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Microsoft OS/2 SDK 03-01-1988

/* Customer.c
 *
 * This program emulates the gatekeeper placing requests in a queue that
 * will be read by the headwaiter (see server.c). The following functions
 * are illustrated here:
 *	DosOpenQueue, DosWriteQueue, DosCloseQueue
 *
 * This example first allocates a shared segment. It loops trying to open
 * the queue until successful. It loops (for an arbitrary number of times)
 * placing data in the shared segment and writing an element (with
 * DataAddress pointing to the data in the shared segment) to the queue.
 * The data is contained in the static array CustData. Each word represents
 * a byte containing the priority of the request and a byte for the table.
 * It writes the last element with RequestID set to indicate that this
 * will be the last element to be written to the queue. It then frees the
 * shared segment and then closes the queue.
 *
 * Compile as: cl -AL -G2 -Lp customer.c
 *
 * Created by Microsoft Corp. 1986
 */

#define INCL_DOSMEMMGR
#define INCL_DOSQUEUES
#define INCL_DOSERRORS
#define INCL_DOSPROCESS

#include <os2def.h>			/* contains SELECTOROF and
					   OFFSETOF macros */
#include <bse.h>			/* MS OS/2 function declarations */
#include "defines.h"                    /* definitions for example programs */


void main (argc, argv, envp)
    int argc;
    char *argv[];
    char *envp;
{
        register unsigned i;    /* loop control variable         */
        unsigned  TableID,      /* table where a customer group is seated */
                  Priorty,       /* Priority of Table */
                  *SharedSeg;   /* pointer to shared segment     */
	USHORT	 OwnerPID;	/* queue owner's PID             */
	HQUEUE	 QueueHandle;	/* handle of queue		 */
	SEL	 SharedSel;	/* selector to shared segment	 */
        char     type;          /* type of example selected      */
        static unsigned CustData[MAXQWRITES] = {0x0600, 0x0501, 0x0802, 0x0003,
                                                0x0104, 0x0305, 0x0406, 0x0707};
                                /* represents customers requests */
                                /* in Format PPTT, where PP is   */
                                /* priority and TT is table number */

        if (argc > 1){
           ++argv;
           type = *argv[0];
        }
        else type = 'd';

        /* allocate shared segment */
	DosAllocShrSeg (SEGSIZE, SEGNAME, &SharedSel);

        /* open the queue */
	while (DosOpenQueue (&OwnerPID, &QueueHandle, QUEUENAME) ==
               ERROR_QUE_NAME_NOT_EXIST) /* keep trying to open the queue...*/
		  DosSleep(1000L);	 /* ...until the server creates it  */

        /* compute the address to the shared segment */
	SELECTOROF(SharedSeg) = SharedSel;
	OFFSETOF(SharedSeg) = 0;

        /* write some requests to the queue, emulating customer's requests  */
        TableID = 1;
        if ((type == 'L') || (type == 'l')){
           /* write data in LIFO format */

	   DosWriteQueue (QueueHandle, NOMORE, DATALENGTH,
			  (PBYTE) &SharedSeg[TableID++], /* any prio OK - not used */
                          LIFOPRIO);

           for (i = 0; i < MAXQWRITES; ++i){
             SharedSeg[TableID] = CustData[i];
	     DosWriteQueue (QueueHandle, REQWAITER, DATALENGTH,
			    (PBYTE) &SharedSeg[TableID++], LIFOPRIO);

           } /* endfor */

        } else {
           /* write data in fifo/prio format */

           for (i = 0; i < MAXQWRITES; ++i){
             SharedSeg[TableID] = CustData[i];
             Priorty = CustData[i] >> 8;      /* Priority must be a WORD */
	     DosWriteQueue (QueueHandle, REQWAITER, DATALENGTH,
			   (PBYTE) &SharedSeg[TableID++], Priorty);
           } /* endfor */


           /* indicate there are no more customers */
	   DosWriteQueue (QueueHandle, NOMORE, DATALENGTH,
			  (PBYTE) &SharedSeg[TableID], /* any prio OK - not used */
                          ELEMPRIORITY);
        } /* endif */


        /* free the shared segment */
	DosFreeSeg (SharedSel);

        /* close the queue */
	DosCloseQueue (QueueHandle);
}

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