1 files changed, 254 insertions, 0 deletions
diff --git a/esp32compat/PolledTimeout.h b/esp32compat/PolledTimeout.h
new file mode 100644
index 0000000..64677b7
--- /dev/null
+++ b/esp32compat/PolledTimeout.h
@@ -0,0 +1,254 @@
+#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 esp32
+{
+
+
+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;
+};
+
+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 >;
+
+} //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;
+};
+
+// standard versions (based on millis())
+// timeMax() is 49.7 days ((2^32)-2 ms)
+
+using oneShotMs = polledTimeout::timeoutTemplate<false>;
+using periodicMs = polledTimeout::timeoutTemplate<true>;
+
+
+} //polledTimeout
+
+
+/* A 1-shot timeout that auto-yields when in CONT can be built as follows:
+ * using oneShotYieldMs = esp32::polledTimeout::timeoutTemplate<false, esp32::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.
+ */
+
+}//esp32
+
+#endif