FFI::MemoryPointer

static VALUE
memptr_s_from_string(VALUE klass, VALUE to_str)
{
    VALUE s = StringValue(to_str);
    VALUE args[] = { INT2FIX(1), LONG2NUM(RSTRING_LEN(s) + 1), Qfalse };
    VALUE obj = rb_class_new_instance(3, args, klass);
    rb_funcall(obj, rb_intern("put_string"), 2, INT2FIX(0), s);
    
    return obj;
}

static VALUE
memptr_initialize(int argc, VALUE* argv, VALUE self)
{
    VALUE size = Qnil, count = Qnil, clear = Qnil;
    int nargs = rb_scan_args(argc, argv, "12", &size, &count, &clear);

    memptr_malloc(self, rbffi_type_size(size), nargs > 1 ? NUM2LONG(count) : 1,
        RTEST(clear) || clear == Qnil);
    
    if (rb_block_given_p()) {
        return rb_ensure(rb_yield, self, memptr_free, self);
    }

    return self;
}