Subversion Repositories dp_components

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--

-- Copyright 2020

-- ASTRON (Netherlands Institute for Radio Astronomy) <http://www.astron.nl/>

-- P.O.Box 2, 7990 AA Dwingeloo, The Netherlands

-- 

-- Licensed under the Apache License, Version 2.0 (the "License");

-- you may not use this file except in compliance with the License.

-- You may obtain a copy of the License at

-- 

--     http://www.apache.org/licenses/LICENSE-2.0

-- 

-- Unless required by applicable law or agreed to in writing, software

-- distributed under the License is distributed on an "AS IS" BASIS,

-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

-- See the License for the specific language governing permissions and

-- limitations under the License.

--

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LIBRARY IEEE, common_components_lib;

USE IEEE.std_logic_1164.all;

-- Purpose:

--   Hold hld_ctrl active until next ready high when in_ctrl is active while

--   ready went low

-- Description:

--   When ready goes low there may still arrive one new valid data. The control

--   information for this data can then be held with this component. When ready

--   goes high again the held data can then be output and the hld_ctrl is 

--   released. After that the subsequent data output can come directly from the

--   up stream source, until ready goes low again.

-- Remarks:

-- . Ready latency RL = 1

-- . The in_ctrl is typically in_valid, in_sop or in_eop

-- . Typically used together with dp_hold_data

ENTITY dp_hold_ctrl IS

  PORT (

    rst      : IN  STD_LOGIC;

    clk      : IN  STD_LOGIC;

    ready    : IN  STD_LOGIC;

    in_ctrl  : IN  STD_LOGIC;

    hld_ctrl : OUT STD_LOGIC

  );

END dp_hold_ctrl;

ARCHITECTURE rtl OF dp_hold_ctrl IS

  SIGNAL hi_ctrl : STD_LOGIC;

  SIGNAL lo_ctrl : STD_LOGIC;

BEGIN

  hi_ctrl <=     in_ctrl AND NOT ready;  -- capture

  lo_ctrl <= NOT in_ctrl AND     ready;  -- release

  u_hld_ctrl : ENTITY common_components_lib.common_switch

  PORT MAP (

    rst         => rst,

    clk         => clk,

    switch_high => hi_ctrl,

    switch_low  => lo_ctrl,

    out_level   => hld_ctrl

  );

END rtl;