libraw1394: version 2.0.4
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# 3.3. Ports

A computer may have multiple 1394 buses connected by having multiple 1394 chips. Each of these is called a port, and the handle has to be connected to one port before it can be used for anything. Even if no nodes are connected to the chip in question, it forms a complete bus (with just one node, itself).

A list of available ports together with some information about it (name of the hardware, number of connected nodes) is available via `raw1394_get_port_info()`, which is to be called right after getting a fresh handle. The user should be presented with a choice of available ports if there is more than one. It may be good practice to do that even if there is only one port, since that may result from a normally configured port just not being available, making it confusing to be dropped right into the application attached to a port without a choice and notion of anything going wrong.

The choice of port is then reported using `raw1394_set_port()`. If this function fails and `errno` is set to `ESTALE`, then something has changed about the ports (port was added or removed) between getting the port info and trying to set a port. It is required that the current port list is fetched (presenting the user with the choice again) and setting the port is retried with the new data.

After a successful `raw1394_set_port()`, the get and set port functions must not be used anymore on this handle. Undefined results occur if you do so. To make up for this, all the other functions are allowed now.

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