uint32_unpack man page
uint32_unpack — read an unsigned little-endian 32-bit integer
void uint32_unpack(const char s,uint32 *u);
uint32 is a 32-bit unsigned integer type, normally either unsigned int or unsigned long.
uint32_unpack portably reads a uint32 as stored on a little-endian architecture from s and writes it into u in the native byte order.
uint32_pack(3), uint32_read(3), uint32_read_big(3), uint32_unpack_big(3).