Read an unsigned big-endian 64-bit integer
#include <uint64.h>
uint64 u;
void uint64_unpack_big(const char s[4],uint64 *u);
uint64 is a 64-bit unsigned integer type.
uint64_unpack_big portably reads a uint64 as stored on a big-endian architecture (i.e. in network byte order) from s and writes it into u in the native byte order.