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Imran Nazar


THINGS I'VE WRITTEN OVER THE YEARS

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 * GitHub: Two9A
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SERIES

Longer-form articles released in serial format, as and when parts are completed.

GameBoy Emulation in JavaScript (Feb 2011) JavaScript is often perceived as a
Web scripting language, with a specialist purpose of manipulating HTML pages.
JavaScript is, however, a general-purpose Turing-complete language: the best way
to illustrate this is to emulate another system through JavaScript. In this
series I explore how to build an interpretive emulator in JS, with the example
of the GameBoy. Let's Build a JPEG Decoder (May 2013) The JPEG image format is a
bit of a black box for many: files go in and images come out. Looking inside the
box reveals a bunch of interesting algorithms and ideas, so writing a JPEG
decoder makes for an interesting exercise.


ARTICLES

Explorations of various software development topics, as standalone articles.

Binary Golfing in Commodore BASIC (Oct 2023) This year's Binary Golf Grand Prix
recently closed for submissions, and I only just found about it. This article
covers a couple of approaches for this particular code golf problem on the
Commodore 64. Preprocessor Definitions in WebAssembly (Sep 2023) When
hand-writing WebAssembly it can get problematic to refer to particular constants
by their value instead of being able to put a name to them. I put together a
simple preprocessor to allow for constants to be handled by name, and in this
article I look at how the preprocessor works with the WebAssembly Text format.
RFC 7168 (Apr 2014) An update to HTCPCP (RFC 2324) to allow for the connection
of networked tea-brewing devices. Published under the RFC Informational series.
Steganography with Brainfuck (Nov 2011) There are a number of techniques for
encrypting or hiding information within an image, including the concept of
hiding a program within the image which itself prints the secret information.
This article explores the feasibility of encoding a Brainfuck program within the
bitmap data of an image, with a detailed run-through of a simple example.
Printable Opcodes in x86 Real Mode (Jun 2011) Procedures for transmission of
files over ASCII-text networks generally involve some form of encoding such as
uuencode. When program executable files are being encoded for transmission,
extra steps are required at the receiver before the program can be run. This
article explores the concept of a program which has been encoded for an
ASCII-text network, but can also be run directly without decoding; in this case,
the article is limited to MS-DOS programs. Android NDK Edge Detection (May 2011)
Concluding an introduction to the development of augmented reality software,
this part looks at implementing an edge detection algorithm overlaid on an
Android smartphone's camera preview, and how the process can be optimised
through use of the Android Native Development Kit. Android NDK Camera Overlays
(Apr 2011) One of the major current trends in smartphone applications is
augmented reality: a view of reality with information laid on top. This can be
as simple as a view of what the camera is currently seeing, with calculations
based on position and direction. In the first of a two-part article series on
Android development, this article looks at how to set up a camera view and
access a canvas for the rendering of overlay information. Memory Usage of
Constants in PHP (Jun 2010) PHP provides two methods of defining constants:
global-scope constants and class constants. A friend of mine, while discussing
the issue with Derick Rethans, was informed that class constants are more memory
efficient; this article documents my investigation into the reasons behind that
assertion. Venn Diagrams in PHP with imagick (May 2010) Visualising the overlap
between two sets of data is often achieved through Venn diagrams, but such
diagrams can be difficult to render in a web development environment. This
article covers the mathematics and geometry behind the Venn diagram, and a
simple implementation of the algorithms involved in calculating the appropriate
dimensions. Discordian Dates in Java (Mar 2010) Date handling, and especially
conversion between different calendars, can be a complex issue to deal with.
This article introduces the concept of calendar conversion in Java, and the
issues that need to be dealt with when performing such conversions, by building
a handler for the Discordian calendar and investigating the mappings between
months in the Gregorian calendar and the Discordian seasons. Audio Captchas in
PHP (Jan 2010) The major compromise made when a website uses Captcha images is
that between accessibility and security; those with bad eyesight or
colour-blindness may have trouble viewing a Captcha image. One way around that
is to provide an MP3 download option for the Captcha text, which gives another
path of accessibility to the process. This article looks at how an audio Captcha
can be generated, using common tools. BCD Addition on Atmel AVR (Dec 2009) The
AVR instruction set manual mentions binary-coded decimal exactly once, and
provides no instructions for easily working with BCD values, despite the utility
of BCD in embedded applications. This article explores the issues involved in
working with BCD values, especially in incrementing and adding such values, and
introduces an algorithm for resolving the discrepancies that arise. Gameboy Z80
Opcode Map (Nov 2009) The CPU used by the Nintendo GameBoy is a specially
modified version of the Z80, with various functions removed to make the CPU
cheaper to manufacture. Documentation for this CPU is often lacking; the most
common opcode maps are written down as a standard Z80 map with addenda for the
Nintendo modifications. This opcode map collates the references into a coherent
opcode map for the Nintendo GB-Z80. PayPal Website Payments Pro in PHP (Sep
2009) PayPal is used across the world to authorise payments online, and a
seamless credit card payment service is available through Website Payments Pro.
Unfortunately, the documentation for implementing this can be confusing and
contradictory, and getting your code working can take some time. In this article
I've brought together the documentation and my experience with it, to provide a
coherent source of information on Website Payments Pro. Parsing the DIME Message
Format (Jul 2009) If a SOAP web service requests in a complex response, where
more than one file has to be returned, an encoding format has to be used to fit
the files into one message. One of the more common formats is Microsoft DIME,
used by Jasper Reports and other services. This article looks into how a DIME
message can be parsed, and the files pulled out to work with. Rebuilding Your
Leg After Shooting Yourself in the Foot (Jun 2009) At some point, most
developers have come across 'Shooting yourself in the foot', the comparison of
how different programming languages would implement the process of firing a gun
at your foot. This article assumes success, and the lack of a significant
portion of your leg; Part Two looks at how to rebuild your leg, in various
languages. Vanilla JavaScript Slideshows (Jun 2009) Many developers state that
modern JavaScript effects, such as slide-shows and news tickers, can only be
viably achieved using frameworks such as jQuery and Dojo. This article sets out
to demonstrate that it is in fact a simple affair to construct a slideshow using
JavaScript and DOM manipulation, without the need for such frameworks. Vanilla
JavaScript Tab Controls (Mar 2009) Tabs have always been one of the most useful
elements of a user interface, allowing an interface designer to pack a lot of
information into a small space by only showing a section at a time. This article
explores the implementation of a tabbing interface using HTML and JavaScript,
and goes on to look at pages where more than one set of tabs is used at the same
time. Modified Preorder Tree Traversal (Feb 2009) Exploring the MPTT algorithm,
and how it can be used for hierarchical data storage. Includes algorithms for
addition to and removal from the tree. Asynchronous JavaScript and JSON (Dec
2008) The most common problem that people encounter when using AJAX is that they
can't update more than one region of a Web page at the same time, since the
request only comes back to fill one region. Using JSON, it's possible to update
multiple regions at once, and it's even possible to run inline JavaScript in the
AJAX response, automatically. The magic behind it is explained here. Using
Pointers in C# (Nov 2008) The current crop of programming languages tend to
frown upon the use of pointers, deeming them to be unsafe for everyday work;
indeed, many languages ban their use altogether. C# is different: it is possible
for a C# program to delve into pointers, but there are caveats. An example is
given in this article, using a graphical bitmap effect driven by pointer
arithmetic. Automated Deployment with Subversion (Oct 2008) Version control
systems and development testing servers go hand in hand; you work on your local
working copy, and test on the development server. But what happens when you want
to take your work live: to deploy the developments you've completed? This
article presents one way to solve that problem, by using the scripting
facilities provided by Subversion. Building Complex Emails with PHP (Aug 2008)
The first script that a budding PHP developer builds is often a tool to send
simple email messages from a website, with a couple of paragraphs of text
inside. What these scripts lack is the ability to send HTML-formatted emails, or
to attach documents and other files to the message. In this article, I cover the
MIME standard for building complex emails, and how to format and send a
MIME-compliant email message in PHP. Extended Text Mode on the C64 (Aug 2008)
When you mention the Commodore 64, most people think that it's an obsolete
computer from the 80s which no-one could ever use nowadays. One of the major
problems is that you can't fit enough information onto a C64's screen: the
standard size of a work terminal is 80 characters by 25 lines, and 40x25 just
isn't enough. In the first part of a series (which may take some time to
complete), I look into rendering an 80x25 text screen on the Commodore 64, and
how it can be done. The Structure Pattern in PHP (Jul 2008) Reading and
manipulating binary files can be troublesome in PHP, primarily because the
language doesn't have a native type to represent structures of encoded data.
Using the Structure pattern allows PHP to load and work with these files, by
providing a method of decoding the data into a class and performing
calculations. Examples are given in this article of the Windows BMP and TrueType
file formats. Intranet DNS Resolution with BIND Views (Jun 2008) When you're
working on a web site that's hosted in the same office, it can be a problem to
see the fruits of your labour: the web site's domain resolves to the external IP
of the office, and can't be routed from inside. It's quite easy to overcome this
problem, by using the 'view' facility of BIND to provide two different views of
the domain: one for the office LAN, and one for the outside world. An
Introduction to Compression (May 2008) An exploration of the different types of
compression, looking at the workings of lossless compression methods such as RLE
and Huffman encoding, and taking an overview of perceptive compression and why
it works. If you've ever wondered how a CD can be shrunk down from 650MB of
sound to 65MB, this article tells you how it's done. Whitelisting SSH Access
with OpenWRT (May 2008) If you're tired of constant login attacks against your
SSH server, you can use your OpenWRT router to implement a whitelisting
firewall, allowing the people you know and trust to connect to your shell, and
blocking everything else. It's even possible to automatically modify the
whitelist from an intranet Web page, through the use of extensions to PHP; this
article will show you how it's done. Booting Linux from a USB Flash Drive (Oct
2007) For those who build home theatre PCs and other computers which need to be
quiet in operation, most of the noise from computer hardware can be eliminated:
fans can be removed, heatsinks and smaller power supplies can be used. The
largest remaining source of noise is the hard disk containing the operating
system. If the HTPC is running Linux, it's possible to move that operating
system from hard disk to a USB flash drive, and boot it from there; this article
shows you how. ARMv4/5 Opcode Map (Oct 2007) There are many places in which you
can look if you want an explanation of the instructions available on the ARM
series of processor cores. However, there is no overview of the instruction set
in the form of a table or map; not even the official ARM instruction reference
provides this anywhere in its 811 pages. I produced an opcode map in 2006, in an
attempt to rectify this problem: it provides a mapping of all the instructions
and addressing modes for cores up to ARM version 4, with version 5 extensions
highlighted in blue and the DSP extensions in green. Tetris in Vanilla
JavaScript (Oct 2007) It's often said by some that JavaScript isn't a real
programming language, that it can't provide the full range of development
possibilities that a more complex language would be able to give. It's quite
easy to prove this argument wrong: JavaScript is a full-blown language, with
some very interesting features that conventional languages fail to bring to the
table. It's also quite easy to write programs with, and I put this example
together to prove the point: an implementation of Tetris in HTML and JavaScript,
playable right in your browser. Running a Windows Partition in VMWare (Jan 2007)
Virtualisation of operating systems is a big trend at the moment: running
multiple servers on one physical box allows a hosting company to save space and
power costs, and running different operating systems lets a Web developer test
their work on various browsers and hosts. The problem with setting up a virtual
machine is the loss of disk space on the host, to hold a disk image for the
guest; what if you've already got an installation on another partition? This
article shows how to use that physical installation in VMware, using the example
of Linux as the host and Windows XP as the guest. Trainfuck (Sep 2006) One of
the most widely-known esoteric programming languages is Brainf*ck, which
attempts to break computing operations down into the simplest possible steps:
just eight operations are provided, along with a small buffer of memory to work
with. The problem with Brainf*ck is that it only provides the most basic I/O,
interfacing with the console. Trainf*ck is an extension of the language, which
endeavours to provide the ability to read and write files, and communicate over
a TCP/IP network. Collapsible Nested Lists in Vanilla JavaScript (Sep 2006)
Details regarding the implementation of a collapsible tree-style nested list
using standards-compliant HTML and CSS, utilising JavaScript and the Document
Object Model. An Introduction to Bitwise Operators (Sep 2006) For almost as long
as the computer has existed, programmers and developers have had to deal with
the computer's representation of numbers, the binary numbering system. The
unique properties of binary allow the application of Boolean mathematics to
common manipulations. This article provides a run-down of the common Boolean
operations, including their syntax in C-derived programming languages, and
provides examples of where such operations might be used in everyday
development. The Smallest Nintendo DS ROM (Sep 2006) Embedded development is
often focused on the size of the resultant binary, especially on platforms where
this factor is important. On the Nintendo GBA and DS, the homebrew toolchain is
able to generate well-optimised binaries, but programs with equivalent
functionality tend to have very different sizes. This article looks into why
that is the case, and explores the format of a Nintendo DS binary file in an
attempt to make the smallest DS binary possible.


QUICK HACKS

Things which didn't make it to article length, or that don't need detailed
exposition.

That Time My Encrypted RAID Failed (May 2015) A short postmortem of the time my
LUKS volume failed, what I did wrong at the time, and how I got the data back.
svn branchlist (Oct 2012) Ever run into a codebase with multiple Subversion
repositories, where you just wanted to find out which branch they were all on
without tediously cd'ing into each working copy? How Emulators Work (Jun 2012)
At deviantART's technology team meetup in France ('Breadlands 2012'), I gave a
short Ignite talk distilling the first three articles in the Gameboy Emulation
in Javascript. The slides from that talk are now available here. linecolor.pl
for irssi (Feb 2010) The irssi IRC client has a built-in capability for
rule-based highlighting of nicknames, but does not allow for the full line to be
highlighted; nor does irssi allow arbitrary colours to be set against different
rules. linecolor is an extension script for irssi that allows for this
functionality to be added, in an intuitive fashion. NotPDO for PHP (Feb 2009) It
doesn't happen very often, but it does happen: you're deploying a PDO-based PHP
application to a shared host, and they don't run PDO. If you can't reconfigure
the server, you can always wrap MySQL to look like PDO; that's what NotPDO does.
CRC32 Calculation in 256 Bytes (Feb 2009) A quick look at a 256-byte program
capable of calculating the CRC32 checksum of a file. Countries and Dependent
Territories (Dec 2008) If you've ever needed to know which country is at UTC+3.5
(it's Iran), or who is responsible for administrating the Western Sahara (that's
Morocco), it's all in here. List is also available in SQL, for such situations
as a 'select your country' dropdown on an e-commerce Website. Making PDO Look
Like ADODB (Apr 2008) Many developers who come to PHP from ASP bring their
experience of using ActiveX Data Objects (ADO) to interface with databases;
however, existing solutions to allow ADO usage from PHP suffer from performance
and support issues. Using PHP's native Data Objects (PDO) library can be
infeasible for legacy applications: with the code provided here, PDO can be used
with no redevelopment of the application. Virus Detection with Message Digests
(Sep 2006) One day in 2006, I was set a short challenge: write an article of
around 500 words on the topic of MD5 digests. This article was the result: an
explanation of what it means when a computer generates a digest of a message,
and a look at where message digests can be used. In particular, focus is given
to automatic generation of digests for executable files, and how this can be
used to detect possible manipulations of the files by viruses.


SCIENCE FICTION

Short stories and flash fiction I've written in the sci-fi genre.

Ticketed (Mar 2017) A long-awaited sequel to Prime Point, in which our brave
protagonist finally jumps into a hyperspace-capable ship and ends up...
somewhere. Behind the Mirror (Jan 2012) The day after the night before, a
hungover flatmate notices that the wall mirror looks a bit strange. Speculative
flash fiction. Betel (Aug 2011) Written on the theme of "thirty". On the far
edge of the galaxy, a planet where only thirty stars are visible notices that
one of the thirty has disappeared. Flash sci-fi. The Harness (Feb 2011) The tide
of an interplanetary war is turned when a rogue black hole enters the solar
system, and is captured by Earth forces. First published in IFWG Story Quest
magazine, hard sci-fi. Power (Nov 2010) A spaceship crewman is faced with a
Catch-22 while maintaining the engines. Flash sci-fi. Light (May 2010) A curious
trespasser investigates the nuclear fallout zone around Cheyenne Mountain. First
published in the My Writers Circle "Rascals" anthology; flash fiction. New
Science (Mar 2010) Winning entry for a writing contest, with the length
stipulation of exactly 100 words. First published by My Writers Circle; flash
fiction. Prime Point (Aug 2009) A spacecraft is sent to the Earth-Sun L5
Lagrange point, where it undergoes testing. Vignette, sci-fi. Highrise (Apr
2009) A man is sealed into an apartment for four days. Short story,
science-fiction. Go Northeast (Apr 2009) A man finds himself standing in an open
field west of a white house, with a boarded front door. (There is a small
mailbox here.) First published by 365tomorrows.com; flash sci-fi. Hideout (Sep
2006) Two hackers must destroy their evidence when a team of armed police show
up outside their apartment. Screenplay. Thirteen (Sep 2006) Terrorists use a
distributed computer system to model the destruction of a continent by multiple
warhead detonations. Book prologue. Tau (Sep 2006) A physics researcher is
alerted to a contact who can help him realise his theories. Book prologue.
Microwave (Sep 2006) Description of a system for generation and distribution of
electrical power from orbiting nuclear power plants. Novel introduction. Sand
(Sep 2006) A man reflects on the detonation of a compressed antimatter bomb in
his city. Short story. A Change of Clothing (Sep 2006) A chase and murder by a
trained serial killer, as described from the killer's point of view. Short
story.

Content and design by Imran Nazar, 2006 — 2023

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