162 строки
3.7 KiB
C
162 строки
3.7 KiB
C
/**
|
|
@file packet.c
|
|
@brief ENet packet management functions
|
|
*/
|
|
#include <string.h>
|
|
#define ENET_BUILDING_LIB 1
|
|
#include "enet/enet.h"
|
|
|
|
/** @defgroup Packet ENet packet functions
|
|
@{
|
|
*/
|
|
|
|
/** Creates a packet that may be sent to a peer.
|
|
@param dataContents initial contents of the packet's data; the packet's data will remain uninitialized if dataContents is NULL.
|
|
@param dataLength size of the data allocated for this packet
|
|
@param flags flags for this packet as described for the ENetPacket structure.
|
|
@returns the packet on success, NULL on failure
|
|
*/
|
|
ENetPacket *
|
|
enet_packet_create (const void * data, size_t dataLength, enet_uint32 flags)
|
|
{
|
|
ENetPacket * packet = (ENetPacket *) enet_malloc (sizeof (ENetPacket));
|
|
if (packet == NULL)
|
|
return NULL;
|
|
|
|
if (flags & ENET_PACKET_FLAG_NO_ALLOCATE)
|
|
packet -> data = (enet_uint8 *) data;
|
|
else
|
|
if (dataLength <= 0)
|
|
packet -> data = NULL;
|
|
else
|
|
{
|
|
packet -> data = (enet_uint8 *) enet_malloc (dataLength);
|
|
if (packet -> data == NULL)
|
|
{
|
|
enet_free (packet);
|
|
return NULL;
|
|
}
|
|
|
|
if (data != NULL)
|
|
memcpy (packet -> data, data, dataLength);
|
|
}
|
|
|
|
packet -> referenceCount = 0;
|
|
packet -> flags = flags;
|
|
packet -> dataLength = dataLength;
|
|
packet -> freeCallback = NULL;
|
|
|
|
return packet;
|
|
}
|
|
|
|
/** Destroys the packet and deallocates its data.
|
|
@param packet packet to be destroyed
|
|
*/
|
|
void
|
|
enet_packet_destroy (ENetPacket * packet)
|
|
{
|
|
if (packet -> freeCallback != NULL)
|
|
(* packet -> freeCallback) (packet);
|
|
if (! (packet -> flags & ENET_PACKET_FLAG_NO_ALLOCATE) &&
|
|
packet -> data != NULL)
|
|
enet_free (packet -> data);
|
|
enet_free (packet);
|
|
}
|
|
|
|
/** Attempts to resize the data in the packet to length specified in the
|
|
dataLength parameter
|
|
@param packet packet to resize
|
|
@param dataLength new size for the packet data
|
|
@returns 0 on success, < 0 on failure
|
|
*/
|
|
int
|
|
enet_packet_resize (ENetPacket * packet, size_t dataLength)
|
|
{
|
|
enet_uint8 * newData;
|
|
|
|
if (dataLength <= packet -> dataLength || (packet -> flags & ENET_PACKET_FLAG_NO_ALLOCATE))
|
|
{
|
|
packet -> dataLength = dataLength;
|
|
|
|
return 0;
|
|
}
|
|
|
|
newData = (enet_uint8 *) enet_malloc (dataLength);
|
|
if (newData == NULL)
|
|
return -1;
|
|
|
|
memcpy (newData, packet -> data, packet -> dataLength);
|
|
enet_free (packet -> data);
|
|
|
|
packet -> data = newData;
|
|
packet -> dataLength = dataLength;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int initializedCRC32 = 0;
|
|
static enet_uint32 crcTable [256];
|
|
|
|
static enet_uint32
|
|
reflect_crc (int val, int bits)
|
|
{
|
|
int result = 0, bit;
|
|
|
|
for (bit = 0; bit < bits; bit ++)
|
|
{
|
|
if(val & 1) result |= 1 << (bits - 1 - bit);
|
|
val >>= 1;
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
static void
|
|
initialize_crc32 ()
|
|
{
|
|
int byte;
|
|
|
|
for (byte = 0; byte < 256; ++ byte)
|
|
{
|
|
enet_uint32 crc = reflect_crc (byte, 8) << 24;
|
|
int offset;
|
|
|
|
for(offset = 0; offset < 8; ++ offset)
|
|
{
|
|
if (crc & 0x80000000)
|
|
crc = (crc << 1) ^ 0x04c11db7;
|
|
else
|
|
crc <<= 1;
|
|
}
|
|
|
|
crcTable [byte] = reflect_crc (crc, 32);
|
|
}
|
|
|
|
initializedCRC32 = 1;
|
|
}
|
|
|
|
enet_uint32
|
|
enet_crc32 (const ENetBuffer * buffers, size_t bufferCount)
|
|
{
|
|
enet_uint32 crc = 0xFFFFFFFF;
|
|
|
|
if (! initializedCRC32) initialize_crc32 ();
|
|
|
|
while (bufferCount -- > 0)
|
|
{
|
|
const enet_uint8 * data = (const enet_uint8 *) buffers -> data,
|
|
* dataEnd = & data [buffers -> dataLength];
|
|
|
|
while (data < dataEnd)
|
|
{
|
|
crc = (crc >> 8) ^ crcTable [(crc & 0xFF) ^ *data++];
|
|
}
|
|
|
|
++ buffers;
|
|
}
|
|
|
|
return ENET_HOST_TO_NET_32 (~ crc);
|
|
}
|
|
|
|
/** @} */
|