AdaCore Blog

An Insight Into the AdaCore Ecosystem

by Claire Dross –
Relaxing the Data Initialization Policy of SPARK

Relaxing the Data Initialization Policy of SPARK

SPARK always being under development, new language features make it in every release of the tool, be they previously unsupported Ada features (like access types) or SPARK specific developments. However, new features generally take a while to make it into actual user code. The feature I am going to present here is in my experience an exception, as it was used both internally and by external users before it made it into any actual release. It was designed to enhance the verification of data initialization, whose limitations have been a long standing issue in SPARK.

#Formal Verification    #SPARK   

by Jon Andrew (B.E.A.T. LLC.) – Guest Author
CuBit: A General-Purpose Operating System in SPARK/Ada

CuBit: A General-Purpose Operating System in SPARK/Ada

Last year, I started evaluating programming languages for a formally-verified operating system. I've been developing software for a while, but only recently began work in high integrity software development and formal methods. There are several operating system projects, like the SeL4 microkernel and the Muen separation kernel, that make use of formal verification. But I was interested in using a formally-verified language to write a general-purpose OS - an environment for abstracting the underlying hardware while acting as an arbiter for running the normal applications we're used to.

by Pat Rogers –
From Ada to Platinum SPARK: A Case Study for Reusable Bounded Stacks

From Ada to Platinum SPARK: A Case Study for Reusable Bounded Stacks

This blog entry describes the transformation of an Ada stack ADT into a completely proven SPARK implementation that relies on static verification instead of run-time enforcement of the abstraction’s semantics. We will prove that there are no reads of unassigned variables, no array indexing errors, no range errors, no numeric overflow errors, no attempts to push onto a full stack, no attempts to pop from an empty stack, that subprogram bodies implement their functional requirements, and so on. As a result, we get a maximally robust implementation of a reusable stack abstraction providing all the facilities required for production use.

#SPARK    #Ada    #Transitioning to SPARK   

by Abe Cohen –
An Introduction to Contract-Based Programming in Ada

An Introduction to Contract-Based Programming in Ada

One of the most powerful features of Ada 2012* is the ability to specify contracts on your code. Contracts describe conditions that must be satisfied upon entry (preconditions) and upon exit (postconditions) of your subprogram. Preconditions describe the context in which the subprogram must be called, and postconditions describe conditions that will be adhered to by the subprogram’s implementation. If you think about it, contracts are a natural evolution of Ada’s core design principle. To encourage developers to be as explicit as possible with their expressions, putting both the compiler/toolchain and other developers in the best position to help them develop better code.

by Roderick Chapman (Protean Code Limited) – Guest Author
Proving properties of constant-time crypto code in SPARKNaCl

Proving properties of constant-time crypto code in SPARKNaCl

Over the last few months, I developed a SPARK version of the TweetNaCl cryptographic library. This was made public on GitHub in February 2020, under the 2-clause BSD licence. This blog entry goes into a bit more technical detail on one particular aspect of the project: the challenge of re-writing and verifying "constant time" algorithms using SPARK.

#SPARK    #Cryptography    #Formal Verification   

by Pat Rogers –
Making an RC Car with Ada and SPARK

Making an RC Car with Ada and SPARK

As a demonstration for the use of Ada and SPARK in very small embedded targets, I created a remote-controlled (RC) car using Lego NXT Mindstorms motors and sensors but without using the Lego computer or Lego software. I used an ARM Cortex System-on-Chip board for the computer, and all the code -- the control program, the device drivers, everything -- is written in Ada. Over time, I’ve upgraded some of the code to be in SPARK. This blog post describes the hardware, the software, the SPARK upgrades, and the repositories that are used and created for this purpose.

#Ada    #SPARK    #Robotics   

by Pierre-Marie de Rodat –
A Further Expedition into Libadalang: Save Time with Libadalang.Helpers.App

A Further Expedition into Libadalang: Save Time with Libadalang.Helpers.App

Martyn’s recent blog post showed small programs based on Libadalang to find uses of access types in Ada sources. Albeit short, these programs need to take care of all the tedious logistics around processing Ada sources: find the files to work on, create a Libadalang analysis context, use it to read the source files, etc. Besides, they are not very convenient to run:

#Libadalang   

by Quentin Ochem –
Witnessing the Emergence of a New Ada Era

Witnessing the Emergence of a New Ada Era

For nearly four decades the Ada language (in all versions of the standard) has been helping developers meet the most stringent reliability, safety and security requirements in the embedded market. As such, Ada has become an entrenched player in its historic A&D niche, where its technical advantages are recognized and well understood. Ada has also seen usage in other domains (such as medical and transportation) but its penetration has progressed at a somewhat slower pace. In these other markets Ada stands in particular contrast with the C language, which, although suffering from extremely well known and documented flaws, remains a strong and seldom questioned default choice. Or at least, when it’s not the choice, C is still the starting point (a gateway drug?) for alternatives such as C++ or Java, which in the end still lack the software engineering benefits that Ada embodies..