wip: working on externs loading

- WIP: add extern objects initializing/freeing functions
- Feat: add extern objects loading in VM initializer

include/vm/fzl_vm.h

@@ -5,12 +5,14 @@
 #include <stddef.h>
 #include <stdint.h>
 #include <vm/fzl_vm_env.h>
+#include <vm/fzl_vm_extern.h>
 #include <vm/fzl_vm_reader.h>
 
 // VM descriptor
 typedef struct
 {
   fzl_vm_reader_t *reader;
+  fzl_vm_extern_t *prep_fns;
 
   size_t ip;
 

include/vm/fzl_vm_extern.h

@@ -2,6 +2,8 @@
 #define FZL_VM_EXTERN_H
 
 #include <ffi.h>
+#include <stddef.h>
+#include <vm/fzl_vm_reader.h>
 
 // Loaded extern function definition
 typedef struct
@@ -9,6 +11,25 @@ typedef struct
   void *func_ptr;
   ffi_cif cif;
   ffi_type **arg_types;
+} fzl_vm_sym_t;
+
+// Extern object descriptor
+typedef struct
+{
+  void **libs;
+  size_t libs_loaded;
+
+  fzl_vm_sym_t *syms;
+  size_t syms_loaded;
 } fzl_vm_extern_t;
 
+// Load externs
+fzl_vm_extern_t *fzl_vm_init_externs(fzl_vm_reader_t *reader);
+
+// Get last error from externs loader
+char *fzl_vm_externs_geterror();
+
+// Close and free externs
+void fzl_vm_free_externs(fzl_vm_extern_t *ex);
+
 #endif // FZL_VM_EXTERN_H