SERNUM_BUFFER_LENGTH
uint32_t sernum[SERNUM_BUFFER_LENGTH]; /* the serial numbers */
bool ack[SERNUM_BUFFER_LENGTH]; /* acknowledged? */
t = (t + 1) % SERNUM_BUFFER_LENGTH;
for (; b != t; b = (b + 1) % SERNUM_BUFFER_LENGTH) {
buff->bottom = (b + 1) % SERNUM_BUFFER_LENGTH;
b != t && buff->ack[b]; b = (b + 1) % SERNUM_BUFFER_LENGTH) {