Description

   The va_count macro places the number of quadwords (Alpha only) in
   the argument list into count. The value returned in count is the
   number of quadwords (Alpha only) in the function argument block
   not counting the count field itself.

   If the argument list contains items whose storage requirements
   are a quadword (Alpha only) of memory or less, the number in
   the count argument is also the number of arguments. However, if
   the argument list contains items that are longer than a quadword
   (Alpha only), count must be interpreted to obtain the number of
   arguments. Because a double is 8 bytes, it occupies one argument-
   list position on OpenVMS Alpha and Integrity server systems.

   The va_count macro is specific to VSI C for OpenVMS Systems
   and is not portable.