[Boost-users] [dynamic_bitset] beginner question - concatenation/slicing

From: Kurt Schwehr (schwehr_at_[hidden])
Date: 2007-04-15 10:39:09

Hi All,

I am new to boost and haven't done much c++ programming in the last  
couple years, so apologies if this question is obvious.  I'm looking  
at dynamic_bitset to build a translator between the bits and NMEA  
string packaging for Maritime AIS.  Basically this is each character  
in a string represents 6 bits of data.  I'd like to make two lookup  
tables that let me go back and forth quickly between bitsets and the  
NMEA ASCII.  My dynamic_bitset questions are:

* how can I best concatenate multiple dynamic_bitsets?  For example:   
lookupbits['a']+lookupbits['1']+lookupbits['g'] would return a  
dynamic_bitset of 18 bits.  I'm looking for some sort of join  
operation and append does not seem to do what I want.

* How can I best slice the results?  If I know that, for example, and  
unsigned integer is at bits 11-14, is there way to do quickly get a  
dynamic_bitset of those bits?

I've got all this working in pure python, but it is way to slow   
( http://vislab-ccom.unh.edu/~schwehr/software/noaadata/ in the ais  
package).  Any suggestions would be greatly appreciated.

Thanks!
-kurt
http://schwehr.org