int Extend()

in matlab/strred/matlabPyrTools/MEX/edges.c [421:529]
105 lines of code
28 McCabe index (conditional complexity)

int Extend(filt,x_dim,y_dim,x_pos,y_pos,result,r_or_e)
  register double *filt, *result;
  register int x_dim;
  int y_dim, x_pos, y_pos, r_or_e;
  {
  int filt_sz = x_dim*y_dim;
  register int y_filt,x_filt, y_res,x_res, y_tmp, x_tmp;
  register int x_base = (x_pos>0)?(x_dim-1):0;
  register int y_base = x_dim * ((y_pos>0)?(y_dim-1):0); 
  int x_overhang = (x_pos>0)?(x_pos-1):((x_pos<0)?(x_pos+1):0);
  int y_overhang = x_dim * ((y_pos>0)?(y_pos-1):((y_pos<0)?(y_pos+1):0));
  int mx_pos = (x_pos<0)?(x_dim/2):((x_dim-1)/2);
  int my_pos = x_dim * ((y_pos<0)?(y_dim/2):((y_dim-1)/2));
  int i;

  for (i=0; i<filt_sz; i++) result[i] = 0.0;

  /* Modeled on reflect1() */
  if (r_or_e IS REDUCE)
    for (y_filt=0, y_res=y_overhang;
	 y_filt<filt_sz;
	 y_filt+=x_dim, y_res+=x_dim)
      if ((y_res>=0) AND (y_res<filt_sz))
	for (x_filt=y_filt, x_res=x_overhang;
	     x_filt<y_filt+x_dim;
	     x_filt++, x_res++)
	  if ((x_res>=0) AND (x_res<x_dim))
	    result[y_res+x_res] += filt[x_filt];
	  else
	      {
	      result[y_res+ABS(x_base-ABS(x_res-x_base))] -= filt[x_filt];
	      result[y_res+x_base] += 2*filt[x_filt];
	      }
      else
	for (x_filt=y_filt, x_res=x_overhang;
	     x_filt<y_filt+x_dim;
	     x_filt++, x_res++)
	  if ((x_res>=0) AND (x_res<x_dim))
	      {
	      result[ABS(y_base-ABS(y_res-y_base))+x_res] -= filt[x_filt];
	      result[y_base+x_res] += 2*filt[x_filt];
	      }
	  else
	      {
	      result[ABS(y_base-ABS(y_res-y_base))+ABS(x_base-ABS(x_res-x_base))] 
		-= filt[x_filt];
	      result[y_base+x_base] += 2*filt[x_filt];
	      }
  else {  /* r_or_e ISNT  REDUCE */
      y_overhang = ABS(y_overhang); 
      x_overhang = ABS(x_overhang);
      for (y_res=y_base, y_filt = y_base-y_overhang;
	   y_filt > y_base-filt_sz;
	   y_filt-=x_dim, y_res-=x_dim)
	  {
	  for (x_res=x_base, x_filt=x_base-x_overhang;
	       x_filt > x_base-x_dim;
	       x_res--, x_filt--)
	    result[ABS(y_res)+ABS(x_res)] += filt[ABS(y_filt)+ABS(x_filt)];
	  if (x_pos ISNT 0)
	    if (x_overhang ISNT mx_pos)
	      for (x_res=x_base, x_filt=x_base-2*mx_pos+x_overhang;
		   x_filt > x_base-x_dim;
		   x_res--, x_filt--)
		result[ABS(y_res)+ABS(x_res)] -= filt[ABS(y_filt)+ABS(x_filt)];
	    else /* x_overhang IS mx_pos */
	      for (x_res=x_base, x_filt=x_base-2*mx_pos+x_overhang-1;
		   x_filt > x_base-x_dim;
		   x_res--, x_filt--)
		for (x_tmp=x_filt; x_tmp > x_base-x_dim; x_tmp--)
		  result[ABS(y_res)+ABS(x_res)] += 2*filt[ABS(y_filt)+ABS(x_tmp)];
	  }
       if (y_pos ISNT 0)
	 if (y_overhang ISNT my_pos)
	   for (y_res=y_base, y_filt = y_base-2*my_pos+y_overhang;
		y_filt > y_base-filt_sz;
		y_filt-=x_dim, y_res-=x_dim)
	       {
	       for (x_res=x_base, x_filt=x_base-x_overhang;
		    x_filt > x_base-x_dim;
		    x_res--, x_filt--)
		 result[ABS(y_res)+ABS(x_res)] -= filt[ABS(y_filt)+ABS(x_filt)];
	       if ((x_pos ISNT 0) AND (x_overhang ISNT mx_pos))
		 for (x_res=x_base, x_filt=x_base-2*mx_pos+x_overhang;
		      x_filt > x_base-x_dim;
		      x_res--, x_filt--)
		   result[ABS(y_res)+ABS(x_res)] -= filt[ABS(y_filt)+ABS(x_filt)];
	       }
	 else /* y_overhang IS my_pos */
	   for (y_res=y_base, y_filt = y_base-2*my_pos+y_overhang-x_dim;
		y_filt > y_base-filt_sz;
		y_res-=x_dim, y_filt-=x_dim)
	     for (y_tmp=y_filt; y_tmp > y_base-filt_sz; y_tmp-=x_dim)
		 {
		 for (x_res=x_base, x_filt=x_base-x_overhang;
		      x_filt > x_base-x_dim;
		      x_res--, x_filt--)
		   result[ABS(y_res)+ABS(x_res)] += 2*filt[ABS(y_tmp)+ABS(x_filt)];
		 if ((x_pos ISNT 0) AND (x_overhang IS mx_pos))
		   for (x_res=x_base, x_filt=x_base-2*mx_pos+x_overhang-1;
			x_filt > x_base-x_dim;
			x_res--, x_filt--)
		     for (x_tmp=x_filt; x_tmp > x_base-x_dim; x_tmp--)
		       result[ABS(y_res)+ABS(x_res)] += 2*filt[ABS(y_tmp)+ABS(x_tmp)];
		 }
      }  /* r_or_e ISNT  REDUCE */

  return(0);
  }