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Power-Programmierung
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vol05
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04
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msgq.c
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1990-07-01
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/* msgq.c RHS
*
* message queue routines
*/
#define INCL_DOS
#include<os2.h>
#include<string.h>
#include<malloc.h>
#include"errexit.h"
#include"msgq.h"
typedef struct _qtable // message queue table stru
{
HQUEUE qhandle;
PID qowner;
} QTABLE;
#define MAXQUEUES 15
QTABLE qtable[MAXQUEUES]; // message queue table
qtableindex = 0;
// creates a new message queue
void MsgQCreate(HQUEUE *qhandle, char *qname)
{
USHORT retval;
if(retval = DosCreateQueue(qhandle,QUE_FIFO,qname))
error_exit(retval,"DosCreateQueue");
}
// opens an existing message queue
USHORT MsgQOpen(HQUEUE *qhandle, char *qname)
{
PID qowner;
USHORT retval;
if(retval = DosOpenQueue(&qowner,qhandle,qname)) // open queue
{
*qhandle = 0;
return retval;
}
qtable[qtableindex].qhandle = *qhandle; // put handle and PID
qtable[qtableindex].qowner = qowner; // into table
qtableindex++;
return 0;
}
// sends a message
void MsgQSend(HQUEUE qhandle, PVOID event, USHORT size, USHORT msg)
{
USHORT retval,i;
SEL sel,newsel;
PVOID qptr;
if(event != NULL) //if data w/ the message
{
for(i = 0; i < qtableindex; i++) // find the queue
if(qtable[i].qhandle == qhandle)
break;
// create a segment for data
if(retval = DosAllocSeg(size,&sel,(SEG_GIVEABLE)))
error_exit(retval,"DosAllocSeg");
DosGiveSeg(sel,qtable[i].qowner,&newsel); // make it giveable
qptr = MAKEP(newsel,0);
memmove(qptr,event,size); // put the data in it
}
else
qptr = NULL;
// write message+data to q
if(retval = DosWriteQueue(qhandle,msg,size,(PBYTE)qptr,0))
error_exit(retval,"DosWriteQueue");
if((qptr != NULL) && (sel != newsel)) // free seg if not ours
DosFreeSeg(sel);
}
// get a message from a queue
void MsgQGet(HQUEUE qhandle, PVOID *event, USHORT *size, USHORT *msg)
{
QUEUERESULT qresult;
BYTE priority;
USHORT retval;
if(retval = DosReadQueue(qhandle,&qresult,size,
(PVOID FAR *)event,0x0000,DCWW_WAIT,&priority,0L))
error_exit(retval,"DosReadQueue");
*msg = qresult.usEventCode;
}
// close queue and remove from table
void MsgQClose(HQUEUE qhandle)
{
USHORT i;
DosCloseQueue(qhandle);
for(i = 0; i < qtableindex; i++)
if(qtable[i].qhandle == qhandle)
break;
if(i != qtableindex)
memmove(&qtable[i],&qtable[i+1],
(sizeof(QTABLE)*(qtableindex-(i+1))));
qtableindex--;
}
/******************************************************/