Function pack_hi_lo

pub fn pack_hi_lo(hi: u32, lo: u32) -> u64

Helper to pack two u32 values into a u64 register.

Pointers to PVM memory are always 32 bit in size. Thus contracts can pack two pointers into a single register when calling a syscall API method.

This is done in syscall API methods where the number of arguments is exceeding the available registers.