Fibonacci - Otter-Taskification/otter GitHub Wiki

#include <stdio.h>
#include <stdlib.h>
#include <otter/otter-task-graph-user.h>

static const char *fib_format = "fib(%d)";

int fib(int n);

int main(int argc, char *argv[]) {

  if (argc != 2) {
    fprintf(stderr, "usage: %s n\n", argv[0]);
    return 1;
  }

  int n = atoi(argv[1]);
  int fibn = 0;

  OTTER_INITIALISE();

  char phase[256] = {0};
  snprintf(&phase[0], 255, "calculate fib(%d)", n);

  OTTER_DECLARE_HANDLE(root);
  OTTER_INIT_TASK(root, OTTER_NULL_TASK, 0, otter_add_to_pool, fib_format, n);

  OTTER_PHASE_BEGIN(phase);
  OTTER_TASK_START(root);
  fibn = fib(n);
  OTTER_TASK_END(root);
  OTTER_PHASE_END();

  OTTER_TASK_WAIT_FOR(OTTER_NULL_TASK, children);

  printf("fib(%d) = %d\n", n, fibn);

  OTTER_FINALISE();

  printf("%s\n", phase);
  return 0;
}

int fib(int n) {
  if (n < 2)
    return n;
  int i, j;

  OTTER_DECLARE_HANDLE(parent);
  OTTER_REMOVE_FROM_POOL(parent, fib_format, n);

  OTTER_DECLARE_HANDLE(child1);
  OTTER_INIT_TASK(child1, parent, 0, otter_add_to_pool, fib_format, n - 1);
  OTTER_TASK_START(child1);
  i = fib(n - 1);
  OTTER_TASK_END(child1);

  OTTER_DECLARE_HANDLE(child2);
  OTTER_INIT_TASK(child2, parent, 0, otter_add_to_pool, fib_format, n - 2);
  OTTER_TASK_START(child2);
  j = fib(n - 2);
  OTTER_TASK_END(child2);

  OTTER_TASK_WAIT_FOR(parent, children);

  return i + j;
}