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/*

 * Copyright (c) 2014, Aleksander Osman

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions are met:

 *

 * * Redistributions of source code must retain the above copyright notice, this

 *   list of conditions and the following disclaimer.

 *

 * * Redistributions in binary form must reproduce the above copyright notice,

 *   this list of conditions and the following disclaimer in the documentation

 *   and/or other materials provided with the distribution.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE

 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR

 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER

 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,

 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

`include "defines.v"

//PARSED_COMMENTS: this file contains parsed script comments

module prefetch_control(

    input           clk,

    input           rst_n,

    input           pr_reset, //same as reset to icache

    //from prefetch

    input   [31:0]  prefetch_address,

    input   [4:0]   prefetch_length,

    input           prefetch_su,

    //from prefetchfifo

    input   [4:0]   prefetchfifo_used,

    //REQ:

    output          tlbcoderequest_do,

    output  [31:0]  tlbcoderequest_address,

    output          tlbcoderequest_su,

    //END

    //RESP:

    input           tlbcode_do,

    input   [31:0]  tlbcode_linear,

    input   [31:0]  tlbcode_physical,

    input           tlbcode_cache_disable,

    //END

    //REQ:

    output          icacheread_do,

    output  [31:0]  icacheread_address,

    output  [4:0]   icacheread_length, // takes into account: page size and cs segment limit

    output          icacheread_cache_disable

    //END

);

//------------------------------------------------------------------------------

reg [1:0]  state;

reg [31:0] linear;

reg [31:0] physical;

reg        cache_disable;

//------------------------------------------------------------------------------

localparam [1:0] STATE_TLB_REQUEST = 2'd0;

localparam [1:0] STATE_ICACHE      = 2'd1;

//------------------------------------------------------------------------------

wire [12:0] left_in_page;

wire [4:0]  length;

wire        offset_update;

wire        page_cross;

//------------------------------------------------------------------------------

assign tlbcoderequest_address = prefetch_address;

assign tlbcoderequest_su      = prefetch_su;

assign left_in_page = 13'd4096 - { 1'b0, prefetch_address[11:0] };

assign length       = (left_in_page < { 8'd0, prefetch_length })?  left_in_page[4:0] : prefetch_length;

assign offset_update = prefetch_address[31:12] == linear[31:12] && prefetch_address[11:0] != linear[11:0];

assign page_cross    = prefetch_address[31:12] != linear[31:12];

//------------------------------------------------------------------------------

//------------------------------------------------------------------------------

//------------------------------------------------------------------------------

//------------------------------------------------------------------------------

/*******************************************************************************SCRIPT

IF(state == STATE_TLB_REQUEST);

    IF(~(pr_reset) && prefetch_length > 5'd0 && prefetchfifo_used < 5'd3);

        SET(tlbcoderequest_do);

        IF(tlbcode_do);

            SAVE(linear,        tlbcode_linear);

            SAVE(physical,      tlbcode_physical);

            SAVE(cache_disable, tlbcode_cache_disable);

            SET(icacheread_do);

            SET(icacheread_address,       tlbcode_physical);

            SET(icacheread_length,        length);

            SET(icacheread_cache_disable, tlbcode_cache_disable);

            SAVE(state, STATE_ICACHE);

        ENDIF();

    ENDIF();

ENDIF();

*/

/*******************************************************************************SCRIPT

IF(state == STATE_ICACHE);

    IF(page_cross || pr_reset || prefetchfifo_used >= 5'd8);

        SAVE(state, STATE_TLB_REQUEST);

    ELSE();

        SET(icacheread_do);

    ENDIF();

    SET(icacheread_address,       (offset_update)? { physical[31:12], prefetch_address[11:0] } : physical);

    SET(icacheread_length,        length);

    SET(icacheread_cache_disable, cache_disable);

    IF(offset_update);

        SAVE(linear,   { linear[31:12],   prefetch_address[11:0] });

        SAVE(physical, { physical[31:12], prefetch_address[11:0] });

    ENDIF();

ENDIF();

*/

//------------------------------------------------------------------------------

//------------------------------------------------------------------------------

//------------------------------------------------------------------------------

`include "autogen/prefetch_control.v"

endmodule