[Rd] How to preserve data across function calls in a library package

[Saptarshi Guha]

Hi,
        I am writing an R package with two functions in C++. So far  
everything works.
        Now, i would like to write a third function which would use a pointer 
(it is a pointer to a class object) created by first function.
        I tried placing this pointer outside of the function definitions  
(i.e to make it global) but when called in the 3rd function i get
>        *** caught bus error ***
address 0x0, cause 'invalid alignment'"

        I tried Callocing it in the 1st function but to no avail. Here is a  
quick summary. When foo is called (through do_foo, **after** having  
called do_kNN_e) i get the aforementioned error.
        Can anyone provide some pointers (no pun intended) on this?

        Thanks
        Saptarshi

ANN* book;
int* foot;

void foo(void){
   Rprintf("many times\n");
   Rprintf("%p\n",book);
   Rprintf("%p\n",foot);
}

SEXP
kNN_e(SEXP data, SEXP Nrow, SEXP Ncol,SEXP K,SEXP Eps)
{
   int nrow=asInteger(Nrow);
   int ncol=asInteger(Ncol);
   int k=asInteger(K);
   double eps=asReal(Eps);

   SEXP ans,distance;
   SEXP retlist;
   PROTECT(ans=allocMatrix(INTSXP,nrow,k)); //The 2nd argument gives  
the number of rows, and the last the number of cols see http://cran.r- 
project.org/doc/manuals/R-exts.html
   PROTECT(distance=allocMatrix(REALSXP,nrow,k));
   ANNpointArray datapoints;
   ANNpoint qpoint;
   ANNkd_tree* kdTree;
   book=Calloc(1,ANN*);
   foot=Calloc(1,int);
   book=kdTree;
  *foot=10;

  .......
}

extern "C" {
   void do_foo(void){
     foo();
   }

SEXP
do_kNN_e(SEXP data, SEXP Nrow, SEXP Ncol,SEXP k,SEXP eps)
{
   return kNN_e(data,Nrow, Ncol,
             k,eps);

}



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