tcltimer.c

linux系统下的音频通信

/* 
 * tclTimer.c --
 *
 *	This file provides timer event management facilities for Tcl,
 *	including the "after" command.
 *
 * Copyright (c) 1997 by Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * SCCS: @(#) tclTimer.c 1.9 97/07/29 16:21:53
 */

#include "tclInt.h"
#include "tclPort.h"

/*
 * This flag indicates whether this module has been initialized.
 */

static int initialized = 0;

/*
 * For each timer callback that's pending there is one record of the following
 * type.  The normal handlers (created by Tcl_CreateTimerHandler) are chained
 * together in a list sorted by time (earliest event first).
 */

typedef struct TimerHandler {
    Tcl_Time time;			/* When timer is to fire. */
    Tcl_TimerProc *proc;		/* Procedure to call. */
    ClientData clientData;		/* Argument to pass to proc. */
    Tcl_TimerToken token;		/* Identifies handler so it can be
					 * deleted. */
    struct TimerHandler *nextPtr;	/* Next event in queue, or NULL for
					 * end of queue. */
} TimerHandler;

static TimerHandler *firstTimerHandlerPtr = NULL;
					/* First event in queue. */
static int lastTimerId;			/* Timer identifier of most recently
					 * created timer. */
static int timerPending;		/* 1 if a timer event is in the queue. */

/*
 * The data structure below is used by the "after" command to remember
 * the command to be executed later.  All of the pending "after" commands
 * for an interpreter are linked together in a list.
 */

typedef struct AfterInfo {
    struct AfterAssocData *assocPtr;
				/* Pointer to the "tclAfter" assocData for
				 * the interp in which command will be
				 * executed. */
    char *command;		/* Command to execute.  Malloc'ed, so must
				 * be freed when structure is deallocated. */
    int id;			/* Integer identifier for command;  used to
				 * cancel it. */
    Tcl_TimerToken token;	/* Used to cancel the "after" command.  NULL
				 * means that the command is run as an
				 * idle handler rather than as a timer
				 * handler.  NULL means this is an "after
				 * idle" handler rather than a
                                 * timer handler. */
    struct AfterInfo *nextPtr;	/* Next in list of all "after" commands for
				 * this interpreter. */
} AfterInfo;

/*
 * One of the following structures is associated with each interpreter
 * for which an "after" command has ever been invoked.  A pointer to
 * this structure is stored in the AssocData for the "tclAfter" key.
 */

typedef struct AfterAssocData {
    Tcl_Interp *interp;		/* The interpreter for which this data is
				 * registered. */
    AfterInfo *firstAfterPtr;	/* First in list of all "after" commands
				 * still pending for this interpreter, or
				 * NULL if none. */
} AfterAssocData;

/*
 * There is one of the following structures for each of the
 * handlers declared in a call to Tcl_DoWhenIdle.  All of the
 * currently-active handlers are linked together into a list.
 */

typedef struct IdleHandler {
    Tcl_IdleProc (*proc);	/* Procedure to call. */
    ClientData clientData;	/* Value to pass to proc. */
    int generation;		/* Used to distinguish older handlers from
				 * recently-created ones. */
    struct IdleHandler *nextPtr;/* Next in list of active handlers. */
} IdleHandler;

static IdleHandler *idleList;
				/* First in list of all idle handlers. */
static IdleHandler *lastIdlePtr;
				/* Last in list (or NULL for empty list). */
static int idleGeneration;	/* Used to fill in the "generation" fields
				 * of IdleHandler structures.  Increments
				 * each time Tcl_DoOneEvent starts calling
				 * idle handlers, so that all old handlers
				 * can be called without calling any of the
				 * new ones created by old ones. */

/*
 * Prototypes for procedures referenced only in this file:
 */

static void		AfterCleanupProc _ANSI_ARGS_((ClientData clientData,
			    Tcl_Interp *interp));
static void		AfterProc _ANSI_ARGS_((ClientData clientData));
static void		FreeAfterPtr _ANSI_ARGS_((AfterInfo *afterPtr));
static AfterInfo *	GetAfterEvent _ANSI_ARGS_((AfterAssocData *assocPtr,
			    char *string));
static void		InitTimer _ANSI_ARGS_((void));
static void		TimerExitProc _ANSI_ARGS_((ClientData clientData));
static int		TimerHandlerEventProc _ANSI_ARGS_((Tcl_Event *evPtr,
			    int flags));
static void		TimerCheckProc _ANSI_ARGS_((ClientData clientData,
			    int flags));
static void		TimerSetupProc _ANSI_ARGS_((ClientData clientData,
			    int flags));

/*
 *----------------------------------------------------------------------
 *
 * InitTimer --
 *
 *	This function initializes the timer module.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Registers the idle and timer event sources.
 *
 *----------------------------------------------------------------------
 */

static void
InitTimer()
{
    initialized = 1;
    lastTimerId = 0;
    timerPending = 0;
    idleGeneration = 0;
    firstTimerHandlerPtr = NULL;
    lastIdlePtr = NULL;
    idleList = NULL;

    Tcl_CreateEventSource(TimerSetupProc, TimerCheckProc, NULL);
    Tcl_CreateExitHandler(TimerExitProc, NULL);
}

/*
 *----------------------------------------------------------------------
 *
 * TimerExitProc --
 *
 *	This function is call at exit or unload time to remove the
 *	timer and idle event sources.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Removes the timer and idle event sources.
 *
 *----------------------------------------------------------------------
 */

static void
TimerExitProc(clientData)
    ClientData clientData;	/* Not used. */
{
    Tcl_DeleteEventSource(TimerSetupProc, TimerCheckProc, NULL);
    initialized = 0;
}

/*
 *--------------------------------------------------------------
 *
 * Tcl_CreateTimerHandler --
 *
 *	Arrange for a given procedure to be invoked at a particular
 *	time in the future.
 *
 * Results:
 *	The return value is a token for the timer event, which
 *	may be used to delete the event before it fires.
 *
 * Side effects:
 *	When milliseconds have elapsed, proc will be invoked
 *	exactly once.
 *
 *--------------------------------------------------------------
 */

Tcl_TimerToken
Tcl_CreateTimerHandler(milliseconds, proc, clientData)
    int milliseconds;		/* How many milliseconds to wait
				 * before invoking proc. */
    Tcl_TimerProc *proc;	/* Procedure to invoke. */
    ClientData clientData;	/* Arbitrary data to pass to proc. */
{
    register TimerHandler *timerHandlerPtr, *tPtr2, *prevPtr;
    Tcl_Time time;

    if (!initialized) {
	InitTimer();
    }

    timerHandlerPtr = (TimerHandler *) ckalloc(sizeof(TimerHandler));

    /*
     * Compute when the event should fire.
     */

    TclpGetTime(&time);
    timerHandlerPtr->time.sec = time.sec + milliseconds/1000;
    timerHandlerPtr->time.usec = time.usec + (milliseconds%1000)*1000;
    if (timerHandlerPtr->time.usec >= 1000000) {
	timerHandlerPtr->time.usec -= 1000000;
	timerHandlerPtr->time.sec += 1;
    }
    
    /*
     * Fill in other fields for the event.
     */

    timerHandlerPtr->proc = proc;
    timerHandlerPtr->clientData = clientData;
    lastTimerId++;
    timerHandlerPtr->token = (Tcl_TimerToken) lastTimerId;

    /*
     * Add the event to the queue in the correct position
     * (ordered by event firing time).
     */

    for (tPtr2 = firstTimerHandlerPtr, prevPtr = NULL; tPtr2 != NULL;
	    prevPtr = tPtr2, tPtr2 = tPtr2->nextPtr) {
	if ((tPtr2->time.sec > timerHandlerPtr->time.sec)
		|| ((tPtr2->time.sec == timerHandlerPtr->time.sec)
		&& (tPtr2->time.usec > timerHandlerPtr->time.usec))) {
	    break;
	}
    }
    timerHandlerPtr->nextPtr = tPtr2;
    if (prevPtr == NULL) {
	firstTimerHandlerPtr = timerHandlerPtr;
    } else {
	prevPtr->nextPtr = timerHandlerPtr;
    }

    TimerSetupProc(NULL, TCL_ALL_EVENTS);
    return timerHandlerPtr->token;
}

/*
 *--------------------------------------------------------------
 *
 * Tcl_DeleteTimerHandler --
 *
 *	Delete a previously-registered timer handler.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	Destroy the timer callback identified by TimerToken,
 *	so that its associated procedure will not be called.
 *	If the callback has already fired, or if the given
 *	token doesn't exist, then nothing happens.
 *
 *--------------------------------------------------------------
 */

void
Tcl_DeleteTimerHandler(token)
    Tcl_TimerToken token;	/* Result previously returned by
				 * Tcl_DeleteTimerHandler. */
{
    register TimerHandler *timerHandlerPtr, *prevPtr;

    for (timerHandlerPtr = firstTimerHandlerPtr, prevPtr = NULL;
	    timerHandlerPtr != NULL; prevPtr = timerHandlerPtr,
	    timerHandlerPtr = timerHandlerPtr->nextPtr) {
	if (timerHandlerPtr->token != token) {
	    continue;
	}
	if (prevPtr == NULL) {
	    firstTimerHandlerPtr = timerHandlerPtr->nextPtr;
	} else {
	    prevPtr->nextPtr = timerHandlerPtr->nextPtr;
	}
	ckfree((char *) timerHandlerPtr);
	return;
    }
}

/*
 *----------------------------------------------------------------------
 *
 * TimerSetupProc --
 *
 *	This function is called by Tcl_DoOneEvent to setup the timer
 *	event source for before blocking.  This routine checks both the
 *	idle and after timer lists.
 *
 * Results:
 *	None.
 *
 * Side effects:
 *	May update the maximum notifier block time.
 *
 *----------------------------------------------------------------------
 */

static void
TimerSetupProc(data, flags)
    ClientData data;		/* Not used. */
    int flags;			/* Event flags as passed to Tcl_DoOneEvent. */
{
    Tcl_Time blockTime;

    if (((flags & TCL_IDLE_EVENTS) && idleList)
	    || ((flags & TCL_TIMER_EVENTS) && timerPending)) {
	/*
	 * There is an idle handler or a pending timer event, so just poll.
	 */

	blockTime.sec = 0;
	blockTime.usec = 0;

    } else if ((flags & TCL_TIMER_EVENTS) && firstTimerHandlerPtr) {
	/*
	 * Compute the timeout for the next timer on the list.
	 */

	TclpGetTime(&blockTime);
	blockTime.sec = firstTimerHandlerPtr->time.sec - blockTime.sec;
	blockTime.usec = firstTimerHandlerPtr->time.usec - blockTime.usec;
	if (blockTime.usec < 0) {
	    blockTime.sec -= 1;
	    blockTime.usec += 1000000;
	}
	if (blockTime.sec < 0) {
	    blockTime.sec = 0;
	    blockTime.usec = 0;
	}
    } else {
	return;
    }
	
    Tcl_SetMaxBlockTime(&blockTime);
}

/*
 *----------------------------------------------------------------------
 *
 * TimerCheckProc --
 *
 *	This function is called by Tcl_DoOneEvent to check the timer
 *	event source for events.  This routine checks both the