#include <stdbool.h> // bool
#define _DEFAULT_SOURCE
#include <stdlib.h> // drand48_r()
#include <stdio.h> // fopen()
#include "util.h"
#include "km.h"

// get N get_floats
static bool
on_get_floats(
  km_rand_t * const rs,
  const size_t num_vals,
  float * const vals
) {
  unsigned short * const data = rs->data;

  // generate results
  for (size_t i = 0; i < num_vals; i++) {
    vals[i] = erand48(data);
  }

  // return success
  return true;
}

// fill sizes callback for system random source
static bool
on_get_sizes(
  km_rand_t * const rs,
  const size_t num_vals,
  size_t * const vals
) {
  unsigned short * const data = rs->data;

  // generate results
  for (size_t i = 0; i < num_vals; i++) {
    vals[i] = nrand48(data);
  }

  // return success
  return true;
}

static void
on_fini(
  km_rand_t * const rs
) {
  unsigned short * data = rs->data;

  // free rng data
  free(data);

  // clear pointer
  rs->data = NULL;
}

// path random source callbacks
static const km_rand_cbs_t
ERAND48_RAND_CBS = {
  .get_floats = on_get_floats,
  .get_sizes  = on_get_sizes,
  .fini       = on_fini,
};

// init system random source (uses system rand())
bool
km_rand_init_erand48(
  km_rand_t * const rs,
  const uint64_t seed
) {
  // alloc rng data
  unsigned short * const data = malloc(3 * sizeof(unsigned short));
  if (!data) {
    // return failure
    return false;
  }

  // populate seed
  data[0] = seed & 0xffff;
  data[1] = (seed >> 16) & 0xffff;
  data[2] = (seed >> 32) & 0xffff;

  // populate context
  rs->cbs = &ERAND48_RAND_CBS;
  rs->data = data;

  // return success
  return true;
}