+/*
+ * When erasing a flight log, make sure the config block
+ * has an up-to-date version of the current flight number
+ */
+
+struct ao_log_erase {
+ uint8_t unused;
+ uint16_t flight;
+};
+
+static __xdata struct ao_log_erase erase;
+
+#define LOG_MAX_ERASE 16
+
+static uint32_t
+ao_log_erase_pos(uint8_t i)
+{
+ return i * sizeof (struct ao_log_erase) + AO_STORAGE_ERASE_LOG;
+}
+
+void
+ao_log_write_erase(uint8_t pos)
+{
+ erase.unused = 0x00;
+ erase.flight = ao_flight_number;
+ ao_storage_write(ao_log_erase_pos(pos), &erase, sizeof (erase));
+ ao_storage_flush();
+}
+
+static void
+ao_log_read_erase(uint8_t pos)
+{
+ ao_storage_read(ao_log_erase_pos(pos), &erase, sizeof (erase));
+}
+
+
+static void
+ao_log_erase_mark(void)
+{
+ uint8_t i;
+
+ for (i = 0; i < LOG_MAX_ERASE; i++) {
+ ao_log_read_erase(i);
+ if (erase.unused == 0 && erase.flight == ao_flight_number)
+ return;
+ if (erase.unused == 0xff) {
+ ao_log_write_erase(i);
+ return;
+ }
+ }
+ ao_config_put();
+}
+
+static uint8_t
+ao_log_slots()
+{
+ return (uint8_t) (ao_storage_config / ao_config.flight_log_max);
+}
+
+static uint32_t
+ao_log_pos(uint8_t slot)
+{
+ return ((slot) * ao_config.flight_log_max);
+}
+
+static uint16_t
+ao_log_flight(uint8_t slot)
+{
+ if (!ao_storage_read(ao_log_pos(slot),
+ &log,
+ sizeof (struct ao_log_record)))
+ return 0;
+
+ if (ao_log_dump_check_data() && log.type == AO_LOG_FLIGHT)
+ return log.u.flight.flight;
+ return 0;
+}
+
+static uint16_t
+ao_log_max_flight(void)
+{
+ uint8_t log_slot;
+ uint8_t log_slots;
+ uint16_t log_flight;
+ uint16_t max_flight = 0;
+
+ /* Scan the log space looking for the biggest flight number */
+ log_slots = ao_log_slots();
+ for (log_slot = 0; log_slot < log_slots; log_slot++) {
+ log_flight = ao_log_flight(log_slot);
+ if (!log_flight)
+ continue;
+ if (max_flight == 0 || (int16_t) (log_flight - max_flight) > 0)
+ max_flight = log_flight;
+ }
+ return max_flight;
+}
+
+static void
+ao_log_scan(void) __reentrant
+{
+ uint8_t log_slot;
+ uint8_t log_slots;
+ uint8_t log_want;
+
+ ao_config_get();
+
+ ao_flight_number = ao_log_max_flight();
+ if (ao_flight_number)
+ if (++ao_flight_number == 0)
+ ao_flight_number = 1;
+
+ /* Now look through the log of flight numbers from erase operations and
+ * see if the last one is bigger than what we found above
+ */
+ for (log_slot = LOG_MAX_ERASE; log_slot-- > 0;) {
+ ao_log_read_erase(log_slot);
+ if (erase.unused == 0) {
+ if (ao_flight_number == 0 ||
+ (int16_t) (erase.flight - ao_flight_number) > 0)
+ ao_flight_number = erase.flight;
+ break;
+ }
+ }
+ if (ao_flight_number == 0)
+ ao_flight_number = 1;
+
+ /* With a flight number in hand, find a place to write a new log,
+ * use the target flight number to index the available log slots so
+ * that we write logs to each spot about the same number of times.
+ */
+
+ /* Find a log slot for the next flight, if available */
+ ao_log_current_pos = ao_log_end_pos = 0;
+ log_slots = ao_log_slots();
+ log_want = (ao_flight_number - 1) % log_slots;
+ log_slot = log_want;
+ do {
+ if (ao_log_flight(log_slot) == 0) {
+ ao_log_current_pos = ao_log_pos(log_slot);
+ ao_log_end_pos = ao_log_current_pos + ao_config.flight_log_max;
+ break;
+ }
+ if (++log_slot >= log_slots)
+ log_slot = 0;
+ } while (log_slot != log_want);
+
+ ao_wakeup(&ao_flight_number);
+}
+