Adding enet library for future replacement of tcp

Externals/enet/packet.c

@@ -0,0 +1,165 @@
+/** 
+ @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 data         initial contents of the packet's data; the packet's data will remain uninitialized if data 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;
+    packet -> userData = NULL;
+
+    return packet;
+}
+
+/** Destroys the packet and deallocates its data.
+    @param packet packet to be destroyed
+*/
+void
+enet_packet_destroy (ENetPacket * packet)
+{
+    if (packet == NULL)
+      return;
+
+    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 (void)
+{
+    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);
+}
+
+/** @} */