The IRAPI maintains state information about channel activities. These library states prevent applications from overloading telephony hardware and eliminate ambiguities in the library. For example, an idle channel is in the IRS_IDLE library state, and a playing channel is in the IRS_PLAYING library state. Most states indicate the activity currently active on the channel. There are also several state modifiers including:

• IRS_PENDING – Indicates that some activity is waiting until resources are available. The activity cannot be started until resources are available, at which time the IRS_PENDING modifier is cleared.
• IRS_QUEUED – Indicates that an activity has been queued but not yet started
• IRS_DEINITING – Indicates that a channel is being deinitialized. A channel_id in this state can not be used.

The irLibState(3IRAPI) function is used to determine the library state of a channel. The irSName(3IRAPI) function returns a character string containing the name of the states and/or modifiers of the library state passed as an argument.

Library states are useful for resolving ambiguities about the ordering of events, such and IRE_INPUT and IRE_PLAY_DONE, or for debugging applications. Applications should not use the library state to drive behavior. Application behavior should be driven by the events that result from asynchronous activities.

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