You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: my_gcc_phat.m
    path of file: ./repos/Microphone-sound-source-localization
    
    the code of the file until where you have to start completion: function y = my_gcc_phat(x1, x2)
% Note:
%       This function is used to calculate the GCC-PHAT function.
% Usage:
%       y = my_gcc_phat(x1, x2)
% Input arguments:
%       x1 : the input signal of first channel (1*N)
%       x2 : the input signal of second channel (1*N)
% Output arguments:
%       y  : the GCC-PHAT function (1*(2*N-1))
% For example:
%       x1 = randn(1,2000);
%       x2 = delayseq(x1, 5e-3, 8000); % 对x1进行平移5ms，采样率为8kHz
%       y  = %%%;
% 说明：
%       本函数用来实现两路信号的GCC-PHAT的计算
%       输入：两路具有时延关系的信号（要求两信号等长）
%       输出：GCC-PHAT

% --------------------------------------------------------------

    
function y = my_gcc_phat(x1, x2)
% Note:
%       This function is used to calculate the GCC-PHAT function.
% Usage:
%       y = my_gcc_phat(x1, x2)
% Input arguments:
%       x1 : the input signal of first channel (1*N)
%       x2 : the input signal of second channel (1*N)
% Output arguments:
%       y  : the GCC-PHAT function (1*(2*N-1))
% For example:
%       x1 = randn(1,2000);
%       x2 = delayseq(x1, 5e-3, 8000); % 对x1进行平移5ms，采样率为8kHz
%       y  = %%%;
% 说明：
%       本函数用来实现两路信号的GCC-PHAT的计算
%       输入：两路具有时延关系的信号（要求两信号等长）
%       输出：GCC-PHAT

% --------------------------------------------------------------
% 初始化
Ncorr = 2*length(x1)-1;   % 线性互相关长度
NFFT = 2^nextpow2(Ncorr); % 计算FFT点数

% --------------------------------------------------------------
% 计算GCC-PAHT
Gss = fft(x1, NFFT).*conj(fft(x2, NFFT));                 % 计算互功率谱
% xcorr_cac = fftshift(ifft(Gss));
xcorr_cac = fftshift(ifft(exp(1i*angle(Gss))));           % 直接GCC-PHAT
y = xcorr_cac(NFFT/2+1-(Ncorr-1)/2:NFFT/2+1+(Ncorr-1)/2); % 确定索引

end