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Diffstat (limited to 'esp8266compat/PolledTimeout.h')
| -rw-r--r-- | esp8266compat/PolledTimeout.h | 289 |
1 files changed, 289 insertions, 0 deletions
diff --git a/esp8266compat/PolledTimeout.h b/esp8266compat/PolledTimeout.h new file mode 100644 index 0000000..dc12bba --- /dev/null +++ b/esp8266compat/PolledTimeout.h @@ -0,0 +1,289 @@ +#ifndef __POLLEDTIMING_H__ +#define __POLLEDTIMING_H__ + + +/* + PolledTimeout.h - Encapsulation of a polled Timeout + + Copyright (c) 2018 Daniel Salazar. All rights reserved. + This file is part of the esp8266 core for Arduino environment. + + This library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + This library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with this library; if not, write to the Free Software + Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#include <limits> + +#include <Arduino.h> + +namespace ESP8266 +{ + + +namespace polledTimeout +{ + +namespace YieldPolicy +{ + +struct DoNothing +{ + static void execute() {} +}; + +struct YieldOrSkip +{ + static void execute() {delay(0);} +}; + +template <unsigned long delayMs> +struct YieldAndDelayMs +{ + static void execute() {delay(delayMs);} +}; + +} //YieldPolicy + +namespace TimePolicy +{ + +struct TimeSourceMillis +{ + // time policy in milli-seconds based on millis() + + using timeType = decltype(millis()); + static timeType time() {return millis();} + static constexpr timeType ticksPerSecond = 1000; + static constexpr timeType ticksPerSecondMax = 1000; +}; + +struct TimeSourceCycles +{ + // time policy based on ESP.getCycleCount() + // this particular time measurement is intended to be called very often + // (every loop, every yield) + + using timeType = decltype(ESP.getCycleCount()); + static timeType time() {return ESP.getCycleCount();} + static constexpr timeType ticksPerSecond = F_CPU; // 80'000'000 or 160'000'000 Hz + static constexpr timeType ticksPerSecondMax = 160000000; // 160MHz +}; + +template <typename TimeSourceType, unsigned long long second_th> + // "second_th" units of timeType for one second +struct TimeUnit +{ + using timeType = typename TimeSourceType::timeType; + +#if __GNUC__ < 5 + // gcc-4.8 cannot compile the constexpr-only version of this function + // using #defines instead luckily works + static constexpr timeType computeRangeCompensation () + { + #define number_of_secondTh_in_one_tick ((1.0 * second_th) / ticksPerSecond) + #define fractional (number_of_secondTh_in_one_tick - (long)number_of_secondTh_in_one_tick) + + return ({ + fractional == 0? + 1: // no need for compensation + (number_of_secondTh_in_one_tick / fractional) + 0.5; // scalar multiplier allowing exact division + }); + + #undef number_of_secondTh_in_one_tick + #undef fractional + } +#else + static constexpr timeType computeRangeCompensation () + { + return ({ + constexpr double number_of_secondTh_in_one_tick = (1.0 * second_th) / ticksPerSecond; + constexpr double fractional = number_of_secondTh_in_one_tick - (long)number_of_secondTh_in_one_tick; + fractional == 0? + 1: // no need for compensation + (number_of_secondTh_in_one_tick / fractional) + 0.5; // scalar multiplier allowing exact division + }); + } +#endif + + static constexpr timeType ticksPerSecond = TimeSourceType::ticksPerSecond; + static constexpr timeType ticksPerSecondMax = TimeSourceType::ticksPerSecondMax; + static constexpr timeType rangeCompensate = computeRangeCompensation(); + static constexpr timeType user2UnitMultiplierMax = (ticksPerSecondMax * rangeCompensate) / second_th; + static constexpr timeType user2UnitMultiplier = (ticksPerSecond * rangeCompensate) / second_th; + static constexpr timeType user2UnitDivider = rangeCompensate; + // std::numeric_limits<timeType>::max() is reserved + static constexpr timeType timeMax = (std::numeric_limits<timeType>::max() - 1) / user2UnitMultiplierMax; + + static timeType toTimeTypeUnit (const timeType userUnit) {return (userUnit * user2UnitMultiplier) / user2UnitDivider;} + static timeType toUserUnit (const timeType internalUnit) {return (internalUnit * user2UnitDivider) / user2UnitMultiplier;} + static timeType time () {return TimeSourceType::time();} +}; + +using TimeMillis = TimeUnit< TimeSourceMillis, 1000 >; +using TimeFastMillis = TimeUnit< TimeSourceCycles, 1000 >; +using TimeFastMicros = TimeUnit< TimeSourceCycles, 1000000 >; +using TimeFastNanos = TimeUnit< TimeSourceCycles, 1000000000 >; + +} //TimePolicy + +template <bool PeriodicT, typename YieldPolicyT = YieldPolicy::DoNothing, typename TimePolicyT = TimePolicy::TimeMillis> +class timeoutTemplate +{ +public: + using timeType = typename TimePolicyT::timeType; + static_assert(std::is_unsigned<timeType>::value == true, "timeType must be unsigned"); + + static constexpr timeType alwaysExpired = 0; + static constexpr timeType neverExpires = std::numeric_limits<timeType>::max(); + static constexpr timeType rangeCompensate = TimePolicyT::rangeCompensate; //debug + + timeoutTemplate(const timeType userTimeout) + { + reset(userTimeout); + } + + IRAM_ATTR // fast + bool expired() + { + YieldPolicyT::execute(); //in case of DoNothing: gets optimized away + if(PeriodicT) //in case of false: gets optimized away + return expiredRetrigger(); + return expiredOneShot(); + } + + IRAM_ATTR // fast + operator bool() + { + return expired(); + } + + bool canExpire () const + { + return !_neverExpires; + } + + bool canWait () const + { + return _timeout != alwaysExpired; + } + + IRAM_ATTR // called from ISR + void reset(const timeType newUserTimeout) + { + reset(); + _timeout = TimePolicyT::toTimeTypeUnit(newUserTimeout); + _neverExpires = (newUserTimeout < 0) || (newUserTimeout > timeMax()); + } + + IRAM_ATTR // called from ISR + void reset() + { + _start = TimePolicyT::time(); + } + + void resetToNeverExpires () + { + _timeout = alwaysExpired + 1; // because canWait() has precedence + _neverExpires = true; + } + + timeType getTimeout() const + { + return TimePolicyT::toUserUnit(_timeout); + } + + static constexpr timeType timeMax() + { + return TimePolicyT::timeMax; + } + +private: + + IRAM_ATTR // fast + bool checkExpired(const timeType internalUnit) const + { + // canWait() is not checked here + // returns "can expire" and "time expired" + return (!_neverExpires) && ((internalUnit - _start) >= _timeout); + } + +protected: + + IRAM_ATTR // fast + bool expiredRetrigger() + { + if (!canWait()) + return true; + + timeType current = TimePolicyT::time(); + if(checkExpired(current)) + { + unsigned long n = (current - _start) / _timeout; //how many _timeouts periods have elapsed, will usually be 1 (current - _start >= _timeout) + _start += n * _timeout; + return true; + } + return false; + } + + IRAM_ATTR // fast + bool expiredOneShot() const + { + // returns "always expired" or "has expired" + return !canWait() || checkExpired(TimePolicyT::time()); + } + + timeType _timeout; + timeType _start; + bool _neverExpires; +}; + +// legacy type names, deprecated (unit is milliseconds) + +using oneShot = polledTimeout::timeoutTemplate<false> /*__attribute__((deprecated("use oneShotMs")))*/; +using periodic = polledTimeout::timeoutTemplate<true> /*__attribute__((deprecated("use periodicMs")))*/; + +// standard versions (based on millis()) +// timeMax() is 49.7 days ((2^32)-2 ms) + +using oneShotMs = polledTimeout::timeoutTemplate<false>; +using periodicMs = polledTimeout::timeoutTemplate<true>; + +// Time policy based on ESP.getCycleCount(), and intended to be called very often: +// "Fast" versions sacrifices time range for improved precision and reduced execution time (by 86%) +// (cpu cycles for ::expired(): 372 (millis()) vs 52 (ESP.getCycleCount())) +// timeMax() values: +// Ms: max is 26843 ms (26.8 s) +// Us: max is 26843545 us (26.8 s) +// Ns: max is 1073741823 ns ( 1.07 s) +// (time policy based on ESP.getCycleCount() is intended to be called very often) + +using oneShotFastMs = polledTimeout::timeoutTemplate<false, YieldPolicy::DoNothing, TimePolicy::TimeFastMillis>; +using periodicFastMs = polledTimeout::timeoutTemplate<true, YieldPolicy::DoNothing, TimePolicy::TimeFastMillis>; +using oneShotFastUs = polledTimeout::timeoutTemplate<false, YieldPolicy::DoNothing, TimePolicy::TimeFastMicros>; +using periodicFastUs = polledTimeout::timeoutTemplate<true, YieldPolicy::DoNothing, TimePolicy::TimeFastMicros>; +using oneShotFastNs = polledTimeout::timeoutTemplate<false, YieldPolicy::DoNothing, TimePolicy::TimeFastNanos>; +using periodicFastNs = polledTimeout::timeoutTemplate<true, YieldPolicy::DoNothing, TimePolicy::TimeFastNanos>; + +} //polledTimeout + + +/* A 1-shot timeout that auto-yields when in CONT can be built as follows: + * using oneShotYieldMs = esp8266::polledTimeout::timeoutTemplate<false, esp8266::polledTimeout::YieldPolicy::YieldOrSkip>; + * + * Other policies can be implemented by the user, e.g.: simple yield that panics in SYS, and the polledTimeout types built as needed as shown above, without modifying this file. + */ + +}//esp8266 + +#endif |