Method switch_sectors

libraries/AP_FlashStorage/AP_FlashStorage.cpp:396–447

switch to next sector for writing

// switch to next sector for writing
bool AP_FlashStorage::switch_sectors(void)
{
    if (reserved_space != 0) {
        // other sector is already full
        debug("both sectors are full\n");
        return false;
    }

    struct sector_header header;

    uint8_t new_sector = current_sector ^ 1;
    debug("switching to sector %u\n", new_sector);
    
    // check sector is available
    if (!flash_read(new_sector, 0, (uint8_t *)&header, sizeof(header))) {
        return false;
    }
    if (!header.signature_ok()) {
        write_error = true;
        return false;
    }
    if (SECTOR_STATE_AVAILABLE != header.get_state()) {
        write_error = true;
        debug("new sector unavailable; state=0x%02x\n", (unsigned)header.get_state());
        return false;
    }

    // mark current sector as full. This needs to be done before we
    // mark the new sector as in-use so that a power failure between
    // the two steps doesn't leave us with an erase on the
    // reboot. Thanks to night-ghost for spotting this.
    header.set_state(SECTOR_STATE_FULL);
    if (!flash_write(current_sector, 0, (const uint8_t *)&header, sizeof(header))) {
        return false;
    }

    // mark new sector as in-use
    header.set_state(SECTOR_STATE_IN_USE);
    if (!flash_write(new_sector, 0, (const uint8_t *)&header, sizeof(header))) {
        return false;
    }

    // switch sectors
    current_sector = new_sector;
        
    // we need to reserve some space in next sector to ensure we can successfully do a
    // full write out on init()
    reserved_space = reserve_size;
    
    write_offset = sizeof(header);
    return true;    
}

/*
  re-initialise, using current mem_buffer