src/arena_allocator.c

@@ -2,7 +2,6 @@
 #include <assert.h>
 #include <stddef.h>
 #include <stdlib.h>
-#include <string.h>
 
 #define DEFAUL_REGION_SIZE 1048576 /* 8 * 1024 * 1024 = 8MB */
 
@@ -13,44 +12,33 @@ Region *new_region(size_t capacity) {
   Region *region = malloc(capacity + sizeof(Region));
   assert(region != NULL);
   *region = (Region){.next = NULL, .capacity = capacity, .cursor = 0};
-
-  // Zero initialise memory
-  memset(region->data, 0, capacity);
-
   return region;
 }
 
-Arena *arena_init(Arena *parent, size_t capacity) {
+Arena arena_init(Arena *parent, size_t capacity) {
   Region *region = new_region(capacity);
 
   if (parent != NULL) {
     // Allocate new arena in parent to reduce likelyhood of loss
     Arena *current_arena = arena_alloc(parent, sizeof(Arena));
-    *current_arena = (Arena){.is_root = false,
+    *current_arena = (Arena){
-                             .begin = region,
+        .begin = region, .end = region, .child = NULL, .sibling = NULL};
-                             .end = region,
-                             .child = NULL,
-                             .sibling = NULL};
 
     // if parent has no children this arena is now it's child
     if (parent->child == NULL) {
       parent->child = current_arena;
-      return current_arena;
+      return *current_arena;
     }
 
     // Push the arena onto the first childs sibling list
     current_arena->sibling = parent->child;
     parent->child = current_arena;
-    return current_arena;
+    return *current_arena;
   }
 
-  // Create root of arena tree
+  // This is the root of the arena tree
-  Arena *arena = malloc(sizeof(Arena));
+  Arena arena = {
-  *arena = (Arena){.is_root = true,
+      .begin = region, .end = region, .child = NULL, .sibling = NULL};
-                   .begin = region,
-                   .end = region,
-                   .child = NULL,
-                   .sibling = NULL};
   return arena;
 }
 
@@ -74,16 +62,10 @@ void arena_deinit(Arena *arena) {
     region = next_region;
   }
 
-  arena->begin = NULL;
+  *arena = (Arena){.begin = NULL, .end = NULL};
-  arena->end = NULL;
-  if (arena->is_root) {
-    free(arena);
-  }
 }
 
 void *arena_alloc(Arena *arena, size_t size) {
-  // TODO: only align when needed
-  size = (size + 7) & ~7; // align size increase to multiple of 8
   Region *region = arena->end;
   assert(region != NULL);
 
@@ -95,8 +77,6 @@ void *arena_alloc(Arena *arena, size_t size) {
 
   void *result = &region->data[region->cursor];
   region->cursor += size;
-  // TODO: only align when needed
-  size = (size + 7) & ~7; // align size increase to multiple of 8
   return result;
 }
 

src/arena_allocator.h

@@ -1,6 +1,5 @@
 #pragma once
 
-#include <stdbool.h>
 #include <stddef.h>
 
 typedef struct Region_s Region;
@@ -13,14 +12,13 @@ struct Region_s {
 
 typedef struct Arena_s Arena;
 struct Arena_s {
-  bool is_root;
   Arena *child;
   Arena *sibling;
   Region *begin;
   Region *end;
 };
 
-Arena *arena_init(Arena *parent, size_t capacity);
+Arena arena_init(Arena *parent, size_t capacity);
 void arena_deinit(Arena *arena);
 
 void *arena_alloc(Arena *arena, size_t size);

src/main.c

@@ -13,23 +13,23 @@
 
 int main(int argc, char *argv[]) {
   // arena allocation test
-  printf("Allocation test\n");
+  printf("Allocation test");
-  Arena *global_arena = arena_init(NULL, 0);
+  Arena global_arena = arena_init(NULL, 0);
-  for (int i = 0; i <= 1048576 + 100; i++) {
+  for (int i = 0; i <= 1048576+100; i++) {
-    int *number = arena_alloc(global_arena, sizeof(int));
+    int *number = arena_alloc(&global_arena, sizeof(int));
     *number = 42;
   }
 
+  printf("children test");
+
   // arena children test
-  printf("children test\n");
+  Arena child_arena = arena_init(&global_arena, 0);
-  Arena *child_arena = arena_init(global_arena, 0);
+  //Arena sibling_arena = arena_init(&global_arena, 0);
-  Arena *sibling_arena = arena_init(global_arena, 0);
+  //Arena grandchild_arena = arena_init(&child_arena, 0);
-  Arena *grandchild_arena = arena_init(child_arena, 0);
+
+  arena_deinit(&global_arena);
 
-  printf("deinit test\n");
-  arena_deinit(global_arena);
   
-  printf("tests complete\n");
 }
 
 /*int main(int argc, char *argv[]) {