TclWinCPUID(
    int index,		/* Which CPUID value to retrieve. */
    int *regsPtr)	/* Registers after the CPUID. */
{
    int status = TCL_ERROR;

    /* See: <http://en.wikipedia.org/wiki/CPUID> */
#if defined(HAVE_CPUID)
#if defined(__x86_64__) || defined(_M_AMD64) || defined (_M_X64)
    __asm__ __volatile__("movq %%rbx, %%rsi     \n\t" /* save %rbx */
                 "cpuid            \n\t"
                 "xchgq %%rsi, %%rbx   \n\t" /* restore the old %rbx */
                 : "=a"(regsPtr[0]), "=S"(regsPtr[1]), "=c"(regsPtr[2]), "=d"(regsPtr[3])
                 : "a"(index));
    status = TCL_OK;
#else
#elif defined(__i386__) || defined(_M_IX86)
    __asm__ __volatile__("mov %%ebx, %%esi     \n\t" /* save %ebx */
                 "cpuid            \n\t"
                 "xchg %%esi, %%ebx   \n\t" /* restore the old %ebx */
                 : "=a"(regsPtr[0]), "=S"(regsPtr[1]), "=c"(regsPtr[2]), "=d"(regsPtr[3])
                 : "a"(index));
#endif
    status = TCL_OK;
#else
    (void)index;
    (void)regsPtr;
#endif
    return status;
}