diff --git a/Codes/Group A/Assignment-A3/EXPLANATION.md b/Codes/Group A/Assignment-A3/EXPLANATION.md new file mode 100644 index 0000000..12f1d95 --- /dev/null +++ b/Codes/Group A/Assignment-A3/EXPLANATION.md @@ -0,0 +1,32 @@ +# Explanation + +Please note the files referred in this guide: +- [A3.java] +- [A3.c] + +- We're using Java for writing the main program. +- To demonstrate Dynamic Linking Library (DLL) in Java, we'll be declaring functions in Java and implementing them in C (can be C/C++). +- First, we create a Java program `A3.java`, + - This is the main Java file containing function definition and the main function. + - Functions (add, sub, mul, div) in `A3` class in this file are native functions, meaning their body is written in C/C++ in a different file. +- After creating this file, you need to compile it. To do so, run `javac A3.java` (assuming you're already in the directory that contains this file). +- Now, we will generate the header file. For this, run `javac -h A3.java`. +- There will be a new file called `A3.h` in your current working directory, + - This is the header file. + - It contains signatures for native functions we created in the Java file. + - Thus, there's **no need to memorized `A3.c` file** since the functions defined in that file can be found in the header file. +- Create a new `A3.c` file which is the C program file containing function definitions (for add, sub, mul, div) + - Define all the functions (add, sub, mul, div) +- Then, we have to compile the C program file, i.e. `A3.c`. For this, run `gcc -shared -o libA3.so -fPIC -I"$JAVA_HOME/include" -I"$JAVA_HOME/include/linux" A3.c`, + - `gcc` -> GNU compiler for C program + - `-shared` -> tells the compiler to create a shared file (.so) instead of a regular executable file + - `-o libA3.so` -> tells the compiler to save the output to `libA3.so` file + - `fPIC` -> stands for Position-Independent Code. Needed for creating shared libraries. + - `-I"$JAVA_HOME/include"` and `-I"$JAVA_HOME/include/linux"` -> `-I` flag used for specifiying directories to include. Values in double quotes are directories + - `A3.c` -> name of the C program file to compile +- Lastly, run the program using `java -Djava.library.path=. A3` + - `java` -> Loads Java Virtual Machine (JVM) + - `-Djava.library.path=.` -> `-D` is used to set a system property. In this case, we’re setting the `java.library.path` (for .so or .dll files) property. + - `A3` -> name of the Java class containing the main method + +--- diff --git a/Codes/Group A/Assignment-A3/README.md b/Codes/Group A/Assignment-A3/README.md index cea8072..e724972 100644 --- a/Codes/Group A/Assignment-A3/README.md +++ b/Codes/Group A/Assignment-A3/README.md @@ -4,6 +4,8 @@ These are the steps to run code for Assignment-A3. --- +### Refer [EXPLANATION](https://git.kska.io/sppu-te-comp-content/SystemsProgrammingAndOperatingSystem/src/branch/main/Codes/Group%20A/Assignment-A3/EXPLANATION.md) to understand how everything works. + > [!IMPORTANT] > Tested on Linux and Windows.