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Minor cleanup #560

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Merged
merged 4 commits into from
Aug 25, 2020
Merged

Minor cleanup #560

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b7fc0a2
Remove semaphore from tone()
henrygab Aug 24, 2020
1097f1a
inline != __attribute__((always_inline))
henrygab Aug 24, 2020
cda1dba
More constexpr
henrygab Aug 24, 2020
eb60126
not constexpr enough for C++14?
henrygab Aug 24, 2020
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31 changes: 5 additions & 26 deletions cores/nRF5/Tone.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -64,7 +64,6 @@ class TonePwmConfig {
uint8_t nrf_pin; //< the nrf pin for playback
nrf_pwm_task_t task_to_start; //< Whether to start playback at SEQ0 or SEQ1
nrf_pwm_short_mask_t shorts; //< shortcuts to enable

public:
bool ensurePwmPeripheralOwnership(void);
bool initializeFromPulseCountAndTimePeriod(uint64_t pulse_count, uint16_t time_period);
Expand All @@ -74,7 +73,7 @@ class TonePwmConfig {
};
TonePwmConfig _pwm_config;

inline static bool _is_pwm_enabled(NRF_PWM_Type const * pwm_instance) {
static bool _is_pwm_enabled(NRF_PWM_Type const * pwm_instance) {
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inline is still OK, it is more like suggestion to gcc. It is up to gcc to decide e.g Ofast may inline the function, but Os may not since it increase the size. attribute always inline is more like directive to gcc to force it to do so. So yeah, it is normally not an issue on non timing-sensitive function. Anyway, I normally just put inline where I would like, and leave the decision to gcc.

bool isEnabled =
(pwm_instance->ENABLE & PWM_ENABLE_ENABLE_Msk) ==
(PWM_ENABLE_ENABLE_Enabled << PWM_ENABLE_ENABLE_Pos);
Expand All @@ -93,13 +92,13 @@ inline static bool _is_pwm_enabled(NRF_PWM_Type const * pwm_instance) {
See https://gist.github.com/henrygab/6b570ebd51354bf247633c72b8dc383b
for code that compares the new lambdas to the old calculations.
*/
constexpr inline static uint16_t _calculate_time_period(uint32_t frequency) {
constexpr static uint16_t _calculate_time_period(uint32_t frequency) {
// range for frequency == [20..25000],
// so range of result == [ 5..62500]
// which fits in 16 bits.
return 125000 / frequency;
};
constexpr inline static uint64_t _calculate_pulse_count(uint32_t frequency, uint32_t duration) {
constexpr static uint64_t _calculate_pulse_count(uint32_t frequency, uint32_t duration) {
// range for frequency == [20..25000],
// range for duration == [ 1..0xFFFF_FFFF]
// so range of result == [ 1..0x18_FFFF_FFE7] (requires 37 bits)
Expand All @@ -112,15 +111,15 @@ constexpr inline static uint64_t _calculate_pulse_count(uint32_t frequency, uint
(duration / 1000ULL) * frequency :
(((uint64_t)duration) * frequency / 1000ULL);
};
inline static int _bits_used(unsigned long x) {
static int _bits_used(unsigned long x) {
if (0 == x) return 0;
unsigned int result = 0;
do {
result++;
} while (x >>= 1);
return result;
}
inline static int _bits_used(unsigned long long x) {
static int _bits_used(unsigned long long x) {
if (0 == x) return 0;
unsigned int result = 0;
do {
Expand Down Expand Up @@ -172,32 +171,13 @@ inline static int _bits_used(unsigned long long x) {
*/
void tone(uint8_t pin, unsigned int frequency, unsigned long duration)
{
// Used only to protect calls against simultaneous multiple calls to tone().
// Using a function-local static to avoid accidental reference from ISR or elsewhere,
// and to simplify ensuring the semaphore gets initialized.
static StaticSemaphore_t _tone_semaphore_allocation;
static auto init_semaphore = [] () { //< use a lambda to both initialize AND give the mutex
SemaphoreHandle_t handle = xSemaphoreCreateMutexStatic(&_tone_semaphore_allocation);
auto mustSucceed = xSemaphoreGive(handle);
(void)mustSucceed;
NRFX_ASSERT(mustSucceed == pdTRUE);
return handle;
};
static SemaphoreHandle_t _tone_semaphore = init_semaphore();

// limit frequency to reasonable audible range
if((frequency < 20) | (frequency > 25000)) {
LOG_LV1("TON", "frequency outside range [20..25000] -- ignoring");
return;
}

if(xSemaphoreTake(_tone_semaphore, portMAX_DELAY) != pdTRUE) {
LOG_LV1("TON", "error acquiring semaphore (should never occur?)");
return;
}
uint64_t pulse_count = _calculate_pulse_count(frequency, duration);
uint16_t time_period = _calculate_time_period(frequency);

if (!_pwm_config.ensurePwmPeripheralOwnership()) {
LOG_LV1("TON", "Unable to acquire PWM peripheral");
} else if (!_pwm_config.stopPlayback()) {
Expand All @@ -211,7 +191,6 @@ void tone(uint8_t pin, unsigned int frequency, unsigned long duration)
} else {
//LOG_LV2("TON", "Started playback of tone at frequency %d duration %ld", frequency, duration);
}
xSemaphoreGive(_tone_semaphore);
return;
}
void noTone(uint8_t pin)
Expand Down