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The pages on this site contain documentation for very old MS-DOS software, purely for historical purposes. If you're looking for up-to-date documentation, particularly for programming, you should not rely on the information found here, as it will be woefully out of date.

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─────C/C++ Language─────────────────────────────────────────────────────────
 
     An __asm block can refer to any C symbol in the scope where the
     block appears. This includes arguments, functions, and local,
     static local, and global variables. Each assembly-language
     statement can contain only one C symbol (except in LENGTH, TYPE,
     and SIZE expressions). Functions referenced in an __asm block must
     be declared (prototyped) earlier in the program.
 
     If a structure or union member has a unique name, an __asm
     block can refer to it by using only the member name
     (mov ax, [bx].unique). If the member name is not unique, you must
     place a variable or typedef name before the period operator
     (mov ax, [bx]var.copy).
 
     You can define functions in C and implement them with the inline
     assembler, as shown below:
 
          int power2( int num, int power )
          {
             __asm
             {
                mov ax, num    ; Get first argument
                mov cx, power  ; Get second argument
                shl ax, cl     ; AX = AX * ( 2 to the power of CL )
             }
          }  // Return with result in AX
 
     This assumes the __cdecl or __pascal calling convention. To avoid
     register conflicts, you should not use the __fastcall calling
     convention for functions with __asm blocks.
                                    -♦-