By now you can write procedures both internal andexternal and pass parameters particularly through stack.Let's us use these concepts to see how assembly language can be interfaced to some high level language programs. It is very significant to learn this theorysince then you can combine the benefits of both the types of languages which is the ease of programming of high level languages and speed and scope of assembly language. Assembly language can be interfaced with most of the high level languages such as C, C + + and database management systems.
What are the major considerations for interfacing assembly to HLL? To answer it we need to answer below questions:
- How is the subroutine invoked?
- How are parameters passed?
- How are the values returned?
- How do you declare various segments so that they are consistent across calling program?
The answer to above questions are dependent on high level language (HLL). Let's take C Language as the language for interfacing. C Language is very useful for writing user interface programs though the code generated by a C compiler doesn't execute fast enough for graphics or telecommunications applications. So system programs are generally written with a combination of C and assembly language functions. The main user interface can be written in C and specialized high speed functions written in assembly language.