Sound.Alsa.Sequencer.Event

This module contains functions for working with events. Reference: http://www.alsa-project.org/alsa-doc/alsa-lib/group___seq_event.html

Documentation

sync_output_queue :: SndSeq -> IO ()

Wait until all events of the client are processed.

event_input :: SndSeq -> IO Event

Get an event from the input buffer. If the input buffer is empty, then it is filled with data from the sequencer queue. If there is no data in the sequencer queue, then the process is either put to sleep (if the sequencer is operating in blocking mode), or we throw EAGAIN (if the sequence is operating in non-blocking mode).

We may also throw ENOSPC, which means that the sequencer queue over-run and some events were lost (this clears the input buffer).

event_input_pending

Arguments

:: SndSeq

-> Bool

refill if empty?

-> IO Word

number of events in buffer

Returns the number of events in the input buffer. If the input buffer is empty and the boolean argument is true, then try to fill the input buffer with data from the sequencer queue. See also: snd_seq_event_input.

event_output

Arguments

:: SndSeq

-> Event

-> IO Word

the number of remaining events (or bytes?)

Output an event and drain the buffer, if it became full. Throws exceptions. See also: event_output_direct, event_output_buffer, event_output_pending, drain_output, drop_output, extract_output, remove_events

event_output_buffer

Arguments

:: SndSeq

-> Event

-> IO Word

the byte size of remaining events

Output an event without draining the buffer. Throws -EAGAIN if the buffer becomes full. See also event_output.

event_output_direct

Arguments

:: SndSeq

-> Event

-> IO Word

number of bytes sent to the sequencer

Output an event directly to the sequencer, NOT through the output buffer. If an error occurs, then we throw an exception. See also event_output.

event_output_pending

Arguments

:: SndSeq

-> IO Word

size of pending events (in bytes)

Return the size (in bytes) of pending events on output buffer. See also snd_seq_event_output.

extract_output

Arguments

:: SndSeq

-> IO Event

the first event in the buffer (if one was present)

Extract the first event in output buffer. Throws an exception on error. See also snd_seq_event_output.

remove_output :: SndSeq -> IO ()

Remove the first event in output buffer. Throws an exception on error. See also snd_seq_event_output.

drain_output

Arguments

:: SndSeq

-> IO Word

byte size of events remaining in the buffer.

Drain output buffer to sequencer. This function drains all pending events on the output buffer. The function returns immediately after the events are sent to the queues regardless whether the events are processed or not. To get synchronization with the all event processes, use sync_output_queue after calling this function. Throws an exception on error. See also: event_output, sync_output_queue.

drop_output :: SndSeq -> IO ()

Remove events from both the user-space output buffer, and the kernel-space sequencer queue. See also: drain_output, drop_output_buffer, remove_events.

drop_output_buffer :: SndSeq -> IO ()

Remove events from the user-space output buffer. See also: drop_output.

drop_input :: SndSeq -> IO ()

Remove events from both the user-space input buffer, and the kernel-space sequencer queue. See also: drop_input_buffer, remove_events.

drop_input_buffer :: SndSeq -> IO ()

Remove events from the user-space input buffer. See also: drop_input.