/
netplay.c
1209 lines (989 loc) · 32.5 KB
/
netplay.c
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/*
* This program 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 Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 Library General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#include "netplay.h"
extern int gtk_stop_asked;
#define DEBUG
const int PACKET_IDENTIFIER = 0;
const int PACKET_IDENTIFICATION_ID = 0x55;
const int PACKET_IDENTIFICATION_ACKNOWLEDGE_ID = 0x96;
const int PACKET_STATUS_ID = 0xC2;
const int PACKET_DIGEST_ID = 0x3B;
const int PACKET_INTERNET_DIGEST_ID = 0x1F;
const int PACKET_IDENTIFICATION_NUMBER_REQUESTED_SLOTS = 1;
const int PACKET_IDENTIFICATION_INPUT_DEVICE_INDEX = 2;
const int PACKET_IDENTIFICATION_INPUT_DEVICE_NUMBER = 5;
const int PACKET_IDENTIFICATION_CHECKSUM = 7;
const int PACKET_IDENTIFICATION_LENGTH = 8;
const int PACKET_IDENTIFICATION_ACKNOWLEDGE_NUMBER_ALLOCATED_SLOTS = 1;
const int PACKET_IDENTIFICATION_ACKNOWLEDGE_CHECKSUM = 2;
const int PACKET_IDENTIFICATION_ACKNOWLEDGE_LENGTH = 3;
const int PACKET_STATUS_FRAME_NUMBER = 1;
const int PACKET_STATUS_INPUT_DEVICE_INDEX = 5;
const int PACKET_STATUS_INPUT_DEVICE_NUMBER = 5;
const int PACKET_STATUS_CHECKSUM = 10;
const int PACKET_STATUS_LENGTH = 11;
const int PACKET_INTERNET_DIGEST_FRAME_NUMBER = 1;
const int PACKET_INTERNET_DIGEST_NUMBER_DIGEST = 5;
const int PACKET_INTERNET_DIGEST_DIGEST_INDEX = 6;
const int PACKET_INTERNET_DIGEST_DIGEST_NUMBER = 5;
const int PACKET_INTERNET_DIGEST_BASE_LENGTH = 7;
const int PACKET_INTERNET_DIGEST_INCREMENT_LENGTH = 5;
const int MAX_NUMBER_PLAYER = 5;
const int MIN_NUMBER_PLAYER = 1;
const int SERVER_SOCKET_TIMEOUT = 1000; /* In millisecond */
const int CLIENT_SOCKET_TIMEOUT = 10; /* In millisecond */
const int CLIENT_SOCKET_INTERNET_TIMEOUT = 20; /* In millisecond */
const int CLIENT_PACKET_SIZE = 11;
const int SERVER_PACKET_SIZE = 7 + 5 * 5;
const int DEFAULT_SERVER_PORT = 25679;
const int FRAME_PER_SECOND = 60;
const int DIGEST_SIZE = 5;
const int BUFFER_SIZE_SECONDS = 60 * 2; /* two minuts */
const int BUFFER_SIZE_BYTES = 60 * 2 * 60 * 5; /* size in seconds * frame per seconds * digest size */
const int AUTO_OUTDATE = 60 * 2 * 60; /* size in seconds * frame per seconds */
const double DOUBLE_FRAME_DURATION = 1.0 / 60.0; /* In second */
const int SDL_TICKS_PER_SECOND = 1000;
/*!
* In the lan protocol implementation, this array holds the input for the previous frame
*/
static UChar previous_input_value[5];
/*!
* In the internet protocol implementation, this pointer holds the history */
static UChar *history_digest = NULL;
//! Send packet for the previous frame
void send_previous_digest_packet (global_status_type * global_status,
global_option_type * global_option,
IPaddress address);
/*!
* Initializes the network for netplay. SDL has to be initialized first.
*/
int
init_network ()
{
if (SDLNet_Init () == -1)
{
printf ("SDLNet_Init: Error\n");
return 2;
}
return 0;
}
/*!
* Release the network for netplay. It doesn't change the state of SDL
*/
void
shutdown_network ()
{
SDLNet_Quit ();
}
/*!
* Compute the rotation of the value (equivalent of ROL in ia32 asm)
* \param value the value to rotate
* \return the rotated value
*/
UChar
rotate_left (UChar value)
{
return (UChar) ((value << 1) + ((value & 0x80) ? 1 : 0));
}
/*!
* Compute the check sum value according to the algorithm found in the header file
* \param data the array on which perform the computation
* \param index_min first index in the array to take into account
* \param index_max last index (EXCLUSIVE) in the array to take into account
*/
unsigned char
compute_checksum (unsigned char *data, int index_min, int index_max)
{
UChar checksum;
int index;
checksum = 0;
for (index = index_min; index < index_max; index++)
{
checksum ^= data[index];
checksum = rotate_left (checksum);
}
return checksum;
}
/*!
* Side effect free minimum computation
*/
static int
min (int lhs, int rhs)
{
return (lhs < rhs) ? lhs : rhs;
}
/*!
* Returns the number of free (unidentified and under the limit requested) slots
*/
int
count_remaining_slot (global_status_type * global_status,
global_option_type * global_option)
{
return global_option->number_player -
global_status->number_identified_players;
}
/*!
* Check if two SDLNet addresses are the same
* \return non null value is addresses match, else 0
*/
int
equals_address (IPaddress lhs, IPaddress rhs)
{
return (lhs.host == rhs.host) && (lhs.port == rhs.port);
}
/*!
* Build and send a packet to acknowledge an identification. We use the digest
* packet structure to prepare it.
*/
void
send_identification_acknowledge_packet (global_status_type * global_status,
int number_allocated_slots)
{
int number_destination;
/* Set the identifier */
global_status->digest_packet->data[PACKET_IDENTIFIER] =
PACKET_IDENTIFICATION_ACKNOWLEDGE_ID;
/* Set the number of allocated slots */
global_status->digest_packet->
data[PACKET_IDENTIFICATION_ACKNOWLEDGE_NUMBER_ALLOCATED_SLOTS] =
number_allocated_slots;
/* Compute the checksum */
global_status->digest_packet->
data[PACKET_IDENTIFICATION_ACKNOWLEDGE_CHECKSUM] =
compute_checksum (global_status->digest_packet->data, PACKET_IDENTIFIER,
PACKET_IDENTIFICATION_ACKNOWLEDGE_CHECKSUM);
global_status->digest_packet->len =
PACKET_IDENTIFICATION_ACKNOWLEDGE_LENGTH;
/* Back to sender */
global_status->digest_packet->address =
global_status->current_packet->address;
number_destination = SDLNet_UDP_Send (global_status->server_socket,
-1, global_status->digest_packet);
if (number_destination != 1)
{
fprintf (stderr,
"Couldn't send the identification acknowledge packet to client\n");
}
}
/*!
* Compare given address with previous address from which slot allocation have been successfully processed
* \param global_status the global status for the server
* \parem address the address to check
* \return -1 is the address was never seen
* \return the number of slots we allocated for it back then, else
*/
int
compare_request_to_previous (global_status_type * global_status,
IPaddress address)
{
int slot_index;
for (slot_index = 0; slot_index < global_status->number_allocation_request;
slot_index++)
{
if (equals_address
(address, global_status->allocation_request[slot_index].address))
{
/* We found a previous request */
return global_status->allocation_request[slot_index].
allocated_slots;
}
}
return -1;
}
/*!
* Process an identification request from a client, filling the interesting
* fields in the global_status structure to find later the client
*/
void
identify_client (global_status_type * global_status,
global_option_type * global_option)
{
int requested_slots;
int allocated_slots;
int slot_index;
int already_allocated_slot_by_client;
if (global_status->current_packet->len != PACKET_IDENTIFICATION_LENGTH)
{
/* Discarding invalid packet */
#if defined(DEBUG)
fprintf (stderr,
"Invalid packet received when in identification phase (received length: %d, expected length: %d)\n",
global_status->current_packet->len,
PACKET_IDENTIFICATION_LENGTH);
#endif
return;
}
if (global_status->current_packet->data[PACKET_IDENTIFIER] !=
PACKET_IDENTIFICATION_ID)
{
/* Discarding invalid packet */
#if defined(DEBUG)
fprintf (stderr,
"Invalid packet received when in identification phase (received ID: 0x%02x, expected ID: 0x%02x)\n",
global_status->current_packet->data[PACKET_IDENTIFIER],
PACKET_IDENTIFICATION_ID);
#endif
return;
}
if (global_status->current_packet->data[PACKET_IDENTIFICATION_CHECKSUM] !=
compute_checksum (global_status->current_packet->data,
PACKET_IDENTIFIER, PACKET_IDENTIFICATION_CHECKSUM))
{
/* Discarding invalid packet */
#if defined(DEBUG)
fprintf (stderr,
"Packet checksum received when in identification phase (received checksum: 0x%02x, expected checksum: 0x%02x)\n",
global_status->current_packet->
data[PACKET_IDENTIFICATION_CHECKSUM],
compute_checksum (global_status->current_packet->data,
PACKET_IDENTIFIER,
PACKET_IDENTIFICATION_CHECKSUM));
#endif
return;
}
requested_slots =
global_status->current_packet->
data[PACKET_IDENTIFICATION_NUMBER_REQUESTED_SLOTS];
allocated_slots =
min (requested_slots,
count_remaining_slot (global_status, global_option));
/* Check if it's a new request or a re-request (happens when the client didn't get the acknowledgement) */
already_allocated_slot_by_client =
compare_request_to_previous (global_status,
global_status->current_packet->address);
if (already_allocated_slot_by_client != -1)
{
/* We already answered this client, we'll reacknowledge */
send_identification_acknowledge_packet (global_status,
already_allocated_slot_by_client);
return;
}
for (slot_index = global_status->number_identified_players;
slot_index <
global_status->number_identified_players + allocated_slots;
slot_index++)
{
/* Set the address for identified player */
global_status->input_mapping[slot_index].address.port =
global_status->current_packet->address.port;
global_status->input_mapping[slot_index].address.host =
global_status->current_packet->address.host;
/* Set the remote input device number */
global_status->input_mapping[slot_index].remote_input_device =
global_status->current_packet->
data[PACKET_IDENTIFICATION_INPUT_DEVICE_INDEX + slot_index -
global_status->number_identified_players];
/* Change status from UNIDENTIFIED */
global_status->player_status[slot_index] = WAITING;
}
global_status->allocation_request[global_status->number_allocation_request].
address.port = global_status->current_packet->address.port;
global_status->allocation_request[global_status->number_allocation_request].
address.host = global_status->current_packet->address.host;
global_status->allocation_request[global_status->number_allocation_request].
allocated_slots = allocated_slots;
global_status->number_allocation_request++;
global_status->number_identified_players += allocated_slots;
send_identification_acknowledge_packet (global_status, allocated_slots);
}
/*!
* Read an incoming packet and stores it for future computations
* \return non null if a packet was read
* \return 0 if no packet is available
*/
int
read_incoming_server_packet (global_status_type * global_status)
{
switch (SDLNet_UDP_Recv
(global_status->server_socket, global_status->current_packet))
{
case 0:
return 0;
case 1:
#if defined(DEBUG)
fprintf (stderr, "Stored a packet from client.\n");
#endif
return 1;
default:
fprintf (stderr, "Internal warning: impossible case (%s:%s)\n",
__FILE__, __LINE__);
return 0;
}
return 0;
}
/*!
* Process a status packet and updates global input status and client status
*/
void
store_remote_status_lan (global_status_type * global_status,
global_option_type * global_option)
{
int input_index;
if (global_status->current_packet->len != PACKET_STATUS_LENGTH)
{
/* Discarding invalid packet */
#if defined(DEBUG)
fprintf (stderr,
"Invalid packet received when in status receiving phase (received length: %d, expected length: %d)\n",
global_status->current_packet->len, PACKET_STATUS_LENGTH);
#endif
/* If may be an identification packet which was lost at some point */
identify_client (global_status, global_option);
return;
}
if (global_status->current_packet->data[PACKET_IDENTIFIER] !=
PACKET_STATUS_ID)
{
/* Discarding invalid packet */
#if defined(DEBUG)
fprintf (stderr,
"Invalid packet received when in status receiving phase (received ID: 0x%02x, expected ID: 0x%02x)\n",
global_status->current_packet->data[PACKET_IDENTIFIER],
PACKET_STATUS_ID);
#endif
return;
}
if (global_status->frame_number !=
SDLNet_Read32 (global_status->current_packet->data +
PACKET_STATUS_FRAME_NUMBER))
{
if (global_status->frame_number ==
SDLNet_Read32 (global_status->current_packet->data +
PACKET_STATUS_FRAME_NUMBER) + 1)
{
/*
* This a request for the previous frame, i.e. a client lost his digest, we resend it to him
*/
send_previous_digest_packet (global_status, global_option,
global_status->current_packet->
address);
return;
}
/* Discarding status not corresponding to this frame */
#if defined(DEBUG)
fprintf (stderr,
"Invalid packet received when in status receiving phase (status for frame %d, awaiting for frame %d)\n",
SDLNet_Read32 (global_status->current_packet->data +
PACKET_STATUS_FRAME_NUMBER),
global_status->frame_number);
#endif
return;
}
for (input_index = 0; input_index < MAX_NUMBER_PLAYER; input_index++)
{
if (equals_address
(global_status->current_packet->address,
global_status->input_mapping[input_index].address))
{
if (global_status->player_status[input_index] == READY)
{
#if defined(DEBUG)
fprintf (stderr,
"We have another status for the same frame, same origin.");
#endif
/* TODO : check if it's the same status we already have stored */
}
/* Global input number input_index will be filled by this packet status */
global_status->input_value[input_index] =
global_status->current_packet->
data[PACKET_STATUS_INPUT_DEVICE_INDEX +
global_status->input_mapping[input_index].
remote_input_device];
#if defined(DEBUG)
fprintf (stderr, "input value[%d] = 0x%02x (data[%d])\n",
input_index,
global_status->current_packet->
data[PACKET_STATUS_INPUT_DEVICE_INDEX +
global_status->input_mapping[input_index].
remote_input_device],
PACKET_STATUS_INPUT_DEVICE_INDEX +
global_status->input_mapping[input_index].
remote_input_device);
#endif
/* Slot is now filled */
global_status->player_status[input_index] = READY;
}
}
}
/*!
* Reset the input value to begin with a new frame
*/
void
init_frame_status (global_status_type * global_status,
global_option_type * global_option)
{
int player_index;
for (player_index = 0; player_index < global_option->number_player;
player_index++)
{
previous_input_value[player_index] =
global_status->input_value[player_index];
global_status->input_value[player_index] = 0;
global_status->player_status[player_index] = WAITING;
}
}
/*!
* Send a digest packet to a single client
*/
void
send_individual_digest_packet (IPaddress client_address,
global_status_type * global_status)
{
int number_destination;
global_status->digest_packet->address = client_address;
number_destination = SDLNet_UDP_Send (global_status->server_socket,
-1, global_status->digest_packet);
if (number_destination != 1)
{
fprintf (stderr, "Couldn't send the status packet to client\n");
}
}
/*!
* Send a digest packet to clients if they reeeeeeeeeally deserve it
*/
void
send_digest_lan_packets (global_status_type * global_status,
global_option_type * global_option)
{
int player_index;
for (player_index = 0; player_index < global_option->number_player;
player_index++)
{
if (global_status->player_status[player_index] != READY)
{
#if defined(DEBUG)
fprintf (stderr,
"Player number %d not being READY prevent the sending of the digest packet\n",
player_index);
#endif
return;
}
}
/* If we're here, all concerned clients are READY (== we got their status) */
/* Set the identifier */
global_status->digest_packet->data[PACKET_IDENTIFIER] = PACKET_DIGEST_ID;
/* Set the current frame */
SDLNet_Write32 (global_status->frame_number,
global_status->digest_packet->
data + PACKET_STATUS_FRAME_NUMBER);
/* Set the digest input values */
for (player_index = 0; player_index < global_option->number_player;
player_index++)
{
global_status->digest_packet->data[PACKET_STATUS_INPUT_DEVICE_NUMBER +
player_index] =
global_status->input_value[player_index];
}
/* Compute the checksum */
global_status->digest_packet->
data[PACKET_STATUS_CHECKSUM] =
compute_checksum (global_status->digest_packet->data, PACKET_IDENTIFIER,
PACKET_STATUS_CHECKSUM);
global_status->digest_packet->len = PACKET_STATUS_LENGTH;
/* Now, global_status->digest_packet is THE digest packet we can send to all clients */
for (player_index = 0; player_index < global_option->number_player;
player_index++)
{
/* TODO : find a much more elegant and efficient way to find unique client addresses */
int duplicate_index;
int already_sent;
already_sent = 0;
for (duplicate_index = 0; duplicate_index < player_index;
duplicate_index++)
{
if (equals_address
(global_status->input_mapping[player_index].address,
global_status->input_mapping[duplicate_index].address))
{
already_sent = 1;
break;
}
}
if (!already_sent)
{
send_individual_digest_packet (global_status->
input_mapping[player_index].address,
global_status);
}
}
/* We're done with this frame, skip to the next one */
global_status->frame_number++;
/* Get ready for receiving status for next (now current) frame */
init_frame_status (global_status, global_option);
}
/*!
* Send the digest packet of the previous frame to a single client
*/
void
send_previous_digest_packet (global_status_type * global_status,
global_option_type * global_option,
IPaddress address)
{
int player_index;
/* Set the identifier */
global_status->digest_packet->data[PACKET_IDENTIFIER] = PACKET_DIGEST_ID;
/* Set the previous frame */
SDLNet_Write32 (global_status->frame_number - 1,
global_status->digest_packet->
data + PACKET_STATUS_FRAME_NUMBER);
/* Set the digest input values */
for (player_index = 0; player_index < global_option->number_player;
player_index++)
{
global_status->digest_packet->data[PACKET_STATUS_INPUT_DEVICE_NUMBER +
player_index] =
previous_input_value[player_index];
}
/* Compute the checksum */
global_status->digest_packet->
data[PACKET_STATUS_CHECKSUM] =
compute_checksum (global_status->digest_packet->data, PACKET_IDENTIFIER,
PACKET_STATUS_CHECKSUM);
global_status->digest_packet->len = PACKET_STATUS_LENGTH;
/* Now, global_status->digest_packet is the previous digest packet we can send to this given client */
send_individual_digest_packet (global_status->input_mapping[player_index].
address, global_status);
}
/*!
* Main loop of the lan protocol service
*/
void
serve_clients_lan_protocol (global_status_type * global_status,
global_option_type * global_option)
{
init_frame_status (global_status, global_option);
for (;;)
{
int number_ready_socket;
#if defined(DEBUG)
fprintf (stderr, "Waiting for status packets for frame %u\n",
global_status->frame_number);
#endif
#if defined(GTK)
while (gtk_events_pending())
{
if (gtk_main_iteration())
{
return;
}
}
if (gtk_stop_asked)
{
return;
}
#endif
number_ready_socket =
SDLNet_CheckSockets (global_status->server_socket_set,
SERVER_SOCKET_TIMEOUT);
if (number_ready_socket == -1)
{
fprintf (stderr, "Error in socket waiting (disconnection ?).\n");
break;
}
if (number_ready_socket == 1)
{
#if defined(DEBUG)
fprintf (stderr, "Got a packet\n");
#endif
/* We're awaiting a packet in the server socket */
if (read_incoming_server_packet (global_status))
{
/* Stores the incoming status and updates clients status accordingly */
store_remote_status_lan (global_status, global_option);
/* Sends packet (if needed) to client accordingly to their status */
send_digest_lan_packets (global_status, global_option);
}
}
}
}
/*!
* Return the time remaining before the next timeout to which issue a digest to all clients
* \param global_status the global status of the server
*/
int
get_remaining_time (global_status_type * global_status)
{
double next_time;
UInt32 current_time;
current_time = SDL_GetTicks ();
next_time =
global_status->start_time +
global_status->frame_number * DOUBLE_FRAME_DURATION;
#if defined(DEBUG)
fprintf (stderr,
"Current time : %u ticks (%f second(s))\nTime up next frame (frame %d) : %u ticks (%f second(s))\n",
current_time,
(double) current_time / (double) SDL_TICKS_PER_SECOND,
global_status->frame_number,
(UInt32) (next_time * 1000.0) - current_time,
next_time - current_time / (double) SDL_TICKS_PER_SECOND);
#endif
if ((UInt32) (next_time * 1000.0) < current_time)
{
fprintf (stderr, "The server is too slow, we're late for frame %u\n",
global_status->frame_number);
return 0;
}
return (UInt32) (next_time * 1000.0) - current_time;
}
/*!
* Store an individual input value
*/
void
store_individual_status (global_status_type * global_status,
int input_index, UChar input_value)
{
global_status->input_value[input_index] = input_value;
}
/*!
* Store a packet information and updates the current status as well as the next frame asked by the client
*/
void
store_remote_status_internet (global_status_type * global_status,
global_option_type * global_option)
{
int input_index;
if (global_status->current_packet->len != PACKET_STATUS_LENGTH)
{
/* Discarding invalid packet */
#if defined(DEBUG)
fprintf (stderr,
"Invalid packet received when in status receiving phase (received length: %d, expected length: %d)\n",
global_status->current_packet->len, PACKET_STATUS_LENGTH);
#endif
/* If may be an identification packet which was lost at some point */
identify_client (global_status, global_option);
return;
}
if (global_status->current_packet->data[PACKET_IDENTIFIER] !=
PACKET_STATUS_ID)
{
/* Discarding invalid packet */
#if defined(DEBUG)
fprintf (stderr,
"Invalid packet received when in status receiving phase (received ID: 0x%02x, expected ID: 0x%02x)\n",
global_status->current_packet->data[PACKET_IDENTIFIER],
PACKET_STATUS_ID);
#endif
return;
}
/* TODO : add checksum testing */
for (input_index = 0; input_index < MAX_NUMBER_PLAYER; input_index++)
{
if (equals_address
(global_status->current_packet->address,
global_status->input_mapping[input_index].address))
{
/* Update the status with the client status */
store_individual_status (global_status, input_index,
global_status->current_packet->
data[PACKET_STATUS_INPUT_DEVICE_INDEX +
global_status->
input_mapping[input_index].
remote_input_device]);
if (SDLNet_Read32
(global_status->current_packet->data +
PACKET_STATUS_FRAME_NUMBER) != 0)
{
/* The client requested a given frame */
/* Update the next frame to send to this player */
global_status->next_frame_asked[input_index] =
SDLNet_Read32 (global_status->current_packet->data +
PACKET_STATUS_FRAME_NUMBER);
#if defined(DEBUG)
if (global_status->next_frame_asked[input_index] ==
global_status->frame_number)
{
fprintf (stderr,
"Great, player is waiting for the current frame, lag is less than a frame delay (player %d).\n",
input_index);
}
if (global_status->next_frame_asked[input_index] ==
global_status->next_frame_to_send[input_index])
{
fprintf (stderr,
"Half great, we don't have packets loss, the game should be smooth (player %d).\n",
input_index);
}
#endif
if (global_status->next_frame_asked[input_index] >
global_status->frame_number)
{
fprintf (stderr,
"Error, player asked a frame which hasn't been reached yet! (asked: %d, maximum: %d)\n",
global_status->next_frame_asked[input_index],
global_status->frame_number);
global_status->next_frame_asked[input_index] =
global_status->frame_number;
}
if ((global_status->frame_number > AUTO_OUTDATE)
&& (global_status->next_frame_asked[input_index] <=
global_status->frame_number - AUTO_OUTDATE))
{
fprintf (stderr,
"FATAL ERROR !! Player requested an outdated frame, we can't provide it! (requested : %d, available range : %d - %d)\n",
global_status->next_frame_asked[input_index],
global_status->frame_number - AUTO_OUTDATE,
global_status->frame_number);
/* TODO: think about actions which should be performed in this case. */
}
/* Update the counter for sending frames */
global_status->next_frame_to_send[input_index] =
global_status->next_frame_asked[input_index];
}
else
{
#if defined(DEBUG)
fprintf (stderr,
"Client sends a status without requesting a specific frame.\n");
#endif
}
}
}
}
/*!
* Allocate memory for the history
*/
void
init_internet_history ()
{
if (history_digest != NULL)
{
fprintf (stderr, "Attempting to reallocate the history.\n");
return;
}
history_digest = (UChar *) malloc ((size_t) BUFFER_SIZE_BYTES);
if (history_digest == NULL)
{
fprintf (stderr,
"FATAL ERROR ! Couldn't allocate memory for the history. Exiting.\n");
exit (2);
}
}
/*!
* Free memory for the history
*/
void
release_internet_history ()
{
if (history_digest == NULL)
{
fprintf (stderr, "Attempting to free non allocated history.\n");
return;
}
free (history_digest);
}
/*!
* Push the current frame status in the history
*/
void
store_current_status_in_history (global_status_type * global_status)
{
memcpy (history_digest +
(global_status->frame_number % AUTO_OUTDATE) * DIGEST_SIZE,
global_status->input_value, DIGEST_SIZE);
}
/*!
* Send a packet to a client to fit the need in term of frame number(s)
* \param global_status global status for the application
* \param client_index index of the global player to which send a packet
*/
void
send_individual_internet_digest_packet (global_status_type * global_status,
int client_index)
{
unsigned int frame_number;
unsigned int frame_number_start;
int number_digest;
int digest_index;
int number_destination;
/* Set the identifier */
global_status->digest_packet->data[PACKET_IDENTIFIER] =
PACKET_INTERNET_DIGEST_ID;
/* Set the number of the first frame digest */
SDLNet_Write32 (global_status->next_frame_to_send[client_index],
global_status->digest_packet->data +
PACKET_INTERNET_DIGEST_FRAME_NUMBER);
/* Compute the number of digest to send */
number_digest =
min (PACKET_INTERNET_DIGEST_DIGEST_NUMBER, global_status->frame_number);