`timescale 1us/1us

`include "nandgame_types.v"

module alu_tb;

logic [15:0] in1;
logic [15:0] in2;
logic [1:0] opcode;
logic [15:0] result;
logic u, zx, sw;

alu uut (
  .X(in1),
  .Y(in2),
  .opcode(opcode),
  .RES(result),
  .u(u),
  .zx(zx),
  .sw(sw)
);

string filename;
initial begin
`ifdef DUMP_FILE_NAME
  filename=`DUMP_FILE_NAME;
`else
  filename="alu.lxt2";
`endif
  $dumpfile(filename); $dumpvars();
end

initial begin
  zx = 0;
  sw = 0;

  // Arith tests
  u = 1;
  in1 = 13;
  in2 = 17;
  opcode = ARITH_PLUS;
  #1
  assert(result == 30)
  else $error("Expected: 30, got: %d", result);
  #1
  in1 = 12;
  in2 = 4;
  opcode = ARITH_MINUS;
  #1
  assert(result == 8)
  else $error("Expected: 8, got: %d", result);
  #1
  in1 = 12;
  in2 = 13;
  opcode = ARITH_MINUS;
  #1
  assert(result == 16'hffff)
  else $error("Expected: 16'hffff, got: %d", result);
  #1
  in1 = 13;
  in2 = 17;
  opcode = ARITH_INC;
  #1
  assert(result == 14)
  else $error("Expected: 14, got: %d", result);
  #1
  in1 = 13;
  in2 = 17;
  opcode = ARITH_DEC;
  #1
  assert(result == 12)
  else $error("Expected: 12, got: %d", result);
  #1
  in1 = 0;
  in2 = 17;
  opcode = ARITH_DEC;
  #1
  assert(result == 16'hffff)
  else $error("Expected: 16'hffff, got: %d", result);
  #1

  // logic tests
  u  = 0;
  in1 = 16'b1010;
  in2 = 16'b1100;
  opcode = LOGIC_AND;
  #1
  assert(result == 16'b1000)
  else $error("Expected: 16'b1000, got: %d", result);
  #1
  in1 = 16'b1010;
  in2 = 16'b1100;
  opcode = LOGIC_OR;
  #1
  assert(result == 16'b1110)
  else $error("Expected: 16'b1110, got: %d", result);
  #1
  in1 = 16'b1010;
  in2 = 16'b1100;
  opcode = LOGIC_XOR;
  #1
  assert(result == 16'b0110)
  else $error("Expected: 16'b0110, got: %d", result);
  #1
  in1 = 16'b1010101010101010;
  opcode = LOGIC_NEGT;
  #1
  assert(result == 16'b0101010101010101)
  else $error("Expected: 16'b0101010101010101, got: %d", result);
  #1

  // zero - tests
  zx = 1;
  sw = 0;
  // back to logic
  u = 0;
  in1 = 2;
  in2 = 4;
  opcode = LOGIC_OR;
  #1
  assert(result == 4)
  else $error("Expected 4, got %d", result);
  #1

  // back to arith
  u = 1;
  in1 = 2;
  in2 = 4;
  opcode = ARITH_PLUS;
  #1
  assert(result == 4)
  else $error("Expected 4, got %d", result);
  #1

  // swap tests
  zx = 0;
  sw = 1;
  u = 1;
  in1 = 2;
  in2 = 3;
  opcode = ARITH_MINUS;
  #1
  // 3 - 2
  assert(result == 1)
  else $error("Expected 1, got %d", result);

  // zero-swap
  zx = 1;
  sw = 1;
  u = 1;
  in1 = 2;
  in2 = 3;
  opcode = ARITH_PLUS;
  #1
  // 2 + 0
  assert(result == 2)
  else $error("Expected 2, got %d", result);

  $finish();
end

endmodule