uint32_t result;
 
cli();
uint16_t my_tcnt = TCNT1;
__sync_synchronize(); // memory barrier
if ((TIFR1 & (1 << TOV1))) {
    // Timer overflowed but interrupt hasn't run yet,
    // and it won't here because we cli.
    // Re-capture TCNT1 to make sure we get a post-overflow sample,
    // and use ovfs+1 for the result.
    result = (((TimeType)(ovfs + 1) << 16) + TCNT1);
} else {
    // Timer hasn't yet overflowed when we captured TCNT,
    // and cli makes sure ovfs is consistent with my_tcnt.
    result = (((TimeType)ovfs << 16) + my_tcnt);
}
sei();
 

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