If you need to truncate and return only 2 bits after shifting you can "bitand" the result with appropriate number.
for last bit, you use 00000001 --> 1
for last 2 bits, 00000011 --> 3
for last 3 bits, 00000111 --> 7
and so on
For example to get last 2 bits after right shifting 3 bits
bitand( bitshift(a,-3,'uint8') , 3)
