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peteralieb |
//-----------------------------------------------------------------------------
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// Title : 8-bit Client to Local-link Transmitter FIFO
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// Project : Virtex-4 Embedded Tri-Mode Ethernet MAC Wrapper
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// File : tx_client_fifo_8.v
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// Version : 4.8
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//-----------------------------------------------------------------------------
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//
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// (c) Copyright 2004-2010 Xilinx, Inc. All rights reserved.
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//
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// This file contains confidential and proprietary information
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// of Xilinx, Inc. and is protected under U.S. and
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// international copyright and other intellectual property
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// laws.
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//
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// DISCLAIMER
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// This disclaimer is not a license and does not grant any
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// rights to the materials distributed herewith. Except as
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// otherwise provided in a valid license issued to you by
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// Xilinx, and to the maximum extent permitted by applicable
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// law: (1) THESE MATERIALS ARE MADE AVAILABLE "AS IS" AND
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// WITH ALL FAULTS, AND XILINX HEREBY DISCLAIMS ALL WARRANTIES
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// AND CONDITIONS, EXPRESS, IMPLIED, OR STATUTORY, INCLUDING
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// BUT NOT LIMITED TO WARRANTIES OF MERCHANTABILITY, NON-
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// INFRINGEMENT, OR FITNESS FOR ANY PARTICULAR PURPOSE; and
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// (2) Xilinx shall not be liable (whether in contract or tort,
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// including negligence, or under any other theory of
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// liability) for any loss or damage of any kind or nature
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// related to, arising under or in connection with these
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// materials, including for any direct, or any indirect,
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// special, incidental, or consequential loss or damage
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// (including loss of data, profits, goodwill, or any type of
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// loss or damage suffered as a result of any action brought
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// by a third party) even if such damage or loss was
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// reasonably foreseeable or Xilinx had been advised of the
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// possibility of the same.
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//
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// CRITICAL APPLICATIONS
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// Xilinx products are not designed or intended to be fail-
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// safe, or for use in any application requiring fail-safe
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// performance, such as life-support or safety devices or
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// systems, Class III medical devices, nuclear facilities,
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// applications related to the deployment of airbags, or any
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// other applications that could lead to death, personal
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// injury, or severe property or environmental damage
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// (individually and collectively, "Critical
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// Applications"). Customer assumes the sole risk and
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// liability of any use of Xilinx products in Critical
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// Applications, subject only to applicable laws and
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// regulations governing limitations on product liability.
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//
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// THIS COPYRIGHT NOTICE AND DISCLAIMER MUST BE RETAINED AS
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// PART OF THIS FILE AT ALL TIMES.
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//
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//-----------------------------------------------------------------------------
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// Description: This is a transmitter side local link fifo implementation for
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// the design example of the Virtex-4 Ethernet MAC Wrapper
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// core.
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//
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// The transmit FIFO is created from 2 Block RAMs of size 2048
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// words of 8-bits per word, giving a total frame memory capacity
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// of 4096 bytes.
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//
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// Valid frame data received from local link interface is written
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// into the Block RAM on the write clock. The FIFO will store
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// frames upto 4kbytes in length. If larger frames are written
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// to the FIFO the local-link interface will accept the rest of the
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// frame, but that frame will be dropped by the FIFO and
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// the overflow signal will be asserted.
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//
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// The FIFO is designed to work with a minimum frame length of 14 bytes.
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//
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// When there is at least one complete frame in the FIFO,
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// the MAC transmitter client interface will be driven to
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// request frame transmission by placing the first byte of
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// the frame onto tx_data[7:0] and by asserting
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// tx_data_valid. The MAC will later respond by asserting
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// tx_ack. At this point the remaining frame data is read
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// out of the FIFO in a continuous burst. Data is read out
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// of the FIFO on the rd_clk.
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//
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// If the generic FULL_DUPLEX_ONLY is set to false, the FIFO will
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// requeue and retransmit frames as requested by the MAC. Once a
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// frame has been transmitted by the FIFO it is stored until the
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// possible retransmit window for that frame has expired.
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//
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// The FIFO has been designed to operate with different clocks
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// on the write and read sides. The write clock (locallink clock)
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// can be an equal or faster frequency than the read clock (client clock).
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// The minimum write clock frequency is the read clock frequency divided
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// by 4.
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//
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// The FIFO memory size can be increased by expanding the rd_addr
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// and wr_addr signal widths, to address further BRAMs.
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//
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//-----------------------------------------------------------------------------
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`timescale 1ps / 1ps
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module tx_client_fifo_8
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(
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// MAC Interface
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rd_clk,
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rd_sreset,
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rd_enable,
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tx_data,
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tx_data_valid,
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tx_ack,
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tx_collision,
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tx_retransmit,
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overflow,
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// Local-link Interface
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wr_clk,
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wr_sreset,
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wr_data,
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wr_sof_n,
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wr_eof_n,
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wr_src_rdy_n,
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wr_dst_rdy_n,
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wr_fifo_status
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);
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//---------------------------------------------------------------------------
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// Define Interface Signals
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//---------------------------------------------------------------------------
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// MAC Interface
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input rd_clk;
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input rd_sreset;
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input rd_enable;
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output [7:0] tx_data;
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output tx_data_valid;
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input tx_ack;
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input tx_collision;
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input tx_retransmit;
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output overflow;
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// Local-link Interface
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input wr_clk;
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input wr_sreset;
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input [7:0] wr_data;
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input wr_sof_n;
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input wr_eof_n;
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input wr_src_rdy_n;
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output wr_dst_rdy_n;
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output [3:0] wr_fifo_status;
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// If FULL_DUPLEX_ONLY is 1 then all the half duplex logic in the FIFO is removed.
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// The default for the fifo is to include the half duplex functionality
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parameter FULL_DUPLEX_ONLY = 0;
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reg [7:0] tx_data;
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reg tx_data_valid;
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reg [3:0] wr_fifo_status;
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//---------------------------------------------------------------------------
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// Define Internal Signals
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//---------------------------------------------------------------------------
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wire GND;
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wire VCC;
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wire [7:0] GND_BUS;
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// Encode rd_state_machine states
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parameter IDLE_s = 4'b0000; parameter QUEUE1_s = 4'b0001;
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parameter QUEUE2_s = 4'b0010; parameter QUEUE3_s = 4'b0011;
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parameter QUEUE_ACK_s = 4'b0100; parameter WAIT_ACK_s = 4'b0101;
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parameter FRAME_s = 4'b0110; parameter DROP_s = 4'b0111;
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parameter RETRANSMIT_s = 4'b1000;
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reg [3:0] rd_state;
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reg [3:0] rd_nxt_state;
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// Encode wr_state_machine states
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parameter WAIT_s = 2'b00; parameter DATA_s = 2'b01;
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parameter EOF_s = 2'b10; parameter OVFLOW_s = 2'b11;
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reg [1:0] wr_state;
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reg [1:0] wr_nxt_state;
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reg [7:0] wr_data_bram;
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reg [7:0] wr_data_pipe[0:1];
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reg wr_sof_pipe[0:1];
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reg wr_eof_pipe[0:1];
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reg wr_accept_pipe[0:1];
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reg wr_accept_bram;
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reg [0:0] wr_eof_bram;
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reg [11:0] wr_addr;
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wire wr_addr_inc;
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wire wr_start_addr_load;
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wire wr_addr_reload;
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reg [11:0] wr_start_addr;
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reg wr_fifo_full;
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wire wr_en;
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wire wr_en_u;
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wire wr_en_l;
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reg wr_ovflow_dst_rdy;
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wire wr_dst_rdy_int_n;
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reg frame_in_fifo_sync;
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reg frame_in_fifo;
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reg rd_eof;
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reg rd_eof_reg;
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reg rd_eof_pipe;
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reg [11:0] rd_addr;
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wire rd_addr_inc;
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wire rd_addr_reload;
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wire [7:0] rd_data_bram_u;
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wire [7:0] rd_data_bram_l;
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reg [7:0] rd_data_pipe_u;
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reg [7:0] rd_data_pipe_l;
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reg [7:0] rd_data_pipe;
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wire [0:0] rd_eof_bram_u;
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wire [0:0] rd_eof_bram_l;
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wire rd_en;
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wire rd_en_bram;
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reg rd_bram_u;
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reg rd_bram_u_reg;
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reg rd_tran_frame_tog;
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reg wr_tran_frame_tog;
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reg wr_tran_frame_sync;
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reg wr_tran_frame_delay;
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reg rd_retran_frame_tog;
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reg wr_retran_frame_tog;
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reg wr_retran_frame_sync;
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reg wr_retran_frame_delay;
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wire wr_store_frame;
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reg wr_transmit_frame;
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reg wr_retransmit_frame;
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reg [8:0] wr_frames;
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reg wr_frame_in_fifo;
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reg [3:0] rd_16_count;
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wire rd_txfer_en;
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reg [11:0] rd_addr_txfer;
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reg rd_txfer_tog;
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reg wr_txfer_tog;
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reg wr_txfer_tog_sync;
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reg wr_txfer_tog_delay;
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wire wr_txfer_en;
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reg [11:0] wr_rd_addr;
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reg [11:0] wr_addr_diff;
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reg rd_drop_frame;
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reg rd_retransmit;
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reg [11:0] rd_start_addr;
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wire rd_start_addr_load;
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wire rd_start_addr_reload;
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reg [11:0] rd_dec_addr;
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wire rd_transmit_frame;
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wire rd_retransmit_frame;
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reg rd_col_window_expire;
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reg rd_col_window_pipe[0:1];
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reg wr_col_window_pipe[0:1];
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wire wr_eof_state;
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reg wr_eof_state_reg;
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wire wr_fifo_overflow;
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reg [9:0] rd_slot_timer;
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reg wr_col_window_expire;
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wire rd_idle_state;
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reg rd_enable_delay;
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reg rd_enable_delay2;
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//---------------------------------------------------------------------------
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// Attributes for FIFO simulation and synthesis
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//---------------------------------------------------------------------------
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// ASYNC_REG attributes added to simulate actual behaviour under
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// asynchronous operating conditions.
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// synthesis attribute ASYNC_REG of wr_tran_frame_tog is "TRUE";
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// synthesis attribute ASYNC_REG of wr_retran_frame_tog is "TRUE";
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// synthesis attribute ASYNC_REG of frame_in_fifo_sync is "TRUE";
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// synthesis attribute ASYNC_REG of wr_rd_addr is "TRUE";
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// synthesis attribute ASYNC_REG of wr_txfer_tog is "TRUE";
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// synthesis attribute ASYNC_REG of wr_col_window_pipe[0] is "TRUE";
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// WRITE_MODE attributes added to Block RAM to mitigate port contention
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// synthesis attribute WRITE_MODE_A of ramgen_u is "READ_FIRST";
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// synthesis attribute WRITE_MODE_B of ramgen_u is "READ_FIRST";
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// synthesis attribute WRITE_MODE_A of ramgen_l is "READ_FIRST";
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// synthesis attribute WRITE_MODE_B of ramgen_l is "READ_FIRST";
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//---------------------------------------------------------------------------
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// Begin FIFO architecture
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//---------------------------------------------------------------------------
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assign GND = 1'b0;
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assign VCC = 1'b1;
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assign GND_BUS = 8'b0;
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// shouldn't have a functional impact - at 1G flop is high all the time
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// at other speeds it is high every other cycle with 2nd stage ensuring it is in phase with the normal
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// clk enable - THE ONLY PURPOSE OF THIS FLOP IS TO ENABLE THE rd_enable and rd_en FANOUT TO BE CONTROLLED
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always @(posedge rd_clk)
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begin
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rd_enable_delay <= rd_enable;
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rd_enable_delay2 <= rd_enable_delay;
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end
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//---------------------------------------------------------------------------
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// Write State machine and control
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//---------------------------------------------------------------------------
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// Write state machine
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// states are WAIT, DATA, EOF, OVFLOW
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// clock through next state of sm
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always @(posedge wr_clk)
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begin
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if (wr_sreset == 1'b1)
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wr_state <= WAIT_s;
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else
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wr_state <= wr_nxt_state;
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end
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// decode next state, combinitorial
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// should never be able to overflow whilst not in the data state.
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always @(wr_state or wr_sof_pipe[1] or wr_eof_pipe[0] or wr_eof_pipe[1] or wr_eof_bram[0] or wr_fifo_overflow)
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begin
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case (wr_state)
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WAIT_s : begin
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if (wr_sof_pipe[1] == 1'b1)
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wr_nxt_state <= DATA_s;
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else
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wr_nxt_state <= WAIT_s;
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end
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DATA_s : begin
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// wait for the end of frame to be detected
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if (wr_fifo_overflow == 1'b1 && wr_eof_pipe[0] == 1'b0 && wr_eof_pipe[1] == 1'b0)
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wr_nxt_state <= OVFLOW_s;
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else if (wr_eof_pipe[1] == 1'b1)
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wr_nxt_state <= EOF_s;
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else
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wr_nxt_state <= DATA_s;
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end
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EOF_s : begin
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|
// if the start of frame is already in the pipe, a back to back frame
|
345 |
|
|
// transmission has occured. move straight back to frame state
|
346 |
|
|
if (wr_sof_pipe[1] == 1'b1)
|
347 |
|
|
wr_nxt_state <= DATA_s;
|
348 |
|
|
else if (wr_eof_bram[0] == 1'b1)
|
349 |
|
|
wr_nxt_state <= WAIT_s;
|
350 |
|
|
else
|
351 |
|
|
wr_nxt_state <= EOF_s;
|
352 |
|
|
end
|
353 |
|
|
OVFLOW_s : begin
|
354 |
|
|
// wait until the end of frame is reached before clearing the overflow
|
355 |
|
|
if (wr_eof_bram[0] == 1'b1)
|
356 |
|
|
wr_nxt_state <= WAIT_s;
|
357 |
|
|
else
|
358 |
|
|
wr_nxt_state <= OVFLOW_s;
|
359 |
|
|
end
|
360 |
|
|
default : begin
|
361 |
|
|
wr_nxt_state <= WAIT_s;
|
362 |
|
|
end
|
363 |
|
|
endcase
|
364 |
|
|
end
|
365 |
|
|
|
366 |
|
|
|
367 |
|
|
// decode output signals.
|
368 |
|
|
assign wr_en = (wr_state == OVFLOW_s) ? 1'b0 : wr_accept_bram;
|
369 |
|
|
assign wr_en_l = wr_en & !wr_addr[11];
|
370 |
|
|
assign wr_en_u = wr_en & wr_addr[11];
|
371 |
|
|
|
372 |
|
|
assign wr_addr_inc = wr_en;
|
373 |
|
|
|
374 |
|
|
assign wr_addr_reload = (wr_state == OVFLOW_s) ? 1'b1 : 1'b0;
|
375 |
|
|
assign wr_start_addr_load = (wr_state == EOF_s && wr_nxt_state == WAIT_s) ? 1'b1 :
|
376 |
|
|
(wr_state == EOF_s && wr_nxt_state == DATA_s) ? 1'b1 : 1'b0;
|
377 |
|
|
|
378 |
|
|
|
379 |
|
|
// pause the local link flow when the fifo is full.
|
380 |
|
|
assign wr_dst_rdy_int_n = (wr_state == OVFLOW_s) ? wr_ovflow_dst_rdy : wr_fifo_full;
|
381 |
|
|
assign wr_dst_rdy_n = wr_dst_rdy_int_n;
|
382 |
|
|
|
383 |
|
|
// when in overflow and have captured ovflow eof send dst rdy high again.
|
384 |
|
|
assign overflow = (wr_state == OVFLOW_s) ? 1'b1 : 1'b0;
|
385 |
|
|
|
386 |
|
|
// when in overflow and have captured ovflow eof send dst rdy high again.
|
387 |
|
|
always @(posedge wr_clk)
|
388 |
|
|
begin
|
389 |
|
|
if (wr_sreset == 1'b1)
|
390 |
|
|
wr_ovflow_dst_rdy <= 1'b0;
|
391 |
|
|
else
|
392 |
|
|
begin
|
393 |
|
|
if (wr_fifo_overflow == 1'b1 && wr_state == DATA_s)
|
394 |
|
|
wr_ovflow_dst_rdy <= 1'b0;
|
395 |
|
|
else if (wr_eof_n == 1'b0 && wr_src_rdy_n == 1'b0)
|
396 |
|
|
wr_ovflow_dst_rdy <= 1'b1;
|
397 |
|
|
end
|
398 |
|
|
end
|
399 |
|
|
|
400 |
|
|
// eof signals for use in overflow logic
|
401 |
|
|
assign wr_eof_state = (wr_state == EOF_s) ? 1'b1 : 1'b0;
|
402 |
|
|
|
403 |
|
|
always @(posedge wr_clk)
|
404 |
|
|
begin
|
405 |
|
|
if (wr_sreset == 1'b1)
|
406 |
|
|
wr_eof_state_reg <= 1'b0;
|
407 |
|
|
else
|
408 |
|
|
wr_eof_state_reg <= wr_eof_state;
|
409 |
|
|
end
|
410 |
|
|
|
411 |
|
|
//---------------------------------------------------------------------------
|
412 |
|
|
// Read state machine and control
|
413 |
|
|
//---------------------------------------------------------------------------
|
414 |
|
|
|
415 |
|
|
// clock through the read state machine
|
416 |
|
|
always @(posedge rd_clk)
|
417 |
|
|
begin
|
418 |
|
|
if (rd_sreset == 1'b1)
|
419 |
|
|
rd_state <= IDLE_s;
|
420 |
|
|
else if (rd_enable == 1'b1)
|
421 |
|
|
rd_state <= rd_nxt_state;
|
422 |
|
|
end
|
423 |
|
|
|
424 |
|
|
//---------------------------------------------------------------------------
|
425 |
|
|
// Full Duplex Only State Machine
|
426 |
|
|
generate if (FULL_DUPLEX_ONLY == 1) begin : gen_fd_sm
|
427 |
|
|
// decode the next state
|
428 |
|
|
always @(rd_state or frame_in_fifo or rd_eof or tx_ack)
|
429 |
|
|
begin
|
430 |
|
|
case (rd_state)
|
431 |
|
|
IDLE_s : begin
|
432 |
|
|
// if there is a frame in the fifo start to queue the new frame
|
433 |
|
|
// to the output
|
434 |
|
|
if (frame_in_fifo == 1'b1)
|
435 |
|
|
rd_nxt_state <= QUEUE1_s;
|
436 |
|
|
else
|
437 |
|
|
rd_nxt_state <= IDLE_s;
|
438 |
|
|
end
|
439 |
|
|
QUEUE1_s : begin
|
440 |
|
|
rd_nxt_state <= QUEUE2_s;
|
441 |
|
|
end
|
442 |
|
|
QUEUE2_s : begin
|
443 |
|
|
rd_nxt_state <= QUEUE3_s;
|
444 |
|
|
end
|
445 |
|
|
QUEUE3_s : begin
|
446 |
|
|
rd_nxt_state <= QUEUE_ACK_s;
|
447 |
|
|
end
|
448 |
|
|
QUEUE_ACK_s : begin
|
449 |
|
|
rd_nxt_state <= WAIT_ACK_s;
|
450 |
|
|
end
|
451 |
|
|
WAIT_ACK_s : begin
|
452 |
|
|
// the output pipe line is fully loaded, so wait for ack from mac
|
453 |
|
|
// before moving on
|
454 |
|
|
if (tx_ack == 1'b1)
|
455 |
|
|
rd_nxt_state <= FRAME_s;
|
456 |
|
|
else
|
457 |
|
|
rd_nxt_state <= WAIT_ACK_s;
|
458 |
|
|
end
|
459 |
|
|
FRAME_s : begin
|
460 |
|
|
// when the end of frame has been reached wait another frame in
|
461 |
|
|
// the fifo
|
462 |
|
|
if (rd_eof == 1'b1)
|
463 |
|
|
rd_nxt_state <= IDLE_s;
|
464 |
|
|
else
|
465 |
|
|
rd_nxt_state <= FRAME_s;
|
466 |
|
|
end
|
467 |
|
|
default : begin
|
468 |
|
|
rd_nxt_state <= IDLE_s;
|
469 |
|
|
end
|
470 |
|
|
endcase
|
471 |
|
|
end
|
472 |
|
|
// full duplex state machine
|
473 |
|
|
|
474 |
|
|
end // gen_fd_sm
|
475 |
|
|
endgenerate
|
476 |
|
|
|
477 |
|
|
|
478 |
|
|
//---------------------------------------------------------------------------
|
479 |
|
|
// Full and Half Duplex State Machine
|
480 |
|
|
generate if (FULL_DUPLEX_ONLY != 1) begin : gen_hd_sm
|
481 |
|
|
// decode the next state
|
482 |
|
|
// should never receive a rd_drop_frame pulse outside of the Frame state
|
483 |
|
|
always @(rd_state or frame_in_fifo or rd_eof_reg or tx_ack or rd_drop_frame or rd_retransmit)
|
484 |
|
|
begin
|
485 |
|
|
case (rd_state)
|
486 |
|
|
IDLE_s : begin
|
487 |
|
|
// if a retransmit request is detected go to retransmit state
|
488 |
|
|
if (rd_retransmit == 1'b1)
|
489 |
|
|
rd_nxt_state <= RETRANSMIT_s;
|
490 |
|
|
// if there is a frame in the fifo then queue the new frame to
|
491 |
|
|
// the output
|
492 |
|
|
else if (frame_in_fifo == 1'b1)
|
493 |
|
|
rd_nxt_state <= QUEUE1_s;
|
494 |
|
|
else
|
495 |
|
|
rd_nxt_state <= IDLE_s;
|
496 |
|
|
end
|
497 |
|
|
QUEUE1_s : begin
|
498 |
|
|
if (rd_retransmit == 1'b1)
|
499 |
|
|
rd_nxt_state <= RETRANSMIT_s;
|
500 |
|
|
else
|
501 |
|
|
rd_nxt_state <= QUEUE2_s;
|
502 |
|
|
end
|
503 |
|
|
QUEUE2_s : begin
|
504 |
|
|
if (rd_retransmit == 1'b1)
|
505 |
|
|
rd_nxt_state <= RETRANSMIT_s;
|
506 |
|
|
else
|
507 |
|
|
rd_nxt_state <= QUEUE3_s;
|
508 |
|
|
end
|
509 |
|
|
QUEUE3_s : begin
|
510 |
|
|
if (rd_retransmit == 1'b1)
|
511 |
|
|
rd_nxt_state <= RETRANSMIT_s;
|
512 |
|
|
else
|
513 |
|
|
rd_nxt_state <= QUEUE_ACK_s;
|
514 |
|
|
end
|
515 |
|
|
QUEUE_ACK_s : begin
|
516 |
|
|
if (rd_retransmit == 1'b1)
|
517 |
|
|
rd_nxt_state <= RETRANSMIT_s;
|
518 |
|
|
else
|
519 |
|
|
rd_nxt_state <= WAIT_ACK_s;
|
520 |
|
|
end
|
521 |
|
|
WAIT_ACK_s : begin
|
522 |
|
|
// the output pipeline is now fully loaded so wait for ack from
|
523 |
|
|
// mac before moving on.
|
524 |
|
|
if (rd_retransmit == 1'b1)
|
525 |
|
|
rd_nxt_state <= RETRANSMIT_s;
|
526 |
|
|
else if (tx_ack == 1'b1)
|
527 |
|
|
rd_nxt_state <= FRAME_s;
|
528 |
|
|
else
|
529 |
|
|
rd_nxt_state <= WAIT_ACK_s;
|
530 |
|
|
end
|
531 |
|
|
FRAME_s : begin
|
532 |
|
|
// if a collision only request, then must drop the rest of the
|
533 |
|
|
// current frame, move to drop state
|
534 |
|
|
if (rd_drop_frame == 1'b1)
|
535 |
|
|
rd_nxt_state <= DROP_s;
|
536 |
|
|
else if (rd_retransmit == 1'b1)
|
537 |
|
|
rd_nxt_state <= RETRANSMIT_s;
|
538 |
|
|
// continue transmitting frame until the end of the frame is
|
539 |
|
|
// detected, then wait for a new frame to be sent.
|
540 |
|
|
else if (rd_eof_reg == 1'b1)
|
541 |
|
|
rd_nxt_state <= IDLE_s;
|
542 |
|
|
else
|
543 |
|
|
rd_nxt_state <= FRAME_s;
|
544 |
|
|
end
|
545 |
|
|
DROP_s : begin
|
546 |
|
|
// wait until rest of frame has been cleared.
|
547 |
|
|
if (rd_eof_reg == 1'b1)
|
548 |
|
|
rd_nxt_state <= IDLE_s;
|
549 |
|
|
else
|
550 |
|
|
rd_nxt_state <= DROP_s;
|
551 |
|
|
end
|
552 |
|
|
RETRANSMIT_s : begin
|
553 |
|
|
// reload the data pipe from the start of the frame
|
554 |
|
|
rd_nxt_state <= QUEUE1_s;
|
555 |
|
|
end
|
556 |
|
|
default : begin
|
557 |
|
|
rd_nxt_state <= IDLE_s;
|
558 |
|
|
end
|
559 |
|
|
endcase
|
560 |
|
|
end
|
561 |
|
|
|
562 |
|
|
end // gen_hd_sm // half duplex state machine
|
563 |
|
|
endgenerate
|
564 |
|
|
|
565 |
|
|
//---------------------------------------------------------------------------
|
566 |
|
|
// decode output signals
|
567 |
|
|
// decode output data
|
568 |
|
|
always @(posedge rd_clk)
|
569 |
|
|
begin
|
570 |
|
|
if (rd_enable == 1'b1)
|
571 |
|
|
begin
|
572 |
|
|
if (rd_nxt_state == FRAME_s)
|
573 |
|
|
tx_data <= rd_data_pipe;
|
574 |
|
|
else
|
575 |
|
|
begin
|
576 |
|
|
case (rd_state)
|
577 |
|
|
QUEUE_ACK_s :
|
578 |
|
|
tx_data <= rd_data_pipe;
|
579 |
|
|
WAIT_ACK_s :
|
580 |
|
|
tx_data <= tx_data;
|
581 |
|
|
FRAME_s :
|
582 |
|
|
tx_data <= rd_data_pipe;
|
583 |
|
|
default :
|
584 |
|
|
tx_data <= 8'b0;
|
585 |
|
|
endcase
|
586 |
|
|
end
|
587 |
|
|
end
|
588 |
|
|
end
|
589 |
|
|
|
590 |
|
|
// decode output data valid
|
591 |
|
|
always @(posedge rd_clk)
|
592 |
|
|
begin
|
593 |
|
|
if (rd_enable == 1'b1)
|
594 |
|
|
begin
|
595 |
|
|
if (rd_nxt_state == FRAME_s)
|
596 |
|
|
tx_data_valid <= ~(tx_collision && ~(tx_retransmit));
|
597 |
|
|
else
|
598 |
|
|
begin
|
599 |
|
|
case (rd_state)
|
600 |
|
|
QUEUE_ACK_s :
|
601 |
|
|
tx_data_valid <= 1'b1;
|
602 |
|
|
WAIT_ACK_s :
|
603 |
|
|
tx_data_valid <= 1'b1;
|
604 |
|
|
FRAME_s :
|
605 |
|
|
tx_data_valid <= ~(rd_nxt_state == DROP_s);
|
606 |
|
|
default :
|
607 |
|
|
tx_data_valid <= 1'b0;
|
608 |
|
|
endcase
|
609 |
|
|
end
|
610 |
|
|
end
|
611 |
|
|
end
|
612 |
|
|
|
613 |
|
|
//---------------------------------------------------------------------------
|
614 |
|
|
// decode full duplex only control signals
|
615 |
|
|
generate if (FULL_DUPLEX_ONLY == 1) begin : gen_fd_decode
|
616 |
|
|
|
617 |
|
|
assign rd_en = (rd_state == IDLE_s) ? 1'b0 :
|
618 |
|
|
(rd_nxt_state == FRAME_s) ? 1'b1 :
|
619 |
|
|
(rd_state == WAIT_ACK_s) ? 1'b0 : 1'b1;
|
620 |
|
|
|
621 |
|
|
assign rd_addr_inc = rd_en;
|
622 |
|
|
|
623 |
|
|
assign rd_addr_reload = (rd_state == FRAME_s && rd_nxt_state == IDLE_s) ? 1'b1 : 1'b0;
|
624 |
|
|
|
625 |
|
|
// Transmit frame pulse is only 1 clock enabled pulse long.
|
626 |
|
|
// Transmit frame pulse must never be more frequent than 64 clocks to allow toggle to cross clock domain
|
627 |
|
|
assign rd_transmit_frame = (rd_state == WAIT_ACK_s && rd_nxt_state == FRAME_s) ? 1'b1 : 1'b0;
|
628 |
|
|
|
629 |
|
|
// unused for full duplex only
|
630 |
|
|
assign rd_start_addr_reload = 1'b0;
|
631 |
|
|
assign rd_start_addr_load = 1'b0;
|
632 |
|
|
assign rd_retransmit_frame = 1'b0;
|
633 |
|
|
|
634 |
|
|
end // gen_fd_decode // full duplex control signals
|
635 |
|
|
endgenerate
|
636 |
|
|
|
637 |
|
|
//---------------------------------------------------------------------------
|
638 |
|
|
// decode half duplex control signals
|
639 |
|
|
generate if (FULL_DUPLEX_ONLY != 1) begin : gen_hd_decode
|
640 |
|
|
|
641 |
|
|
assign rd_en = (rd_state == IDLE_s) ? 1'b0 :
|
642 |
|
|
(rd_nxt_state == DROP_s && rd_eof == 1'b1) ? 1'b0 :
|
643 |
|
|
(rd_nxt_state == FRAME_s) ? 1'b1 :
|
644 |
|
|
(rd_state == RETRANSMIT_s) ? 1'b0 :
|
645 |
|
|
(rd_state == WAIT_ACK_s) ? 1'b0 : 1'b1;
|
646 |
|
|
|
647 |
|
|
assign rd_addr_inc = rd_en;
|
648 |
|
|
|
649 |
|
|
assign rd_addr_reload = (rd_state == FRAME_s && rd_nxt_state == IDLE_s) ? 1'b1 :
|
650 |
|
|
(rd_state == DROP_s && rd_nxt_state == IDLE_s) ? 1'b1 : 1'b0;
|
651 |
|
|
|
652 |
|
|
assign rd_start_addr_reload = (rd_state == RETRANSMIT_s) ? 1'b1 : 1'b0;
|
653 |
|
|
|
654 |
|
|
assign rd_start_addr_load = (rd_state == WAIT_ACK_s && rd_nxt_state == FRAME_s) ? 1'b1 :
|
655 |
|
|
(rd_col_window_expire == 1'b1) ? 1'b1 : 1'b0;
|
656 |
|
|
|
657 |
|
|
// Transmit frame pulse must never be more frequent than 64 clocks to allow toggle to cross clock domain
|
658 |
|
|
assign rd_transmit_frame = (rd_state == WAIT_ACK_s && rd_nxt_state == FRAME_s) ? 1'b1 : 1'b0;
|
659 |
|
|
|
660 |
|
|
// Retransmit frame pulse must never be more frequent than 16 clocks to allow toggle to cross clock domain
|
661 |
|
|
assign rd_retransmit_frame = (rd_state == RETRANSMIT_s) ? 1'b1 : 1'b0;
|
662 |
|
|
|
663 |
|
|
end // gen_hd_decode // half duplex control signals
|
664 |
|
|
endgenerate
|
665 |
|
|
|
666 |
|
|
//---------------------------------------------------------------------------
|
667 |
|
|
// Frame Count
|
668 |
|
|
// We need to maintain a count of frames in the fifo, so that we know when a
|
669 |
|
|
// frame is available for transmission. The counter must be held on the
|
670 |
|
|
// write clock domain as this is the faster clock.
|
671 |
|
|
//---------------------------------------------------------------------------
|
672 |
|
|
|
673 |
|
|
// A frame has been written to the fifo
|
674 |
|
|
assign wr_store_frame = (wr_state == EOF_s && wr_nxt_state != EOF_s) ? 1'b1 : 1'b0;
|
675 |
|
|
|
676 |
|
|
// generate a toggle to indicate when a frame has been transmitted from the fifo
|
677 |
|
|
always @(posedge rd_clk)
|
678 |
|
|
begin // process
|
679 |
|
|
if (rd_sreset == 1'b1)
|
680 |
|
|
rd_tran_frame_tog <= 1'b0;
|
681 |
|
|
else if (rd_enable == 1'b1)
|
682 |
|
|
if (rd_transmit_frame == 1'b1) // assumes EOF_s is valid for one clock
|
683 |
|
|
// cycle only ever! check
|
684 |
|
|
rd_tran_frame_tog <= !rd_tran_frame_tog;
|
685 |
|
|
end
|
686 |
|
|
|
687 |
|
|
// move the read transmit frame signal onto the write clock domain
|
688 |
|
|
always @(posedge wr_clk)
|
689 |
|
|
begin
|
690 |
|
|
if (wr_sreset == 1'b1)
|
691 |
|
|
begin
|
692 |
|
|
wr_tran_frame_tog <= 1'b0;
|
693 |
|
|
wr_tran_frame_sync <= 1'b0;
|
694 |
|
|
wr_tran_frame_delay <= 1'b0;
|
695 |
|
|
wr_transmit_frame <= 1'b0;
|
696 |
|
|
end
|
697 |
|
|
else
|
698 |
|
|
begin
|
699 |
|
|
wr_tran_frame_tog <= rd_tran_frame_tog;
|
700 |
|
|
wr_tran_frame_sync <= wr_tran_frame_tog;
|
701 |
|
|
wr_tran_frame_delay <= wr_tran_frame_sync;
|
702 |
|
|
// edge detector
|
703 |
|
|
if ((wr_tran_frame_delay ^ wr_tran_frame_sync) == 1'b1)
|
704 |
|
|
wr_transmit_frame <= 1'b1;
|
705 |
|
|
else
|
706 |
|
|
wr_transmit_frame <= 1'b0;
|
707 |
|
|
end
|
708 |
|
|
end
|
709 |
|
|
|
710 |
|
|
//---------------------------------------------------------------------------
|
711 |
|
|
generate if (FULL_DUPLEX_ONLY == 1) begin : gen_fd_count
|
712 |
|
|
|
713 |
|
|
// count the number of frames in the fifo. the counter is incremented when a
|
714 |
|
|
// frame is stored and decremented when a frame is transmitted. Need to keep
|
715 |
|
|
// the counter on the write clock as this is the fastest clock.
|
716 |
|
|
always @(posedge wr_clk)
|
717 |
|
|
begin
|
718 |
|
|
if (wr_sreset == 1'b1)
|
719 |
|
|
wr_frames <= 9'b0;
|
720 |
|
|
else
|
721 |
|
|
if ((wr_store_frame & !wr_transmit_frame) == 1'b1)
|
722 |
|
|
wr_frames <= wr_frames + 1;
|
723 |
|
|
else if ((!wr_store_frame & wr_transmit_frame) == 1'b1)
|
724 |
|
|
wr_frames <= wr_frames - 1;
|
725 |
|
|
end
|
726 |
|
|
|
727 |
|
|
end // gen_fd_count
|
728 |
|
|
endgenerate
|
729 |
|
|
|
730 |
|
|
//---------------------------------------------------------------------------
|
731 |
|
|
generate if (FULL_DUPLEX_ONLY != 1) begin : gen_hd_count
|
732 |
|
|
|
733 |
|
|
// generate a toggle to indicate when a frame has been transmitted from the fifo
|
734 |
|
|
always @(posedge rd_clk)
|
735 |
|
|
begin // process
|
736 |
|
|
if (rd_sreset == 1'b1)
|
737 |
|
|
rd_retran_frame_tog <= 1'b0;
|
738 |
|
|
else if (rd_enable == 1'b1)
|
739 |
|
|
if (rd_retransmit_frame == 1'b1) // assumes EOF_s is valid for one clock
|
740 |
|
|
// cycle only ever! check
|
741 |
|
|
rd_retran_frame_tog <= !rd_retran_frame_tog;
|
742 |
|
|
end
|
743 |
|
|
|
744 |
|
|
// move the read transmit frame signal onto the write clock domain
|
745 |
|
|
always @(posedge wr_clk)
|
746 |
|
|
begin
|
747 |
|
|
if (wr_sreset == 1'b1)
|
748 |
|
|
begin
|
749 |
|
|
wr_retran_frame_tog <= 1'b0;
|
750 |
|
|
wr_retran_frame_sync <= 1'b0;
|
751 |
|
|
wr_retran_frame_delay <= 1'b0;
|
752 |
|
|
wr_retransmit_frame <= 1'b0;
|
753 |
|
|
end
|
754 |
|
|
else
|
755 |
|
|
begin
|
756 |
|
|
wr_retran_frame_tog <= rd_retran_frame_tog;
|
757 |
|
|
wr_retran_frame_sync <= wr_retran_frame_tog;
|
758 |
|
|
wr_retran_frame_delay <= wr_retran_frame_sync;
|
759 |
|
|
// edge detector
|
760 |
|
|
if ((wr_retran_frame_delay ^ wr_retran_frame_sync) == 1'b1)
|
761 |
|
|
wr_retransmit_frame <= 1'b1;
|
762 |
|
|
else
|
763 |
|
|
wr_retransmit_frame <= 1'b0;
|
764 |
|
|
end
|
765 |
|
|
end
|
766 |
|
|
|
767 |
|
|
// count the number of frames in the fifo. the counter is incremented when a
|
768 |
|
|
// frame is stored or retransmitted and decremented when a frame is transmitted. Need to keep
|
769 |
|
|
// the counter on the write clock as this is the fastest clock.
|
770 |
|
|
// Assumes transmit and retransmit cannot happen at same time
|
771 |
|
|
always @(posedge wr_clk)
|
772 |
|
|
begin
|
773 |
|
|
if (wr_sreset == 1'b1)
|
774 |
|
|
wr_frames <= 9'b0;
|
775 |
|
|
else
|
776 |
|
|
if ((wr_store_frame & wr_retransmit_frame) == 1'b1)
|
777 |
|
|
wr_frames <= wr_frames + 2;
|
778 |
|
|
else if (((wr_store_frame | wr_retransmit_frame) & !wr_transmit_frame) == 1'b1)
|
779 |
|
|
wr_frames <= wr_frames + 1;
|
780 |
|
|
else if (wr_transmit_frame == 1'b1 & !wr_store_frame)
|
781 |
|
|
wr_frames <= wr_frames - 1;
|
782 |
|
|
end
|
783 |
|
|
|
784 |
|
|
end // gen_hd_count
|
785 |
|
|
endgenerate
|
786 |
|
|
|
787 |
|
|
|
788 |
|
|
//---------------------------------------------------------------------------
|
789 |
|
|
// generate a frame in fifo signal for use in control logic
|
790 |
|
|
always @(posedge wr_clk)
|
791 |
|
|
begin
|
792 |
|
|
if (wr_sreset == 1'b1)
|
793 |
|
|
wr_frame_in_fifo <= 1'b0;
|
794 |
|
|
else
|
795 |
|
|
if (wr_frames != 9'b0)
|
796 |
|
|
wr_frame_in_fifo <= 1'b1;
|
797 |
|
|
else
|
798 |
|
|
wr_frame_in_fifo <= 1'b0;
|
799 |
|
|
end
|
800 |
|
|
|
801 |
|
|
// register back onto read domain for use in the read logic
|
802 |
|
|
always @(posedge rd_clk)
|
803 |
|
|
begin
|
804 |
|
|
if (rd_sreset == 1'b1)
|
805 |
|
|
begin
|
806 |
|
|
frame_in_fifo_sync <= 1'b0;
|
807 |
|
|
frame_in_fifo <= 1'b0;
|
808 |
|
|
end
|
809 |
|
|
else if (rd_enable == 1'b1)
|
810 |
|
|
begin
|
811 |
|
|
frame_in_fifo_sync <= wr_frame_in_fifo;
|
812 |
|
|
frame_in_fifo <= frame_in_fifo_sync;
|
813 |
|
|
end
|
814 |
|
|
end
|
815 |
|
|
|
816 |
|
|
|
817 |
|
|
//---------------------------------------------------------------------------
|
818 |
|
|
// Address counters
|
819 |
|
|
//---------------------------------------------------------------------------
|
820 |
|
|
// Address counters
|
821 |
|
|
// write address is incremented when write enable signal has been asserted
|
822 |
|
|
always @(posedge wr_clk)
|
823 |
|
|
begin
|
824 |
|
|
if (wr_sreset == 1'b1)
|
825 |
|
|
wr_addr <= 12'b0;
|
826 |
|
|
else if (wr_addr_reload == 1'b1)
|
827 |
|
|
wr_addr <= wr_start_addr;
|
828 |
|
|
else if (wr_addr_inc == 1'b1)
|
829 |
|
|
wr_addr <= wr_addr + 1;
|
830 |
|
|
end
|
831 |
|
|
|
832 |
|
|
// store the start address incase the address must be reset
|
833 |
|
|
always @(posedge wr_clk)
|
834 |
|
|
begin
|
835 |
|
|
if (wr_sreset == 1'b1)
|
836 |
|
|
wr_start_addr <= 12'b0;
|
837 |
|
|
else if (wr_start_addr_load == 1'b1)
|
838 |
|
|
wr_start_addr <= wr_addr + 1;
|
839 |
|
|
end
|
840 |
|
|
|
841 |
|
|
//---------------------------------------------------------------------------
|
842 |
|
|
generate if (FULL_DUPLEX_ONLY == 1) begin : gen_fd_addr
|
843 |
|
|
// read address is incremented when read enable signal has been asserted
|
844 |
|
|
always @(posedge rd_clk)
|
845 |
|
|
begin
|
846 |
|
|
if (rd_sreset == 1'b1)
|
847 |
|
|
rd_addr <= 12'b0;
|
848 |
|
|
else if (rd_enable == 1'b1)
|
849 |
|
|
if (rd_addr_reload == 1'b1)
|
850 |
|
|
rd_addr <= rd_dec_addr;
|
851 |
|
|
else if (rd_addr_inc == 1'b1)
|
852 |
|
|
rd_addr <= rd_addr + 1;
|
853 |
|
|
end
|
854 |
|
|
|
855 |
|
|
// do not need to keep a start address, but the address is needed to
|
856 |
|
|
// calculate fifo occupancy.
|
857 |
|
|
always @(posedge rd_clk)
|
858 |
|
|
begin
|
859 |
|
|
if (rd_sreset == 1'b1)
|
860 |
|
|
rd_start_addr <= 12'b0;
|
861 |
|
|
else if (rd_enable == 1'b1)
|
862 |
|
|
rd_start_addr <= rd_addr;
|
863 |
|
|
end
|
864 |
|
|
|
865 |
|
|
|
866 |
|
|
|
867 |
|
|
end // gen_fd_addr // full duplex address counters
|
868 |
|
|
endgenerate
|
869 |
|
|
|
870 |
|
|
//---------------------------------------------------------------------------
|
871 |
|
|
generate if (FULL_DUPLEX_ONLY != 1) begin : gen_hd_addr
|
872 |
|
|
// read address is incremented when read enable signal has been asserted
|
873 |
|
|
always @(posedge rd_clk)
|
874 |
|
|
begin
|
875 |
|
|
if (rd_sreset == 1'b1)
|
876 |
|
|
rd_addr <= 12'b0;
|
877 |
|
|
else if (rd_enable == 1'b1)
|
878 |
|
|
if (rd_addr_reload == 1'b1)
|
879 |
|
|
rd_addr <= rd_dec_addr;
|
880 |
|
|
else if (rd_start_addr_reload == 1'b1)
|
881 |
|
|
rd_addr <= rd_start_addr;
|
882 |
|
|
else if (rd_addr_inc == 1'b1)
|
883 |
|
|
rd_addr <= rd_addr + 1;
|
884 |
|
|
end
|
885 |
|
|
|
886 |
|
|
always @(posedge rd_clk)
|
887 |
|
|
begin
|
888 |
|
|
if (rd_sreset == 1'b1)
|
889 |
|
|
rd_start_addr <= 12'b0;
|
890 |
|
|
else if (rd_enable == 1'b1)
|
891 |
|
|
if (rd_start_addr_load == 1'b1)
|
892 |
|
|
rd_start_addr <= rd_addr - 4;
|
893 |
|
|
end
|
894 |
|
|
|
895 |
|
|
// Collision window expires after MAC has been transmitting for required slot
|
896 |
|
|
// time. This is 512 clock cycles at 1G. Also if the end of frame has fully
|
897 |
|
|
// been transmitted by the mac then a collision cannot occur.
|
898 |
|
|
// this collision expire signal goes high at 768 cycles from the start of the
|
899 |
|
|
// frame.
|
900 |
|
|
// inefficient for short frames, however should be enough to prevent fifo
|
901 |
|
|
// locking up.
|
902 |
|
|
always @(posedge rd_clk)
|
903 |
|
|
begin
|
904 |
|
|
if (rd_sreset == 1'b1)
|
905 |
|
|
rd_col_window_expire <= 1'b0;
|
906 |
|
|
else if (rd_enable == 1'b1)
|
907 |
|
|
if (rd_transmit_frame == 1'b1)
|
908 |
|
|
rd_col_window_expire <= 1'b0;
|
909 |
|
|
else if (rd_slot_timer[9:8] == 2'b11)
|
910 |
|
|
rd_col_window_expire <= 1'b1;
|
911 |
|
|
end
|
912 |
|
|
|
913 |
|
|
assign rd_idle_state = (rd_state == IDLE_s) ? 1'b1 : 1'b0;
|
914 |
|
|
|
915 |
|
|
always @(posedge rd_clk)
|
916 |
|
|
begin
|
917 |
|
|
if (rd_enable == 1'b1)
|
918 |
|
|
begin
|
919 |
|
|
rd_col_window_pipe[0] <= rd_col_window_expire & rd_idle_state;
|
920 |
|
|
if (rd_txfer_en == 1'b1)
|
921 |
|
|
rd_col_window_pipe[1] <= rd_col_window_pipe[0];
|
922 |
|
|
end
|
923 |
|
|
end
|
924 |
|
|
|
925 |
|
|
always @(posedge rd_clk)
|
926 |
|
|
begin
|
927 |
|
|
if (rd_sreset == 1'b1) // will not count until after first
|
928 |
|
|
// frame is sent.
|
929 |
|
|
rd_slot_timer <= 10'b0;
|
930 |
|
|
else if (rd_enable == 1'b1)
|
931 |
|
|
if (rd_transmit_frame == 1'b1) // reset counter
|
932 |
|
|
rd_slot_timer <= 10'b0;
|
933 |
|
|
// do not allow counter to role over.
|
934 |
|
|
// only count when frame is being transmitted.
|
935 |
|
|
else if (rd_slot_timer != 10'b1111111111)
|
936 |
|
|
rd_slot_timer <= rd_slot_timer + 1;
|
937 |
|
|
end
|
938 |
|
|
|
939 |
|
|
|
940 |
|
|
end // gen_hd_addr // half duplex address counters
|
941 |
|
|
endgenerate
|
942 |
|
|
|
943 |
|
|
always @(posedge rd_clk)
|
944 |
|
|
begin
|
945 |
|
|
if (rd_sreset == 1'b1)
|
946 |
|
|
rd_dec_addr <= 12'b0;
|
947 |
|
|
else if (rd_enable == 1'b1)
|
948 |
|
|
if (rd_addr_inc == 1'b1)
|
949 |
|
|
rd_dec_addr <= rd_addr - 1;
|
950 |
|
|
end
|
951 |
|
|
|
952 |
|
|
//---------------------------------------------------------------------------
|
953 |
|
|
always @(posedge rd_clk)
|
954 |
|
|
begin
|
955 |
|
|
if (rd_sreset == 1'b1)
|
956 |
|
|
begin
|
957 |
|
|
rd_bram_u <= 1'b0;
|
958 |
|
|
rd_bram_u_reg <= 1'b0;
|
959 |
|
|
end
|
960 |
|
|
else if (rd_enable == 1'b1)
|
961 |
|
|
if (rd_addr_inc == 1'b1)
|
962 |
|
|
begin
|
963 |
|
|
rd_bram_u <= rd_addr[11];
|
964 |
|
|
rd_bram_u_reg <= rd_bram_u;
|
965 |
|
|
end
|
966 |
|
|
end
|
967 |
|
|
|
968 |
|
|
//---------------------------------------------------------------------------
|
969 |
|
|
// Data Pipelines
|
970 |
|
|
//---------------------------------------------------------------------------
|
971 |
|
|
// register input signals to fifo
|
972 |
|
|
// no reset to allow srl16 target
|
973 |
|
|
always @(posedge wr_clk)
|
974 |
|
|
begin
|
975 |
|
|
wr_data_pipe[0] <= wr_data;
|
976 |
|
|
if (wr_accept_pipe[0] == 1'b1)
|
977 |
|
|
wr_data_pipe[1] <= wr_data_pipe[0];
|
978 |
|
|
if (wr_accept_pipe[1] == 1'b1)
|
979 |
|
|
wr_data_bram <= wr_data_pipe[1];
|
980 |
|
|
end
|
981 |
|
|
|
982 |
|
|
// no reset to allow srl16 target
|
983 |
|
|
always @(posedge wr_clk)
|
984 |
|
|
begin
|
985 |
|
|
wr_sof_pipe[0] <= !wr_sof_n;
|
986 |
|
|
if (wr_accept_pipe[0] == 1'b1)
|
987 |
|
|
wr_sof_pipe[1] <= wr_sof_pipe[0];
|
988 |
|
|
end
|
989 |
|
|
|
990 |
|
|
always @(posedge wr_clk)
|
991 |
|
|
begin
|
992 |
|
|
if (wr_sreset == 1'b1)
|
993 |
|
|
begin
|
994 |
|
|
wr_accept_pipe[0] <= 1'b0;
|
995 |
|
|
wr_accept_pipe[1] <= 1'b0;
|
996 |
|
|
wr_accept_bram <= 1'b0;
|
997 |
|
|
end
|
998 |
|
|
else
|
999 |
|
|
begin
|
1000 |
|
|
wr_accept_pipe[0] <= !wr_src_rdy_n & !wr_dst_rdy_int_n;
|
1001 |
|
|
wr_accept_pipe[1] <= wr_accept_pipe[0];
|
1002 |
|
|
wr_accept_bram <= wr_accept_pipe[1];
|
1003 |
|
|
end
|
1004 |
|
|
end
|
1005 |
|
|
|
1006 |
|
|
always @(posedge wr_clk)
|
1007 |
|
|
begin
|
1008 |
|
|
wr_eof_pipe[0] <= !wr_eof_n;
|
1009 |
|
|
if (wr_accept_pipe[0] == 1'b1)
|
1010 |
|
|
wr_eof_pipe[1] <= wr_eof_pipe[0];
|
1011 |
|
|
if (wr_accept_pipe[1] == 1'b1)
|
1012 |
|
|
wr_eof_bram[0] <= wr_eof_pipe[1];
|
1013 |
|
|
end
|
1014 |
|
|
|
1015 |
|
|
// register data outputs from bram
|
1016 |
|
|
// no reset to allow srl16 target
|
1017 |
|
|
always @(posedge rd_clk)
|
1018 |
|
|
begin
|
1019 |
|
|
if (rd_enable == 1'b1)
|
1020 |
|
|
if (rd_en == 1'b1)
|
1021 |
|
|
begin
|
1022 |
|
|
rd_data_pipe_u <= rd_data_bram_u;
|
1023 |
|
|
rd_data_pipe_l <= rd_data_bram_l;
|
1024 |
|
|
if (rd_bram_u_reg == 1'b1)
|
1025 |
|
|
rd_data_pipe <= rd_data_pipe_u;
|
1026 |
|
|
else
|
1027 |
|
|
rd_data_pipe <= rd_data_pipe_l;
|
1028 |
|
|
end
|
1029 |
|
|
end
|
1030 |
|
|
|
1031 |
|
|
// register data outputs from bram
|
1032 |
|
|
// no reset to allow srl16 target
|
1033 |
|
|
always @(posedge rd_clk)
|
1034 |
|
|
begin
|
1035 |
|
|
if (rd_enable == 1'b1)
|
1036 |
|
|
if (rd_en == 1'b1)
|
1037 |
|
|
begin
|
1038 |
|
|
if (rd_bram_u == 1'b1)
|
1039 |
|
|
rd_eof_pipe <= rd_eof_bram_u[0];
|
1040 |
|
|
else
|
1041 |
|
|
rd_eof_pipe <= rd_eof_bram_l[0];
|
1042 |
|
|
rd_eof <= rd_eof_pipe;
|
1043 |
|
|
rd_eof_reg <= rd_eof | rd_eof_pipe;
|
1044 |
|
|
end
|
1045 |
|
|
end
|
1046 |
|
|
|
1047 |
|
|
//---------------------------------------------------------------------------
|
1048 |
|
|
generate if (FULL_DUPLEX_ONLY != 1) begin : gen_hd_input
|
1049 |
|
|
// register the collision and retransmit signals
|
1050 |
|
|
always @(posedge rd_clk)
|
1051 |
|
|
begin
|
1052 |
|
|
if (rd_enable == 1'b1)
|
1053 |
|
|
rd_drop_frame <= tx_collision & !tx_retransmit;
|
1054 |
|
|
end
|
1055 |
|
|
|
1056 |
|
|
always @(posedge rd_clk)
|
1057 |
|
|
begin
|
1058 |
|
|
if (rd_enable == 1'b1)
|
1059 |
|
|
rd_retransmit <= tx_collision & tx_retransmit;
|
1060 |
|
|
end
|
1061 |
|
|
|
1062 |
|
|
end // gen_hd_input // half duplex register input
|
1063 |
|
|
endgenerate
|
1064 |
|
|
|
1065 |
|
|
//---------------------------------------------------------------------------
|
1066 |
|
|
// Fifo full functionality
|
1067 |
|
|
//---------------------------------------------------------------------------
|
1068 |
|
|
// when full duplex full functionality is difference between read and write addresses.
|
1069 |
|
|
// when in half duplex is difference between read start and write addresses.
|
1070 |
|
|
// Cannot use gray code this time as the read address and read start addresses jump by more than 1
|
1071 |
|
|
|
1072 |
|
|
// generate an enable pulse for the read side every 16 read clocks. This provides for the worst case
|
1073 |
|
|
// situation where wr clk is 20Mhz and rd clk is 125 Mhz.
|
1074 |
|
|
always @(posedge rd_clk)
|
1075 |
|
|
begin
|
1076 |
|
|
if (rd_sreset == 1'b1)
|
1077 |
|
|
rd_16_count <= 4'b0;
|
1078 |
|
|
else if (rd_enable == 1'b1)
|
1079 |
|
|
rd_16_count <= rd_16_count + 1;
|
1080 |
|
|
end
|
1081 |
|
|
|
1082 |
|
|
assign rd_txfer_en = (rd_16_count == 4'b1111) ? 1'b1 : 1'b0;
|
1083 |
|
|
|
1084 |
|
|
// register the start address on the enable pulse
|
1085 |
|
|
always @(posedge rd_clk)
|
1086 |
|
|
begin
|
1087 |
|
|
if (rd_sreset == 1'b1)
|
1088 |
|
|
rd_addr_txfer <= 12'b0;
|
1089 |
|
|
else if (rd_enable == 1'b1)
|
1090 |
|
|
begin
|
1091 |
|
|
if (rd_txfer_en == 1'b1)
|
1092 |
|
|
rd_addr_txfer <= rd_start_addr;
|
1093 |
|
|
end
|
1094 |
|
|
end
|
1095 |
|
|
|
1096 |
|
|
// generate a toggle to indicate that the address has been loaded.
|
1097 |
|
|
always @(posedge rd_clk)
|
1098 |
|
|
begin
|
1099 |
|
|
if (rd_sreset == 1'b1)
|
1100 |
|
|
rd_txfer_tog <= 1'b0;
|
1101 |
|
|
else if (rd_enable == 1'b1)
|
1102 |
|
|
begin
|
1103 |
|
|
if (rd_txfer_en == 1'b1)
|
1104 |
|
|
rd_txfer_tog <= !rd_txfer_tog;
|
1105 |
|
|
end
|
1106 |
|
|
end
|
1107 |
|
|
|
1108 |
|
|
// pass the toggle to the write side
|
1109 |
|
|
always @(posedge wr_clk)
|
1110 |
|
|
begin
|
1111 |
|
|
if (wr_sreset == 1'b1)
|
1112 |
|
|
begin
|
1113 |
|
|
wr_txfer_tog <= 1'b0;
|
1114 |
|
|
wr_txfer_tog_sync <= 1'b0;
|
1115 |
|
|
wr_txfer_tog_delay <= 1'b0;
|
1116 |
|
|
end
|
1117 |
|
|
else
|
1118 |
|
|
begin
|
1119 |
|
|
wr_txfer_tog <= rd_txfer_tog;
|
1120 |
|
|
wr_txfer_tog_sync <= wr_txfer_tog;
|
1121 |
|
|
wr_txfer_tog_delay <= wr_txfer_tog_sync;
|
1122 |
|
|
end
|
1123 |
|
|
end
|
1124 |
|
|
|
1125 |
|
|
// generate an enable pulse from the toggle, the address should have been steady on the wr clock input for at least one clock
|
1126 |
|
|
assign wr_txfer_en = wr_txfer_tog_delay ^ wr_txfer_tog_sync;
|
1127 |
|
|
|
1128 |
|
|
// capture the address on the write clock when the enable pulse is high.
|
1129 |
|
|
always @(posedge wr_clk)
|
1130 |
|
|
begin
|
1131 |
|
|
if (wr_sreset == 1'b1)
|
1132 |
|
|
wr_rd_addr <= 12'b0;
|
1133 |
|
|
else if (wr_txfer_en == 1'b1)
|
1134 |
|
|
wr_rd_addr <= rd_addr_txfer;
|
1135 |
|
|
end
|
1136 |
|
|
|
1137 |
|
|
|
1138 |
|
|
// Obtain the difference between write and read pointers
|
1139 |
|
|
always @(posedge wr_clk)
|
1140 |
|
|
begin
|
1141 |
|
|
if (wr_sreset == 1'b1)
|
1142 |
|
|
wr_addr_diff <= 12'b0;
|
1143 |
|
|
else
|
1144 |
|
|
wr_addr_diff <= wr_rd_addr - wr_addr;
|
1145 |
|
|
end
|
1146 |
|
|
|
1147 |
|
|
|
1148 |
|
|
// Detect when the FIFO is full
|
1149 |
|
|
always @(posedge wr_clk)
|
1150 |
|
|
begin
|
1151 |
|
|
if (wr_sreset == 1'b1)
|
1152 |
|
|
wr_fifo_full <= 1'b0;
|
1153 |
|
|
else
|
1154 |
|
|
// The FIFO is considered to be full if the write address
|
1155 |
|
|
// pointer is within 1 to 3 of the read address pointer.
|
1156 |
|
|
if (wr_addr_diff[11:4] == 8'b0 && wr_addr_diff[3:2] != 2'b0)
|
1157 |
|
|
wr_fifo_full <= 1'b1;
|
1158 |
|
|
else
|
1159 |
|
|
wr_fifo_full <= 1'b0;
|
1160 |
|
|
end
|
1161 |
|
|
|
1162 |
|
|
// memory overflow occurs when the fifo is full and there are no frames
|
1163 |
|
|
// available in the fifo for transmission. If the collision window has
|
1164 |
|
|
// expired and there are no frames in the fifo and the fifo is full, then the
|
1165 |
|
|
// fifo is in an overflow state. we must accept the rest of the incoming
|
1166 |
|
|
// frame in overflow condition.
|
1167 |
|
|
|
1168 |
|
|
generate if (FULL_DUPLEX_ONLY == 1) begin : gen_fd_ovflow
|
1169 |
|
|
// in full duplex mode, the fifo memory can only overflow if the fifo goes
|
1170 |
|
|
// full but there is no frame available to be retranmsitted
|
1171 |
|
|
// do not allow to go high when the frame count is being updated, ie wr_store_frame is asserted.
|
1172 |
|
|
assign wr_fifo_overflow = (wr_fifo_full == 1'b1 && wr_frame_in_fifo == 1'b0
|
1173 |
|
|
&& wr_eof_state == 1'b0 && wr_eof_state_reg == 1'b0) ? 1'b1 : 1'b0;
|
1174 |
|
|
end // gen_fd_ovflow
|
1175 |
|
|
endgenerate
|
1176 |
|
|
|
1177 |
|
|
generate if (FULL_DUPLEX_ONLY != 1) begin : gen_hd_ovflow
|
1178 |
|
|
// register wr col window to give address counter sufficient time to update.
|
1179 |
|
|
// do not allow to go high when the frame count is being updated, ie wr_store_frame is asserted.
|
1180 |
|
|
assign wr_fifo_overflow = (wr_fifo_full == 1'b1 && wr_frame_in_fifo == 1'b0
|
1181 |
|
|
&& wr_eof_state == 1'b0 && wr_eof_state_reg == 1'b0 && wr_col_window_expire == 1'b1) ? 1'b1 : 1'b0;
|
1182 |
|
|
|
1183 |
|
|
// register rd_col_window signal
|
1184 |
|
|
// this signal is long, and will remain high until overflow functionality
|
1185 |
|
|
// has finished, so save just to register the once.
|
1186 |
|
|
always @(posedge wr_clk)
|
1187 |
|
|
begin // process
|
1188 |
|
|
if (wr_sreset == 1'b1)
|
1189 |
|
|
begin
|
1190 |
|
|
wr_col_window_pipe[0] <= 1'b0;
|
1191 |
|
|
wr_col_window_pipe[1] <= 1'b0;
|
1192 |
|
|
wr_col_window_expire <= 1'b0;
|
1193 |
|
|
end
|
1194 |
|
|
else
|
1195 |
|
|
begin
|
1196 |
|
|
if (wr_txfer_en == 1'b1)
|
1197 |
|
|
wr_col_window_pipe[0] <= rd_col_window_pipe[1];
|
1198 |
|
|
wr_col_window_pipe[1] <= wr_col_window_pipe[0];
|
1199 |
|
|
wr_col_window_expire <= wr_col_window_pipe[1];
|
1200 |
|
|
end
|
1201 |
|
|
end
|
1202 |
|
|
|
1203 |
|
|
end // gen_hd_ovflow
|
1204 |
|
|
endgenerate
|
1205 |
|
|
|
1206 |
|
|
|
1207 |
|
|
|
1208 |
|
|
//--------------------------------------------------------------------
|
1209 |
|
|
// Create FIFO Status Signals in the Write Domain
|
1210 |
|
|
//--------------------------------------------------------------------
|
1211 |
|
|
|
1212 |
|
|
// The FIFO status signal is four bits which represents the occupancy
|
1213 |
|
|
// of the FIFO in 16'ths. To generate this signal we therefore only
|
1214 |
|
|
// need to compare the 4 most significant bits of the write address
|
1215 |
|
|
// pointer with the 4 most significant bits of the read address
|
1216 |
|
|
// pointer.
|
1217 |
|
|
|
1218 |
|
|
// The 4 most significant bits of the write pointer minus the 4 msb of
|
1219 |
|
|
// the read pointer gives us our FIFO status.
|
1220 |
|
|
always @(posedge wr_clk)
|
1221 |
|
|
begin
|
1222 |
|
|
if (wr_sreset == 1'b1)
|
1223 |
|
|
wr_fifo_status <= 4'b0;
|
1224 |
|
|
else
|
1225 |
|
|
if (wr_addr_diff == 12'b0)
|
1226 |
|
|
wr_fifo_status <= 4'b0;
|
1227 |
|
|
else
|
1228 |
|
|
begin
|
1229 |
|
|
wr_fifo_status[3] <= !wr_addr_diff[11];
|
1230 |
|
|
wr_fifo_status[2] <= !wr_addr_diff[10];
|
1231 |
|
|
wr_fifo_status[1] <= !wr_addr_diff[9];
|
1232 |
|
|
wr_fifo_status[0] <= !wr_addr_diff[8];
|
1233 |
|
|
end
|
1234 |
|
|
end
|
1235 |
|
|
|
1236 |
|
|
//---------------------------------------------------------------------------
|
1237 |
|
|
// Memory
|
1238 |
|
|
//---------------------------------------------------------------------------
|
1239 |
|
|
assign rd_en_bram = rd_en & rd_enable_delay2;
|
1240 |
|
|
|
1241 |
|
|
// Block Ram for lower address space (rx_addr(11) = 1'b0)
|
1242 |
|
|
defparam ramgen_l.WRITE_MODE_A = "READ_FIRST";
|
1243 |
|
|
defparam ramgen_l.WRITE_MODE_B = "READ_FIRST";
|
1244 |
|
|
RAMB16_S9_S9 ramgen_l (
|
1245 |
|
|
.WEA (wr_en_l),
|
1246 |
|
|
.ENA (VCC),
|
1247 |
|
|
.SSRA (wr_sreset),
|
1248 |
|
|
.CLKA (wr_clk),
|
1249 |
|
|
.ADDRA(wr_addr[10:0]),
|
1250 |
|
|
.DIA (wr_data_bram),
|
1251 |
|
|
.DIPA (wr_eof_bram),
|
1252 |
|
|
.DOA (),
|
1253 |
|
|
.DOPA (),
|
1254 |
|
|
.WEB (GND),
|
1255 |
|
|
.ENB (rd_en_bram),
|
1256 |
|
|
.SSRB (rd_sreset),
|
1257 |
|
|
.CLKB (rd_clk),
|
1258 |
|
|
.ADDRB(rd_addr[10:0]),
|
1259 |
|
|
.DIB (GND_BUS[7:0]),
|
1260 |
|
|
.DIPB (GND_BUS[0:0]),
|
1261 |
|
|
.DOB (rd_data_bram_l),
|
1262 |
|
|
.DOPB (rd_eof_bram_l));
|
1263 |
|
|
|
1264 |
|
|
// Block Ram for lower address space (rx_addr(11) = 1'b0)
|
1265 |
|
|
defparam ramgen_u.WRITE_MODE_A = "READ_FIRST";
|
1266 |
|
|
defparam ramgen_u.WRITE_MODE_B = "READ_FIRST";
|
1267 |
|
|
RAMB16_S9_S9 ramgen_u (
|
1268 |
|
|
.WEA (wr_en_u),
|
1269 |
|
|
.ENA (VCC),
|
1270 |
|
|
.SSRA (wr_sreset),
|
1271 |
|
|
.CLKA (wr_clk),
|
1272 |
|
|
.ADDRA(wr_addr[10:0]),
|
1273 |
|
|
.DIA (wr_data_bram),
|
1274 |
|
|
.DIPA (wr_eof_bram),
|
1275 |
|
|
.DOA (),
|
1276 |
|
|
.DOPA (),
|
1277 |
|
|
.WEB (GND),
|
1278 |
|
|
.ENB (rd_en_bram),
|
1279 |
|
|
.SSRB (rd_sreset),
|
1280 |
|
|
.CLKB (rd_clk),
|
1281 |
|
|
.ADDRB(rd_addr[10:0]),
|
1282 |
|
|
.DIB (GND_BUS[7:0]),
|
1283 |
|
|
.DIPB (GND_BUS[0:0]),
|
1284 |
|
|
.DOB (rd_data_bram_u),
|
1285 |
|
|
.DOPB (rd_eof_bram_u));
|
1286 |
|
|
|
1287 |
|
|
|
1288 |
|
|
|
1289 |
|
|
endmodule
|