#include jos.h

void process_zb(void *arg)
{
  ZB_call *zb, *other;
  JRB tmp;
  Dllist l;
  int nbytes;

  zb = (ZB_call *) arg;
  tmp = jrb_find_str(JG.zb_waiters, zb->name);

  /* If there's no matching call in the tree, insert the ZB_call and return */

  if (tmp == NULL) {
    l = new_dllist();
    dll_append(l, new_jval_v((void *) zb));
    jrb_insert_str(JG.zb_waiters, zb->name, new_jval_v((void *) l));
    return;   
  }

  l = (dllist) tmp->val.v;
  other = (ZB_call *) l->flink;

  /* If the other calls in the tree are of the same type, append the ZB_call and return */

  if (other->send_or_receive == zb->send_or_receive) {
    dll_append(l, new_jval_v((void *) zb));
    return;  
  }

  /* Otherwise, we have a match.  First remove it from the list/tree: */

  dll_delete_node(l->flink);
  if (dll_empty(l)) {
    dll_free_tree(l);
    jrb_delete_node(tmp);
  }

  /* The rest of the code is the same as before. */

  nbytes = zb->size;
  if (other->size < nbytes) nbytes = other->size;
  if (zb->send_or_receive == 'S') {
    memcpy(other->physical->ptr, zb->physical->ptr, nbytes);
  } else {
    memcpy(zb->physical->ptr, other->physical->ptr, nbytes);
  }

  /* Set the return value (it goes is Register 2, but any one would do for this exam). */

  zb->caller->regs[Reg2] = nbytes;
  other->caller->regs[Reg2] = nbytes;

  /* Put the two PCB's onto the ready queue */

  dll_append(JG.readyq, new_jval_v((void *) zb->caller));
  dll_append(JG.readyq, new_jval_v((void *) other->caller));

  /* Finally, free up the memory */

  free(zb);
  free(other);
  return;
}