Composite Image Generation - Texture Synthesis

This is the code for generating composite image. While executing it I get white color patch, instead of the original patch? can anybody help me with this problem?

Code:

function [ CI ] = composite_image_generator( index_table,source_patch_id,source_texture,patchsize )
%UNTITLED2 Summary of this function goes here
%   Detailed explanation goes here
%workbench=zeros(tw,th);
start_point=0;
end_pt=0;
e=1;
f=1;
[m, n]=size(index_table);
[o, p]=size(source_patch_id);
a=1;b=1;
for i=1:m
    e=1;
    a=f;
    for j=1:n
     b=e;
        if(index_table(i,j)>0)
            for k=1:o
                    if(index_table(i,j)==source_patch_id(k,1))
                        start_point=source_patch_id(k,2);
                        end_pt=source_patch_id(k,3);
                    end
            end
              e=b;
                for x = start_point:start_point+patchsize-1
                        for y = end_pt:end_pt+patchsize-1
                            tmp_composite_img(a,b) = source_texture(x,y);
                            b=b+1;
                        end
                        a=a+1;
                        b=e;
                end
                e=e+patchsize;
                a=f;         
                b=e;

          else
              for c=1:patchsize
                  for d=1:patchsize
                      tmp_composite_img(a,b)=0;
                      b=b+1;
                  end

                  a=a+1;
                 b=e;
              end
              e=e+patchsize;
               a=f;
             end

      end
      f=f+patchsize;
  end

CI=tmp_composite_img;
end

[VIGNESH KUMAR RAJAGURU]

You have passed index_table,source_patch_id,source texture,patchsize as input parameters to the function. Where are those definitions?? Provide the definitions to debug the code