stdarg.h

va_start(v, l)   __builtin_va_start(v,l)

Defines the start position of the variable-length argument list.

va_end(v)   __builtin_va_end(v)

Ends a variable-length argument list.

va_arg(v, l)   __builtin_va_arg(v,l)

Obtains the next argument in the variable-length argument list.

va_copy(d, s)   __builtin_va_copy(d,s)

Copies the previously initialized variable argument list s to d.