apool: track total&free elements

src/base/pool.h

@@ -1,6 +1,10 @@
 #pragma once
 #include "core.h"
 
+enum {
+    APoolFlag_AutoGrow = (1 << 0)
+};
+typedef U32 APoolFlags;
 typedef union APoolElement APoolElement;
 union APoolElement {
     APoolElement *next;       // offset from start to next free block (when not allocated)
@@ -11,16 +15,22 @@ struct APool {
     APoolElement *free_list;  // free list
     U8 *start;                // start of user buffer
     Allocator *allocator;
-    U32 element_size;         // aligned size of each block
-    U32 n_elements;           // total number of blocks
-    U32 align;                // alignment
-};
-enum {
-    APOOL_AUTOGROW = 0
+    APoolFlags flags;
+    U32 element_size;         // aligned size of each element
+    U32 element_align;        // alignment
+    U32 n_elements;           // total elements in the pool
+    U32 n_free;               // number of free elements
 };
+typedef struct APoolCreateOptions APoolCreateOptions;
+struct APoolCreateOptions {
+    U32 element_size;         // aligned size of each element
+    U32 element_align;        // alignment of elements
+    U32 n_reserved;           // number of elements reserved
+    APoolFlags flags;
 
-#define apool_create(arena, n_elements, type) \
-        apool_create_ex(arena, n_elements, sizeof(type), alignof(type));
-APool *apool_create_ex(Allocator *allocator, U32 n_elements, U32 element_size, uint32_t element_align);
+};
+#define apool_create(arena, n_reserved, type) \
+        apool_create_ex(arena, &(APoolCreateOptions){sizeof(type), alignof(type), n_reserved, 0})
+APool *apool_create_ex(Allocator *allocator, const APoolCreateOptions *options);
 void *apool_alloc(APool *pool);
 void apool_free(APool *pool, void *element);