Copyright	(c) Henning Thielemann, 2010 (c) Iavor S. Diatchki, 2007
License	BSD3
Maintainer	Henning Thielemann
Stability	provisional
Safe Haskell	Safe
Language	Haskell2010

Sound.ALSA.Sequencer

Contents

Sequencer
- Manage user-space buffers
- Manage kernel-space memory pools

Description

Overview: http://www.alsa-project.org/alsa-doc/alsa-lib/seq.html

WARNING: This whole library does not seem to be particlarly thread aware. Perhaps place the sequencer handle in an MVar?

Synopsis

Sequencer

data T mode Source

The type of sequencer handles.

Instances

Eq (T mode) Source

class OpenMode mode Source

Read/Write permissions for the sequencer device. This way we prevent the ALSA exception 22 "Invalid argument" when calling event_output on an input-only sequencer.

Minimal complete definition

expOpenMode

Instances

OpenMode DuplexMode Source
OpenMode InputMode Source
OpenMode OutputMode Source

class OpenMode mode => AllowOutput mode Source

Instances

AllowOutput DuplexMode Source
AllowOutput OutputMode Source

class OpenMode mode => AllowInput mode Source

Instances

AllowInput DuplexMode Source
AllowInput InputMode Source

data OutputMode Source

Constructors

OutputMode

Instances

Show OutputMode Source
AllowOutput OutputMode Source
OpenMode OutputMode Source

data InputMode Source

Constructors

InputMode

Instances

Show InputMode Source
AllowInput InputMode Source
OpenMode InputMode Source

data DuplexMode Source

Constructors

DuplexMode

Instances

Show DuplexMode Source
AllowOutput DuplexMode Source
AllowInput DuplexMode Source
OpenMode DuplexMode Source

data BlockMode Source

Blocking behavior of the sequencer device.

Constructors

Block	Operations may block.
Nonblock	Throw exceptions instead of blocking.

Instances

Eq BlockMode Source
Show BlockMode Source

open Source

Arguments

:: OpenMode mode
=> String	The sequencer's "name". This is not a name that you make up for your own purposes; it has special significance to the ALSA library. Usually you need to pass `defaultName` here or simply use `openDefault`.
-> BlockMode	Blocking behavior
-> IO (T mode)	Handle to the sequencer.

Creates a new handle and opens a connection to the kernel sequencer interface. After a client is created successfully, a ClientStart event is broadcast to the announce port. May throw an exception. See also: open_lconf, close, get_seq_type, get_seq_name, set_blocking, get_client_id.

openDefault Source

Arguments

:: OpenMode mode
=> BlockMode	Blocking behavior
-> IO (T mode)	Handle to the sequencer.

close Source

Arguments

:: T mode	handle to the sequencer
-> IO ()

Close the sequencer. Closes the sequencer client and releases its resources. After a client is closed, an event with ClientExit is broadcast to announce port. The connection between other clients are disconnected. Call this just before exiting your program. NOTE: we could put this in a finalizer for the handle?

with Source

Arguments

:: OpenMode mode
=> String	The sequencer's "name". This is not a name that you make up for your own purposes; it has special significance to the ALSA library. Usually you need to pass `defaultName` here or simply use `withDefault`.
-> BlockMode	Blocking behavior
-> (T mode -> IO a)	Action on the sequencer, the result must be computed strictly.
-> IO a

withDefault :: OpenMode mode => BlockMode -> (T mode -> IO a) -> IO a Source

defaultName :: String Source

This is the name that should be passed to open in most cases.

getName Source

Arguments

:: T mode	sequencer handle
-> IO String	ALSA identifier for the handle

Get identifier of a sequencer handle. It is the same identifier specified in the call to open.

setBlocking Source

Arguments

:: T mode	sequencer handle
-> BlockMode	blocking mode
-> IO ()

Change the blocking mode of the given client. In block mode, the client falls into sleep when it fills the output pool with events, or when it demands events from an empty input pool. memory pool with full events. Clients that are sleeping due to loack of space in the output pool are woken when a certain amount of free space becomes available (see set_output_room).

Manage user-space buffers

getOutputBufferSize Source

Arguments

:: T mode	Sequencer handle.
-> IO Word	Size of output buffer in bytes.

Return the byte size of the output buffer.

setOutputBufferSize Source

Arguments

:: T mode	Sequencer handle.
-> Word	New buffer size in bytes.
-> IO ()

Resize of the output buffer. This function clears all output events (see drop_output).

getInputBufferSize Source

Arguments

:: T mode	Sequencer handle.
-> IO Word	Size of input buffer in bytes.

Return the byte size of input buffer.

setInputBufferSize Source

Arguments

:: T mode	Sequencer handle.
-> Word	New byffer size in bytes.
-> IO ()

Resize the input buffer. This function clears all input events (see drop_input).

Manage kernel-space memory pools

setPoolOutput Source

Arguments

:: T mode	Sequencer handle.
-> Word	New size in bytes.
-> IO ()

Resize the output memory pool.

setPoolOutputRoom Source

Arguments

:: T mode	Sequencer handle.
-> Word	Number of bytes need to wake up.
-> IO ()

Specify how much space should become free before waking clients that are blocked due to a lack of space in the output pool.

resetPoolOutput Source

Arguments

:: T mode	Sequencer handle.
-> IO ()

Reset the output pool.

setPoolInput Source

Arguments

:: T mode	Sequencer handle.
-> Word	New size in bytes.
-> IO ()

Resize the input memory pool.

resetPoolInput Source

Arguments

:: T mode	Sequencer handle.
-> IO ()

Reset the input pool.