How to interface Modula-2 with C libraries on a Windows 10 system?
Interfacing Modula-2 with C libraries on a Windows 10 system requires several steps, which include understanding the process of interfacing, getting the software setup to run the code, writing the code in both C and Modula-2, and testing the interface.
Hardware Requirements and Software Setup
It's necessary to set up your Windows 10 system with the required software initially. You will need:
- Windows 10 Operating System.
- A text editor or Integrated Development Environment (IDE) for writing C and Modula-2 code, like Visual Studio Code or Eclipse.
- Modula-2 Compiler for Windows, such as GNU Modula-2 or XDS Modula-2.
- C compiler, like GCC, which is most commonly used with C Cygwin or MinGW distributions.
- DLL (Dynamic-link library) Export Viewer: This software is necessary when calling a function from a DLL module.
Find the C function in the DLL file
Every function exported from the DLL file gets assigned an address during runtime. The DLL Export Viewer can be used to get the memory address of the exported function from the DLL file.
1. Launch the Export Viewer.
2. Go to `File` > `Select DLL File` from the menu bar.
3. Select the DLL file containing the C function.
4. In the list of functions, locate the function you want to call from Modula-2.
5. Note down the function's memory address.
Write the C Library
```c
// library.c
#include <stdio.h>
void printHello() {
printf("Hello from C library\n");
}
```
After writing the code, compile it to create a DLL:
`gcc -shared -o library.dll library.c`
Replace "library.c" and "library.dll" with your source file and resulting DLL name, respectively.
Write the Modula-2 Code
In your Modula-2 code, you must declare the C function as an imported procedure, and call that procedure when necessary.
Below is a sample Modula-2 code:
```modula-2
MODULE main;
IMPORT SYSTEM;
PROCEDURE PrintHello(); EXTERNAL SYSTEM.lnklanguage('C') '0x12345678';
BEGIN
PrintHello();
END main.
```
Here, 'PrintHello' function is being declared as an imported procedure. The SYSTEM.lnklanguage declaration tells the linker to use C-style linking. Replace '0x12345678' with your function's memory address from DLL Export Viewer.
Compile and Run Your Modula-2 Code
The final step is to compile your Modula-2 code. You will have to use the Modula-2 compiler for this, and the process will depend on the particular compiler you chose. For instance, if you are using GNU Modula-2, you might use a command like:
`gm2 -fiso main.mod`
Replace "main.mod" with your Modula-2 source file.
Running the executable file will call the C function from the DLL via the Modula-2 program.
This is a comprehensive process of how to interface Modula-2 with C libraries on a Windows 10 system. You are free to expand this process by using more complex C functions and calling them from Modula-2.
