wireshark-xml-dissector

Hi currently i'm writing xml and dissecting the xml through wireshark,but i'm facing with one issue if anybody help me

i need to modify the below logic:

nas_system_information_gsm_map = octet(1+ val(len_nas_system_information_gsm_map),

the code for this logic in attachment 1 please verify the attachment-1 ,it contains xml code it is showing in wireshark in the below written way:

len_nas_system_information_gsm_map = 111 bit (3) = 7 
nas_system_information_gsm_map = 0000 0001 bit (8) = 1

but i need to implement the logic in this form :

nas_system_information_gsm_map = octet(1+ val(len_nas_system_information_gsm_map)

it means,this field nas_system_information_gsm_map has to repeat up to 8 times and it has to decode 8 bits for each iteration can any body help me how to write this logic in xml..