Almost full flag in fifos

[GMellar]

The almost full flag in all FIFO should be 1 when there are less elements left than the threshold. That is what the documentation states. There is this check for head and tail:

      if head_v /= tail_v then
        if head_v > tail_v then
          if Almost_full_thresh >= MEM_SIZE - (head_v - tail_v) then
            Almost_full <= '1';
          end if;
          if Almost_empty_thresh >= head_v - tail_v then
            Almost_empty <= '1';
          end if;
        else
          if Almost_full_thresh >= tail_v - head_v then
            Almost_full <= '1';
          end if;
          if Almost_empty_thresh >= MEM_SIZE - (tail_v - head_v) then
            Almost_empty <= '1';
          end if;
        end if;
      end if;

As I understand that in a FIFO with a size of 16 and 8 bytes where the almost full threshold is 8 the almost full flag would be 1 after the write sequence of 8 elements which conflicts the documentation. Is there anything I miss here?