The thread associated with the callback must call ProcessSystemEvents (or RunUserInterface or GetUserEvent) for the callback to actually get called. You can create a simple wait function that processes CVI events while waiting for a specified number of milliseconds. Here is a simple example:
#include <ansi_c.h>
#include <userint.h>
#include <windows.h>
#include <utility.h>
#define READ_BUFFER_SIZE 10
static int quit = 0;
static unsigned int tsq;
int CVICALLBACK ThreadFunction (void *functionData)
{
int buffer[5] = {0};
while (!quit)
{
CmtWriteTSQData(tsq, buffer, sizeof(buffer)/sizeof(buffer[0]), 0, 0);
Sleep(100);
}
return 0;
}
void CVICALLBACK TsqCallback (int queue, unsigned int event, int value, void *cbData)
{
int buffer[READ_BUFFER_SIZE];
CmtReadTSQData(tsq, buffer, READ_BUFFER_SIZE, 0, 0);
puts("In TsqCallback");
}
static void WaitWhileProcessingEvents(int waitTime)
{
// NOTE - GetTickCount wraps every few days!
// So you need to protect for that to be robust.
int startTime = GetTickCount();
do
{
ProcessSystemEvents();
Sleep(0);
} while (GetTickCount() - startTime < waitTime);
}
void main(void)
{
int threadFunctionId;
CmtNewTSQ(1024, sizeof(int), 0, &tsq);
CmtInstallTSQCallback(tsq, EVENT_TSQ_ITEMS_IN_QUEUE, READ_BUFFER_SIZE, TsqCallback, 0,
CmtGetCurrentThreadID(), 0);
CmtScheduleThreadPoolFunction(DEFAULT_THREAD_POOL_HANDLE, ThreadFunction, 0, &threadFunctionId);
while (!KeyHit())
{
WaitWhileProcessingEvents(100);
}
quit = 1;
CmtWaitForThreadPoolFunctionCompletion(DEFAULT_THREAD_POOL_HANDLE,
threadFunctionId, OPT_TP_PROCESS_EVENTS_WHILE_WAITING);
CmtReleaseThreadPoolFunctionID(DEFAULT_THREAD_POOL_HANDLE, threadFunctionId);
CmtDiscardTSQ(tsq);
}
