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mbed_ticker_api remove specific case for 32768 in favor of all frequencies divisible by 2

pull/7009/head
Marc Emmers 2018-05-02 11:15:19 +02:00 committed by Bartek Szatkowski
parent ff39a9874a
commit 1aaef7bc12
2 changed files with 17 additions and 8 deletions
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24
hal/mbed_ticker_api.c
View File

@ -42,6 +42,14 @@ static void initialize(const ticker_data_t *ticker)
frequency = 1000000;
}
uint32_t frequency_shifts = 0;
for (int i = 31; i > 0; --i) {
if ((1 << i) == frequency) {
frequency_shifts = i;
break;
}
}
uint32_t bits = info->bits;
if ((info->bits > 32) || (info->bits < 4)) {
MBED_ASSERT(0);
@ -56,6 +64,7 @@ static void initialize(const ticker_data_t *ticker)
ticker->queue->tick_last_read = ticker->interface->read();
ticker->queue->tick_remainder = 0;
ticker->queue->frequency = frequency;
ticker->queue->frequency_shifts = frequency_shifts;
ticker->queue->bitmask = ((uint64_t)1 << bits) - 1;
ticker->queue->max_delta = max_delta;
ticker->queue->max_delta_us = max_delta_us;
@ -125,14 +134,13 @@ static void update_present_time(const ticker_data_t *const ticker)
// Optimized for 1MHz
elapsed_us = elapsed_ticks;
} else if (32768 == queue->frequency) {
// Optimized for 32KHz
} else if (0 != queue->frequency_shifts) {
// Optimized for frequencies divisible by 2
uint64_t us_x_ticks = elapsed_ticks * 1000000;
elapsed_us = us_x_ticks >> 15;
elapsed_us = us_x_ticks >> queue->frequency_shifts;
// Update remainder
queue->tick_remainder += us_x_ticks - (elapsed_us << 15);
queue->tick_remainder += us_x_ticks - (elapsed_us << queue->frequency_shifts);
if (queue->tick_remainder >= queue->frequency) {
elapsed_us += 1;
queue->tick_remainder -= queue->frequency;
@ -174,10 +182,10 @@ static timestamp_t compute_tick(const ticker_data_t *const ticker, us_timestamp_
if (delta > ticker->queue->max_delta) {
delta = ticker->queue->max_delta;
}
} else if (32768 == queue->frequency) {
// Optimized for 32KHz
} else if (0 != queue->frequency_shifts) {
// Optimized frequencies divisible by 2
delta = (delta_us << 15) / 1000000;
delta = (delta_us << ticker->queue->frequency_shifts) / 1000000;
if (delta > ticker->queue->max_delta) {
delta = ticker->queue->max_delta;
}

1
hal/ticker_api.h
View File

@ -73,6 +73,7 @@ typedef struct {
ticker_event_handler event_handler; /**< Event handler */
ticker_event_t *head; /**< A pointer to head */
uint32_t frequency; /**< Frequency of the timer in Hz */
uint32_t frequency_shifts; /**< Frequency shift if divisible by 2, ohterwise 0 */
uint32_t bitmask; /**< Mask to be applied to time values read */
uint32_t max_delta; /**< Largest delta in ticks that can be used when scheduling */
uint64_t max_delta_us; /**< Largest delta in us that can be used when scheduling */