Running Ada 2012 On The Cortex-M4

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我喜欢认为我编写了好的代码，并且自从他们成立以来，我已经使用了C ++。我承认将多个不需要的错误纳入C应用程序中，这些c应用程序有时是乏味的诊断会议后被淘汰的。几乎所有新的微控制器都发布了与之相关的免费C/C ++编译器工具链。

Unfortunately, C is very unforgiving, and C++ is only a little better. But they are the mainstay for embedded programmers these days. That’s one reason why I have been waiting forAdaCore’sdelivery of its Ada 2012 toolchain for Arm’s Cortex-M platform. It is a free download atlibre.adacore.com。

Cortex-M是几乎所有采用ARM架构的主要微控制器供应商使用的主要低端，32位微控制器。供应商喜欢Green Hills软件,Atego， 和Adacorehave supported the Cortex platform in the past but with earlier Ada standards. Ada 2012 includes a range of new features including contracts（看 ”ADA 2012：合同的喜悦” on electronicdesign.com)。

卷起我的袖子

I had already tried out a version of AdaCore’s GNAT Programming Studio (GPS). It generated applications that would run on Linux on the BeagleBone based on the Texas Instruments Cortex-A8 platform（看 ”武装ADA” on electronicdesign.com)。新的工具链靶向裸金属，这是许多应用所需的。

由于已经安装了GPS，因此设置很容易。将STM32板的ST-Link调试接口设置(see the figure)actually took more time. It was then a matter of running through the flashing LED demo. I included a snippet of code from a flashing LED program to highlight some of the advantages of using Ada 2012(see the listing)。

with LEDs; use LEDs; with Button; use Button; with Ada.Real_Time; use Ada.Real_Time; package body Driver is type Index is mod 4; Pattern : constant array (Index) of User_LED := (Orange, Red, Blue, Green); task body Controller is Period : constant Time_Span := Milliseconds (75); -- arbitrary Next_Start : Time := Clock; Next_LED : Index := 0; begin loop Off (Pattern (Next_LED)); Next_LED := Next_LED + (if Button.Current_Direction = Counterclockwise then -1 else 1); On (Pattern (Next_LED)); Next_Start := Next_Start + Period; delay until Next_Start; end loop; end Controller; end Driver;

即使您没有使用ADA，也应该能够了解正在发生的事情。特别是，任务主体定义突出了内置的多任务支持。另请注意，使用“模块化”（无符号）数据类型用于限制图案数组的地址的索引。与C不同，无需检查Next_led的结果。此外，如果/随后/其他条件表达ADA而不是C/C ++？：组合，我更喜欢更详细的内容。我已经在APL中进行了编程，其单线很整洁，但通常是难以理解的。C和C ++代码也可以得到这种方式。

Ada has a number of benefits compared to C and C++（看 ”Ada Offers Advantages Over C And C++” on electronicdesign.com).但是它也有缺点，例如可用性。对于Arm Cortex微控制器，这不再是问题。开发人员可以利用从仿制药到多任务处理的所有ADA 2012功能。

I would encourage anyone wanting to write bulletproof code for embedded applications to check out the AdaCore/STM32 combination. It is inexpensive and very functional. The ST-Link support also allows it to work with platforms like the STM32F401 Nucleo（看 ”Extensible Prototyping Board Built For STM32 MCUs” on electronicdesign.com)。I tried it on my Nucleo as well.

爆发的虫子（看 ”What Heartbleed Should Teach Embedded Programmers” on electronicdesign.com)is just one of many reminders of how one range check error can wreak havoc. C does not do it, but Ada does check—and not just on array access, by default. Ada will not eliminate all bugs from your code, but it does make it a lot harder to create them.

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