verilator/test_regress/t/t_math_cmp.v

// DESCRIPTION: Verilator: Verilog Test module
//
// This file ONLY is placed under the Creative Commons Public Domain.
// SPDX-FileCopyrightText: 2004 Wilson Snyder
// SPDX-License-Identifier: CC0-1.0

module t (
    input clk
);


  reg [2:0] index_a;
  reg [2:0] index_b;

  prover #(4) p4 (  /*AUTOINST*/
      // Inputs
      .clk(clk),
      .index_a(index_a),
      .index_b(index_b)
  );
  prover #(32) p32 (  /*AUTOINST*/
      // Inputs
      .clk(clk),
      .index_a(index_a),
      .index_b(index_b)
  );
  prover #(63) p63 (  /*AUTOINST*/
      // Inputs
      .clk(clk),
      .index_a(index_a),
      .index_b(index_b)
  );
  prover #(64) p64 (  /*AUTOINST*/
      // Inputs
      .clk(clk),
      .index_a(index_a),
      .index_b(index_b)
  );
  prover #(72) p72 (  /*AUTOINST*/
      // Inputs
      .clk(clk),
      .index_a(index_a),
      .index_b(index_b)
  );
  prover #(126) p126 (  /*AUTOINST*/
      // Inputs
      .clk(clk),
      .index_a(index_a),
      .index_b(index_b)
  );
  prover #(128) p128 (  /*AUTOINST*/
      // Inputs
      .clk(clk),
      .index_a(index_a),
      .index_b(index_b)
  );

  integer cyc;
  initial cyc = 0;
  initial index_a = 3'b0;
  initial index_b = 3'b0;
  always @* begin
    index_a = cyc[2:0];
    if (index_a > 3'd4) index_a = 3'd4;
    index_b = cyc[5:3];
    if (index_b > 3'd4) index_b = 3'd4;
  end

  always @(posedge clk) begin
    cyc <= cyc + 1;
    if (cyc == 99) begin
      $write("*-* All Finished *-*\n");
      $finish;
    end
  end

endmodule


module prover (
    input clk,
    input [2:0] index_a,
    input [2:0] index_b
);

  parameter WIDTH = 4;


  reg signed [WIDTH-1:0] as;
  reg signed [WIDTH-1:0] bs;
  wire [WIDTH-1:0] b = bs;

  // verilator lint_off LATCH
  always @* begin
    casez (index_a)
      3'd0: as = {(WIDTH) {1'd0}};  // 0
      3'd1: as = {{(WIDTH - 1) {1'd0}}, 1'b1};  // 1
      3'd2: as = {1'b0, {(WIDTH - 1) {1'd0}}};  // 127 or equiv
      3'd3: as = {(WIDTH) {1'd1}};  // -1
      3'd4: as = {1'b1, {(WIDTH - 1) {1'd0}}};  // -128 or equiv
      default: $stop;
    endcase
    casez (index_b)
      3'd0: bs = {(WIDTH) {1'd0}};  // 0
      3'd1: bs = {{(WIDTH - 1) {1'd0}}, 1'b1};  // 1
      3'd2: bs = {1'b0, {(WIDTH - 1) {1'd0}}};  // 127 or equiv
      3'd3: bs = {(WIDTH) {1'd1}};  // -1
      3'd4: bs = {1'b1, {(WIDTH - 1) {1'd0}}};  // -128 or equiv
      default: $stop;
    endcase
  end
  // verilator lint_on LATCH

  reg [7:0] results[4:0][4:0];

  wire gt = as > b;
  wire gts = as > bs;
  wire gte = as >= b;
  wire gtes = as >= bs;
  wire lt = as < b;
  wire lts = as < bs;
  wire lte = as <= b;
  wire ltes = as <= bs;

  reg [7:0] exp;
  reg [7:0] got;

  integer cyc = 0;
  always @(posedge clk) begin
    cyc <= cyc + 1;
    if (cyc > 2) begin
`ifdef TEST_VERBOSE
      $write("results[%d][%d] = 8'b%b_%b_%b_%b_%b_%b_%b_%b;\n", index_a, index_b, gt, gts, gte,
             gtes, lt, lts, lte, ltes);
`endif
      exp = results[index_a][index_b];
      got = {gt, gts, gte, gtes, lt, lts, lte, ltes};
      if (exp !== got) begin
        $display("%%Error: bad comparison width=%0d: %d/%d got=%b exp=%b", WIDTH, index_a, index_b,
                 got, exp);
        $stop;
      end
    end
  end

  // Result table
  initial begin
    // Indexes: 0, 1, -1, 127, -128
    //                Gt Gts Gte Gtes Lt Lts Lte Ltes
    results[0][0] = 8'b0_0_1_1_0_0_1_1;
    results[0][1] = 8'b0_0_0_0_1_1_1_1;
    results[0][2] = 8'b0_0_1_1_0_0_1_1;
    results[0][3] = 8'b0_1_0_1_1_0_1_0;
    results[0][4] = 8'b0_1_0_1_1_0_1_0;
    results[1][0] = 8'b1_1_1_1_0_0_0_0;
    results[1][1] = 8'b0_0_1_1_0_0_1_1;
    results[1][2] = 8'b1_1_1_1_0_0_0_0;
    results[1][3] = 8'b0_1_0_1_1_0_1_0;
    results[1][4] = 8'b0_1_0_1_1_0_1_0;
    results[2][0] = 8'b0_0_1_1_0_0_1_1;
    results[2][1] = 8'b0_0_0_0_1_1_1_1;
    results[2][2] = 8'b0_0_1_1_0_0_1_1;
    results[2][3] = 8'b0_1_0_1_1_0_1_0;
    results[2][4] = 8'b0_1_0_1_1_0_1_0;
    results[3][0] = 8'b1_0_1_0_0_1_0_1;
    results[3][1] = 8'b1_0_1_0_0_1_0_1;
    results[3][2] = 8'b1_0_1_0_0_1_0_1;
    results[3][3] = 8'b0_0_1_1_0_0_1_1;
    results[3][4] = 8'b1_1_1_1_0_0_0_0;
    results[4][0] = 8'b1_0_1_0_0_1_0_1;
    results[4][1] = 8'b1_0_1_0_0_1_0_1;
    results[4][2] = 8'b1_0_1_0_0_1_0_1;
    results[4][3] = 8'b0_0_0_0_1_1_1_1;
    results[4][4] = 8'b0_0_1_1_0_0_1_1;
  end

endmodule