ndk-odin/looper.odin

//+build android
package android

foreign import android "system:android"


/** Option for for ALooper_prepare(). */
/**
* This looper will accept calls to ALooper_addFd() that do not
* have a callback (that is provide NULL for the callback).  In
* this case the caller of ALooper_pollOnce() or ALooper_pollAll()
* MUST check the return from these functions to discover when
* data is available on such fds and process it.
*/
ALOOPER_PREPARE_ALLOW_NON_CALLBACKS = 1<<0

/** Result from ALooper_pollOnce() and ALooper_pollAll(). */
ALooperPollResult :: enum i32 {
    /**
     * The poll was awoken using wake() before the timeout expired
     * and no callbacks were executed and no other file descriptors were ready.
     */
    WAKE = -1,

    /**
     * Result from ALooper_pollOnce() and ALooper_pollAll():
     * One or more callbacks were executed.
     */
    CALLBACK = -2,

    /**
     * Result from ALooper_pollOnce() and ALooper_pollAll():
     * The timeout expired.
     */
    TIMEOUT = -3,

    /**
     * Result from ALooper_pollOnce() and ALooper_pollAll():
     * An error occurred.
     */
    ERROR = -4,
}

PollResultOrIdent :: union {
	ALooperPollResult,
	i32,
}

/**
 * Flags for file descriptor events that a looper can monitor.
 *
 * These flag bits can be combined to monitor multiple events at once.
 */
ALooperFdFlagsBits :: enum i32 {
    /**
     * The file descriptor is available for read operations.
     */
    INPUT = 0,

    /**
     * The file descriptor is available for write operations.
     */
    OUTPUT = 1,

    /**
     * The file descriptor has encountered an error condition.
     *
     * The looper always sends notifications about errors; it is not necessary
     * to specify this event flag in the requested event set.
     */
    ERROR = 2,

    /**
     * The file descriptor was hung up.
     * For example, indicates that the remote end of a pipe or socket was closed.
     *
     * The looper always sends notifications about hangups; it is not necessary
     * to specify this event flag in the requested event set.
     */
    HANGUP = 3,

    /**
     * The file descriptor is invalid.
     * For example, the file descriptor was closed prematurely.
     *
     * The looper always sends notifications about invalid file descriptors; it is not necessary
     * to specify this event flag in the requested event set.
     */
    INVALID = 4,
}

ALooperFdFlags :: bit_set[ALooperFdFlagsBits; i32]

/**
 * ALooper
 *
 * A looper is the state tracking an event loop for a thread.
 * Loopers do not define event structures or other such things; rather
 * they are a lower-level facility to attach one or more discrete objects
 * listening for an event.  An "event" here is simply data available on
 * a file descriptor: each attached object has an associated file descriptor,
 * and waiting for "events" means (internally) polling on all of these file
 * descriptors until one or more of them have data available.
 *
 * A thread can have only one ALooper associated with it.
 */
ALooper :: struct{}

/**
 * For callback-based event loops, this is the prototype of the function
 * that is called when a file descriptor event occurs.
 * It is given the file descriptor it is associated with,
 * a bitmask of the poll events that were triggered (typically ALOOPER_EVENT_INPUT),
 * and the data pointer that was originally supplied.
 *
 * Implementations should return 1 to continue receiving callbacks, or 0
 * to have this file descriptor and callback unregistered from the looper.
 */
ALooper_callbackFunc :: #type proc "c" (fd: i32, events: ALooperFdFlags, data: rawptr) -> i32

foreign android {
	/**
	 * Returns the looper associated with the calling thread, or NULL if
	 * there is not one.
	 */
	ALooper_forThread :: proc() -> ^ALooper ---

	/**
	* Prepares a looper associated with the calling thread, and returns it.
	* If the thread already has a looper, it is returned.  Otherwise, a new
	* one is created, associated with the thread, and returned.
	*
	* The opts may be ALOOPER_PREPARE_ALLOW_NON_CALLBACKS or 0.
	*/
	ALooper_prepare :: proc(opts: i32) -> ^ALooper ---

	/**
	* Acquire a reference on the given ALooper object.  This prevents the object
	* from being deleted until the reference is removed.  This is only needed
	* to safely hand an ALooper from one thread to another.
	*/
	ALooper_acquire :: proc(looper: ^ALooper) ---

	/**
	* Remove a reference that was previously acquired with ALooper_acquire().
	*/
	ALooper_release :: proc(looper: ^ALooper) ---

	/**
	* Waits for events to be available, with optional timeout in milliseconds.
	* Invokes callbacks for all file descriptors on which an event occurred.
	*
	* If the timeout is zero, returns immediately without blocking.
	* If the timeout is negative, waits indefinitely until an event appears.
	*
	* Returns ALOOPER_POLL_WAKE if the poll was awoken using wake() before
	* the timeout expired and no callbacks were invoked and no other file
	* descriptors were ready.
	*
	* Returns ALOOPER_POLL_CALLBACK if one or more callbacks were invoked.
	*
	* Returns ALOOPER_POLL_TIMEOUT if there was no data before the given
	* timeout expired.
	*
	* Returns ALOOPER_POLL_ERROR if an error occurred.
	*
	* Returns a value >= 0 containing an identifier (the same identifier
	* `ident` passed to ALooper_addFd()) if its file descriptor has data
	* and it has no callback function (requiring the caller here to
	* handle it).  In this (and only this) case outFd, outEvents and
	* outData will contain the poll events and data associated with the
	* fd, otherwise they will be set to NULL.
	*
	* This method does not return until it has finished invoking the appropriate callbacks
	* for all file descriptors that were signalled.
	*/
	ALooper_pollOnce :: proc(timeoutMillis: i32, outFd: ^i32, outEvents: ^i32, outData: ^rawptr) -> PollResultOrIdent ---

	/**
	 * Like ALooper_pollOnce(), but performs all pending callbacks until all
	 * data has been consumed or a file descriptor is available with no callback.
	 * This function will never return ALOOPER_POLL_CALLBACK.
	 */
	ALooper_pollAll :: proc(timeoutMillis: i32, outFd: ^i32, outEvents: ^i32, outData: ^rawptr) -> PollResultOrIdent ---

	/**
	* Wakes the poll asynchronously.
	*
	* This method can be called on any thread.
	* This method returns immediately.
	*/
	ALooper_wake :: proc(looper: ^ALooper) ---

	/**
	* Adds a new file descriptor to be polled by the looper.
	* If the same file descriptor was previously added, it is replaced.
	*
	* "fd" is the file descriptor to be added.
	* "ident" is an identifier for this event, which is returned from ALooper_pollOnce().
	* The identifier must be >= 0, or ALOOPER_POLL_CALLBACK if providing a non-NULL callback.
	* "events" are the poll events to wake up on.  Typically this is ALOOPER_EVENT_INPUT.
	* "callback" is the function to call when there is an event on the file descriptor.
	* "data" is a private data pointer to supply to the callback.
	*
	* There are two main uses of this function:
	*
	* (1) If "callback" is non-NULL, then this function will be called when there is
	* data on the file descriptor.  It should execute any events it has pending,
	* appropriately reading from the file descriptor.  The 'ident' is ignored in this case.
	*
	* (2) If "callback" is NULL, the 'ident' will be returned by ALooper_pollOnce
	* when its file descriptor has data available, requiring the caller to take
	* care of processing it.
	*
	* Returns 1 if the file descriptor was added or -1 if an error occurred.
	*
	* This method can be called on any thread.
	* This method may block briefly if it needs to wake the poll.
	*/
	ALooper_addFd :: proc(looper: ^ALooper, fd: i32, ident: i32, events: ALooperFdFlags, callback: ALooper_callbackFunc, data: rawptr) -> i32 ---

	/**
	* Removes a previously added file descriptor from the looper.
	*
	* When this method returns, it is safe to close the file descriptor since the looper
	* will no longer have a reference to it.  However, it is possible for the callback to
	* already be running or for it to run one last time if the file descriptor was already
	* signalled.  Calling code is responsible for ensuring that this case is safely handled.
	* For example, if the callback takes care of removing itself during its own execution either
	* by returning 0 or by calling this method, then it can be guaranteed to not be invoked
	* again at any later time unless registered anew.
	*
	* Returns 1 if the file descriptor was removed, 0 if none was previously registered
	* or -1 if an error occurred.
	*
	* This method can be called on any thread.
	* This method may block briefly if it needs to wake the poll.
	*/
	ALooper_removeFd :: proc(looper: ^ALooper, fd: i32) -> i32 ---
}