cwIo.h/cpp : Add timerSetNextTime().

cwIo.cpp

@@ -58,6 +58,7 @@ namespace cw
       unsigned          index;
       unsigned          periodMicroSec;
       bool              asyncFl;
+      time::spec_t      nextTime;
     } timer_t;
     
     typedef struct serialPort_str
@@ -282,6 +283,7 @@ namespace cw
       }
     }
 
+
     //----------------------------------------------------------------------------------------------------------
     //
     // Timer
@@ -290,7 +292,16 @@ namespace cw
     {
       timer_t* t = (timer_t*)arg;
 
-      sleepUs( t->periodMicroSec );
+      time::spec_t t0;
+      time::get(t0);
+
+      int usec = time::diffMicros(t0,t->nextTime);
+
+      if( usec > 0 )
+        sleepUs(usec);
+
+      time::advanceMicros(t->nextTime,t->periodMicroSec);
+
       
       if( t->startedFl && !t->deletedFl )
       {
@@ -352,6 +363,9 @@ namespace cw
       t->asyncFl        = asyncFl;
       t->periodMicroSec = periodMicroSec;
 
+
+      time::get(t->nextTime);
+            
       if((rc = thread_mach::add(p->threadMachH,_timerThreadCb,t)) != kOkRC )
       {
         rc = cwLogError(rc,"Timer thread assignment failed.");        
@@ -380,7 +394,6 @@ namespace cw
         rc = kInvalidIdRC;
       else
         p->timerA[ timerIdx ].startedFl = startFl;
-    
       return rc;
     }
     
@@ -2516,7 +2529,25 @@ cw::rc_t    cw::io::timerSetPeriodMicroSec( handle_t h, unsigned timerIdx, unsig
   if( t == nullptr )
     rc = kInvalidIdRC;
   else
+  {
     p->timerA[ timerIdx ].periodMicroSec = periodMicroSec;
+  }
+    
+  return rc;
+}
+
+cw::rc_t    cw::io::timerSetNextTime( handle_t h, unsigned timerIdx, const time::spec_t& time  )
+{
+  rc_t     rc = kOkRC;
+  io_t*    p  = _handleToPtr(h);
+  timer_t* t  = _timerIndexToPtr(p, timerIdx);
+
+  if( t == nullptr )
+    rc = kInvalidIdRC;
+  else
+  {
+    p->timerA[ timerIdx ].nextTime = time;
+  }
     
   return rc;
 }

cwIo.h

@@ -190,6 +190,12 @@ namespace cw
     unsigned    timerId(                handle_t h, unsigned timerIdx );
     unsigned    timerPeriodMicroSec(    handle_t h, unsigned timerIdx );
     rc_t        timerSetPeriodMicroSec( handle_t h, unsigned timerIdx, unsigned periodMicroSec );
+
+    // Set an explicit next time to trigger. The 'time' argument will over ride the next periodic callback.
+    // Note that the most reliable way to use this function is by calling it in the timer callback
+    // so that it will deterine the time of the following callback.
+    rc_t        timerSetNextTime(       handle_t h, unsigned timerIdx, const time::spec_t& time );
+
     rc_t        timerStart(             handle_t h, unsigned timerIdx );
     rc_t        timerStop(              handle_t h, unsigned timerIdx );