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// DESCRIPTION: Verilator: Verilog Test module
//
// This file ONLY is placed under the Creative Commons Public Domain, for
// any use, without warranty, 2008 by Wilson Snyder.
// SPDX-License-Identifier: CC0-1.0
module t (/*AUTOARG*/
// Inputs
clk
);
input clk;
integer cyc=0;
reg [63:0] crc;
reg [63:0] sum;
reg reset;
reg enable;
/*AUTOWIRE*/
// Beginning of automatic wires (for undeclared instantiated-module outputs)
wire [31:0] out; // From test of Test.v
// End of automatics
// Take CRC data and apply to testblock inputs
wire [31:0] in = crc[31:0];
Test test (/*AUTOINST*/
// Outputs
.out (out[31:0]),
// Inputs
.clk (clk),
.reset (reset),
.enable (enable),
.in (in[31:0]));
wire [63:0] result = {32'h0, out};
// Test loop
always @ (posedge clk) begin
`ifdef TEST_VERBOSE
$write("[%0t] cyc==%0d crc=%x result=%x\n",$time, cyc, crc, result);
`endif
cyc <= cyc + 1;
crc <= {crc[62:0], crc[63]^crc[2]^crc[0]};
sum <= result ^ {sum[62:0],sum[63]^sum[2]^sum[0]};
reset <= (cyc < 5);
enable <= cyc[4] || (cyc < 2);
if (cyc==0) begin
// Setup
crc <= 64'h5aef0c8d_d70a4497;
end
else if (cyc<10) begin
sum <= 64'h0;
end
else if (cyc<90) begin
end
else if (cyc==99) begin
$write("[%0t] cyc==%0d crc=%x sum=%x\n",$time, cyc, crc, sum);
if (crc !== 64'hc77bb9b3784ea091) $stop;
`define EXPECTED_SUM 64'h01e1553da1dcf3af
if (sum !== `EXPECTED_SUM) $stop;
$write("*-* All Finished *-*\n");
$finish;
end
end
endmodule
module Test (/*AUTOARG*/
// Outputs
out,
// Inputs
clk, reset, enable, in
);
input clk;
input reset;
input enable;
input [31:0] in;
output [31:0] out;
// No gating
reg [31:0] d10;
always @(posedge clk) begin
d10 <= in;
end
reg displayit;
`ifdef VERILATOR // Harder test
initial displayit = $c1("0"); // Something that won't optimize away
`else
initial displayit = '0;
`endif
// Obvious gating + PLI
reg [31:0] d20;
always @(posedge clk) begin
if (enable) begin
d20 <= d10; // Obvious gating
if (displayit) begin
$display("hello!"); // Must glob with other PLI statements
end
end
end
// Reset means second-level gating
reg [31:0] d30, d31a, d31b, d32;
always @(posedge clk) begin
d32 <= d31b;
if (reset) begin
d30 <= 32'h0;
d31a <= 32'h0;
d31b <= 32'h0;
d32 <= 32'h0; // Overlaps above, just to make things interesting
end
else begin
// Mix two outputs
d30 <= d20;
if (enable) begin
d31a <= d30;
d31b <= d31a;
end
end
end
// Multiple ORs for gater
reg [31:0] d40a,d40b;
always @(posedge clk) begin
if (reset) begin
d40a <= 32'h0;
d40b <= 32'h0;
end
if (enable) begin
d40a <= d32;
d40b <= d40a;
end
end
// Non-optimizable
reg [31:0] d91, d92;
reg [31:0] inverted;
always @(posedge clk) begin
inverted = ~d40b;
if (reset) begin
d91 <= 32'h0;
end
else begin
if (enable) begin
d91 <= inverted;
end
else begin
d92 <= inverted ^ 32'h12341234; // Inverted gating condition
end
end
end
wire [31:0] out = d91 ^ d92;
endmodule
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