Slide 14.2: High-level language interface

High-Level Language Interface

There are three methods of connecting C/C++ programs to assembly language programs:

Inline assembly code in C/C++,
Separate assembly language modules linked to C/C++ programs, and
Calling C/C++ functions from an assembly language program.

Inline Assembly Code Inline assembly code is assembly language source code that is inserted directly into high-level language programs.

The __asm Directive
In Visual C++, the __asm directive can be placed at the beginning of a single statement, or it can mark the beginning of a block of assembly language statements (called an asm block). The syntax is

   __asm  statement

   __asm {
     statement-1
     statement-2
     ...
     statement-n
   }

(There are two underline characters before “asm.”)

Comments
Comments can be placed after any statements in the asm block, using either assembly language syntax or C/C++ syntax. Here are examples of permissible comments:

   mov   esi, buf      ;  initialize index register
   mov   esi, buf      // initialize index register
   mov   esi, buf      /* initialize index register */