C-Talk is interpreted scripting language with C-like syntax and dynamic type checking. Variables in C-Talk have no type. So there is no compile time type checking in C-Talk, all checking is performed at runtime. To preserve reference integrity, explicit memory deallocation is prohibited in C-Talk, unused objects are automatically deallocated by garbage collector.
This project attempts to implement a Database using B+Tree. The project has developed a DATABASE SYSTEM with lesser memory consumption. Its API includes simple SQL Statements and the output is displayed on the screen. Certain applications for which several features of existing databases like concurrency control, transaction management, security features are not enabled. B+Trees can be used as an index for factor access to the data. Help facility is provided to know the syntax of SQL Statements.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS AND ANY EXPRESS
* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
* GOODS OR SERVICES LOSS OF USE, DATA, OR PROFITS OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH D
* CONSTRAINTS
* This module does not handle data which is considered out of range by the
* application(i.e. fixed constants which represent error condition)
*
* Maximum weight value must be limited to 128 to prevent an overflow
* condition during the calculation.
*
* The internal data type must be large enough to handle the calculations.
* The maximum possible internal value
* = Max Input Value * (weight - 1) + Max Input Value
* If a maximum weight of 128 is used, the internal data type should be 2
* times the size of the input data type.
There is an example of how to use the LDPC encode/decode with AWGN
channel model in files .\ldpc_decode.m and .\GFq\ldpc_decode.m.
There are a few parity check matrices available in the code but
you can use other matrices provided you have enough memory to load
them. I suggest checking out matrices in Alist format available on
David MacKay s web site.You will need to have access to a MEX compiler
to be able to use a few functions written in C.
LDPC的仿真代碼
This m-file simulates MPSK (theoretical and simulated) with Gray coding
This m-file simulates MPSK (BPSK,QPSK,8PSK)with theoretical and simulated results using Gray coding. Numerical examples of a satellite link design are shown using QPSK and/or 8PSK when the bit rate(Rb)is greater than the channel bandwidth Wc (Band-limited channel).
