This function is called by the Rime code before a packet is to be sent by a device driver. This assures that the entire packet is consecutive in memory.

−

Note that, this code assumes ~~that~~ the lengths and other variables ~~are already~~ set properly.

'''Note that, this code assumes the lengths and other variables to be set properly.'''

The source code of this function is as follows.

</source>

Here is an example illustrating the above mentioned concept.

[[File:Packetbuf_compact2.jpg|500px|center]]

If the data is not external, but the data is not compactly stored, this function makes it compact. If bufptr > 0, then there is a gap or offset between the actual beginning location of the data section and the supposed beginning location of the data section i.e the location with id = PACKETBUF_HDR_SIZE. This function shift the data to the supposed location within the buffer. The following code does that.

The external buffer to which the packetbuf is to be copied must be able to accomodate at least PACKETBUF_HDR_SIZE bytes. The number of bytes that was copied to the external buffer is returned.

The source code this function is as follows.

{

}

#endif /* DEBUG_LEVEL */

−

memcpy(to, packetbuf + hdrptr, PACKETBUF_HDR_SIZE - hdrptr);

memcpy(to, packetbuf + hdrptr, PACKETBUF_HDR_SIZE - hdrptr);//packetbuf points to the beginning of the buffer array.

return PACKETBUF_HDR_SIZE - hdrptr;

}

−

In the above potion of code, the main line is the ~~follwing~~

In the above potion of code, the main line is the following

memcpy(to, packetbuf + hdrptr, PACKETBUF_HDR_SIZE - hdrptr);

Exception encountered, of type "Error"