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Useful C++ patterns for embedded programming.
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Copyright 2005-2018 Digital Aggregates Corporation, Arvada Colorado USA.


Licensed under the terms of FSF LGPL v2.1.


Grandote (Spanish for "ginormous") is a C++ layer on top of the Diminuto (Spanish for "tiny") library. Diminuto is a C-based library specifically written for Linux/GNU. Grandote is fork of Desperadito, which itself is a fork of Desperado. Desperado is a C++ library that was intended to abstract out the underlying operating system so that applications written on top of it would be portable to other hardware targets and software platforms like Linux, Cygwin, VxWorks, etc. In this incarnation, Grandote provides C++ facilities on top of Diminuto's OS abstraction.

To make this even more complicated, Diminuto itself was at one time an OS choice for Desperado, which referred not to the Diminuto library, but to the ARMv4-based hardware target for which Diminuto was originally written. That target, laughably small in light of today's 64-bit gigaHertz multicore microprocessors (and the reason for Diminuto's name), is long gone, but the Diminuto library remains and continues to evolve. I don't know that anyone but me has ever used Desperado, but portions of Diminuto are shipping in a number of commercial products from several of my clients.

The POSIX thread portions of Desperadito - and, hence, Grandote - were forked from Hayloft, a C++ framework for using Amazon Web Service (AWS) Simple Storage Service (S3). A tiny portion of Diminuto was in C++, and those facilities have been moved into Grandote, making Diminuto purely C. The unit tests are a mixture of straight C++ programs (whose implementations were a little strange to make them easier to use in VxWorks) from the ancient Desperado code base, Google Test programs from the Hayloft code base, and even some unit test main programs from the Diminuto code base that use the Diminuto unit test framework. The Google Test programs use a thin helper layer from yet another project, Lariat. For new unit tests, I strongly recommend Google Test, although the Diminuto unit test framework is simple and easy to use.

To use Grandote you need to also install Diminuto, Lariat, and Google Test. This is easier than it sounds. I had issues getting the unittest main program that uses Google Test to link under Ubuntu 14.04 and the problem defied my ability to fix it; I ran the same build on Ubuntu 16.04 and had one tiny dependency issue that was easily remedied; my guess is there was really only that one small issue, and the other error messages that side-tracked me were spurious.

Grandote, Desperado, Desperadito, Hayloft, Lariat, and Diminuto were all written by me, are the intellectual property of the Digital Aggregates Corporation, and are licensed using one FSF GNU license or another.


I started working on Desperado, the core from which Grandote was derived, in 2005. The code has transitioned through a number of source code control systems, as they became available and popular: RCS, CVS, SVN, and finally GIT. There were a number of reasons for my interested in Desperado.

For years I had done development in C++ for embedded systems using the VxWorks real-time operating system (RTOS). I could see that while the platform for many new products was going to transition to Linux, there would be a substantial revenue-generating base of legacy products still based on VxWorks. I wanted to experiment with abstracting the platform dependencies out from the C++ applications so that those applications could be run on either VxWorks and Linux.

I had had a lot of experience integrating C++ systems into existing C systems, or vice versa, and wanted to establish a mechanism for C code to take advantage of C++ frameworks.

I saw a need for a way to abstract data sources and sinks into objects with a common interface that could be used via dependency injection to tie software components together.

Despite other's skepticism around the use of C++ templates in resource constrained embedded systems, I believed templates could be used as a kind of type-safety wrapper, and also to judiciously generate code for hardware platforms whose underlying integer types were of different sizes.

I have had a long time interest in timekeeping and calendar systems, a theme that shows up in many of my projects. Desperado gave me a way to explore this in detail.

There are several frameworks - Boost comes to mind most readily - that package most of the complexity of using POSIX Threads into a more easily digestible form. But I have learned from experience working on large product development teams that it is all to easy to use such frameworks and not understand how they work and find yourself unable to debug your own code when wackiness ensues. So developing my own simple Thread framework was my way of learning how POSIX Threads work under the hood.

I explored many of these same themes in Diminuto, my C-based Linux systems programming library. My VxWorks days are - as far as I can tell anyway - long gone. I consider most of my platform-portability work in Grandote obsolete and for the most part no longer worry much about it. But many of the other ideas I explored in Desperado are of continuing value and I maintain them in Grandote.

I have written tens if not hundreds of thousands of lines of C++ for embedded products, mostly during my years at Bell Labs and its various spinoffs. At one time I was a strong advocate for the use of C++ in embedded products. But over the years, I have seen a decline in the use of C++ for such work, and an increase in the use of C for the systems layer, and languages like Python, Java, and even JavaScript for the application layer.

I can't argue with the economics of that: you can hire less expensive developers for those other languages, and writing in those languages is more productive than in C++. As a consequence of dealing with mixed language product development, I've done my share of coding in Python and Java, and have even hacked JavaScript.

Meanwhile, C++ has evolved into a language so complex that my clients can't afford - or can't find - developers with that skill set and that level of expertise. I myself need to come up to speed with some of the more recent C++ features, and determine how I might leverage them in the kind of work that I do. Perhaps my interest in Grandote means I'm not ready to give up on C++ quite yet.



Chip Overclock
Digital Aggregates Corporation
3440 Youngfield Street #209
Wheat Ridge CO 80033


cd ~/src
git clone
( cd googletest; mkdir out; cd out; cmake -Dgtest_build_samples=ON -Dgtest_build_tests=ON ..; make; make test )
git clone
( cd com-diag-diminuto/Diminuto; make pristine depend all )
git clone
( cd com-diag-lariat/Lariat; make pristine depend all )
git clone
( cd com-diag-grandote/Grandote; make pristine depend all )
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