Timers & Timings

Lymington

2.77/5 (7 votes)

Apr 1, 2004

2 min read

64181

4619

Produce timed event flags, functions, threads & timings therof.

Introduction

This DLL provides fifteen routines to satisfy application program requirements for timers and timed activities in a C/C++ and VB environment. The praxis is that 150 timer slots should be enough for any application. Each timer may be set up to raise an event-flag, execute a function (on the ticker thread), or spin off a thread. A timer is allocated a number (i.e., 1 to 150) on creation. Timers may be cancelled or modified by timer number.

Background

At initialization, two threads are spun off. The ticker-ticker thread fires every millisecond, using winmm.dll, the Windows (R) multi-media library (this library contains calls that are accurate to one millisecond). Each execution of this thread decrements positive-value timers. When a timer reaches zero, its action (one of three) is performed and the timer expires (negative state). The ticker thread is used to execute functions-to-be-called when timers expire and to exit the two threads, ticker-ticker and ticker, when so required. This ticker thread could become overtaxed since it must finish one function before it can begin another. In such a case, use make_tmrT instead of make_tmrF. Initialization is done when the first call to any timer or timings routine is made.

Using the code

VC 6.0 projects: Place the TIMDLL.dll in a directory on your path variable. Add the library TIMDLL.lib to the project resources. Add the module TIMcalls.h to the project. Use the routines therein.

VB 6.0 projects: Register the TIMDLL.dll with regsvr32. Add the module TIMDLL.bas to the project. Use the public routines therein.

//
// Source to produce the above console screen
//
#include "TIMcalls.h"
#include "stdio.h"// for printf
static bool pM = true; long timer_id[]= {0,0,0,0};
//
// 'cbr' is a 13sec repeating function, called by the 'ticker' thread
//
void cbr (void*prm) {printf("\nFunction cbr  fires, 
  ictr %5d, prm %d",TIM_ictr(),(long)prm);}
//
// 'one' is a one-shot function, called by the 'ticker' thread, which
// calls itself on 5sec boundaries while TIM_ictr < 30 seconds
//
void one (void*prm)
{
  printf("\nFunction one  fires, ictr %5d, prm %d",TIM_ictr(),(long)prm);
  if (TIM_ictr() < 30000)
  {
    TIM_make_tmrF(5000-(TIM_ictr()%5000),&timer_id[2],
      one,(void*)(TIM_ictr()/1000),false);

    if (timer_id[0] > 0 && TIM_mod_tmr(timer_id[0],
            20000-TIM_ictr()) != TIM_SUCCESS)
       timer_id[0] = 0;//make_tmr has expired, clear ID

    printf("\nIDs %d,%d,%d,%d",timer_id[0],
      timer_id[1],timer_id[2],timer_id[3]);
  }
}
//
// 'thr' is an 18sec repeating thread, 
// spun by 'ticker-ticker' thread
//
void thr (void*prm) {printf("\nThread   thr  fires, ictr %5d, prm %d",
   TIM_ictr(),(long)prm);}
//
//
//
void main (int argc, char*argv[])
{
  HANDLE flg_han; unsigned long sts;
    
  TIM_make_tmr (20000,&timer_id[0],"",false);
  TIM_make_tmrF(13000,&timer_id[1],cbr,(void*)123,true);
  TIM_make_tmrF(11000,&timer_id[2],one,(void*)456,false);
  TIM_make_tmrT(18000,&timer_id[3],thr,(void*)789,true);

  flg_han = TIM_get_handle(timer_id[0]);

  printf("\nIDs %d,%d,%d,%d",timer_id[0],
      timer_id[1],timer_id[2],timer_id[3]);

  while(pM)
  {
    Sleep(1000-(TIM_ictr()%1000));// next second boundary

    sts = WaitForSingleObject(flg_han,0);// check for flag set

    if (sts != WAIT_OBJECT_0)
    printf("\nFlag    not yet set, ictr %5d",TIM_ictr());
    else{printf("\nFlag            set, ictr %5d",TIM_ictr()); pM=false;}
  }

  Sleep(57000-TIM_ictr());// 57second boundary

  printf("\nAbout to reset TIM sub-system");
  long ictr = TIM_ictr();
  TIM_reset();
  printf("\n  ...TIM_reset, about to exit");

  Sleep(80000-ictr);// 80second boundary (i.e.23secs) to read the screen
}

Points of Interest

For C/C++ only users, a static library can be built using the workspace and the project files provided. Slots used by event-flag setting timers are not re-used until absolutely necessary, thus the handle is available and the flag state may be queried after expiry. The more accurate 2^nd demo VB project uses ccrpTmr.dll. Register the ccrpTmr.dll with regsvr32, ("common controls replacement project" DLL, free from ccrp.mvps.org).

History

3.4 TIM_Src.cpp - Comment/Logging maintenance.