dst

    A pointer to the destination array for converted multibyte
    character sequence.

 src

    An address of the pointer to an array containing the sequence of
    wide characters to be converted.

 len

    The maximum number of bytes that can be stored in the array
    pointed to by dst.

 ps

    A pointer to the mbstate_t object. If a NULL pointer is
    specified, the function uses its internal mbstate_t object.
    mbstate_t is an opaque datatype intended to keep the conversion
    state for the state-dependent codesets.