Replace main C subprogram by an Ada subprogram

declared in environment_task.adb to simplify dependency
list in CMakeLists.txt.
Edit README.md

Author: reznikmm

.gitignore

@@ -12,6 +12,7 @@ b__*.ad?
 
 .build*
 obj
+.objs
 test
 doc
 cortex-gnat-rts*
@@ -22,6 +23,7 @@ gnatinspect.db
 gpr_query.*
 
 local/
+examples/*/build/
 
 demos-arduino-due/debounce_hardware
 demos-arduino-due/debounce_software

README.md

@@ -23,12 +23,10 @@ location of Flash, RAM; clock initialization; interrupt naming) is in
 The Ada source is either original or based on FSF GCC (mainly 4.9.1, some
 later releases too).
 
-The boards supported are
+Any board with ESP32 should work. We have tested with
 
 * Wireless Stick (Gecko Board) by Heltec
-  * See `esp32/COPYING*` for licensing terms.
-  * Example in `examples/`.
-
+* TTGO T-Display ESP32 (Make sure to change LED pin to 2).
 
 The package is based on
 [Cortex-GNAT-RTS](https://github.com/simonjwright/cortex-gnat-rts)
@@ -107,8 +105,9 @@ Ada code into ESP-IDF application.
 
 The `hello_world` application is an ESP-IDF project.
 It requires `esp32-gnat-rts` component as dependency.
-The `hello_world.c` main subprogram just calls `main` function (created by
-`gnatbind`).
+The `app_main` subprogram called by FreeRTOS is declared in
+`environment_task.adb`. It creates an _environment task_ that
+calls `main` function (created by `gnatbind`).
 In turn `main` calls `Hello_Ada` procedure.
 The `Hello_Ada` outputs "Hello Ada!" with `puts` provided by FreeRTOS.
 

common/gcc8/environment_task.adb

@@ -64,6 +64,17 @@ package body Environment_Task is
      External_Name => "_environment_task_secondary_stack_size";
    pragma Weak_External (Environment_Task_Secondary_Stack_Size);
 
+   procedure App_Main
+   with
+     Export,
+     Convention => C,
+     External_Name => "app_main";
+
+   procedure App_Main is
+   begin
+      Create;
+   end App_Main;
+
    procedure Create is
       --  Will be overwritten by binder-generated code if the main
       --  program has pragma Priority.

esp32/README.md

@@ -1,19 +1,16 @@
-This is an Ada Runtime System (RTS) for the GCC Ada compiler (GNAT), targeted to the [BBC micro:bit board](http://microbit.org/).
+This is an Ada Runtime System (RTS) for the GCC Ada compiler (GNAT),
+targeted to boards based on the [ESP32](https://en.wikipedia.org/wiki/ESP32).
 
 The RTS supports Ravenscar tasking. Package System contains the following additional restrictions:
 
 *  `pragma Restrictions (No_Exception_Propagation);`
 *  `pragma Restrictions (No_Finalization);`
 
-Aside from the limitations imposed by the small RAM size of the micro:bit (16K), the system clock runs at 100 Hz rather than the 1000 Hz used in the other RTSs in this family.
-
 The RTS is intended to support commercial binary distributions. The Ada source code has either been derived from FSF GCC (4.9.1, in some cases later) or written for this work; see the files `COPYING3` and `COPYING.RUNTIME`.
 
 The RTS is based on [FreeRTOS]( http://www.freertos.org). See `COPYING.FreeRTOS`.
 
-Board support (spec files only) was generated using [svd2ada](https://github.com/AdaCore/svd2ada) at commit `861c829` from the Nordic SVD. See `COPYING.Nordic`.
-
 The following non-original files don't form part of a binary deliverable, so don't affect the status of the binary:
 
 * `build_runtime.gpr` and `runtime.xml` originated in AdaCore's GNAT GPL 2014 arm-eabi distribution (for Linux).
-* The linker script `nrf51.ld` is under an MIT licence: see COPYING.MIT.
+

examples/gpio/main/CMakeLists.txt

@@ -15,8 +15,7 @@ if(NOT CMAKE_BUILD_EARLY_EXPANSION)
      VERBATIM)
 endif()
 
-idf_component_register(SRCS "blink.c"
-                            ".objs/b__blink.o"
+idf_component_register(SRCS ".objs/b__blink.o"
                             ".objs/blink.o"
                             ".objs/esp32-gpio.o"
                             ".objs/esp32.o"

examples/gpio/main/blink.adb

@@ -6,7 +6,9 @@
 with Ada.Real_Time;
 with ESP32.GPIO;
 
-procedure blink is
+procedure Blink
+  with No_Return
+is
    use type Ada.Real_Time.Time;
 
    Button : constant := 0;   --  Button pad
@@ -22,14 +24,15 @@ begin
         Direction => ESP32.GPIO.Input,
         Input     => ESP32.GPIO.None)));    --  for Get_Level
 
-   for J in 1 .. 10 loop
-      --  Turl LED if button is not pressed
-      ESP32.GPIO.Set_Level
-        (LED, (J mod 2 = 1) and ESP32.GPIO.Get_Level (Button));
+   loop
+      for J in 1 .. 10 loop
+         --  Turl LED if button is not pressed
+         ESP32.GPIO.Set_Level
+           (LED, (J mod 2 = 1) and ESP32.GPIO.Get_Level (Button));
 
-      delay until Ada.Real_Time.Clock + Ada.Real_Time.Seconds (1);
+         delay until Ada.Real_Time.Clock + Ada.Real_Time.Seconds (1);
+      end loop;
    end loop;
 
-  --  NOTE:
-  --  Make sure that main subprogram doen't return in a real project!
-end blink;
+   --  Make sure that main subprogram doen't return in a real project!
+end Blink;

examples/gpio/main/blink.c

@@ -13,8 +13,7 @@ if(NOT CMAKE_BUILD_EARLY_EXPANSION)
      VERBATIM)
 endif()
 
-idf_component_register(SRCS "hello_world.c"
-                            ".objs/b__hello_world.o"
+idf_component_register(SRCS ".objs/b__hello_world.o"
                             ".objs/hello_world.o"
                     INCLUDE_DIRS "."
                     REQUIRES esp32-gnat-rts)

examples/hello_world/main/CMakeLists.txt

@@ -6,7 +6,9 @@
 with System;
 with Ada.Real_Time;
 
-procedure Hello_World is
+procedure Hello_World
+  with No_Return
+is
    use type Ada.Real_Time.Time;
 
    procedure puts
@@ -15,10 +17,10 @@ procedure Hello_World is
 
    Hello : String := "Hello from Ada!" & ASCII.NUL;
 begin
-  for J in 1 .. 10 loop
-    puts (Hello'Address);
-    delay until Ada.Real_Time.Clock + Ada.Real_Time.Seconds (1);
-  end loop;
+   loop
+      puts (Hello'Address);
+      delay until Ada.Real_Time.Clock + Ada.Real_Time.Seconds (1);
+   end loop;
 
   --  NOTE:
   --  Make sure that main subprogram doen't return in a real project!