Representing Arrays as Streams of Bits

Environment: MFC

I wrote this class when I needed to extract separate bits of data from an array, one by one. After some calculations, I found I needed to put modified bits in another array of data. I think this class may be useful, so here it is.

This class operates with data located in the CByteArray object. So, the common steps to use CBitStream are:

  1. Declare a CByteArray object.
  2. Declare a CBitStream object, supplying a reference to the newly created CByteArray object to the constructor of the first one.
  3. Enjoy. :)

To set/get the next bit, you can use either overloaded shifting operators or SetBit()/GetBit() functions. Also, you can navigate inside the array of data. You can set a "pointer" to any bit inside your array.

Also, you can choose the order in which bits of every byte will be processed. The default is a "left-to-right" order. In this order, the bits affected are: 7th, 6th, 5th, 4th, 3rd, 2nd, 1st, and then the 0 bit. You can define the RIGHTTOLEFTFILL identifier to change the order to right-to-left, in which bits are accessed: 0, 1st, 2nd, 3rd, 4th, 5th, 6th, and then 7th. I prefer the left-to-right order because it is easier to understand. Look to the picture below. a) is the left-to-right order (default) and b) is the right-to-left order.

CByteArray array;
CBitStream stream(array);

stream<<0<<1<<0<<0<<1<<0<<0<<1;
// The first byte now consists of 01001001 bits, so it equals 73
// (0x49). It's true when you are using the left-to-right order.
stream.SetBit(0);
stream.SetBit(1);
stream.SetBit(0);
stream.SetBit(0);
stream.SetBit(1);
stream.SetBit(0);
stream.SetBit(0);
stream.SetBit(1);
// The second byte is now the same as the first.

Downloads

Download demo project - 10 Kb
Download source - 3 Kb


Comments

  • Good

    Posted by Legacy on 04/01/2003 12:00am

    Originally posted by: 트론의유령

    Godd! 재밌어요

    Reply
Leave a Comment
  • Your email address will not be published. All fields are required.

Top White Papers and Webcasts

  • Traditional approaches to application modernization, either manual rewrite or auto-migration tools, have been proven time and again as inefficient. Rewrite needs scarce dev skills, is slow, risky and costly; auto-migration is what Verccio Dale of Gartner defines as "a pig with a lipstick, is still a pig." Are there alternatives? Find out, download this short practical guide now!

  • Bonita BPM 7 is here! And for you, an in-depth tour of its innovation. In this webinar, we'll guide you through the brand-new features of this release and demonstrate them live. You will: Discover how business application implementation and maintenance is now even easier, with decoupling of process logic, business data and user interface Learn how to create "living applications" for business processes which present business data in custom views We recommend that you watch the half-hour recording of our …

Most Popular Programming Stories

More for Developers

RSS Feeds

Thanks for your registration, follow us on our social networks to keep up-to-date