partial = RING_BUFFER_SIZE - rb->rb_rt;
memcpy(target, rb->rb_ptr + rb->rb_rt, partial);
memcpy(target + partial, rb->rb_ptr, size - partial);
partial = RING_BUFFER_SIZE - rb->rb_rt;
memcpy(target, rb->rb_ptr + rb->rb_rt, partial);
memcpy(target + partial, rb->rb_ptr, size - partial);