piątek, 26 września 2014

Fork bomb in Windows

It's really simple. Just install Cygwin, write fork bomb (even by accident) and finally run in bash - works fine. I had to restart my machine with restart button.

Intepolation search revisited

Interpolation search revisited -- theoretical complexity of interpolation search is very promising, but...

niedziela, 21 września 2014

Conversion number to hexadecimal representation

Conversion numbers to hexadecimal representation - SWAR, plain SSE, and draft of BMI2 implementation.

Article SSSE3: printing hex values describes the same topic but is limited to exploit PSHUFB.

czwartek, 18 września 2014

String literals are weird (at least in C/C++)

Simple quiz: what is the length of this string "\xbadcafe"?
  1. 5 letters
  2. 4 letters
  3. 2 letters
  4. 1 letter
The correct answer is d, i.e. single letter. In C/C++ escape sequence "\x..." consumes all hexadecimal digits.

czwartek, 11 września 2014

Python: rename file in Windows

Observation: function os.remove under Windows doesn't allow to overwrite an existing file. Python from Cygwin works properly.

Here is a workaround:

def rename_file(old, new):
    if sys.platform != 'win32':
        os.rename(new, old)
        os.rename(new, old)

Conversion numbers to binary representation

New article Conversion numbers to binary representation — SIMD & SWAR versions.

Few years ago I've described an MMX variant of SIMD algorithm. But the text was in Polish, so audience was limited.