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//======================================================================
//
// Copyright (c) 2015, 2018 NORDUnet A/S 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.
//
// - Neither the name of the NORDUnet nor the names of its contributors may
// be used to endorse or promote products derived from this software
// without specific prior written permission.
//
// 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.
//
//======================================================================
module bram_1wo_1ro_readfirst #
(
parameter MEM_WIDTH = 32,
parameter MEM_ADDR_BITS = 8
)
(
input clk,
input [MEM_ADDR_BITS-1:0] a_addr,
input a_wr,
input [MEM_WIDTH -1:0] a_in,
output [MEM_WIDTH -1:0] a_out,
input [MEM_ADDR_BITS-1:0] b_addr,
output [MEM_WIDTH -1:0] b_out
);
//
// BRAM
//
(* RAM_STYLE="BLOCK" *)
reg [MEM_WIDTH-1:0] bram[0:(2**MEM_ADDR_BITS)-1];
//
// Initialization for Simulation
//
/*
integer c;
initial begin
for (c=0; c<(2**MEM_ADDR_BITS); c=c+1)
bram[c] = {MEM_WIDTH{1'b0}};
end
*/
//
// Output Registers
//
reg [MEM_WIDTH-1:0] bram_reg_b;
assign a_out = 32'hDEADCE11;
assign b_out = bram_reg_b;
//
// Note, that when both ports are accessing the same location, conflict can
// potentionally arise. See Xilinx UG473 (pages 19-20, "Conflict
// Avoidance") for more information. In our configuration to avoid that the
// write port must be coded to operate in READ_FIRST mode. If the write
// port is overwriting the same address the read port is accessing, the
// write port must read the previously stored data (not the data it is
// writing, as that would be WRITE_FIRST mode).
//
//
// Write-Only Port A
//
always @(posedge clk)
//
if (a_wr) bram[a_addr] <= a_in;
//
// Read-Only Port B
//
always @(posedge clk)
//
bram_reg_b <= bram[b_addr];
endmodule
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