RDCOUNT_TYPE defines the way status information about the internal state of the FIFO counters is provided to the RDCOUNT output.
- RAW_PNTR – RDCOUNT = FIFO memory read pointer, synchronous to RDCLK domain.
- SYNC_PNTR – RDCOUNT = FIFO memory read pointer, synchronized to WRCLK domain (delayed). Not supported for common-clock FIFO.
- SIMPLE_DATACOUNT – RDCOUNT = Subtraction of read pointer (in the RDCLK domain) from write pointer (synchronized to RDCLK domain) to indicate the number of words in the memory in the RDCLK domain. Does not account for additional words stored in output register stages.
- EXTENDED_DATACOUNT – RDCOUNT = Subtraction of read pointer (in the RDCLK domain) from write pointer (synchronized to the RDCLK domain) plus 0, 1, or 2 (depending on output stages) to indicate the number of words in the memory and in the output stages in the RDCLK domain.