/*  RetroArch - A frontend for libretro.
 *  Copyright (C) 2010-2014 - Hans-Kristian Arntzen
 *  Copyright (C) 2011-2017 - Daniel De Matteis
 *  Copyright (C) 2016-2017 - Gregor Richards
 *
 *  RetroArch is free software: you can redistribute it and/or modify it under the terms
 *  of the GNU General Public License as published by the Free Software Found-
 *  ation, either version 3 of the License, or (at your option) any later version.
 *
 *  RetroArch is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 *  without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 *  PURPOSE.  See the GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along with RetroArch.
 *  If not, see <http://www.gnu.org/licenses/>.
 */

#include <stdlib.h>
#include <sys/types.h>

#include <boolean.h>
#include <encodings/crc32.h>

#include "netplay_private.h"

/**
 * netplay_delta_frame_ready
 *
 * Prepares, if possible, a delta frame for input, and reports whether it is
 * ready.
 *
 * Returns: True if the delta frame is ready for input at the given frame,
 * false otherwise.
 */
bool netplay_delta_frame_ready(netplay_t *netplay, struct delta_frame *delta,
   uint32_t frame)
{
   void *remember_state;
   if (delta->used)
   {
      if (delta->frame == frame) return true;
      if (netplay->other_frame_count <= delta->frame)
      {
         /* We haven't even replayed this frame yet, so we can't overwrite it! */
         return false;
      }
   }
   remember_state = delta->state;
   memset(delta, 0, sizeof(struct delta_frame));
   delta->used = true;
   delta->frame = frame;
   delta->state = remember_state;
   return true;
}

/**
 * netplay_delta_frame_crc
 *
 * Get the CRC for the serialization of this frame.
 */
uint32_t netplay_delta_frame_crc(netplay_t *netplay, struct delta_frame *delta)
{
   if (!netplay->state_size)
      return 0;
   return encoding_crc32(0L, (const unsigned char*)delta->state, netplay->state_size);
}