Using Booleans and Strings

Create a Custom_C block that calls C functions that return a Boolean and output a String

• YearInfo () function takes date (string) as input and outputs the day (string) for the date.
• BoolCheck () function takes date (string) as input. It returns a boolean value as ‘true’ if input date is a leap year and 'false' if is not a leap year.
• The C code for the above functions is available in the file “YearInfo.c” under VS_C_Library/YearInfo directory of VisualSim. The tool does not generate this file and it should be made available by the Designers who wish to interface their code with VisualSim.

Construction Steps

1. Open VisualSim IDE and drag the Custom_C block from Full Library > System_Language > C_and_CPP to the Block Diagram Editor.

Figure 1: Configuring the Custom_C block

• The parameter libraryDirectory is the directory name for the block that is created under the base directory. The base for the libraryDirectory of the block is always set to VS_C_Library directory. Just the directory structure within this level is sufficient.
• The parameter nativefiles could specify the location of the “.C” files which contain the definitions for the C functions that the Designers wish to interface with VisualSim. The absolute path for the file should be specified when they are located outside the libraryDirectory. Use only forward slash ‘/’ while specifying absolute path because the tool permits only forward slash to maintain platform independence.
• The parameter nativeLibrary should specify the same name as the libraryDirectory.

2. Right click the Custom_C block and select Configure Arguments and add the following arguments:

Figure 2: C\C++ Arguments Configuration for YearInfo

Note: Specify the array size except for the char type while using Arrays as C\C++ Arguments.

3. Click the VisualSim menu Interface > Generate Wrapper for interface generation and compilation of source files. Refer Figure 6.
4. A new folder named “YearInfo” is automatically created under VS_C_Library directory if it does not exist. In case if the files in the respective folder already exist, then it is replaced with the new files.
5. Successful compilation of the sources files creates a Jni<libraryname>I<return argument name>.dll file under the blocks directory. The file extension “. Dll” indicates that the file is a dynamic link library (dll).

Note: Open the “vsout.txt” file under the libraryDirectory to check for errors caused by a unsuccessful compilation process. These could help in correcting any mistakes in the interface C code.

6. The blocks directory is provided under VS_C_Library directory to hold “. dll” files, which are in the PATH.
7. Drag the MoniterValue result block from Result > Text. Similarly the Const input block from Full Library > Math Operations > Math and Trig. Control-click to create the relation.
8. Connect all the blocks as shown in the Figure 3.
9. Add an Untimed Digital Simulator (located under Full Library -> Model->Simulator). Double-click the Untimed Digital simulator and change the number of iterations from 0 to 1.
10. To run YearInfo model, click the run button or Press Ctrl+R. The expected result looks similar to the one shown below.

Figure 3. Result of YearInfo Model