/*
 *  call-seq:
 *     index_reader.get_norms_into(field, buffer, offset) -> buffer
 *
 *  Expert: Get the norm values into a string +buffer+ starting at +offset+.
 */
static VALUE
frt_ir_get_norms_into(VALUE self, VALUE rfield, VALUE rnorms, VALUE roffset)
{
    IndexReader *ir = (IndexReader *)DATA_PTR(self);
    int offset;
    offset = FIX2INT(roffset);
    Check_Type(rnorms, T_STRING);
    if (RSTRING(rnorms)->len < offset + ir->max_doc(ir)) {
        rb_raise(rb_eArgError, "supplied a string of length:%d to "
                 "IndexReader#get_norms_into but needed a string of length "
                 "offset:%d + maxdoc:%d",
                 RSTRING(rnorms)->len, offset, ir->max_doc(ir));
    }

    ir_get_norms_into(ir, frt_field(rfield),
                      (uchar *)rs2s(rnorms) + offset);
    return rnorms;
}