What are the functions to do serial to parallel conversion? And reverse ?

Hello. I'm making a code, and at the transmiter, after the block for modulation I have to do a serial to parallel conversion. And the reverse at the reception. How can I write the function ser2par or par2ser ? This is the part of code of that portion. Thanks.

%data source
  N=128; %number of subcarries
  M=4;   %DSPK modulation
  x=randi([0 M-1],N,1);
%modulation scheme      
  h = modem.dpskmod('M', 4,'SymbolOrder', 'binary', 'InputType', 'integer');
  xm=modulate(h,x);
%S/P conversion
  p=ser2par(xm,N);
%IDFT   
  x_ifft=ifft(p)

[Anushi1998]

http://in.mathworks.com/matlabcentral/fileexchange/57887-serial-to-parallel-converter

[Anushi1998]

You can refer to above mentioned link

[Amilton Pensamento]

@Irina Popescu, did the two functions in the link below worked for you?