Add tinyfsm, start converting core functions to an FSM-based event loop

8 files changed, 523 insertions, 0 deletions

diff --git a/lib/tinyfsm/examples/elevator/Makefile b/lib/tinyfsm/examples/elevator/Makefile
new file mode 100644
index 00000000..4c979052
--- /dev/null
+++ b/lib/tinyfsm/examples/elevator/Makefile
@@ -0,0 +1,98 @@
+# Compiler prefix, in case your default compiler does not implement all C++11 features:
+#CROSS = /opt/toolchain/x86_64-pc-linux-gnu-gcc-4.7.0/bin/x86_64-pc-linux-gnu-
+
+PROJECT      = elevator
+
+# HINT: g++ -Q -O2 --help=optimizers
+OPTIMIZER    = -Os
+
+CC           = $(CROSS)gcc
+CXX          = $(CROSS)g++
+AS           = $(CROSS)gcc -x assembler-with-cpp
+LD           = $(CROSS)g++
+OBJCOPY      = $(CROSS)objcopy
+OBJDUMP      = $(CROSS)objdump
+SIZE         = size -d
+RM           = rm -f
+RM_R         = rm -rf
+CP           = cp
+MKDIR_P      = mkdir -p
+DOXYGEN      = doxygen
+
+
+SRC_DIRS     = .
+INCLUDE      = -I ../../include
+
+SRCS         = $(wildcard $(addsuffix /*.cpp, $(SRC_DIRS)))
+OBJS         = $(SRCS:.cpp=.o)
+DEPENDS      = $(OBJS:.o=.d)
+
+EXE          = $(PROJECT)
+MAP          = $(PROJECT).map
+
+
+#------------------------------------------------------------------------------
+# flags
+#
+
+# commmon flags propagated to CFLAGS, CXXFLAGS, ASFLAGS (not LDFLAGS)
+FLAGS       += $(INCLUDE)
+FLAGS       += -MMD
+
+CXXFLAGS     = $(FLAGS)
+CXXFLAGS    += $(OPTIMIZER)
+CXXFLAGS    += -std=c++11
+CXXFLAGS    += -fno-exceptions
+CXXFLAGS    += -fno-rtti
+
+CXXFLAGS    += -Wall -Wextra
+CXXFLAGS    += -Wctor-dtor-privacy
+CXXFLAGS    += -Wcast-align -Wpointer-arith -Wredundant-decls
+CXXFLAGS    += -Wshadow -Wcast-qual -Wcast-align -pedantic
+
+LDFLAGS     += -fno-exceptions
+LDFLAGS     += -fno-rtti
+
+# Produce debugging information (for use with gdb)
+#OPTIMIZER  = -Og
+#FLAGS     += -g
+
+# Use LLVM
+#CXX = $(CROSS)clang++
+#CXXFLAGS  += -stdlib=libc++
+#LDFLAGS   += -lc++
+
+# Enable link-time optimizer
+#CXXFLAGS += -flto
+#LDFLAGS  += -flto
+
+# Strip dead code (enable garbage collection)
+#OPTIMIZER += -ffunction-sections -fdata-sections
+#LDFLAGS   += -Wl,$(if $(shell ld -v | grep GNU),--gc-sections,-dead_strip)
+
+# Enable automatic template instantiation at link time
+#CXXFLAGS += -frepo
+#LDFLAGS  += -frepo
+
+# Create link map file
+#LDFLAGS  += -Wl,-Map="$(MAP)",--cref
+
+
+.PHONY: all clean
+
+all: $(EXE)
+
+$(EXE): $(OBJS)
+	$(LD) $(OBJS) $(LDFLAGS) -o $(EXE)
+	$(SIZE) $@
+
+%.o: %.cpp
+	$(CXX) -c $(CXXFLAGS) -o $@ $<
+
+clean:
+	$(RM) *.o
+	$(RM) *.d
+	$(RM) $(EXE)
+
+
+-include $(DEPENDS)
diff --git a/lib/tinyfsm/examples/elevator/README.md b/lib/tinyfsm/examples/elevator/README.md
new file mode 100644
index 00000000..6de14ceb
--- /dev/null
+++ b/lib/tinyfsm/examples/elevator/README.md
@@ -0,0 +1,86 @@
+Elevator Project
+================
+
+Example implementation of a simplified elevator logic, using [TinyFSM].
+
+  [TinyFSM]: https://digint.ch/tinyfsm/
+
+
+Overview
+--------
+
+Imagine a elevator having:
+
+ - "Call" button on each floor,
+ - "Floor Sensor" on each floor, triggering an event as soon as the
+   elevator arrives there,
+ - "Alarm" button.
+
+
+Implementation
+--------------
+
+The elevator example implements two state machines interacting with
+each other:
+
+ 1. Elevator
+    - State: Idle
+    - State: Moving
+    - State: Panic
+
+ 2. Motor
+    - State: Stopped
+    - State: Up
+    - State: Down
+
+
+A good state machine design avoids circular dependencies at all
+cost: While the elevator sends events to the motor, the motor NEVER
+sends events to the elevator (top-down only).
+
+
+FAQ
+---
+
+Did you notice the motor starting twice? This is by design, let's
+have a look at the call stack of fsm_list::start() in main.cpp:
+
+    FsmList<Motor, Elevator>::start()
+       Motor::set_initial_state()
+          Motor::current_state = Stopped
+       Elevator::set_initial_state()
+          Elevator::current_state = Idle
+       Motor::enter()
+          Motor:Stopped->entry()
+             cout << "Motor: stopped"               <-- HERE
+             Motor::direction = 0
+       Elevator::enter()
+          Elevator:Idle->entry()
+             send_event(MotorStop)
+                Motor::react(MotorStop)
+                   Motor:Stopped->transit<Stopped>
+                      Motor:Stopped->exit()
+                      Motor::current_state = Stopped
+                      Motor:Stopped->entry()
+                         cout << "Motor: stopped"   <-- HERE
+                         Motor::direction = 0
+                Elevator::react(MotorStop)
+
+If we really had to work around this, we could either:
+
+ 1. Change the initialization (bad design practice!) in main.cpp:
+
+        - fsm_list::start();
+        + fsm_list::set_initial_state();
+        + Elevator::enter();
+
+
+ 2. Modify the Motor:Stopped->entry() function in motor.cpp:
+
+          class Stopped : public Motor {
+            void entry() override {
+        +     if(direction == 0)
+        +       return;
+              cout << "Motor: stopped" << endl;
+              direction = 0;
+            };
diff --git a/lib/tinyfsm/examples/elevator/elevator.cpp b/lib/tinyfsm/examples/elevator/elevator.cpp
new file mode 100644
index 00000000..6e792f64
--- /dev/null
+++ b/lib/tinyfsm/examples/elevator/elevator.cpp
@@ -0,0 +1,115 @@
+#include <tinyfsm.hpp>
+
+#include "elevator.hpp"
+#include "fsmlist.hpp"
+
+#include <iostream>
+
+class Idle; // forward declaration
+
+
+// ----------------------------------------------------------------------------
+// Transition functions
+//
+
+static void CallMaintenance() {
+  std::cout << "*** calling maintenance ***" << std::endl;
+}
+
+static void CallFirefighters() {
+  std::cout << "*** calling firefighters ***" << std::endl;
+}
+
+
+// ----------------------------------------------------------------------------
+// State: Panic
+//
+
+class Panic
+: public Elevator
+{
+  void entry() override {
+    send_event(MotorStop());
+  }
+};
+
+
+// ----------------------------------------------------------------------------
+// State: Moving
+//
+
+class Moving
+: public Elevator
+{
+  void react(FloorSensor const & e) override {
+    int floor_expected = current_floor + Motor::getDirection();
+    if(floor_expected != e.floor)
+    {
+      std::cout << "Floor sensor defect (expected " << floor_expected << ", got " << e.floor << ")" << std::endl;
+      transit<Panic>(CallMaintenance);
+    }
+    else
+    {
+      std::cout << "Reached floor " << e.floor << std::endl;
+      current_floor = e.floor;
+      if(e.floor == dest_floor)
+        transit<Idle>();
+    }
+  };
+};
+
+
+// ----------------------------------------------------------------------------
+// State: Idle
+//
+
+class Idle
+: public Elevator
+{
+  void entry() override {
+    send_event(MotorStop());
+  }
+
+  void react(Call const & e) override {
+    dest_floor = e.floor;
+
+    if(dest_floor == current_floor)
+      return;
+
+    /* lambda function used for transition action */
+    auto action = [] { 
+      if(dest_floor > current_floor)
+        send_event(MotorUp());
+      else if(dest_floor < current_floor)
+        send_event(MotorDown());
+    };
+
+    transit<Moving>(action);
+  };
+};
+
+
+// ----------------------------------------------------------------------------
+// Base state: default implementations
+//
+
+void Elevator::react(Call const &) {
+  std::cout << "Call event ignored" << std::endl;
+}
+
+void Elevator::react(FloorSensor const &) {
+  std::cout << "FloorSensor event ignored" << std::endl;
+}
+
+void Elevator::react(Alarm const &) {
+  transit<Panic>(CallFirefighters);
+}
+
+int Elevator::current_floor = Elevator::initial_floor;
+int Elevator::dest_floor    = Elevator::initial_floor;
+
+
+// ----------------------------------------------------------------------------
+// Initial state definition
+//
+FSM_INITIAL_STATE(Elevator, Idle)
diff --git a/lib/tinyfsm/examples/elevator/elevator.hpp b/lib/tinyfsm/examples/elevator/elevator.hpp
new file mode 100644
index 00000000..be3d0053
--- /dev/null
+++ b/lib/tinyfsm/examples/elevator/elevator.hpp
@@ -0,0 +1,55 @@
+#ifndef ELEVATOR_HPP_INCLUDED
+#define ELEVATOR_HPP_INCLUDED
+
+#include <tinyfsm.hpp>
+
+
+// ----------------------------------------------------------------------------
+// Event declarations
+//
+
+struct FloorEvent : tinyfsm::Event
+{
+  int floor;
+};
+
+struct Call        : FloorEvent { };
+struct FloorSensor : FloorEvent { };
+struct Alarm       : tinyfsm::Event { };
+
+
+
+// ----------------------------------------------------------------------------
+// Elevator (FSM base class) declaration
+//
+
+class Elevator
+: public tinyfsm::Fsm<Elevator>
+{
+  /* NOTE: react(), entry() and exit() functions need to be accessible
+   * from tinyfsm::Fsm class. You might as well declare friendship to
+   * tinyfsm::Fsm, and make these functions private:
+   *
+   * friend class Fsm;
+   */
+public:
+
+  /* default reaction for unhandled events */
+  void react(tinyfsm::Event const &) { };
+
+  virtual void react(Call        const &);
+  virtual void react(FloorSensor const &);
+  void         react(Alarm       const &);
+
+  virtual void entry(void) { };  /* entry actions in some states */
+  void         exit(void)  { };  /* no exit actions at all */
+
+protected:
+
+  static constexpr int initial_floor = 0;
+  static int current_floor;
+  static int dest_floor;
+};
+
+
+#endif
diff --git a/lib/tinyfsm/examples/elevator/fsmlist.hpp b/lib/tinyfsm/examples/elevator/fsmlist.hpp
new file mode 100644
index 00000000..d340f8a1
--- /dev/null
+++ b/lib/tinyfsm/examples/elevator/fsmlist.hpp
@@ -0,0 +1,19 @@
+#ifndef FSMLIST_HPP_INCLUDED
+#define FSMLIST_HPP_INCLUDED
+
+#include <tinyfsm.hpp>
+
+#include "elevator.hpp"
+#include "motor.hpp"
+
+using fsm_list = tinyfsm::FsmList<Motor, Elevator>;
+
+/** dispatch event to both "Motor" and "Elevator" */
+template<typename E>
+void send_event(E const & event)
+{
+  fsm_list::template dispatch<E>(event);
+}
+
+
+#endif
diff --git a/lib/tinyfsm/examples/elevator/main.cpp b/lib/tinyfsm/examples/elevator/main.cpp
new file mode 100644
index 00000000..46570153
--- /dev/null
+++ b/lib/tinyfsm/examples/elevator/main.cpp
@@ -0,0 +1,40 @@
+#include "fsmlist.hpp"
+
+#include <iostream>
+
+
+int main()
+{
+  fsm_list::start();
+
+  Call call;
+  FloorSensor sensor;
+
+  while(1)
+  {
+    char c;
+
+    std::cout << "c=Call, f=FloorSensor, a=Alarm, q=Quit ? ";
+    std::cin >> c;
+    switch(c) {
+    case 'c':
+      std::cout << "Floor ? ";
+      std::cin >> call.floor;
+      send_event(call);
+      break;
+    case 'f':
+      std::cout << "Floor ? ";
+      std::cin >> sensor.floor;
+      send_event(sensor);
+      break;
+    case 'a':
+      send_event(Alarm());
+      break;
+    case 'q':
+      std::cout << "Thanks for playing!" << std::endl;
+      return 0;
+    default:
+      std::cout << "Invalid input" << std::endl;
+    };
+  }
+}
diff --git a/lib/tinyfsm/examples/elevator/motor.cpp b/lib/tinyfsm/examples/elevator/motor.cpp
new file mode 100644
index 00000000..b4668070
--- /dev/null
+++ b/lib/tinyfsm/examples/elevator/motor.cpp
@@ -0,0 +1,60 @@
+#include <tinyfsm.hpp>
+#include "motor.hpp"
+#include <iostream>
+
+
+// ----------------------------------------------------------------------------
+// Motor states
+//
+
+class Stopped
+: public Motor
+{
+  void entry() override {
+    std::cout << "Motor: stopped" << std::endl;
+    direction = 0;
+  };
+};
+
+class Up
+: public Motor
+{
+  void entry() override {
+    std::cout << "Motor: moving up" << std::endl;
+    direction = 1;
+  };
+};
+
+class Down
+: public Motor
+{
+  void entry() override {
+    std::cout << "Motor: moving down" << std::endl;
+    direction = -1;
+  };
+};
+
+
+// ----------------------------------------------------------------------------
+// Base State: default implementations
+//
+
+void Motor::react(MotorStop const &) {
+  transit<Stopped>();
+}
+
+void Motor::react(MotorUp const &) {
+  transit<Up>();
+}
+
+void Motor::react(MotorDown const &) {
+  transit<Down>();
+}
+
+int Motor::direction{0};
+
+
+// ----------------------------------------------------------------------------
+// Initial state definition
+//
+FSM_INITIAL_STATE(Motor, Stopped)
diff --git a/lib/tinyfsm/examples/elevator/motor.hpp b/lib/tinyfsm/examples/elevator/motor.hpp
new file mode 100644
index 00000000..7d2447cf
--- /dev/null
+++ b/lib/tinyfsm/examples/elevator/motor.hpp
@@ -0,0 +1,50 @@
+#ifndef MOTOR_HPP_INCLUDED
+#define MOTOR_HPP_INCLUDED
+
+#include <tinyfsm.hpp>
+
+
+// ----------------------------------------------------------------------------
+// Event declarations
+//
+
+struct MotorUp   : tinyfsm::Event { };
+struct MotorDown : tinyfsm::Event { };
+struct MotorStop : tinyfsm::Event { };
+
+
+// ----------------------------------------------------------------------------
+// Motor (FSM base class) declaration
+//
+class Motor
+: public tinyfsm::Fsm<Motor>
+{
+  /* NOTE: react(), entry() and exit() functions need to be accessible
+   * from tinyfsm::Fsm class. You might as well declare friendship to
+   * tinyfsm::Fsm, and make these functions private:
+   *
+   * friend class Fsm;
+   */
+public:
+
+  /* default reaction for unhandled events */
+  void react(tinyfsm::Event const &) { };
+
+  /* non-virtual declaration: reactions are the same for all states */
+  void react(MotorUp   const &);
+  void react(MotorDown const &);
+  void react(MotorStop const &);
+
+  virtual void entry(void) = 0;  /* pure virtual: enforce implementation in all states */
+  void exit(void)  { };          /* no exit actions at all */
+
+protected:
+
+  static int direction;
+
+public:
+  static int getDirection() { return direction; }
+};
+
+
+#endif