uint32_unpack_big man page
uint32_unpack_big — read an unsigned big-endian 32-bit integer
void uint32_unpack_big(const char s,uint32 *u);
uint32 is a 32-bit unsigned integer type, normally either unsigned int or unsigned long.
uint32_unpack_big portably reads a uint32 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.
uint32_pack_big(3), uint32_read(3), uint32_read_big(3), uint32_unpack(3).