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ncs36510: us ticker improvements 

Do not ticker read in ISR, use reminder to schedule the next interrupt, this should make ticker much faster.

read - disable Timer0 while reading it, if ISR is pending just reread the time again via read() function

These 2 improvements should decrease time spent when reading/scheduling ticker
events.
pull/4679/head
Martin Kojtal 2017-06-30 12:44:02 +01:00
parent 9b082fff55
commit 865f470324
1 changed files with 16 additions and 26 deletions
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42
targets/TARGET_ONSEMI/TARGET_NCS36510/ncs36510_us_ticker_api.c
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@ -38,7 +38,7 @@ static int us_ticker_inited = 0;
static void us_timer_init(void);
static uint32_t us_ticker_target = 0;
static volatile uint32_t msb_counter = 0;
static volatile uint16_t msb_counter = 0;
void us_ticker_init(void)
{
@ -55,7 +55,6 @@ void us_ticker_init(void)
* which is why a software timer is required to get 32-bit word length.
******************************************************************************/
/* TODO - Need some sort of load value/prescale calculation for non-32MHz clock */
/* TODO - Add msb_counter rollover protection at 16 bits count? */
/* TODO - How is overflow handled? */
/* Timer 0 for free running time */
@ -108,22 +107,21 @@ static void us_timer_init(void)
/* Reads 32 bit timer's current value (16 bit s/w timer | 16 bit h/w timer) */
uint32_t us_ticker_read()
{
uint32_t retval, tim0cval;
if (!us_ticker_inited) {
us_timer_init();
}
NVIC_DisableIRQ(Tim0_IRQn);
uint32_t retval, tim0cval;
/* Get the current tick from the hw and sw timers */
tim0cval = TIM0REG->VALUE; /* read current time */
retval = (0xFFFF - tim0cval); /* subtract down count */
NVIC_DisableIRQ(Tim0_IRQn);
if (TIM0REG->CONTROL.BITS.INT) {
TIM0REG->CLEAR = 0;
msb_counter++;
tim0cval = TIM0REG->VALUE; /* read current time again after interrupt */
retval = (0xFFFF - tim0cval);
us_timer_isr(); /* handle ISR again */
NVIC_ClearPendingIRQ(Tim0_IRQn);
retval = (0xFFFF - TIM0REG->VALUE);
}
retval |= msb_counter << 16; /* add software bits */
NVIC_EnableIRQ(Tim0_IRQn);
@ -168,25 +166,21 @@ extern void us_ticker_isr(void)
/* Clear IRQ flag */
TIM1REG->CLEAR = 0;
int32_t delta = us_ticker_target - us_ticker_read();
if (delta <= 0) {
TIM1REG->CONTROL.BITS.ENABLE = False;
us_ticker_irq_handler();
if (us_ticker_target > 0) {
--us_ticker_target;
ticker_set(0xFFFF);
} else {
// Clamp at max value of timer
if (delta > 0xFFFF) {
delta = 0xFFFF;
}
ticker_set(delta);
us_ticker_irq_handler();
}
}
/* Set timer 1 ticker interrupt */
void us_ticker_set_interrupt(timestamp_t timestamp)
{
us_ticker_target = (uint32_t)timestamp;
int32_t delta = us_ticker_target - us_ticker_read();
int32_t delta = timestamp - us_ticker_read();
// we got 16 bit timer, use upper 16bit as a simple counter how many times
// we need to schedule full range ticker count
us_ticker_target = (uint32_t)delta >> 16;
if (delta <= 0) {
/* This event was in the past */
@ -200,10 +194,6 @@ void us_ticker_set_interrupt(timestamp_t timestamp)
return;
}
// Clamp at max value of timer
if (delta > 0xFFFF) {
delta = 0xFFFF;
}
ticker_set(delta);
// we set the full reminder of 16 bit, the next ISR will do the upper part
ticker_set(delta & 0xFFFF);
}