How do i interpret a data received serial ?

I receive from serial a message(60 bytes) divided in 17 data types.I need to extract 1 data of 4 bytes.I tried to get it byte with byte,and using shifting operation I fused those 4 bytes together.The problem is that those bytes represent a signed int number and I don't know how to convert that binary number into a signed int.

Answer 1

[Walter Roberson]

You do not need to use shifting.

t = [byte1, byte2, byte3, byte4];
t_as_signed = typecast(t, 'int32');

[Constantin]

Thank You for your replay,I hope it will work.