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Annotation of os2sdk/demos/examples/timer/timer.c, revision 1.1

1.1     ! root        1: /* This example illustrates the use of the following 286DOS functions:
        !             2:  *     DOSTIMERSTART, DOSTIMERASYNC, DOSTIMERSTOP, DOSSLEEP
        !             3:  *
        !             4:  * Copyright (C) Microsoft Corp. 1986
        !             5:  */
        !             6: 
        !             7: #include       <doscalls.h>    /* contains 286DOS function declarations */
        !             8: 
        !             9: #define SEMNAME        "\\SEM\\SOMESEM"  /* name of semaphore */
        !            10: #define NOEXCLUSIVE 1          /* ownership of semaphore not exclusive  */
        !            11: #define TIMERINTERVAL 1000L    /* timer interval */
        !            12: #define ASYNCINTERVAL 2000     /* asynchronous timer interval */
        !            13: #define NOTIMEOUT -1           /* no timeout */
        !            14: #define BEEPFREQUENCY 400      /* frequency parameter to DOSBEEP */
        !            15: #define BEEPDURATION  50        /* duration parameter to DOSBEEP */
        !            16: 
        !            17: main ()
        !            18: {
        !            19:        unsigned long   SemHandle;      /* storage for semaphore handle */
        !            20:        unsigned        TimerHandle;    /* handle returned by DosTimerStart*/
        !            21: 
        !            22:        /* create a system semaphore */
        !            23:        DOSCREATESEM (NOEXCLUSIVE, &SemHandle, SEMNAME);
        !            24: 
        !            25:        /*
        !            26:         * DOSTIMERSTART/STOP - these functions provide a repetitive
        !            27:         * asynchronous timer which clear a semaphore at a specified interval.
        !            28:         */
        !            29: 
        !            30:        DOSSEMSET (SemHandle);          /* set the system semaphore */
        !            31: 
        !            32:        /* set the interval timer */
        !            33:        DOSTIMERSTART (TIMERINTERVAL, SemHandle, &TimerHandle);
        !            34: 
        !            35:        /* normally, application would do some work in here */
        !            36: 
        !            37:        DOSSEMWAIT (SemHandle, (long) NOTIMEOUT); /* wait on the semaphore */
        !            38:        DOSBEEP (BEEPFREQUENCY, BEEPDURATION);    /* beep when done */
        !            39:        DOSTIMERSTOP (TimerHandle);               /* stop the interval timer */
        !            40: 
        !            41:        /*
        !            42:         * DOSTIMERASYNC example. This function provides a one-shot
        !            43:         * asynchronous timer which clears a specified semaphore after
        !            44:         * a specified time delay.
        !            45:         */
        !            46: 
        !            47:        DOSSEMSET (SemHandle);          /* set the system semaphore */
        !            48: 
        !            49:        /* start the asynchronous timer */
        !            50:        DOSTIMERASYNC ((long) ASYNCINTERVAL, SemHandle, &TimerHandle);
        !            51: 
        !            52:        /* normally, application would do some work in here */
        !            53: 
        !            54:        DOSSEMWAIT (SemHandle,  (long) NOTIMEOUT); /* wait on the semaphore */
        !            55:        DOSBEEP (BEEPFREQUENCY, BEEPDURATION);    /* beep when done */
        !            56: 
        !            57:        /*
        !            58:         * DOSTIMERSTOP is used to cancel either type of timer. After using
        !            59:         * this function you must put the semaphore back into a known state
        !            60:         * if you need to use it again. Example of cancelling a timer:
        !            61:         */
        !            62: 
        !            63:        DOSSEMSET (SemHandle);          /* set the system semaphore */
        !            64: 
        !            65:        /* start the asynchronous timer (specify a long time) */
        !            66:        DOSTIMERASYNC ((long) (10*ASYNCINTERVAL), SemHandle, &TimerHandle);
        !            67: 
        !            68:        DOSTIMERSTOP (TimerHandle);     /* stop the asynchronous timer */
        !            69:        DOSSEMCLEAR (SemHandle);        /* clear the system semaphore */
        !            70:        DOSCLOSESEM (SemHandle);        /* close the system semaphore */
        !            71: 
        !            72:        /*
        !            73:         * DOSSLEEP - simple synchronous suspend for specified interval.
        !            74:         */
        !            75:        DOSSLEEP(TIMERINTERVAL);
        !            76:        DOSBEEP (BEEPFREQUENCY, BEEPDURATION);    /* beep when done */
        !            77: }

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