litex/examples/wb_intercon/slave.v

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/*
* Milkymist SoC
* Copyright (C) 2007, 2008, 2009, 2011 Sebastien Bourdeauducq
*
* 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, version 3 of the License.
*
* 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/>.
*/
module slave #(
parameter id = 0,
parameter p = 3
) (
input sys_clk,
input sys_rst,
input [31:0] dat_w,
output reg [31:0] dat_r,
input [29:0] adr,
input we,
input [3:0] sel,
input cyc,
input stb,
output reg ack
);
always @(posedge sys_clk) begin
if(sys_rst) begin
dat_r <= 0;
ack <= 0;
end else begin
if(cyc & stb & ~ack) begin
if(($random % p) == 0) begin
ack <= 1;
if(~we)
dat_r <= ($random << 16) + id;
if(we)
$display("[S%d] Ack W: %x:%x [%x]", id, adr, dat_w, sel);
else
$display("[S%d] Ack R: %x:%x [%x]", id, adr, dat_r, sel);
end
end else
ack <= 0;
end
end
endmodule