Saturday, July 23, 2011


I still remember encountering the following piece of code while browsing through the Quake 3 source code back in 2005:
float Q_rsqrt( float number )
  long i;
  float x2, y;
  const float threehalfs = 1.5F;

  x2 = number * 0.5F;
  y  = number;
  i  = * ( long * ) &y;  // evil floating point bit level hacking
  i  = 0x5f3759df - ( i >> 1 ); // what the fuck?
  y  = * ( float * ) &i;
  y  = y * ( threehalfs - ( x2 * y * y ) ); // 1st iteration
  // y  = y * ( threehalfs - ( x2 * y * y ) ); // 2nd iteration, this can be removed

  #ifndef Q3_VM
  #ifdef __linux__
    assert( !isnan(y) ); // bk010122 - FPE?
  return y;
That comment on line 10 pretty much sums it up: WTF!?!?

I again ran across this piece of code while browsing an amuzing list of the best comments in source code you've encountered, over on Stackoverflow. It turns out the original author of this illustrious piece of code is still unknown (it's not John Carmack as you might have assumed). A nice write-up of the likely history of this hack can be found on Beyond3D. Interesting reading for sure!
UPDATE: The original author is actually known and it is Greg Walsh. Wikipedia also has a lot of background.

Talking about funny comments in code, my personal favorite from the Stackoverflow list must be the following:
stop(); // Hammertime!
Not so much the comment, but the german version really cracked me up!

Tuesday, July 19, 2011

Java SE 7

It was a long time in the making but all JSRs constituting Java SE 7 have crossed the finish line! The actual Java SE 7 software release is just around the corner (July 28th). Exciting stuff!

Saturday, July 2, 2011

Tech support interference

It's a well known fact that developers and tech support people typically don't get along. The developers want freedom to do as they like with their machines, while the tech support guys want to close everything down, mainly for security reasons.

Sometimes this can get quite ridiculous. I recently heard a story about a development team building a web app that required Firefox compatibility, yet they were not allowed to install Firefox on their machines! Another typical example which recently came up at TSS, is developers going to great lengths to disable virus scanning software because it makes their IDEs unbearably slow.

As always, solving this conflict requires a middle-of-the-road solution. I agree that giving developers unlimited privileges on machines that are connected to production networks is an unwanted security violation. Similarly it's unacceptable to bog down a development machine to the point where the developer can no longer properly do his job. One of the better solutions I have encountered is a separate development network. This development network is an isolated sandbox where the developers reign supreme without putting other parts of the network or organization at risk.