R-alpha: unif_rand() again

Peter Dalgaard BSA writes:

Kurt Hornik <Kurt.Hornik@ci.tuwien.ac.at> writes:

Just out of curiosity, here is a question that might be embarrasingly
stupid.  Hmm ...

What I need is to call runif() (more precisely, `runif(1, 0, 1)') from
inside a C function.  Is this possible using call_S?  If so, how?

Hmm ... Stupid counter-question: Did you study the zfun() function in
$RHOME/demos/dynload/zero.c ? Looks pretty straightforward to me,
except that I have no offhand guess what the 0L argument to call_S is
good for. Peeking at the source should cure that.

I did.  I hoped that something like

static char *func = "runif";

double unif_rand() {
  void *in[3];
  char *modes[] = { "integer", "integer", "integer" };
  long lengths[] = { 1, 1, 1 };  
  void *out[1];
  double *result;

  in[0] = (void *)1L;
  in[1] = (void *)0L;
  in[2] = (void *)1L;  
  call_S((void *)func, 3L, in, modes, lengths, 0L, 1L, out);
  result = (double *)out[0];
  return(result[0]);
}

might work, but it does not ...

-k


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