/**
 * The vararg module is intended to facilitate vararg manipulation in D.
 * It should be interface compatible with the C module "stdarg," and the
 * two modules may share a common implementation if possible (as is done
 * here).
 *
 * Copyright: Public Domain
 * License:   Public Domain
 * Authors:   Hauke Duden, Walter Bright
 */
module core.vararg;


version( GNU )
{
    public import std.stdarg;
}
else
{
    /**
     * The base vararg list type.
     */
    alias void* va_list;


    /**
     * This function initializes the supplied argument pointer for subsequent
     * use by va_arg and va_end.
     *
     * Params:
     *  ap      = The argument pointer to initialize.
     *  paramn  = The identifier of the rightmost parameter in the function
     *            parameter list.
     */
    void va_start(T) ( out va_list ap, inout T parmn )
    {
        ap = cast(va_list) ( cast(void*) &parmn + ( ( T.sizeof + int.sizeof - 1 ) & ~( int.sizeof - 1 ) ) );
    }

    /**
     * This function returns the next argument in the sequence referenced by
     * the supplied argument pointer.  The argument pointer will be adjusted
     * to point to the next arggument in the sequence.
     *
     * Params:
     *  ap  = The argument pointer.
     *
     * Returns:
     *  The next argument in the sequence.  The result is undefined if ap
     *  does not point to a valid argument.
     */
    T va_arg(T) ( inout va_list ap )
    {
        T arg = *cast(T*) ap;
        ap = cast(va_list) ( cast(void*) ap + ( ( T.sizeof + int.sizeof - 1 ) & ~( int.sizeof - 1 ) ) );
        return arg;
    }

    /**
     * This function cleans up any resources allocated by va_start.  It is
     * currently a no-op and exists mostly for syntax compatibility with
     * the variadric argument functions for C.
     *
     * Params:
     *  ap  = The argument pointer.
     */
    void va_end( va_list ap )
    {

    }


    /**
     * This function copied the argument pointer src to dst.
     *
     * Params:
     *  src = The source pointer.
     *  dst = The destination pointer.
     */
    void va_copy( out va_list dst, va_list src )
    {
        dst = src;
    }
}
