differential encoding of binary sequence

Hiiiiiii

I would like to do dpsk modulation in matlab. As I understood dpsk is differing from bpsk interms of differential encoding of input binary sequence and that is given to input for bpsk. I did the XOR operation of input sequence and given to bpsk. But my ouput same as bpsk(ie: the phase shift is taking place for every bit transition). Actually as per dpsk when

input bit is 1----------- tranisition, input bit is 0--------- No transition. This is not happening here. I think I am doing wrong in differential encoding. please could someone help in this.

clc;
clear all;
close all;
b = [0 1 1 1 1 1 0 1];

% n=length(b);
 M(1) =1;
for k=1:length(b)
  M(k+1)=bitxor(M(k),b(k));
end
n =length(M);

I don't know how to take bitdelay in matlab for differential encoder. please suggest solution for this