I'm pretty sure x86 inline assembler is still alive and kicking in the
latest VC++, although I seem to remember that x86_64 might not be.  I'd also
think that inline assembly now recognizes more instructions than ever
before.

However, you're better off writing very simple C code (register transfer
style) and let the optimizer run, it will probably generate better machine
code than you.  Humans can keep track of register spills pretty effectively
but when you add pipelining, branch prediction, cache associativity, and a
whole bunch of other factors, instruction costs are not constant and there's
no way a programmer can optimize them all in a reasonable amount of time.

If you have the full package - Professional Edition - VS does include
an assembler. Just add a .asm file to your project and compile!

It is just that hardly anybody uses it, because it is *extremely* hard
to outsmart the compiler. If you can shave more than one or two asm
instructions from a compiled function, you are at the Guru level !

Bo Persson

Roughly speaking, you want something like:

int main() {
    //c++ code

    __asm {
        //inline assembly code
     }
}

Check out the msdn pages on it, for something authoritative:
http://msdn2.microsoft.com/en-us/library/45yd4tzz.aspx