From f3e6e2d5e0e90f5a1063cc73eb8ff1e0b041a534 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Franti=C5=A1ek=20Boh=C3=A1=C4=8Dek?=
 <fandabohacek@gmail.com>
Date: Wed, 9 Nov 2022 12:41:06 +0100
Subject: [PATCH] feat(link): add part of ilas parsing

---
 src/data_link/ilas_parser.vhd | 93 ++++++++++++++++++++++++++++++++++-
 1 file changed, 92 insertions(+), 1 deletion(-)

diff --git a/src/data_link/ilas_parser.vhd b/src/data_link/ilas_parser.vhd
index 13fc1f2..37095fe 100644
--- a/src/data_link/ilas_parser.vhd
+++ b/src/data_link/ilas_parser.vhd
@@ -1,11 +1,13 @@
 library ieee;
 use ieee.std_logic_1164.all;
+use ieee.numeric_std.all;
 use work.data_link_pkg.all;
 
 entity ilas_parser is
   generic (
     R_character  : std_logic_vector(7 downto 0) := "00011100";
     A_character  : std_logic_vector(7 downto 0) := "01111100";
+    Q_character  : std_logic_vector(7 downto 0) := "01011100";
     frames_count : integer                      := 4);
 
   port (
@@ -23,9 +25,98 @@ entity ilas_parser is
 end entity ilas_parser;
 
 architecture a1 of ilas_parser is
+  constant link_config_length : integer := 111;
+  signal link_config_data : std_logic_vector(link_config_length downto 0) := (others => '0');
+  signal reg_processing_ilas : std_logic := '0';
+  signal reg_frame_index : integer := 0;
+  signal reg_octet_index : integer := 0;
 
+  signal next_processing_ilas : std_logic := '0';
+
+  signal processing_ilas : std_logic := '0';
+
+  function getOctetUpIndex (
+    octet_index : integer)
+    return integer is
+  begin  -- function getByteUpIndex
+    return link_config_length - 1 - 8 * octet_index;
+  end function getByteUpIndex;
+
+  function getDataByIndex (
+    data        : std_logic_vector(link_config_length downto 0);
+    octet_index : integer;
+    bit_index   : integer;
+    length      : integer)
+    return std_logic_vector is
+    variable up_index : integer;
+  begin  -- function getDataByIndex
+    up_index := getOctetUpIndex(data, octet_index);
+    return data(up_index downto up_index - 7)(bit_index + length downto bit_index);
+  end function getDataByIndex;
 begin  -- architecture a1
 
-  
+  -- ILAS
+    -- one multiframe is sent
+    -- 4 frames in a multiframe
+    -- second frame contains ILAS at third character
+    -- each start of a frame should have /R/
+    -- each end of a frame should have /A/
+    -- second frame:
+      -- second_character: /K28.0/
+      -- third_character: starts ILAS
+
+  -- if anything does not match (/R/, /A/, /K28.0/, checksum), set co_error
+  -- and co_wrong_chksum or co_unexpected_char. Stop processing.
+  -- The controller will then request new synchronization try.
+
+  check_chars: process (ci_char_clk, ci_reset) is
+    variable up_index : integer;
+  begin  -- process check_chars
+    if ci_reset = '0' then              -- asynchronous reset (active low)
+      co_error <= '0';
+      co_unexpected_char <= '0';
+      co_wrong_chksum <= '0';
+      link_config_data <= (others => '0');
+    elsif ci_char_clk'event and ci_char_clk = '1' and processing_ilas = '0' then
+      co_error <= '0';
+      co_unexpected_char <= '0';
+      co_wrong_chksum <= '0';
+      link_config_data <= (others => '0');
+    elsif ci_char_clk'event and ci_char_clk = '1' and processing_ilas = '1' then  -- rising clock edge
+      if reg_octet_index = 0 then       -- Should be /R/
+        if di_char.d8b /= R_character then
+          co_error <= '1';
+          co_unexpected_char <= '1';
+        end if;
+      elsif reg_octet_index = ci_F - 1 then
+        if di_char.d8b /= A_character then  -- Should be /A/
+          co_error <= '1';
+          co_unexpected_char <= '1';
+        end if;
+      elsif reg_frame_index = 1 then
+        if reg_octet_index = 1 and di_char.d8b /= Q_character then  -- Should be /Q/
+          co_error <= '1';
+          co_unexpected_char <= '1';
+        elsif reg_octet_index > 1 and reg_octet_index < 16 then    -- This is config data
+          up_index := getOctetUpIndex(reg_octet_index - 2);
+          link_config_data(up_index downto up_index - 7) <= di_char.d8b;
+        end if;
+
+        if reg_octet_index = 15 then    -- This is a checksum
+
+        end if;
+      end if;
+    end if;
+  end process check_chars;
+
+  processing_ilas <= next_processing_ilas or reg_processing_ilas;
+
+  next_processing_ilas <= '0' when ci_state = INIT else
+                          '1' when reg_processing_ilas = '1' or ci_state = ILAS
+                          else '0';
+
+  -- config
+  do_config.ADJCNT <= to_integer(unsigned(getDataByIndex(link_config_data, 0, 0, 8)));
+  do_config.ADJDIR <= getDataByIndex(link_config_data, 2, 6, 1);
 
 end architecture a1;
-- 
2.49.0