Compiler Specific Operators

[brooks at lll-crg.UUCP]

>C already has a hook for such things.  It's called the "asm" statement.
>Despite its name, there is no law that says that what follows "asm"
>must in fact be assembly language.  If you're writing the compiler,
>you can implement whatever syntax you like with whatever semantics you like.
It would be nice if asm was more "printf like" instead of just dumping
a string.  I have made quite a lot of use of asms when writing things like
multitasking packages and other things which need assembler hooks.  Most
of the code can be in C and be reasonably portable.  I have often needed
the ability to stick a stack address in an asm without knowing just what
stack address you want to load...

ie

suppose you want to change the stack pointer...

	char *oldpointer;
	char *newpointer;

	asm("store sp,%a", oldpointer);
	asm("load sp,%a", newpointer);

The code is machine dependent, but the compiler takes care of the
C name -> AS name  mapping for you.   Of course I guess the compiler
should not encourage such screwing around.