Added arena library

inc-c/ufn/ufn_arena.h

@@ -0,0 +1,96 @@
+// UFN Arena library. MIT-Licensed (c) Eric-Paul Ickhorn (epickh)
+
+#ifndef UFN_ARENA_H
+#define UFN_ARENA_H
+
+#include <stdint.h>
+
+#define UFN_UNLIMITED_ARENA 0xffffffff
+
+typedef struct ufn_arena ufn_arena_s;
+
+struct ufn_arena
+{
+    uint32_t capacity;
+    uint32_t usage;
+    char *allocation;
+
+    uint32_t maximum;
+    ufn_arena_s *continuation;
+};
+
+ufn_arena_s * ufn_new_dynamic_arena(uint32_t capacity, uint32_t max_tree_size);
+ufn_arena_s * ufn_new_static_arena(uint32_t capacity);
+void ufn_free_arena(ufn_arena_s *arena);
+
+void * ufn_arena_alloc(ufn_arena_s *arena, uint32_t size);
+
+
+
+#ifdef UFN_IMPLEMENTATION
+
+#include <stdlib.h>
+
+ufn_arena_s * ufn_new_dynamic_arena(uint32_t capacity, uint32_t max_tree_size)
+{
+    ufn_arena_s *arena = malloc(sizeof(ufn_arena_s));
+    arena->capacity = capacity;
+    arena->usage = 0;
+    arena->allocation = malloc(capacity);
+    arena->maximum = max_tree_size;
+    arena->continuation = NULL;
+    return arena;
+}
+ufn_arena_s * ufn_new_static_arena(uint32_t capacity)
+{
+    return ufn_new_dynamic_arena(capacity, 0);
+}
+
+void ufn_free_arena(ufn_arena_s *arena)
+{
+    if(arena->continuation != NULL)
+    {
+        ufn_free_arena(arena->continuation);
+    }
+    free(arena->allocation);
+    free(arena);
+}
+
+void * ufn_arena_alloc(ufn_arena_s *arena, uint32_t size)
+{
+    if((arena->usage = size) >= arena->capacity)
+    {
+        if(arena->continuation == NULL)
+        {
+            uint32_t continuation_size = arena->capacity * 2;
+            // Clamp the continuation's size to the maximum allowed one.
+            if(continuation_size > (arena->maximum))
+            {
+                continuation_size = arena->maximum;
+            }
+            uint32_t continued_maximum = continuation_size - arena->maximum;
+            // If no continuation of this arena tree can fulfill
+            // a request of this size,
+            // -> Deny the request and return NULL.
+            if(size > arena->maximum)
+            {
+                return NULL;
+            }
+            // If no more arena can be allocated (The tree has its maximum size)
+            // -> return NULL.
+            if(continuation_size == 0)
+            {
+                return NULL;
+            }
+            arena->continuation = ufn_new_dynamic_arena(continuation_size, continued_maximum);
+        }
+        ufn_arena_alloc(arena->continuation, size);
+    }
+    void *block = arena->allocation + arena->usage;
+    arena->usage += size;
+    return block;
+}
+
+
+#endif // UFN_IMPLEMENTATION
+#endif // UFN_ARENA_H