Blog Entries

Embedded Lua

al.williams@awce.com — Mon, 08 Feb 2010 19:00:00 +0100

No one with any sense would include me in a market research focus group. Things I like are definitely atypical—at least for the general population. I like to think I'm pretty typical for a geek though. But even geeks have some variation. One thing's for sure: I like C. Especially for embedded programs. You've probably noticed I like Forth too, especially when I have to write my own language tools. Beyond C, Forth, and assembler, I rarely have much [...]

Distributing Work across Cores using .NET

cdiggins@gmail.com — Mon, 08 Feb 2010 19:00:00 +0100

The easiest way in C# using .NET 3.5 to distribute work across cores is to use the ThreadPool static class. I found however, it wasn't quite as effective as it could be so I rolled my own.

One of the goals of Heron is to make it easy to express parallel operations without having to worry about threads. I am doing this because I find multi-threaded code too darn hard. The irony is that to implement these operators I had to resort to rolling my own work distribution l [...]

How to Get Tomorrow's Date in Perl

popx@j-paine.org — Sun, 07 Feb 2010 19:00:00 +0100

From Mark-Jason Dominus's Infrequently Asked Questions About Perl:

tomorrow_date {
sleep 86_400;
return localtime();
}

Dominus's function is reminiscent of the transistor tester that shoots 240 volts across all three pairs of leads and then announces "Dead".

Practical Arduino Book Review

mike@mikeriley.com — Sat, 06 Feb 2010 19:00:00 +0100

Long-time Dobbs Codetalk readers may recall my Arduino review nearly a year ago. At the time, only a brief book programming the product existed. Apress has recently published a book that dives much deeper on the subject and walks readers through over a dozen Arduino projects. Read on for the review.

For any software developer interested in exploring embedded systems programming, the Arduino board provides an easy, expandable hardware platform to experiment on.&nbs [...]

(Still) be explicit to avoid those array/pointer decay ambiguities

matthew@synesis.com.au — Sat, 06 Feb 2010 19:00:00 +0100

I'm multitasking between three clients at the moment, two of whose projects are based primarily around C++. It's interesting seeing the differences between all the languages, programming styles, and tools, involved. For a consultant - horrid word - it's a refreshing and enlightening experience.

Although there is a C standard and a C++ standard, there are also different degrees of support for the standards by different compilers, not to mention some subtle (a [...]

LLVM Self-Hosting C Compiler

al.williams@awce.com — Sat, 06 Feb 2010 19:00:00 +0100

I always have the idea to port a C compiler to target one of my custom CPU projects, but I haven't done it (yet). But I'm always looking at tools to simplify the job.

One of these is the LLVM (Low Level Virtual Machine) compiler infrastructure. The LLVM itself isn't a compiler -- it helps you build things like compilers. However, the project ships clang , a front end for C, C++, Objective C, and Objective C++.

I found it interesting that in a recent [...]

Snobol Patterns in Prolog IV: bal, and the Use of Failure to Diagnose Patterns

popx@j-paine.org — Sat, 06 Feb 2010 19:00:00 +0100

It's a pun between logic and control flow: a pun where you hear "A or B" with one ear but "Do A; until something fails, then try B" with the other. In most languages, there are Boolean expressions that return a TRUE or a FALSE, and conditions that jump to a THEN or an ELSE. But in Snobol, there are pattern matches that succeed or they fail; and if a match fails, the matcher will backtrack to already-matched subpatterns, seeking alternative matches that make the curren [...]

Oh Hey, It's A Rails 3 Beta

nap@zerosum.org — Fri, 05 Feb 2010 19:00:00 +0100

It's been well over a year since the Ruby on Rails and Merb teams announced that the projects would merge for the upcoming Rails 3 release. Like most of you, I haven't been closely tracking the progress on a regular basis. Fortunately, a number of my friends and colleagues have been much more involved, contributing to and tracking the progress of the effort.

From an outsider point of view, watching their updates and conversations, I've seen a mixture of intense enthusiasm a [...]

FPGA CPUs

al.williams@awce.com — Fri, 05 Feb 2010 19:00:00 +0100

When you need a CPU with custom I/O or features, there seems to be three very distinct ways that people employ FPGAs. One solution is to simply incorporate an FPGA along side a standard CPU. You keep using your usual development tools and just build some interface between the CPU and the logic on the FPGA.

Another way to handle a design like this is to build the CPU right on the FPGA along with whatever custom things you need. There are an endless number of possibilities here, but, as a [...]

It's Catch Up Time Again

jerickson@ddj.com — Thu, 04 Feb 2010 19:00:00 +0100

From time-to-time, its time to catch up, which means I have to go into the office, re-introduce myself to the staff, and wander through the various departments to find out what I've missed. Here's what my most recent sojourn turned up.

From the "so that's what the iPad is all about" department...

I've been reading overtime in trying to figure out what's the point of the iPad, Apple's recently announced Tablet Personal Computer. Oops, there's [...]

Can You Prove It?

bil@lambdacs.com — Thu, 04 Feb 2010 19:00:00 +0100

A few years back there was a case brought against Larry Ellison for

sexual harassment. I forget the details, but the "proof" of his

culpability was a set of emails purportedly exchanged between him and

Why are women underrepresented in Science, Technology, Engineering, and Math (STEM) careers? I’ve posted a couple of articles about this, which taught me that people have very strong opinions about the topic.

Unfortunately, this is one of those areas where the strongest opinions and the loudest voices come from personal experiences. Detailed academic study of the problem often takes a back seat to arguing about life histories.

Cocoa Programming Developer's Handbook Book Review

mike@mikeriley.com — Sun, 31 Jan 2010 19:00:00 +0100

With the announcement of the Apple iPad, even more developers are turning their interest toward learning and mastering the Cocoa framework required for Apple application development. How does this latest Addison-Wesley Developer's Library title stack up to other Cocoa programming books? Read on to find out.

I have a fairly agnostic view of Apple products. On the one hand, Apple creates some of the most elegant consumer electronics products that the world has e [...]

Associative Programming and Snobol's Unusual Indirect-Referencing Operator

popx@j-paine.org — Sun, 31 Jan 2010 19:00:00 +0100

In most languages, to "dereference" a pointer is to treat its value as a machine address and look up the data therein. Snobol is different. Strings are one analogue of pointers. And one can go, at run-time, from a string to the variable with the same name. Or even to a label with the same name: a string computed goto.

Snobol does this with the indirect-referencing operator, unary dollar. So suppose the value of variable "dog" is the string "bark". And [...]

Marc Stiegler's Gentle Seduction

popx@j-paine.org — Sun, 31 Jan 2010 19:00:00 +0100

I saw Eternity the other night
Like a great Ring of pure and endless light
    All calm as it was bright;
And round beneath it, Time, in hours, days, years,
    Driven by the spheres.
Like a vast shadow moved, in which the world
    And all her train were hurled.
                      & [...]

Elusive Gravity Waves

jax@well.com — Sat, 30 Jan 2010 19:00:00 +0100

Quite a lot of effort has gone into the theory, construction and opertation of a planetarily distributed network of gravitometric installations in search of gravity waves. Such efforts have not been successful and may be in vain, whether or not gravity waves exist.

The search for gravity waves may be more difficult than experiments such as LIGO suggest.

If gravity waves exist, they're not going to be neat in their impact on any target or necessarily identifiable as coupled t [...]

Implementing Thread Local Storage on OS X

walter@digitalmars.com — Sat, 30 Jan 2010 19:00:00 +0100

Many programming languages allow defining global data with simple declarations like:

int x = 3;

This global data is, well, global and is accessible to any thread started up by that program. This is called implicit sharing. But since there is no inherent synchronization to accessing it, all kinds of inadvertent threading problems can arise from using it.

One way to resolve this is for each thread to have its own distinct and separate copy of the data. This [...]