Added timer library

esp32/include/arduino-timer.h

@@ -0,0 +1,202 @@
+/**
+   arduino-timer - library for delaying function calls
+
+   Copyright (c) 2018, Michael Contreras
+   All rights reserved.
+
+   Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions are
+   met:
+
+   1. Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+
+   2. Redistributions in binary form must reproduce the above copyright
+   notice, this list of conditions and the following disclaimer in the
+   documentation and/or other materials provided with the distribution.
+
+   3. Neither the name of the copyright holder nor the names of its
+   contributors may be used to endorse or promote products derived from
+   this software without specific prior written permission.
+
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
+   IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+   TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+   PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+   HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
+   TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+   LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+   SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+#ifndef _CM_ARDUINO_TIMER_H__
+#define _CM_ARDUINO_TIMER_H__
+
+#if defined(ARDUINO) && ARDUINO >= 100
+#include <Arduino.h>
+#else
+#include <WProgram.h>
+#endif
+
+#ifndef TIMER_MAX_TASKS
+    #define TIMER_MAX_TASKS 0x10
+#endif
+
+template <
+    size_t max_tasks = TIMER_MAX_TASKS, /* max allocated tasks */
+    unsigned long (*time_func)() = millis, /* time function for timer */
+    typename T = void * /* handler argument type */
+>
+class Timer {
+  public:
+
+    typedef uintptr_t Task; /* public task handle */
+    typedef bool (*handler_t)(T opaque); /* task handler func signature */
+
+    /* Calls handler with opaque as argument in delay units of time */
+    Task
+    in(unsigned long delay, handler_t h, T opaque = T())
+    {
+        return task_id(add_task(time_func(), delay, h, opaque));
+    }
+
+    /* Calls handler with opaque as argument at time */
+    Task
+    at(unsigned long time, handler_t h, T opaque = T())
+    {
+        const unsigned long now = time_func();
+        return task_id(add_task(now, time - now, h, opaque));
+    }
+
+    /* Calls handler with opaque as argument every interval units of time */
+    Task
+    every(unsigned long interval, handler_t h, T opaque = T())
+    {
+        return task_id(add_task(time_func(), interval, h, opaque, interval));
+    }
+
+    /* Cancel the timer task */
+    void
+    cancel(Task &task)
+    {
+        if (!task) return;
+
+        for (size_t i = 0; i < max_tasks; ++i) {
+            struct task * const t = &tasks[i];
+
+            if (t->handler && (t->id ^ task) == (uintptr_t)t) {
+                remove(t);
+                break;
+            }
+        }
+
+        task = (Task)NULL;
+    }
+
+    /* Ticks the timer forward - call this function in loop() */
+    unsigned long
+    tick()
+    {
+        unsigned long ticks = (unsigned long)-1;
+
+        for (size_t i = 0; i < max_tasks; ++i) {
+            struct task * const task = &tasks[i];
+
+            if (task->handler) {
+                const unsigned long t = time_func();
+                const unsigned long duration = t - task->start;
+
+                if (duration >= task->expires) {
+                    task->repeat = task->handler(task->opaque) && task->repeat;
+
+                    if (task->repeat) task->start = t;
+                    else remove(task);
+                } else {
+                    const unsigned long remaining = task->expires - duration;
+                    ticks = remaining < ticks ? remaining : ticks;
+                }
+            }
+        }
+
+        return ticks == (unsigned long)-1 ? 0 : ticks;
+    }
+
+  private:
+
+    size_t ctr;
+
+    struct task {
+        handler_t handler; /* task handler callback func */
+        T opaque; /* argument given to the callback handler */
+        unsigned long start,
+                      expires; /* when the task expires */
+        size_t repeat, /* repeat task */
+               id;
+    } tasks[max_tasks];
+
+    inline
+    void
+    remove(struct task *task)
+    {
+        task->handler = NULL;
+        task->opaque = T();
+        task->start = 0;
+        task->expires = 0;
+        task->repeat = 0;
+        task->id = 0;
+    }
+
+    inline
+    Task
+    task_id(const struct task * const t)
+    {
+        const Task id = (Task)t;
+
+        return id ? id ^ t->id : id;
+    }
+
+    inline
+    struct task *
+    next_task_slot()
+    {
+        for (size_t i = 0; i < max_tasks; ++i) {
+            struct task * const slot = &tasks[i];
+            if (slot->handler == NULL) return slot;
+        }
+
+        return NULL;
+    }
+
+    inline
+    struct task *
+    add_task(unsigned long start, unsigned long expires,
+             handler_t h, T opaque, bool repeat = 0)
+    {
+        struct task * const slot = next_task_slot();
+
+        if (!slot) return NULL;
+
+        if (++ctr == 0) ++ctr; // overflow
+
+        slot->id = ctr;
+        slot->handler = h;
+        slot->opaque = opaque;
+        slot->start = start;
+        slot->expires = expires;
+        slot->repeat = repeat;
+
+        return slot;
+    }
+};
+
+/* create a timer with the default settings */
+inline Timer<>
+timer_create_default()
+{
+    return Timer<>();
+}
+
+#endif