extern int parse_delta_buffer(struct delta *item, void *buffer, unsigned long size);
extern int parse_delta(struct delta *item, unsigned char sha1);
extern int process_deltas(void *src, unsigned long src_size,
extern int parse_delta_buffer(struct delta *item, void *buffer, unsigned long size);
extern int parse_delta(struct delta *item, unsigned char sha1);
extern int process_deltas(void *src, unsigned long src_size,