128bit binary to decimal and hexadecimal , and versa also?

I have

plain_tex = ('1111110000011111001111011110100010100110110111000110011010110')

this string I want to convert to that form

   plaintext_hex = {'39' '8a' '59' 'b4' 'ac' '00' '00' '00' ...
                    '00' '00' '00' '00' '00' '00' '00' '00'};
    %plaintext_hex = {'398a59b4ac000000000000000000000'};
    %str=num2hex(plaintext_hex)
    %plaintext_hex = {'32' '43' 'f6' 'a8' '88' '5a' '30' '8d' ...
    %                 '31' '31' '98' 'a2' 'e0' '37' '07' '34'};

or directly dec as I will then do that Convert plaintext from hexadecimal (string) to decimal representation

    plaintext = hex2dec(plaintext_hex)

[James Tursa]

What is the format of the binary string? Signed or unsigned? Ones-complement or twos-complement? Or ...?

[Radwa]

 plaintext_hex = {'39' '8a' '59' 'b4' 'ac' '00' '00' '00' ...
                    '00' '00' '00' '00' '00' '00' '00' '00'};
this is 1* 16 cell , ot is hexa.string 
plain_tex = ('1111110000011111001111011110100010100110110111000110011010110')
this is 1*32 char. it is binary

[Radwa]

I have symbolic toolbox I have 2 problem 1. to make bin 2 dec deal with more than 52 bit 2.to convert 32 char to 16 cell