diff --git a/src/rvprof_internal.h b/src/rvprof_internal.h
index 767b449..4104ed8 100644
--- a/src/rvprof_internal.h
+++ b/src/rvprof_internal.h
@@ -122,9 +122,36 @@ typedef struct{
     uint64_t total_program_tiem;
     uint64_t total_program_cycles;
     size_t total_memory_allocated;
-    
 } rvprof_context_t;
 
+
+// ONLY GLOBAL VARIABLE
+extern rvprof_context_t g_rvprof;
+
+
+// internal API
+
+// memory management
+void* rvprof_malloc(size_t size);
+void* rvprof_reallovc(void* ptr, size_t old_size, size_t new_size);
+void rvprof_free(void* ptr, size_t size);
+
+// dynamic array management
+int region_array_ensure_capacity(region_array_t* arr, int needed);
+int function_stats_array_ensure_capacity(function_stats_array_t* arr, int needed);
+int stack_info_array_ensure_capacity(stack_info_array_t* arr, int needed);
+int symbol_array_ensure_capacity(symbol_array_t* arr, int needed);
+
+void region_array_cleanup(region_array_t* arr);
+void function_stats_array_cleanup(function_stats_array_t* arr);
+void stack_info_array_cleanup(stack_info_array_t* arr);
+void symbol_array_cleanup(symbol_array_t* arr);
+
+// memory operations: fyunction statistics
+int rvprof_memory_add_stack_id_to_function(int func_id, int stack_id);
+int rvprof_memory_add_caller_to_function(int func_id, const char* caller);
+
+
 #ifdef __cplusplus
 }
 #endif