Click here to Skip to main content
15,885,739 members
Articles / Programming Languages / C++
Article

A circular character buffer

Rate me:
Please Sign up or sign in to vote.
2.00/5 (1 vote)
9 Dec 1999 91.1K   1.5K   27   7
A circular, thread-safe read/write character buffer
  • Download demo project - 11 Kb
  • I recently needed a class that stored a character array as a circular buffer. If you are unfamiliar with circular buffer, it is a permanently allocated buffer that has both a read and write position. I have done a few of them in the past, but had lost all of my examples. So I wrote a new one and placed it into a class called CircularBuffer. The CircularBuffer can be read from and written to, and it has methods to get the read and write count. As the buffer is written to the write position increases til the end of the buffer is reached, at that point the write position is wrapped back to the start of the buffer and writing starts from there. The same happens to the read operation also, but the read position is incremented. It is important to note that the read position will never be greater than the write position, since if it were we would be reading data that had not been written to the buffer. Likewise, the write position will never wrap the read position otherwise data that had not been read would be overwritten.

    The basic operations are read and write, both fail if an overlap condition could occur.

    To get the number of availible characters to read the readCount method is used. If the count is greater than zero use the read method to get the latest contents written into the buffer.

    I have included a small test application in a project TestQue. The test driver is in the TestQue.cpp. It is multithreaded win32 console app developed using VC6.

    The CircularBuffer code is in CicularBuffer.cpp and h.

    License

    This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

    A list of licenses authors might use can be found here


    Written By
    United States United States
    This member has not yet provided a Biography. Assume it's interesting and varied, and probably something to do with programming.

    Comments and Discussions

     
    GeneralA circular buffer that can grow or decrease Pin
    UDria4-Dec-01 0:01
    UDria4-Dec-01 0:01 
    GeneralRe: A circular buffer that can grow or decrease Pin
    moshe beeri22-May-05 2:45
    moshe beeri22-May-05 2:45 

    General General    News News    Suggestion Suggestion    Question Question    Bug Bug    Answer Answer    Joke Joke    Praise Praise    Rant Rant    Admin Admin   

    Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.