main   xtlang

(bind-func main
  (let ((domain_size:i32 100)
        (max_walk_size:i32 500)
        (num_walkers_per_proc:i32 20))
    (lambda ()
      (MPI_Init null null)
      (let ((world_size_ptr:i32* (salloc))
            (world_size (begin
                          (MPI_Comm_size MPI_COMM_WORLD world_size_ptr)
                          (pref world_size_ptr 0)))
            (world_rank_ptr:i32* (salloc))
            (world_rank (begin
                          (MPI_Comm_rank MPI_COMM_WORLD world_rank_ptr)
                          (pref world_rank_ptr 0)))
            (region (decompose_domain domain_size world_rank world_size))
            (incoming_walkers (initialize_walkers num_walkers_per_proc max_walk_size region))
            (walker_ptr (tref incoming_walkers 1))
            (outgoing_walkers (create_walker_array (* num_walkers_per_proc 4)))
            ;; Determine the maximum amount of sends and receives needed to
            ;; complete all walkers
            (maximum_sends_recvs (+ (/ max_walk_size (/ domain_size world_size)) 1)))
        ;; (println
        ;;  "Process" world_rank "initiated" num_walkers_per_proc
        ;;  "walkers in subdomain" (tref region 0) " - " (+ (tref region 0)
        ;;                                                  (tref region 1)
        ;;                                                  -1))
        (doloop (m maximum_sends_recvs)
          (doloop (i (tref incoming_walkers 0))
            (walk (walker_at_index incoming_walkers i) region domain_size outgoing_walkers))
          ;; (println "Process" world_rank "sending" (tref outgoing_walkers 0)
          ;;          "outgoing walkers to process" (% (+ world_rank 1) world_size))
          (if (= (% world_rank 2) 0)
              (begin
                ;; Send all outgoing walkers to the next process.
                (send_outgoing_walkers outgoing_walkers world_rank world_size)
                ;; Receive all the new incoming walkers
                (receive_incoming_walkers incoming_walkers world_rank world_size))
              (begin
                ;; Receive all the new incoming walkers
                (receive_incoming_walkers incoming_walkers world_rank world_size)
                ;; Send all outgoing walkers to the next process.
                (send_outgoing_walkers outgoing_walkers world_rank world_size)))
          (println "Process" world_rank "received" (tref incoming_walkers 0)
                   "incoming walkers"))
        (println "Process" world_rank "done.")