Monday, 6 December 2010

New Video Camera

Last week they boys were playing with their remote control car in the snow (which was fun) and Alex wanted to record what his car saw. I immediately dissuaded him from the idea that he can use the family's DV camcorder taped to his car!

The camera and a UK penny
Later on that day though I saw a rocket project on LMR which used a micro camera and suggested such cameras were available from ebay very cheaply. I did a quick search and ordered on from a UK seller at £15 plus £2.99 pnp and thought no more of it.

This afternoon the camera arrived and it really is tiny and Alex is already scheming of ways to use it in addition to attaching it to his RC car.

The video output is low quality (very blurry in low light) and I have yet to figure out how to disable the time stamp (which is wrong) but it does indeed record video to the storage and can download it via USB and played using VLC.

So if you want a tiny video camera (and an 8Gig micro SD card) which is so cheap you do not care if it gets broken, I can recommend these.

Monday, 29 November 2010

Mobile Telecommunication Luddite

Actually I can not really be called a Luddite because I am not really against telecommunication progress nor do I fear it will negatively effect my employment...but the title sounded good? ;-)
Anyhow, I have a strange relationship with mobile phones. My ability to have a functioning device has historically limited their usefulness to me.

Because of my low usage and odd attitude for a techie I have always used PAYG for my personal phone. Work may have provided me with a device with a contract for being on-call etc. but in general its been PAYG all the way. My first phone was a Nokia 1610 back in the late nineties, second user after my employer at the time contract upgraded and had a load of "leftovers". I paid 50quid for it and bought a ten quid SIM and ten pounds credit.

My phones
The standing joke among my friends for the next decade has been that whatever provider I moved to they would go out of business within the year. I went through about eight providers in ten years. And for the first six the same tenner credit went with me! Each time the PAYG provider folded etc. I would be moved on to someone new with a tenners credit and a new SIM and number.

After Easy Mobile closed they did not have an option of a new provider with credit and the "recommended" provider was very poor, so this time I shopped around and went with Tesco mobile but remembered to take my number, which did at least stop my colleagues making fun of me for another move.

During this period my phones were no better than my providers. I bought a Nokia 1100 and used other peoples leftovers. Culminating in Daniel Silverstone taking pity on me and giving me his Sony Ericsson K800 at the end of his contract, despite acquiring an ADP1 and a G1 (both have which have dropped dead) this is the phone I have been using for three years now.

Due to my dreadful relationship I did not get the most from the technology and felt like I was missing out. Over the last few years to try and address this I have set myself a target of having a phone physically with me, turned on and in credit at all times. This I have finally managed for a whole six month stretch and as a reward I have bought myself a nice Android based smartphone on contract with T-Mobile.

I have done all the administrative things to port the number so no-one will need to alter their address books :-)

After only a few days of usage I have already discovered why the combination of smart phone and decent contract are so appealing. The freedom to just call and text and use the internet wherever you are without stopping to worry if you have enough credit is a wonderful thing. And decent hardware with the guarantee that if it breaks all I have to do is go into the store and they give me a new one.

I went for the HTC Wildfire instead of the Desire on cost grounds (100 pounds up front instead of 290) which seems perfectly reasonable hardware performance wise. My one and only niggle is T-mobile have nobbled the media player so it only plays some mp3s and not oggs or flacs. No real challenge, just a bit disappointing that vendurs seem to think they need to fiddle.

Friday, 5 November 2010

Keeping kindling dry

I, along with a great number of people I know, now posses a 3rd generation Kindle. It seems Amazon have found a feature set and price point which makes this device a winning solution.

My bookshelf complete with covered kindle
I did look at a huge number of alternatives like the Sony PRS600 and others but they were all more expensive than the £110 for the Kindle and did not have enough features to make a compelling argument for spending more.

Yes it has DRM. Yes it "only" supports PDF, MOBI and mp3. Yes it will not win any style or usability awards. But I went into this eyes open the device is "good enough".

The device lets me read books from a reasonable display. The integration with is so seamless it poses a serious danger to my bank account. I should expand on that last point :-) Amazon have got the whole spending money for a book thing executed so well that you do not think twice about a couple of pounds here and there, this soon adds up. I have set myself a rigid budget.

My main complaints are really just niggles:

  • Another different USB connector! Wahh, I thought everyone had agreed on mini USB? seems that I now have to have yet another lead for micro USB

  • The commercial book selection is a bit limited and missing a surprising number of popular titles. Some of this appears to be the publishers and authors simply clinging to their old business model. I fear some of them might not survive and early indications are they are behaving like the music industry did...Guys you are selling an infinite good a scarcity model is going to fail!

  • The price of some of the books is absurd...they are asking hardback prices for the electronic edition! Seriously? how on earth can that possibly be justified? I can see that a hardback book with its print run could cost £5 per physical item (going from hulu print on demand prices as a worst case) plus shipping and stocking fees. So how can you possibly justify charging the same price for a pile of bits where none of that applies? Also the pile of bits cannot be lent or sold, not impressed.

  • eBook formatting is generally dreadful. I do not know who is mastering these books but they need to do a better job. If they tried to pull this in the physical editions they would get a seriously large number of returns.

  • I still have to pay for whispernet delivery fees even though, because its the wi-fi model, I am providing the bandwidth myself. I can see that differentiating between 3G and wi-fi delivery is a bit hard for them though.
However my one and only real complaint with the offering as a whole is the astronomical asking price for the leather cover. The cover is currently 25% of the price of the kindle itself! (£30 cover £110 kindle) which is just silly. It is a pretty nice cover and the clever clip attachment means it does offer an integrated solution to protecting your kindle, but not £30 nice.

Kindle in a sock cover
So my lovely wife (her kindle was bought with the cover) made me a sock for mine. This is great for casual round the house usage to stop me scuffing the screen but was a bit lightweight for protecting the kindle when out and about.

One day last week I had an idea. I would make my own protective cover by crafting something I had wanted to do for ages. And the (unoriginal I am sure) project of a hollowed out book for housing my kindle was implemented.

My hollowed out book kindle cover
A quick Google later and I had a set of plausible instructions to follow. I used possibly the most out of date book ever (published 1981) on electronic test equipment, partly because it was a ex library sell off book which cost 10pence back in 1995 but mainly because it was the right size to just enclose the kindle without adding to much size.

I learnt a couple of things doing this:
  • Do not let your pva (white) glue mix get too runny, you want it fluid enough to be easily absorbed but not watery - this is important because otherwise the paper absorbs too much water and crinkles
  • Do not use a book where the binding has gone bad already and select a "clean" book. The spine of this book was yellowed and cracking before I started. This means the book spine simply cracks open at the hollowed out bit and it is very obvious.
  • Work out where the "solid" part at the back is going to be and treat that separately so you get a nice solid base at the back of the hole. In mine its not all stuck together and is a bit wavy. Do be sure you left enough depth for the kindle though.
  • Take your time and be careful with the glue, it is amazing how obvious even a simple splash of glue in the wrong place is. Use a small brush for this a paint brush is fast but sloppy.
  • Measure carefully and cut only a few pages at a time, it takes a bit longer but looks much better. Also I did not drill the corners of my hole which means they are a little scruffy.
  • Use the sharpest thinnest knife you can, this really helps. I started with a small stanley knife but switching to my hobby scalpel gave much better results.
  • If you have some, use woodworking clamps to clamp a bit of timber (I had some offcuts of shelving) around the book to compress it while the glue dries. Do not clamp the spine if you can avoid it. This method ensures:
    1. Heavy things do not fall off the book while it dries.
    2. An even strong pressure is applied.
    3. The book does not warp or bend while the glue dries
All in all I kinda like the results and I think I will try again with a more modern book where the spine is not so broken to begin with.

Saturday, 16 October 2010

Coming to terms

Yesterday was not a great day. One of the family's cats died.

Molly just after she arrived 26th September 2000
Molly, for that was her name, came to us the week Melodie and I moved into our first house together. September 15th 2000, in the middle of the fuel protests which were raging at the time, we hired a van and moved in.

Most people would have considered that enough for one week! We happened to be in Halifax on the Sunday afternoon at the supermarket and decided to visit the RSPCA because somehow we decided what our new home needed was a cat.

On that day a decade ago we saw Molly and Lucy, a pair of cats who needed a new home as their previous owners had a baby who was allergic to them. I still recall them skulking at the back of their cage in the cattery, Lucy who was reluctant to come down of a perch to be petted and Molly looking generally unhappy. No-one else wanted this misfit pair because they were already both over 5 years old, the warden despairing of ever finding them a home.

Of course they were obviously the right animals for us! ;-) So by the end of the week we had taken them home. Molly immediately showed how things were going to be by shredding her way out of the RSPCA provided double walled cardboard carrier. To the day she died she detested being placed inside a carrier, funny that.

Melodie and Molly in the snow 28th December 2000
By the end of the year, when the snow came, the cats ruled the house and we were all happy together.

Little did we realise that soon in the summer of 2001 there would be another arrival to the family.

Molly with Melodie and Alex 2001
The arrival of our first child in June 2001 was a complete change in all our lives but we all managed to settle back into a routine. Although the banishment of the cats from upstairs remained a point of disagreement for a long time.

As Alex grew up the cats learned that feeding times for Alex could result in all manner of things falling from above. Soon Alex was mobile which resulted in different lessons on cats being sharp objects if not treated with respect. In February 2003 our family grew once more with the arrival of Joshua. The cats, now used to infants, took this in their stride.

Molly in Febuary 2004 hiding on a windowsill
While still about day to day the cats are not captured on camera so often form this point on.

Over the forthcoming months they ensured they were out of reach of the newborn and the precocious toddler.

By the time of Joshuas first birthday in 2004 Molly had taken to hiding "out of the way" as much as possible but remained as affectionate as ever.

Molly in a box March 2007
As the children grew up and life progressed Molly became ever more at home and developed the odd aggravating trait like taking clean washing off airers and dragging it out the window, through the cat flap and upstairs so she could sleep on it!

She still enjoyed participating in claiming boxes and defending them vigorously though!

The kids took on the job of feeding the cats which made their bond closer ensuring they were greeted by happy cats sitting lookout as they came home from school each day.

Molly continued to be a good companion and an infuriating self centred animal like all good cats.
Molly asleep in the kitchen sink
Then on Tuesday evening our Neighbour knocked on our front door. They gave us the news that one of our cats had been run over and taken to the Vet. I immediately went to the back door and called and shook the treat box.

Lucy came running, but molly did not. We rang the vets who confirmed they had molly (we had them electronically tagged back in Halifax) and that they advised we did not come and see her until they had chance to asses her and deal with the shock.

As the days progressed her prognosis improved and then sank. She had a broken jaw, broken teeth, a dislocated hip, extensive bruising and something was definitely wrong with her kidney function.

Thursday evening the whole family went to see her and she purred and seemed happy to see us, she looked as bad as I feared though and somehow I knew there and then that this was probably goodbye. The children stroked her and petted her for a while and we left with an odd sadness, oh and to the sound of molly trying to gouge the veterinary nurse.

Yesterday she was due to have surgery to fix her jaw and hip...Alas when she was anaesthetised and x-rayed once more it became evident the hip was not just dislocated but her femur was fractured and there was additional damage. So just after midday came the call to ask what we wanted to do. The vet could attempt the repairs but due to her age and the other complications it was probably futile. So with heavy heart we agreed the best thing was not to revive her and she died a short time later.

I shall miss her morning greetings, her demands for attention, her sleeping in odd places and her companionship. I keep calling for her at meal times forgetting she will never come. I think Lucy is upset too, after spending their lives together her friend is gone and I cannot explain that to her.

So that is the end of Molly, a good cat.

Tuesday, 5 October 2010


When I am writing software sometimes XKCD is accurate!

Alas I can only fully participate in that activity when the boys get home from school.

The rest of the time I have to make do with other distractions.

I am currently participating in a "higher" speed broadband trial (I already have a 50Mbit service). This appears to involve the drastic step of remotely reconfiguring my Cable Modem :-)

In the last week there has been the odd request from the trial organisers to test throughput using various website based testing applications. These applications seem completely unable to cope with these 50Mbit+ connections and the results are as unreliable as expected.

To address this the trial organisers asked us to time downloading of a gigabyte file from one of their servers. I was surprised to discover that it took over 350 seconds to download the example file giving a less than stellar 3Megabyte/second rate.

So I used some "compiling" time today to look at what was going on. Firstly I went looking for an iperf like tool for http. Turns out there isn't one which came as a bit of a surprise...oh well with a little help from my friends I came up with
curl -o /dev/null http://target.domain/1GB.bin 2>&1 | tr "\r" "\n" |awk '{print $12 }' >test1.dat
Which gets a file with a "Current transfer speed" for each second of the transfer. Well ok so lets do the transfer a few times and collect the output so we have a reasonable data set.

So we have a pile of numbers...not terribly useful, lets visualise them! to the gnuplot mobile!

We need a gnuplot script something like say this:
set terminal png nocrop enhanced font arial 8 size 1024,600 xffffff
set output 'xfer.png'
set style data linespoints
set title "1Gigabyte file transfer throughput"
set ylabel "Throughput in Kilobytes per second"
set y2label "Speed in Megabits per second"
set xlabel "Seconds of transfer"
set ytics 1024
set y2tics ("10" 1220, "20" 2441, "50" 6102, "100" 12204)
set grid noxtics y2tics
set yrange [0:13000]
set datafile missing "-"
plot 'test1.dat' using 1 title 'Test1', \
'test2.dat' using 1 title 'Test2', \
'test3.dat' using 1 title 'Test3'
Once run through gnuplot I extracted a lovely graph which shows a couple of things.

Mainly that even with a nice fat downstream you are unlikely to realise the maximum throughput very often even from a server on your ISP local network.

On the other hand I now have a way to examine throughput of downloads ;-)

Wednesday, 22 September 2010

I like driving in my car. It is not quite a Jaguar

I work from home, this is a good thing. I benefit from a 20 metre commute, comfortable working environment and generally low carbon lifestyle.

Except on Wednesdays, on Wednesday I have to get up early and go to the office, this is not usually too much of a chore and takes around 90 minutes each way.

Today was different, I made a small five minute diversion to collect a colleague to whom I was giving a lift and then due to a little problem near the M6/M61 junction spent a fun filled three hours sitting in traffic crawling along the M56. At least I had company instead of being on my own.

Before I did the return journey I decided to check the traffic news sites. Oh dear now the M60 was stuffed, I altered the route and only had to queue on the M56 for twenty minutes or so. I dropped my colleague off at his place (avoiding the worst bits of the M62/M66 junctions by use of a rather convoluted back route) and proceeded to queue on the M62 for a while for no apparent reason.

Basically I have spent almost seven hours in the car today to do a 150 miles or a little over 20 miles per hour average. I was just going to rant about the dreadful lack of any redundancy or resilience in the UK road system which often grinds to a complete and utter halt if there is a single failure.

However a different thought has wandered across my travel weary mind. It has occurred to me that this average speed is faster than anyone could reasonably expect to do this trip for the majority of human existence.

In 1810 and indeed for all time before, your best possible speed by good horse, for 150 miles, would have been two days (and your horse would have probably been very poorly afterwards) This assumes your horse could do the 75miles (120km) each way in times consistent with modern world endurance trials... across a mountain range! Yes the Pennines are only tiny but even so!

A hundred years later, in 1910, the British railway network was nearing its zenith in most measurable terms. The influence across the north of England was profound and pushed the industrial revolution ever faster towards its climax before the first world war. Even at this point in time my best reading of the available timetables says I would have needed to change trains four times each way, purchased eight separate tickets from six different companies and taken around nine hours to make the journey allowing for hanging around on platforms.

Another fifty years on, in 1960, the trans-pennine car journey would have been on poorly maintained trunk routes through the decaying cores of the declining post-industrial northern cities. The route would probably have involved the A646, A59 or the A58 which at this time were not the well maintained (if slightly shabby) roads of today but instead were dangerous twisty and, from the looks of the archive photographs, positively heaving with traffic. On these pre-motorway strips of tarmac the 150 mile round trip would have taken in excess of seven hours (even today's mapping systems suggest over four and a half hours would be needed)

So instead of being frustrated that my commute took an extended period today I have instead decided that I shall enjoy the fact it was faster and certainly more comfortable than at any time in the past. Well that and I need to get the cars air-conditioning fixed ;-)

Thursday, 16 September 2010

The turmoil of an entropy key release.

Last week we released 1.1.3 of the Entropy Key software. Poor Daniel struggled for days to get this out the door but finally he managed to build all the various debs, rpms and tars for the supported platforms and Rob got it all uploaded and announced.

The release is kinda strange in that it was the first in which the main changes were for performance. OK there is an improvement to resilience in the face of failed re-keying which some users were seeing in high load situations, but that high load was (in some cases) being caused by the daemon itself.

The process was mainly driven by one of our users, Nix, who was experiencing ekeyd using "too much" CPU on his system.

Of course on our servers during testing ekeyd it had used around a percent of CPU, certainly nothing that flagged as a problem in our own use (yes we eat our own dogfood ;-) Alas for this user on a 500MHz geode it was guzzling down 10% of his CPU which was clearly unacceptable.

This user however instead of guessing what the problem might be or simply leaving it up to us did something about it. He instrumented ekeyd, located the garbage collector tuning parameters as being incorrectly set and supplied a patch. Did he stop there? no! he then went on to profile the code further and clean up the hotspots. This resulted in ekeyd falling to less than 1% of the runtime of his system.

By reducing the CPU usage of ekeyd to this level it became more apparent where a previously reported bug was coming from, which enabled me to address it.

I know sometimes I complain about Open Source software but at times like this it makes me happy that we released the ekeyd software freely. This is how its supposed to be! Everyone working to make better software and benefiting together.

It has not just been on this occasion either, throughout the last year since our very first 1.0 release there has been helpful and useful feedback, patches from several users and even the odd thankyou mail. This project then has been a positive Open Source experience and I look forward to another constructive year maintaining this software.

Thursday, 2 September 2010

You shall go to the ball!

Contrary to my last post I was able to attend the Debian UK BBQ at the weekend. My wonderful wife ditched me at Portsmouth station with permission to go play with my friends ;-)

Perhaps a bit more explanation is warranted about that last statement! We travelled back from France last Saturday. We were on the 12:15 (CET) ferry so had to be awake and on the road for the five hour France drive at "oh my gosh its early" time. The crossing to Portsmouth was slow as it was very choppy and we were leaving the Port at 15:30 at which point Melodie was good enough to let me go play with my friends while she drove home.

I did have the "fun" of doing the Portsmouth->London->Cambridge trip on UK public transport but it went pretty smoothly. Walking from Cambridge station to the BBQ location was a bit dumb, next time I am taking a cab!

The BBQ was excellent fun and big thanks for Steve for holding it again. Its always fun to meet the usual suspects. We also got to set a new occupancy record at Steves house Saturday night and discovered that certain members of Debian UK snore rather loudly (I think at one point we could measure it on the Richter scale).

Back home now of course. Work is the same as when I left so no change there and the Boys first day back at school seems to have gone smoothly too.

Thursday, 26 August 2010

Sunny Brittany

Alas I did not go to Debconf 10 which looked like everyone had a blast, congratulations to the organisers. Nor will I be able to attend the traditional Steve McIntyre BBQ at the weekend, hope everyone has fun.

On the other hand I have managed to take a family holiday in sunny Brittany...

OK perhaps sunny is pushing it, we did have several nice days last week which we spent on the Le Pouldu plages but this week has been more challenging.

Fortunately the camp site where we are staying has reasonable bandwidth so I can continue to waste time online.

This has given me time to look at some Debian packaging. Specifically the mingw32-runtime packages. Their maintainer seems to be unwilling to allow an updated version to be uploaded despite there being numerous upstream releases since the last packaged release in 2007.

The packaging manual makes it clear that hijacking is not permitted and I discover my desire for having a huge, unhelpful argument about maintaining a package is non existent.

I guess when I have my updated packages available I will maybe announce them but its not the same. I guess this is one of those problems with being a Debian maintainer, we all have to rub along even with decisions we disagree with. Hmm thought I had more to say on the subject ...perhaps next time.

Anyway must go and entertain the kids for an hour or two, maybe go to the beach in the rain, hell they cannot get any soggier ;-)

Wednesday, 30 June 2010

Programmers are suckers for a meme

Many Open Source projects have and IRC # for developers. The NetSurf project is no different. During a discussion someone jokingly suggested that one contributor should be asked to take the FizzBuzz test. Can you guess what happened next?

Ten minutes later Michael Drake posted this solid example in C which is where it all ought to have ended.

Being programmers, of course this had a predictable result. The original question, the reason for asking it and any the serious point being made in the original article were discarded. Just so everyone (including myself) could play silly buggers over our lunch break. Coders, it would seem, simply like to produce a solution even if it is only for fun.

None of these programs took more than ten minutes (except the JAVA monstrosity), are reproduced with permission and I am to blame for none of them (ok maybe just the one ;-).

First up was Rob Kendrick with the classic solution in C (his day job is as a support team lead which seems to make those programmers who cannot do this seem even more scary bad.)

Next was Daniel Silverstone who turned this Lua solution out very quickly and berated the rest of us for not following the rules ;-)

The final C solution was my own uber silly sieve implementation

Peter Howkins decided the world required a solution in PHP

When pointed out that his solution stopped at 50 he presented this vastly superior and obviously idiomatic solution

Finally after a long time James Shaw caused mental anguish and wailing with this abomination unto Nuggin.

With Luck everyone has now got it out of their system and we will never have to put up with this again (yeah right). And now you also know why Open Source projects sometimes take ages to release ;-)

Thursday, 27 May 2010

Ex Phone

I went to the Linux Plumbers Conference (LPC) last year (which was very interesting and productive). While I was there Qualcomm were in attendance giving out penguin mints and running a competition. The lucky winners of this draw were to receive an ADP1 Android phone. So I dutifully filled in the entry form, handed it in and thought no more about it.

In the break after attending a particularly interesting workshop on the last day of the conference several other people congratulated me on winning the Qualcomm draw, this was the first I knew about it! I went in search of the nice people from Qualcomm and sure enough they handed over an ADP1 after getting a couple of photos.

Once I returned home I switched to using ADP1 as my phone and started experimenting with Android kernel stuff. Then one day the Wi-Fi stopped working which while odd could be overcome by repeatedly unloading and reloading the driver until it worked once more. Then one day the USB stopped working, no more ADB, no more console, no more debugging, no more hacking.

Then one day it turned itself off and never came back. I have been forced to return to using a hand me down, very kindly given to me by Daniel Silverstone. Alas it is not a smart phone of any kind and my finances do not allow for me to spend the money to replace it.

I have repeatedly tried to contact Qualcomm open source to see if there is any kind of warranty I might be able to use to get the phone repaired alas all the contact addresses I have are now simply returning SMTP errors.

So this is pretty much a tale without a happy ending, unless anyone out there knows the right people to contact? Perhaps someone at Google maybe? I only revisit the subject at all because of the recent announcement of an Android 2.1 based edition for these devices which reminded me I like to play with these things.

Sunday, 25 April 2010

XCB programming is hard

I have been looking at writing a program with XCB today. I seem to pick projects that are an exercise in undocumented frustration.

All I wanted to do was have an x window open and be able to plot an arbitrary changeable image to it (no I am not writing yet another image viewer!). The XCB documentation seems to be a cross between "good luck with that" and some rather erratic doxygen output.

The utility libraries are rather skimpy on examples and its tiresome worrying that when you feed any of the xcb function names into Google (web or codesearch) there are very, very few hits beyond the freedesktop API docs.

My favourite has to be the xcb_image_create documentation, go on I challenge anyone to follow that logic without going and reading the sources! The answer (afaict) is that if you pass a pointer in base that pointer will be freed by xcb_image_destroy otherwise the data pointer will be used, unless the bytes value is too small in which case memory will be allocated with malloc and the passed pointer ignored.
Anyhow, I have succeeded and the result is below, mainly so I do not loose it :-)

/* XCB application drawing an updating bitmap in a window
* Inspired by the xcb black rectangle in a window example
* Copyright 2010 V. R. Sanders, released under the MIT licence

/* compile with:
* gcc -Wall -lxcb-icccm -lxcb -lxcb-image -o disp disp.c

#include <string.h>

#include <xcb/xcb.h>
#include <xcb/xcb_image.h>
#include <xcb/xcb_atom.h>
#include <xcb/xcb_icccm.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>

static xcb_format_t *
find_format (xcb_connection_t * c, uint8_t depth, uint8_t bpp)
const xcb_setup_t *setup = xcb_get_setup(c);
xcb_format_t *fmt = xcb_setup_pixmap_formats(setup);
xcb_format_t *fmtend = fmt + xcb_setup_pixmap_formats_length(setup);
for(; fmt != fmtend; ++fmt)
if((fmt->depth == depth) && (fmt->bits_per_pixel == bpp)) {
/* printf("fmt %p has pad %d depth %d, bpp %d\n",
fmt,fmt->scanline_pad, depth,bpp); */
return fmt;
return 0;

fillimage(unsigned char *p, int width, int height)
int i, j;
for(i=0; i < width; i++)
for(j=0; j < height; j++)
if((i < 256)&&(j < 256))
*p++=rand()%256; // blue
*p++=rand()%256; // green
*p++=rand()%256; // red
} else {
*p++=i%256; // blue
*p++=j%256; // green
if(i < 256)
*p++=i%256; // red
else if(j < 256)
*p++=j%256; // red
*p++=(256-j)%256; // red
p++; /* unused byte */

xcb_image_t *
CreateTrueColorImage(xcb_connection_t *c,
int width,
int height)
const xcb_setup_t *setup = xcb_get_setup(c);
unsigned char *image32=(unsigned char *)malloc(width*height*4);
xcb_format_t *fmt = find_format(c, 24, 32);
if (fmt == NULL)
return NULL;

fillimage(image32, width, height);

return xcb_image_create(width,

main (int argc, char **argv)
xcb_connection_t *c;
xcb_screen_t *s;
xcb_window_t w;
xcb_pixmap_t pmap;
xcb_gcontext_t gc;
xcb_generic_event_t *e;
uint32_t mask;
uint32_t values[2];
int done=0;
xcb_image_t *image;
uint8_t *image32;
xcb_expose_event_t *ee;
char *title="Hello World!";
xcb_size_hints_t *hints;

/* open connection with the server */
c = xcb_connect (NULL, NULL);

if (!c) {
printf ("Cannot open display\n");
exit (1);

s = xcb_setup_roots_iterator (xcb_get_setup (c)).data;

/* printf("root depth %d\n",s->root_depth); */

/* create image */
image = CreateTrueColorImage(c, 640, 480);
if (image == NULL) {
printf ("Cannot create iamge\n");
return 1;
image32 = image->data;

/* create window */
values[0] = s->white_pixel;

w = xcb_generate_id (c);
xcb_create_window (c, XCB_COPY_FROM_PARENT, w, s->root,
10, 10, image->width, image->height, 1,
mask, values);

/* set title on window */
xcb_set_wm_name(c, w, STRING, strlen(title), title);

/* set size hits on window */
hints = xcb_alloc_size_hints();
xcb_size_hints_set_max_size(hints, image->width,image->height);
xcb_size_hints_set_min_size(hints, image->width,image->height);
xcb_set_wm_size_hints(c, w, WM_NORMAL_HINTS, hints);

/* create backing pixmap */
pmap = xcb_generate_id(c);
xcb_create_pixmap(c, 24, pmap, w, image->width, image->height);

/* create pixmap plot gc */
values[0] = s->black_pixel;
values[1] = 0xffffff;

gc = xcb_generate_id (c);
xcb_create_gc (c, gc, pmap, mask, values);

/* put the image into the pixmap */
xcb_image_put(c, pmap, gc, image, 0, 0, 0);

/* show the window */
xcb_map_window (c, w);
xcb_flush (c);

/* event loop */
while (!done && (e = xcb_wait_for_event (c))) {
switch (e->response_type) {
ee=(xcb_expose_event_t *)e;
/* printf ("expose %d,%d - %d,%d\n",
ee->x,ee->y,ee->width,ee->height); */
xcb_copy_area(c, pmap, w, gc,
xcb_flush (c);

/* exit on keypress */
done = 1;

fillimage(image->data, image->width, image->height);
memset(image->data, 0, image32 - image->data);
xcb_image_put(c, pmap, gc, image, 0, 0, 0);
xcb_copy_area(c, pmap, w, gc, 0,0,0,0,image->width,image->height);
xcb_flush (c);
free (e);

/* free pixmap */
xcb_free_pixmap(c, pmap);

/* close connection to server */
xcb_disconnect (c);

return 0;

Friday, 16 April 2010

Claudia black makes this look good

OK maybe the title is a bit of a reach, but she is pretty and my topic is dull.

It is the school holidays and between entertaining the kids I have been experimenting with the vala (see there is the link to the title) language. Overall I really like it, building a usable graphical GTK application is a snap and that side of it works well.

Unfortunately, and here comes a a whole pile of fail, the documentation is lacking, not just poor but mostly non-existent. You rapidly discover yourself using the Glib and GTK library documentation to try and infer how things work.

Underneath, the vala compiler is clever, it is really a c code generator. It takes your vala source file converts it to c and compiles it. When it works smoothly it works very well, when something is not quite right you can end up with a large pile of pieces complete with the C compiler spitting out cryptic nonsense.

This is all exasperated to new heights of madness when you want to access a simple c library. I say simple because if you want to access a Glib based library its easy and "there is an app for that". Because vala is object oriented c interfaces must be described as an object. This description is performed using vapi files. The file format is documented by the simple approach of "we already wrapped a load of libs go look at their vapi files"

For my small starter project I wanted to access a tiny c library I had written. The entire interface described in a single header header (excluding copyright) is:
typedef enum motor_dir {
motor_off = 0,
motor_forward = 1,
motor_back = 2,
motor_brake = 3,
} motor_dir;

int edgerbtarm_init(void);
int edgerbtarm_close(void);
void edgerbtarm_ctrl_motor(int motorn, motor_dir direction);

Yes that is it! one enum, an initialise a finalise and a single operation function. The vapi file I came up with after a great deal of trial, error and head scratching was.
[CCode(cheader_filename = "libedgerbtarm.h",
lower_case_cprefix = "edgerbtarm_",
cprefix = "")]
namespace edgerbtarm {
[CCode(cprefix = "motor_")]
public enum motor_dir {

public int init();
public int close();
public void ctrl_motor(int motorn, motor_dir direction);
This seemed to work until I tried to use the motor_dir type within my vala code at which point the c compiler started throwing errors about undeclared macros
arm.vala.c:297: error: ‘EDGERBTARM_TYPE_MOTOR_DIR’ undeclared (first use in this function)
I struggled for some time and finally ended up asking my friend Enrico for help. He initially suggested I simply use an int instead of the motor_dir type and cast when I needed to. This approch worked and let me compile the program, it did however seem a bit grubby and removed the type safety of the enum.

Then Enrico came up with the "correct" solution. the enum description in the in the vapi file needed an extra parameter so vala would know the enum did not have a Glib type...yeah it was obvious to me too :-/

so by altering the vapi file enum declaration to
[CCode(cprefix = "motor_", has_type_id = false)]
public enum motor_dir {
Everything works as you might expect and the motor_dir enum can be used as a type within the vala program with no more fuss.

So the outcome of all this is that while vala is an interesting language which I may well use again in future, one should be aware that it is still very immature as a solution and has nowhere near enough documentation especially round the awkward stuff where it needs it most.

Monday, 8 March 2010

Music hath charms to soothe a savage breast, to soften rocks, or bend a knotted oak.

Since I last mentioned music back in January I have accumulated another ten albums and unlike last time where there were only a couple of stand outs, this time I have he opposite problem.

The unordered list:

Justin Sandercoe - "Small town eyes"

I am learning to play the guitar, I have been using Justins' course, it is very very good, this album? Also very good. If you like melodic guitar lead music with varied influences this is for you. A couple of tracks made me immediately think of some Crowded House riffs (which is not a bad thing). Only minor niggle is the uneven levels on some of the louder pieces, but it really is a minor observation on an otherwise fine first album.

Molly Lewis - "I made you a CD, but I eated it."

Although this is only a short selection of original material from Molly, it is a very promising first album. I really like her voice and although a ukulele is not generally the most well respected of instruments, in her hands, it has an odd charm. This album is available from DFTBA records.

Rhett and Link - "Up to this point"

A pair of talented comedians who use music very effectively to highlight their humour. I originally stumbled across them on youtube and decided to take a punt. The album is 27 short pieces which fit together surprisingly well. Difficult to categorise but think a cross between Flight of the Choncords and Jonathan Coulton with a dash of youtube immediacy.

They Might Be Giants - "Flood", "Apollo 18" and "John Henry"

Strictly a replacement of the old tapes which have completely disintegrated in the intervening couple of decades since first purchased. Flood is still one of my favourite albums ever, certainly in my top 10. If you do not know them TMBG are just ace, please try their music!

Seasick Steve - "Started out with nothin and i still got most of it left"

Well its a kinda fun album primarily based on blues electric "guitar" (some of the instruments are little more than a stick with a nail in and a guitar pickup.) Nothing bad, easy to get along with, definitely worth a listen.

La Roux - "La Roux"

This synth pop album was on remainder in ASDA and I took a gamble. Its OK I guess and for 3quid I cannot really complain.

Red Hot Chili Peppers - "By the way"

Not their best, but competent enough.

Aqua - "Aquarium" , "Aquarius"

Um...yes, I have a soft spot for 90's cheese OK? Nothing more than a gross self indulgence of my silly side. But they are fun ;-)

So that is my new music since January all 166 tracks of it . Most of it pretty good, certainly no lemons (well aside from the Aqua but that is supposed to be silly!)

Oh and The XX has really grown on me from last time and I am looking forward to their next release.


Well my last post elicited a response from Mr Lougher the squashfs author. Just not one I was expecting. Apparently he did receive one of my emails (I sent five in total) to which he has not replied as I have accidentally come across as critical.

This is absolutely not my intent and I wish to publicly say that, It would have perhaps been more constructive to actually tell me this by email and this misunderstanding could have been avoided.

For reference The final email in the series is reproduced below, if I have been overly unhelpful please let me know in the comments so I can avoid this mistake in future.

Hi, we are using Squashfs and have come across several issues. We
initialy tried to use the Debian source package of the 4.0 release but
then moved to using the the CVS edition which fixed some bugs but had
issues of its own.

Couple of things to start with:

- The commit you made recently titled "Change get_basename() to use
getcwd rather than getting the PWD env var." does not seem to be
what you intended?

- I would like to assist in improving these tools so they work better
for our use cases. To aid in this have you considered updating the
revision control system the project is kept in? an SVN or GIT
repository is much easier to work with than CVS.

- I will probably assist with maintainership of the Debian and Ubuntu
packages (I am a Debian Developer ) and would
like to bring a couple of patches to your attention, one to avoid a
division by zero error and a second to enable building with
alternative libc. These are both attached to this mail.

- The tools currently make a number of assumptions about structure
alignment which are incorrect on some architectures. I am crafting
a patch to address this which should make the tools work correctly
on ARM (they currently simply segfault).

I hope this is seen as constructive and we can work together to
improve this software. If you do not feel you want to interact with me
and choose to take a differnt route, please let me know at your earliest

I do hope that Mr. Lougher will accept that I intended to be helpful and constructive and not cause offence. I have chosen to use the blog format for this as that is the form I made the previous complaint and also email between myself and Mr. Lougher appears somewhat erratic.

It should be noted that some of there points have already been addressed, however there are several more issues which I hope to be able to contribute towards.

Wednesday, 3 March 2010

Limited Success

I spent the day working with Daniel. He has been trying to get the correct runes for a GCC build in a strange environment. Turns out all he needed was me to throw stupid ideas at him until one caused him to examine some of the generated intermediate symbol maps...

Turns out that busybox awk fails in an interesting way which (eventually) causes half the symbols to be missing in the stage 1 object. Switched to using gawk and managed a successful build.

Seems to be a relatively good time for solutions, last week I managed to make squashfs-tools work on ARM. Unfortunately the author seems to be completely unresponsive to my (repeated) emails (if anyone wants the patch series feel free to mail me). The main issue with the tools is their complete blind assumption that a c structure can simply be cast to an arbitrary character array and get sensible results.

The structure casting method simply does not work on ARM (or indeed any platform which has alignment restrictions) without at least adhering to some minimal rules, primary among these is that the structure *must* be aligned to a word (32bit) boundary and that if you have 16bit or 8bit quantities within the structure they may cause gaps between members i.e. the structures are not packed by default.

No this behaviour is not a bug, it is perfectly acceptable by the c standard. Just because on x86 the practice of arbitrary casting works does not mean it is safe or sensible. Nonetheless many programmers simply do not want to believe its wrong.

Anyhow, rant over, back to work!

Tuesday, 16 February 2010

Tempus fugit

Seems I managed to loose a month in there. Been working very hard on a project with an improbable deadline which has not left much time for anything else.

Finally brought to a standstill this weekend by something Joshua brought home (I think it was some form of micro biological warfare agent, judging by how I feel) It is incrediably hard to shrug off the lethargy of illness when you realize all you have to go back to is work.

On the plus side the project deadline is in three weeks time so whatever happens It will all be over by then! Whereupon I can take some time off, calm down and then start all over on the next project...


Tuesday, 5 January 2010

Back to work

Well that is the end of my time off, tomorrow it is back to work. However my break started with snow and it seems its finishing that way.

Unfortunately despite my previous enthusiasm this weather is becoming a little tedious. Schools have been closed today so I had to child mind instead of getting anything done.

Speaking of getting things done...I have completely failed to do anything productive whatsoever for the last couple of weeks. I have played some computer games, watched some TV read some books and listened to music and you know what? Aside from a tiny guilty feeling, I have thoroughly enjoyed myself.

I suppose I should apologize for not contributing to all those open source projects that could have used my help, but that would imply remorse which I seem to be lacking. Oh well

Mentioning music, I have acquired a selection of new music over the holiday which I ought to talk about. In no particular order:
  • Iron and Wine - "Our Endless, Numbered Days"
  • Paramore - "All We Know Is Falling", "RIOT" and "Brand new eyes"
  • Phoenix - "Wolfgang Amadeus Phoenix"
  • Lady Gaga - "The Fame Monster"
  • The xx - "XX"
  • Muse - "The Resistance"
  • Cymbals Eat Guitars - "Why There Are Mountains"
  • St. Vincent - "Actor"
  • Carter Burwell - "Twilight-The Score"
  • The Darkness - "Permission to Land"
  • Oasis - "Stop the Clocks"
  • Chameleon Circuit - "Chameleon Circuit"
  • Hank_Green - "I'm So Bad at This" and "So Jokes"
Unfortunately none of it was outstanding which sometimes happens when I take a punt on a large pile of new music. On the upside none of it was particularly bad either, so a kind of "no win" deal. Though on re-listening the "XX" album is starting to grow on me and the albums from the DFTBA label are so inexpensive they are more than worth it.