skyn9ne/power-of-bdj

Power of BDJ

This BD-J Xlet was created to demonstrate the possibility of using more memory than officially allowed. It allocates 32 1000x1000px DVBBufferedImages, with each RGB pixel holding 24 bits of data, resulting in 96 MB total (instead of 6 MB available via normal arrays).

The calculation of 32 million powers of 3 (hence the name) and the verification of a result takes 2 seconds on my PS4, giving an effective BogoMIPS of 32.

Compiling and running

This demo has been built using the so-called Minimal PS3 BD-J SDK, which has been tweaked to be compatible with a PS4.

Math behind the sanity check

The program calculates 3**n (i.e. int("1", 3), int("10", 3), int("100", 3)) for each n=0..32000000. Then it sums the powers for n=0..31999999 to get int("1"*32000000, 3). int("1"*32000000, 3) * 2 + 1 == int("2"*32000000, 3) + 1 == int("1"+"0"*32000000) == 3**32000000, which has been calculated earlier. All calculations are performed modulo 2**24, as there are only 24 bits of precision in DVBBufferedImage.