$D3 = ( $num >> 0 ) & ( 1 << 4 ) - 1; # 4 bits starting at bit 0 $D2 = ( $num >> 4 ) & ( 1 << 3 ) - 1; # 3 bits starting at bit 4 $D1 = ( $num >> 7 ) & ( 1 << 1 ) - 1; # 1 bit starting at bit 7