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Marshall Brown
10/03/12 21:08
Read: 1750 times
New Zealand

#188566 - Timers - Function Pointers
Hi all

I would like to create an array of timer structs, that on expiration call a function - that's easy enough.

The functions that they call have differing argument types (void, through to pointers to other structs)

I am using Raisonance compiler RC51 on a silabs F040

Here is my header

typedef enum timer_types{
	timer_one_shot	=0,
	timer_periodic	=1


typedef void (*func_pointer)(void *);

typedef struct timer{
	unsigned int reset_value;
	unsigned int current_value;
	unsigned char timer_priority;
	timer_type_t timer_type;
	func_pointer timeout_func;
	void *func_args;



extern s_timer_t timer_array[];


and here is my timer code (called on 1mSec tick)

void TIMERS_sort_out_timers(void){
	unsigned char i;

	for (i = 0; i < NUMBER_OF_TIMERS; i++){				//step through each of our timers
		if (timer_array[i].current_value != 0){			//see if we have already expired.
			timer_array[i].current_value --;			//if not then decrement the timer toward 0 
			if (timer_array[i].current_value == 0){		//now see if we have timed out
				if (timer_array[i].timer_type == timer_periodic){	//if we run on a periodic timer 
					timer_array[i].current_value = timer_array[i].reset_value;	//reload the timer 
				timer_array[i].timeout_func(timer_array[i].func_args);			//if we have timed out then perform the function in our callback.


This is one of the timer functions that I would like to run, note that it has no arguments, this is the problem as the timer function is expecting to pas an argument of void *.

void MAIN_blink(void){


for completeness, this is how I am initialising the timers

void TIMERS_init_timers(void){
		//start the timeout timer now
		timer_array[cctalk_msg_timeout].reset_value = CCTALK_MSG_TIMEOUT_MSEC;
		timer_array[cctalk_msg_timeout].current_value = 0;
		timer_array[cctalk_msg_timeout].timer_type   = timer_one_shot;
		timer_array[cctalk_msg_timeout].timeout_func = UART_null_function;

			//start the timeout timer now
		timer_array[keep_alive_led].reset_value = KEEP_ALIVE_BLINK_RATE;
		timer_array[keep_alive_led].current_value = KEEP_ALIVE_BLINK_RATE;	//this must be non 0 to start the timer running.
		timer_array[keep_alive_led].timer_type   = timer_periodic;
		timer_array[keep_alive_led].timeout_func = MAIN_blink;

		timer_array[cctalk_char_timeout].reset_value = CCTALK_CHAR_TIMEOUT_MSEC;
		timer_array[cctalk_char_timeout].current_value = 0;
		timer_array[cctalk_char_timeout].timer_type   = timer_one_shot;
		timer_array[cctalk_char_timeout].timeout_func = UART_null_function ;



so the question is, how do I correctly create a callback to a function with zero or more arguments?

Thanks for the ideas.



List of 13 messages in thread
Timers - Function Pointers      Marshall Brown      10/03/12 21:08      
   Too much for a '51?      Oliver Sedlacek      10/04/12 02:05      
      I Agree      Marshall Brown      10/04/12 03:27      
   Function Pointers...      Andy Neil      10/04/12 05:50      
   you are violating KISS      Erik Malund      10/04/12 08:41      
   Various Timer Functions        Michael Karas      10/06/12 01:14      
      Thanks Michael      Marshall Brown      10/06/12 23:34      
         regardless, you are violating KISS        Erik Malund      10/09/12 07:44      
            even on ARM      Stefan KAnev      10/09/12 13:40      
            The timer simply increments      Marshall Brown      10/11/12 15:58      
               bug      Marshall Brown      10/11/12 16:08      
                  more bugs      Maarten Brock      10/13/12 14:30      
                     thanks      Marshall Brown      10/14/12 13:31      

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