Useful for temporarily storing data when the consumer and producer process data at different speeds.
I used it in the morse blinker because data-in was at 9600Hz while blinking was at 2 Hz or something so that the flashes were actually visible.
FIFO - first in, first out - is literally a queue.

FIFO ring buffer with overwrite protection

I essentially wanted the board to buffer up to 10 characters as it transmitted the chars.
I also wanted it to ignore data-in and flash red if I sent in too many characters.
It’s a 10 element array, with each element being 20 bits wide (20 bits for morse).
I have two registers that essentially function as read and write pointers which store the address within the buffer I’m reading/writing to/from.

reg [3:0] r_addr;
reg [3:0] w_addr;
reg [19:0] memory [10];

If a pointer reached end of the array, it would wrap around to the start.
The overwrite protection was an if block checking if the write pointer caught up to the read pointer and just setting the warning signal to high.

if (r_addr == w_addr + 1) begin
    buff_warn <= 1;
end else begin
    memory[w_addr + 1] <= i_w_data;
    w_addr <= w_addr + 1;
end

The tricky part was relearning non-blocking assignments and ensuring that I’m writing to the address I’m supposed to.