From eb8643ddbef43547eb7bfe58789a3908926c7258 Mon Sep 17 00:00:00 2001
From: Vaino Kauppila <vaino@vke.fi>
Date: Sun, 19 Apr 2026 12:32:58 +0300
Subject: refactor dir structure, add fib.c

---
 PIC/fifo.vhd | 75 ------------------------------------------------------------
 1 file changed, 75 deletions(-)
 delete mode 100644 PIC/fifo.vhd

(limited to 'PIC/fifo.vhd')

diff --git a/PIC/fifo.vhd b/PIC/fifo.vhd
deleted file mode 100644
index 9dd8523..0000000
--- a/PIC/fifo.vhd
+++ /dev/null
@@ -1,75 +0,0 @@
-library ieee;
-use ieee.std_logic_1164.all;
-use ieee.numeric_std.all;
-
--- First-word fall-through (FWFT) FIFO.
--- dout always presents the current head combinatorially (no read latency).
--- rd_en advances the read pointer; the next head is visible on the same cycle.
--- DEPTH must be a power of 2; ADDR_BITS = log2(DEPTH).
-
-entity fifo is
-  generic (
-    DEPTH     : positive := 16;
-    ADDR_BITS : positive := 4;
-    WIDTH     : positive := 8
-  );
-  port (
-    clk   : in  std_logic;
-    wr_en : in  std_logic;
-    rd_en : in  std_logic;
-    din   : in  std_logic_vector(WIDTH - 1 downto 0);
-    dout  : out std_logic_vector(WIDTH - 1 downto 0);
-    full  : out std_logic;
-    empty : out std_logic
-  );
-end entity fifo;
-
-architecture rtl of fifo is
-
-  -- MSB pointer trick: pointers are ADDR_BITS+1 wide.
-  -- Empty: read_ptr = write_ptr
-  -- Full:  (read_ptr XOR write_ptr) = DEPTH  (MSBs differ, lower bits equal)
-  signal read_ptr  : unsigned(ADDR_BITS downto 0) := (others => '0');
-  signal write_ptr : unsigned(ADDR_BITS downto 0) := (others => '0');
-
-  type mem_t is
-    array (0 to DEPTH - 1)
-    of std_logic_vector(WIDTH - 1 downto 0);
-
-  signal mem : mem_t := (others => (others => '0'));
-
-  signal empty_i : std_logic;
-  signal full_i  : std_logic;
-
-begin
-
-  empty_i <= '1' when read_ptr = write_ptr else '0';
-  full_i  <= '1' when (read_ptr xor write_ptr) = to_unsigned(DEPTH, ADDR_BITS + 1)
-             else '0';
-
-  empty <= empty_i;
-  full  <= full_i;
-
-  -- FWFT: head is always visible without asserting rd_en
-  dout <= mem(to_integer(read_ptr(ADDR_BITS - 1 downto 0)));
-
-  enqueue : process(clk)
-  begin
-    if rising_edge(clk) then
-      if wr_en = '1' and full_i = '0' then
-        mem(to_integer(write_ptr(ADDR_BITS - 1 downto 0))) <= din;
-        write_ptr <= write_ptr + 1;
-      end if;
-    end if;
-  end process enqueue;
-
-  dequeue : process(clk)
-  begin
-    if rising_edge(clk) then
-      if rd_en = '1' and empty_i = '0' then
-        read_ptr <= read_ptr + 1;
-      end if;
-    end if;
-  end process dequeue;
-
-end architecture rtl;
-- 
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