timer.c

以ST公司CPU为核心的彩色电视机的完整源程序。

/********************* SGS-THOMSON MICROELECTRONICS ************************
FILENAME     : TIMER.C
VERSION      : V1.0
DATE         : JAN 1999
AUTHOR(s)    : ASHISH RUDOLA / DEEPAK DOSHI
PROCESSOR    : ST92195
DESCRIPTION  : This module contains functions used for handling software
	       timers.
MODIFICATIONS:
   -
*****************************************************************************/

#include "timer.h"
#include "macro.h"
#include "clock.h"
#include "register.h"
#include "st92196.h"
#include "io.h"

#include "macro.h"
/* Software timers definitions (Keyboard timer, Volume timer...)
These are fast (lower than 5 seconds time-out) and accurate timers.*/
unsigned char fast_timers[NUMBER_OF_FAST_TIMERS];

/* Software timers definitions (Menu timer...)
These are slow timers (from 1 second to less than 5 minutes)*/
unsigned char slow_timers[NUMBER_OF_SLOW_TIMERS];

/*****************************************************************************
INPUTS     : none
OUTPUTS    : ST9 Slice Timer registers
DESCRIPTION: This function initializes the Slice Timer to provide an
	     interrupt every 20ms.
	     1/10Mhz x 4 x 20 x 2500 = 20ms     (=1/50Hz, vertical time)
*****************************************************************************/
//void init_slice_timer(void)
//{
	/* Select Slice Timer page */
//	spp(ST_PG);

	/* Set prescaler to 20 */
//	ST_PR = 19;

	/* Set the 16 bits counter to 4000 (in fact 3999 gives better results) */
//	ST_R = 2499; /* Value for 10MHz operation */

	/* Select the continuous mode and start the Slice Timer */
//	ST_CR = 0x80;
//}

/*================================================================================================
      INIT STDT01
--------------------------------------------------------------------------------------------------
FUNCTION	: 	init_STDT01

Input		: 	none

Output 		: 	none

DESCRIPTION	:	initialize standard timer with 1 IT each 0.020s
 
	 			1/24Mhz x 4 x 2 (ST_PR=0 means no prescaler) x 30000 = 5ms     
==================================================================================================*/
void init_STDT01(void)
{
	spp(ST_PG);             /* set page pointer to standard timer */
    ST_PR = 0x01;       	/* CPU = 24MHz -> STDT is feed with (24/4)/2 = 3 MHz clock*/
	ST_HR = 0xEA;           /* IT each 0.020s (CPU = 24MHz) */
	ST_LR = 0x60;
	ST_CR = 0x80;           /* start counter, continuous mode, no input, no output */
}



/*****************************************************************************
INPUTS     : none
OUTPUTS    : see update_clock
	     see update_fast_timers
	     ST9 OSD registers
DESCRIPTION: This function services the Slice Timer interrupt. Fast software
	     and accurate timers are updated every 20ms.
	     The time of day is also updated here...
*****************************************************************************/
#pragma interrupt(STD_IT)
void STD_IT(void)
{
	SAVE_PPR;
    /* Force program space in case it has been modified by the OSD module */
	/* spm TC */;
	/* Enable interrupts to make sure the OSD and IR interrupts will not be
	delayed */
	asm ("ei");

	/* Update fast and accurate timers */
	update_fast_timers();

	/* Update current time of day */
	update_clock();

	RESTORE_PPR;
}

/*****************************************************************************
INPUTS     : none
OUTPUTS    : Software timers
DESCRIPTION: This function updates fast and accurate timers like the clock
	     timer.
*****************************************************************************/
void update_fast_timers(void)
{
	/* Decrement fast software timers up to zero */
	asm volatile ("ldw rr0, #%0
		       ld r2,%1
STI0:                  cp (rr0),#0
		       jxz STI1
		       sub (rr0),#1
STI1:                  incw rr0
		       djnz r2,STI0" : : "m"(fast_timers), "i"(NUMBER_OF_FAST_TIMERS));

      ++count_20ms;
}

/*****************************************************************************
INPUTS     : none
OUTPUTS    : Software timers
DESCRIPTION: This function updates slow timers and not accurate timers like
	     status or menu timers.
*****************************************************************************/
void update_slow_timers(void)
{
	unsigned char i;                                                        /* Temporary storage */

	/* Decrement software timers up to zero */
	for (i = 0; i < NUMBER_OF_SLOW_TIMERS; i++)
		if (slow_timers[i] != 0)
			slow_timers[i]--;
}

/*****************************************************************************
INPUTS     : timer to check
	     ONE_SECOND - Set when one second has elapsed
	     ONE_MINUTE - Set when one minute has elapsed             
OUTPUTS    : SECOND_TIMER - Reset
	     ONE_MINUTE - Reset
	     Return 1 every seconds and minutes. Return 0 otherwise
DESCRIPTION: This function returns 1 every seconds so as to update processes
	     which require 1 second time base. This function also returns 1
	     every minutes so as to update preocesses which require 1 minute
	     time base. 
*****************************************************************************/
unsigned char check_time(unsigned char timer_to_check)
{
	unsigned char i = 0;                                                    /* Temporary storage */

/*    if (timer_to_check == CHECK_HALF_SECOND)
    {
        if (time_flags & HALF_SECOND)
        {
            time_flags = time_flags & ~HALF_SECOND;
            i = 1;  
        }
    }
*/

	if (timer_to_check == CHECK_SECOND)
	{
		if (time_flags & ONE_SECOND)
		{
			time_flags = time_flags & ~ONE_SECOND;
			i = 1;  
		}
	}

	if (timer_to_check == CHECK_MINUTE)
	{
		if (time_flags & ONE_MINUTE)
		{
			time_flags = time_flags & ~ONE_MINUTE;
			i = 1;  
		}
	}
	return i;
}