-extern void *diff_delta(void *from_buf, unsigned long from_size,
- void *to_buf, unsigned long to_size,
- unsigned long *delta_size, unsigned long max_size,
- void **from_index);
+extern void *diff_delta(const void *from_buf, unsigned long from_size,
+ const void *to_buf, unsigned long to_size,
+ unsigned long *delta_size, unsigned long max_size);