https://www.altera.com/en_US/pdfs/literature/ug/ug_fifo.pdf
If you receive some data, say via a serial interface, you may wish to temporarily store the received data in a FIFO.
A sequence of data, 40h, 41h, 42h, … is fed into a 256 words FIFO, and a delayed sequence of 20h, 21h, 22h, …is coming out of the FIFO.
if (! almost_empgy) rdreq <= 1'b1;
defparam scfifo_componet.almost_emtpy_value = 32; // hex 20