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Gehstock.Mist_FPGA/Arcade_MiST/Atari MissileCommand/rtl/dpvram.v
2022-10-16 12:36:58 +02:00

55 lines
1.6 KiB
Verilog

/*============================================================================
Dual-port RAM module with bit-level write enable and read-only second port
Copyright (C) 2022 - Jim Gregory - https://github.com/JimmyStones/
This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the Free
Software Foundation; either version 3 of the License, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License along
with this program. If not, see <http://www.gnu.org/licenses/>.
===========================================================================*/
`timescale 1 ps / 1 ps
`default_nettype none
module dpvram #(
parameter address_width = 10,
parameter data_width = 8
) (
input wire clock_a,
input wire [data_width-1:0] wren_a,
input wire [address_width-1:0] address_a,
input wire [data_width-1:0] data_a,
output reg [data_width-1:0] q_a,
input wire clock_b,
input wire [address_width-1:0] address_b,
output reg [data_width-1:0] q_b
);
localparam ramLength = (2**address_width);
reg [data_width-1:0] mem [ramLength-1:0];
integer i;
always @(posedge clock_a)
begin
q_a <= mem[address_a];
for(i=0;i<data_width;i=i+1)
begin
if(!wren_a[i]) mem[address_a][i] <= data_a[i];
end
end
always @(negedge clock_b) begin
q_b <= mem[address_b];
end
endmodule