Software Development

840 Articles

Samsung’s Leap Month Bug Teaches Not To Skimp On Testing

June 15, 2020 by 23 Comments

Date and time handling is hard, that’s an ugly truth about software development we’ll all learn the hard way one day. Sure, it might seem like some trivial everyday thing that you can easily implement yourself without relying on a third-party library. I mean, it’s basically just adding seconds on top of one another, roll them over to minutes, and from there keep rolling to hours, days, months, up until you hit the years. Throw in the occasional extra day every fourth February, and you’re good to go, right?

Well, obviously not. Assuming you thought about leap years in the first place — which sadly isn’t a given — there are a few exceptions that for instance cause the years 1900 and 2100 to be regular years, while the year 2000 was still a leap year. And then there’s leap seconds, which occur irregularly. But there are still more gotchas lying in wait. Case in point: back in May, a faulty lunar leap month handling in the Chinese calendar turned Samsung phones all over China into bricks. And while you may not plan to ever add support for non-Gregorian calendars to your own project, it’s just one more example of unanticipated peculiarities gone wild. Except, Samsung did everything right here.

So what happened?

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Programming In Plain English

June 12, 2020 by 79 Comments

Star Trek had really smart computers, that you could simply tell what you wanted to do and they did it. The [Rzeppa] family has started a plain English compiler. It runs under Windows and appears to be fairly capable.

Plain language programming isn’t exactly a new idea. COBOL was supposed to mimic natural language with statements like:

MULTIPLY HOURS BY RATE GIVING PAYAMOUNT

You could argue this didn’t go over very well, but there is still a whole lot of COBOL doing a whole lot of things in the business world. Today computers have more memory and speed, so programmers have been getting more and more verbose for decades. No more variable names such as X1 and fprdx. Maybe this will catch on.

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Adding WiFi To Black Magic For Wireless GDB Action

June 4, 2020 by 11 Comments

[Thoquz] wrote to us about an interesting GitHub project by [Valmantas Palikša] involving the porting of the Black Magic firmware to ESP8266. For those who are unaware, Black Magic Probe is firmware along with a range of official and third-party boards that targets the debugging of Cortex-M and Cortex-A MCUs and SoCs.

With this blackmagic-espidf project, one can use any ESP8266 board that has at least 2 MB of Flash program storage, though 1 MB should be possible if OTA updated are disabled. After flashing the firmware to the ESP8266 board, the GDB server can be reached on TCP port 2022 and UDP 2023, with a serial port available via TCP/23, UDP2323, or via the physical TX0/RX0 pins on the ESP8266.

The target board to be debugged  is hooked up by default to GPIO0 (SWDIO) and GPIO2 (SWCLK) for Serial Wire Debugging, though JTAG is also said to be supported. If set up properly, next one should be able to pop into a fresh remote GDB session:

gdb connection

If you don’t want the WiFi, you can buy a wired one, or just roll your own from any STM32 board that you’ve got kicking around.

Peeking Inside Executables And Libraries To Make Debugging Easier

May 28, 2020 by 5 Comments

At first glance, both the executables that a compiler produces, and the libraries that are used during the building process seem like they’re not very accessible. They are these black boxes that make an application go, or make the linker happy when you hand it the ‘right’ library file. There is also a lot to be said for not digging too deeply into either, as normally things will Just Work™ without having to bother with such additional details.

The thing is that both executables and libraries contain a lot of information that normally is just used by the OS, toolchain, debuggers and similar tools. Whether these files are in Windows PE format, old-school Linux a.out or modern-day .elf, when things go south during development, sometimes one has to break out the right tools to inspect them in order to make sense of what is happening.

This article will focus primarily on the Linux platform, though most of it also applies to BSD and MacOS, and to some extent Windows.

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Simple Sprite Routines Ease Handheld Gaming DIY

May 26, 2020 by 2 Comments

Making your own handheld games is made much easier with [David Johnson-Davies’] simple sprite routines for the Adafruit PyBadge and PyGamer boards. Sprites can be thought of as small, fixed-size graphical objects that are drawn, erased, moved, and checked for collision with other screen elements.

xorSprite() plots an 8×8 sprite, moveSprite() moves a given sprite by one pixel without any flicker, and hitSprite() checks a sprite for collision with any screen elements in a given color. That is all it takes to implement a simple game, and [David] makes them easy to use, even providing a demo program in the form of the rolling ball maze shown here.

These routines work out-of-the-box with the PyBadge and PyGamer, but should be easy to adapt to any TFT display based on the ST7735 controller. The PyGamer is the board shown here, but you can see the PyBadge as it was used to create an MQTT-enabled conference badge.

If you really want to take a trip down the rabbit hole of sprite-based gaming graphics, you simply can’t miss hearing about the system [Sprite_TM] built into the FPGA Game Boy badge.

Using Valgrind To Analyze Code For Bottlenecks Makes Faster, Less Power-Hungry Programs

May 20, 2020 by 27 Comments

What is the right time to optimize code? This is a very good question, which usually comes down to two answers. The first answer is to have a good design for the code to begin with, because ‘optimization’ does not mean ‘fixing bad design decisions’. The second answer is that it should happen after the application has been sufficiently debugged and its developers are at risk of getting bored.

There should also be a goal for the optimization, based on what makes sense for the application. Does it need to process data faster? Should it send less data over the network or to disk? Shouldn’t one really have a look at that memory usage? And just what is going on inside those CPU caches that makes performance sometimes drop off a cliff on a single core?

All of this and more can be analyzed using tools from the Valgrind suite, including Cachegrind, Callgrind, DHAT and Massif.

Keeping Those Cores Cool

Modern day processors are designed with low power usage in mind, regardless of whether they are aimed at servers, desktop systems or embedded applications. This essentially means that they are in a low power state when not doing any work (idle loop), with some CPUs and microcontrollers turning off power to parts of the chip which are not being used. Consequently, the more the processor has to do, the more power it will use and the hotter it will get.

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Poking Around Inside Of A Linux Security Camera

May 20, 2020 by 21 Comments

This deep dive into the Linux-powered Reolink B800 IP camera started because of a broken promise from its manufacturer. When [George Hilliard] purchased a kit that included six of the cameras and a video recorder, the website said they were capable of outputting standard RTSP video. But once he took delivery of the goods, and naturally after his return window had closed, the site was updated to say that the cameras can only function with the included recorder.

Taking that as something of challenge, [George] got to work. His first big break came when he desoldered the camera’s SPI flash chip and replaced it with a socket. That allowed him to easily take the chip out of the device for reading and flashing as he tinkered with modifying the firmware. After adding cross-compiled versions of busybox, gdb, and strace to the extracted firmware, he bundled it back up and flashed it back to the hardware.

If you think that’s the end of the story, it isn’t. In fact, it’s just the beginning. While getting root-level access to the camera’s OS would have potentially allowed for [George] to dump all the proprietary software it was running and replace it with open alternatives, he decided to take a different approach.

Instead of replacing the camera’s original software, he used his newly granted root powers to analyze it and figure out how it worked. This allowed for to sniff out some very suspect “encryption” routines built into the software, and eventually write his own server side in Rust that finally allowed him to use the cameras with his own server…albeit with a bit more work than he bargained for.

Projects like these are a fantastic look at real world reverse engineering, and a reminder that sometimes achieving your ultimate goal means taking the long way around. Even if you’re not in the market for a hacked security camera, there’s no doubt that reading the thorough write-up [George] has prepared will teach you a few things. But of course, we’d expect no less from a guy who runs Linux on his business card.