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Diffstat (limited to 'modules/enet/packet.c')
| -rw-r--r-- | modules/enet/packet.c | 165 |
1 files changed, 165 insertions, 0 deletions
diff --git a/modules/enet/packet.c b/modules/enet/packet.c new file mode 100644 index 0000000000..5fa78b28ae --- /dev/null +++ b/modules/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); +} + +/** @} */ |