How to use a for loop in matlab to take consecutive 972 bits out of a 1 by 9999980 bits matrix ?

In the following code, I have a u matrix of 1 by 9999980 size. I have to take consecutive 972 bits of this u matrix, to use in following expressions of p1, p2, and c.

p1 = mod(phi*xtra*(u'),2)';
p2 = mod(invt*(a*(u') + b*(p1')),2)';
c = [u p1 p2];

My question is how I should write for loop to complete above tasks ?

Answer 1

[Walter Roberson]

Nbit = 972;
Koffset = randi([0 length(u) - Nbit]);

for K = 1 : Nbit
    p1 = mod(phi*xtra*(u(K+Koffset)'),2)';
    p2 = mod(invt*(a*(u(K+Koffset)') + b*(p1')),2)';
    c(K,:) = [u(K+Koffset) p1 p2];
end

[Vishal Sharma]

I modify my question little bit. Already I have a matrix of random bits of size 1 by 9999980 (Assume this matrix name is b_seq64. It is of size 1 by 9999980 random bits). This is not u matrix. The parameter u is a random bits (random message bits) of length 972 bits. I don't want to use randi command, as already I have random bits (named here as b_seq64). Now please reply how can I use this b_seq64 to take consequetive 972 bits as u, means every consequtive 972 bits from b_seq64 is u, which will be used in the following expressions

p1 = mod(phi*xtra*(u'),2)';

p2 = mod(invt*(a*(u') + b*(p1')),2)';

c = [u p1 p2];

How to perform this using for loop in matlab ? Please reply

[Walter Roberson]

buffer() from the Communications System Toolbox. Or blockproc() from Imsge Processing Toolbox

[Vishal Sharma]

Thanks for the reply. Let me use this command.