if (seq->qual.n > *n) {
*xs = realloc_or_die(*xs, 255 * seq->qual.n * sizeof(unsigned int));
memset(*xs + *n, 0, 255 * (seq->qual.n - *n) * sizeof(unsigned int));
if (seq->qual.n > *n) {
*xs = realloc_or_die(*xs, 255 * seq->qual.n * sizeof(unsigned int));
memset(*xs + *n, 0, 255 * (seq->qual.n - *n) * sizeof(unsigned int));