will contain the allocated buffers. The following are all of the
@@ -39,8 +58,7 @@
 // configured by redefining it before including the header file. This function
 // is not strictly necessary for initializing an arena (see example).
 //
-//     void *arena_alloc(Arena *a,
+//     void *arena_alloc(Arena *a, size_t bytes)
-//                       size_t bytes)
 //
 // This function allocates a buffer of size <bytes> into the specified arena
 // and returns it's pointer.
@@ -59,8 +77,9 @@
 // Warning: this functions may cause fragmentation, consider setting an
 // appropriate region capacity.
 //
-// Example:
+// [Example]
-/*
+//
+#if 0
 #define ARENA_IMPLEMENTATION
 #include "arena.h"
 
@@ -75,7 +94,7 @@ int main(void)
     arena_free(&a); // The arena can still be reused
     return 0;
 }
-*/
+#endif // [Example]
 
 #ifndef ARENA_H_
 #define ARENA_H_
@@ -87,10 +106,14 @@ int main(void)
 #    define ARENA_REGION_CAPACITY (8*1024)
 #endif // ARENA_REGION_CAPACITY
 
+#ifndef ARENA_NO_ASSERT
 #    ifndef ARENA_ASSERT
 #        include <assert.h>
 #        define ARENA_ASSERT assert
 #    endif // ARENA_ASSERT
+#else
+#    define ARENA_ASSERT(...) ((void)0)
+#endif // ARENA_NO_ASSERT
 
 #ifndef ARENA_REALLOC
 #    include <stdlib.h>
@@ -147,7 +170,8 @@ Arena arena_create(size_t region_capacity)
 
 void *arena_alloc(Arena *a, size_t bytes)
 {
-    if (a == NULL) {
+    if (a == NULL || bytes == 0) {
+        ARENA_ASSERT(!"Invalid, parameters");
         return NULL;
     }
 
@@ -158,10 +182,13 @@ void *arena_alloc(Arena *a, size_t bytes)
     if (a->head == NULL) {
         size_t size = (bytes > region_capacity ? bytes : region_capacity);
         a->head = (Arena_Region*)ARENA_REALLOC(NULL, sizeof(*a->head) + size);
-        ARENA_ASSERT(a->head != NULL);
+
         if (a->head == NULL) {
+            ARENA_ASSERT(!"Reallocation failed");
             return NULL;
         }
+
+        a->head->next = NULL;
         a->head->count = bytes;
         a->head->capacity = size;
         a->tail = a->head;
@@ -179,11 +206,14 @@ void *arena_alloc(Arena *a, size_t bytes)
         if (bytes > a->tail->capacity - a->tail->count) {
             size_t size = (bytes > region_capacity ? bytes : region_capacity);
             a->tail->next = (Arena_Region*)ARENA_REALLOC(NULL, sizeof(*a->tail) + size);
-            ARENA_ASSERT(a->head != NULL);
+
             if (a->tail->next == NULL) {
+                ARENA_ASSERT(!"Reallocation failed");
                 return NULL;
             }
+
             a->tail = a->tail->next;
+            a->tail->next = NULL;
             a->tail->count = bytes;
             a->tail->capacity = size;
             return a->tail->data;
@@ -191,7 +221,7 @@ void *arena_alloc(Arena *a, size_t bytes)
     }
 
     a->tail->count += bytes;
-    return a->tail->data + a->tail->count;
+    return a->tail->data + a->tail->count - bytes;
 }
 
 void arena_free(Arena *a)
@@ -203,7 +233,7 @@ void arena_free(Arena *a)
     Arena_Region *cur = a->head;
     while (cur != NULL) {
         Arena_Region *next = cur->next;
-        free(cur);
+        ARENA_FREE(cur);
         cur = next;
     }
 
@@ -234,6 +264,7 @@ void arena_reset(Arena *a)
 /*
  * Revision history:
  *
+ *     1.0.2 (2025-09-06) Bug fixes; new ARENA_NO_ASSERT macro
  *     1.0.1 (2025-08-02) Prevent name mangling of functions; don't reset
  *                        region_capacity in arena_free()
  *     1.0.0 (2025-07-24) Initial release