extern int sha1write(struct sha1file *, void *, unsigned int);
extern void crc32_begin(struct sha1file *);
extern uint32_t crc32_end(struct sha1file *);
extern int sha1write(struct sha1file *, void *, unsigned int);
extern void crc32_begin(struct sha1file *);
extern uint32_t crc32_end(struct sha1file *);