I saw a FIFO example here, and once I was trying to synthesize it didn't work.
I took out the "assign", I removed the "always" and "begin" and it works, but now I have another problem. I am using a button to write data, but I think the clock is too fast, since it should be 16 data that I can write, and the 16 data are the same, there is no time to change it. I was trying to use a clock divider, any advice on this?