diff --git a/flake.nix b/flake.nix index 8a9b2f0..724fb84 100644 --- a/flake.nix +++ b/flake.nix @@ -32,6 +32,15 @@ mkdir "$out/bin" && cp "$out/Valu" "$out/bin/alu-sim" ''; + alu-sim-trace = pkgs.runCommandCC "alu-sim-trace" {} '' + ${verilate-src "--cc --build --exe --trace -CFLAGS -DTRACE=1 ./simulation/tester.cpp ./simulation/test_alu.cpp -top alu"} + mv obj_dir "$out" + mkdir "$out/bin" && cp "$out/Valu" "$out/bin/alu-sim" + $out/bin/alu-sim $out/trace.vcd + echo "${pkgs.gtkwave}/bin/gtkwave $out/trace.vcd" > $out/bin/alu-sim-trace + chmod u+x $out/bin/alu-sim-trace + ''; + alu-synth = pkgs.runCommandCC "alu-synth" {} '' mkdir -p "$out" find ${./src} -name '*.v' -exec ${yosys}/bin/yosys -Q -p "synth_ice40 -top topmost -json $out/synth.json -dsp" {} + @@ -42,7 +51,7 @@ ''; deps = [ - yosys pkgs.nextpnrWithGui pkgs.icestorm verilator + yosys pkgs.nextpnrWithGui pkgs.icestorm verilator pkgs.gtkwave ]; in rec { packages.verilator = verilator; @@ -50,6 +59,8 @@ packages.lint = lint; packages.alu-sim = alu-sim; + packages.alu-sim-trace = alu-sim-trace; + packages.alu-synth = alu-synth; packages.alu-synth-view = alu-synth-view; diff --git a/simulation/test_alu.cpp b/simulation/test_alu.cpp index 474ad42..324b41b 100644 --- a/simulation/test_alu.cpp +++ b/simulation/test_alu.cpp @@ -3,9 +3,24 @@ #include "tester.hpp" #include +#include #include +#ifdef TRACE +#include "verilated_vcd_c.h" +#endif + +struct state { + VerilatedContext *ctx; + Valu *valu; + #ifdef TRACE + VerilatedVcdC *trace; + #endif +}; + struct alu_testcase { + state *state; + std::string name; // Inputs uint32_t A, B; @@ -30,77 +45,156 @@ std::string fmt_hex(uint32_t n) { return hex; } -void test_op(Valu *valu, Tester *tester, alu_testcase test) { +void posedge(state *state) { + #ifdef TRACE + state->ctx->timeInc(1); + state->valu->CLK = 1; + state->valu->eval(); + state->trace->dump(state->ctx->time()); + + state->ctx->timeInc(1); + state->valu->CLK = 0; + state->valu->eval(); + state->trace->dump(state->ctx->time()); + #else + state->ctx->timeInc(1); + state->valu->CLK = 1; + state->valu->eval(); + + state->ctx->timeInc(1); + state->valu->CLK = 0; + state->valu->eval(); + #endif +} + +void test_op(Tester *tester, alu_testcase test) { Tester subtester(tester, test.name); - // assign inputs - valu->op = test.op; - valu->A = test.A; - valu->B = test.B; + posedge(test.state); - valu->eval(); + // assign inputs + test.state->valu->op = test.op; + test.state->valu->A = test.A; + test.state->valu->B = test.B; + test.state->valu->EN = 1; + posedge(test.state); + test.state->valu->EN = 0; + + int max_cycles = test.max_cycles.has_value() ? *test.max_cycles : 10000; + + int n_cycles = 1; + for (; !test.state->valu->RDY && n_cycles < 10 + max_cycles * 2; n_cycles++) { + posedge(test.state); + } + + char rdy_after_s[100]; + snprintf(rdy_after_s, sizeof rdy_after_s, "RDY = 1 (after %d cycle(s))", n_cycles); + subtester.assert_eq(rdy_after_s, test.state->valu->RDY, 1); + + if (test.max_cycles.has_value()) { + if (n_cycles <= test.max_cycles) { + char n_cycles_s[100]; + snprintf(n_cycles_s, sizeof n_cycles_s, "Finished within %d cycle(s) (actually %d)", test.max_cycles, n_cycles); + subtester.assert_eq(n_cycles_s, n_cycles, n_cycles); + } else { + subtester.assert_eq("Finished within correct number of cycles", n_cycles, test.max_cycles); + } + } std::string o_name("O == "); o_name.append(fmt_hex(test.O)); - subtester.assert_eq(o_name, valu->O, test.O); + subtester.assert_eq(o_name, test.state->valu->O, test.O); if (test.overflow.has_value()) { if (*test.overflow) - subtester.assert_eq("overflow flag set", valu->Fflow, 1); + subtester.assert_eq("overflow flag set", test.state->valu->Fflow, 1); else - subtester.assert_eq("no overflow flag", valu->Fflow, 0); + subtester.assert_eq("no overflow flag", test.state->valu->Fflow, 0); } if (test.zero.has_value()) { if (*test.zero) - subtester.assert_eq("zero flag set", valu->Fzero, 1); + subtester.assert_eq("zero flag set", test.state->valu->Fzero, 1); else - subtester.assert_eq("no zero flag", valu->Fzero, 0); + subtester.assert_eq("no zero flag", test.state->valu->Fzero, 0); } } int main(int argc, char **argv) { + bool DO_AUTO = false; + VerilatedContext *vctx = new VerilatedContext; + Verilated::traceEverOn(true); Valu *valu = new Valu(vctx); + #ifdef TRACE + if (argc != 2) { + std::cout << "Run with argument for destination!" << std::endl; + return 1; + } + + VerilatedVcdC *trace = new VerilatedVcdC; + valu->trace(trace, 99); + trace->open(argv[1]); + std::cout << "(writing trace to " << argv[1] << ")" << std::endl; + + state state = { + .ctx = vctx, + .valu = valu, + .trace = trace, + }; + #else + state state = { + .ctx = vctx, + .valu = valu, + }; + #endif + Tester alu_t("alu"); { Tester add_t(&alu_t, "add", true); - test_op(valu, &add_t, { + test_op(&add_t, { + .state = &state, .name = "0x2137+0x1234", .A = 0x2137, .B = 0x1234, .op = 0b000, .O = 0x336b, .overflow = false, }); - test_op(valu, &add_t, { + test_op(&add_t, { + .state = &state, .name = "0x09+0x10", .A = 0x09, .B = 0x10, .op = 0b000, .O = 0x19, .overflow = false, }); - test_op(valu, &add_t, { + test_op(&add_t, { + .state = &state, .name = "0x5555+0x5555", .A = 0x5555, .B = 0x5555, .op = 0b000, .O = 0xaaaa, .overflow = false, }); - test_op(valu, &add_t, { + test_op(&add_t, { + .state = &state, .name = "0xfffffffe+0x1", .A = 0xfffffffe, .B = 0x1, .op = 0b000, .O = 0xffffffff, .overflow = false, .zero = false, }); - test_op(valu, &add_t, { + test_op(&add_t, { + .state = &state, .name = "0xffffffff+0x1", .A = 0xffffffff, .B = 0x1, .op = 0b000, .O = 0x0, .overflow = true, .zero = true, }); - test_op(valu, &add_t, { + test_op(&add_t, { + .state = &state, .name = "0xffffffff+0x2", .A = 0xffffffff, .B = 0x2, .op = 0b000, .O = 0x1, .overflow = true, .zero = false, }); - test_op(valu, &add_t, { + test_op(&add_t, { + .state = &state, .name = "0x0+0x0", .A = 0x0, .B = 0x0, .op = 0b000, .O = 0x0, .overflow = false, .zero = true, @@ -110,31 +204,36 @@ int main(int argc, char **argv) { { Tester sub_t(&alu_t, "sub", true); - test_op(valu, &sub_t, { + test_op(&sub_t, { + .state = &state, .name = "0x2137-0x0420", .A = 0x2137, .B = 0x0420, .op = 0b001, .O = 0x1d17, .overflow = false, }); - test_op(valu, &sub_t, { + test_op(&sub_t, { + .state = &state, .name = "0x0-0x1", .A = 0x0, .B = 0x1, .op = 0b001, .O = 0xffffffff, .overflow = true, }); - test_op(valu, &sub_t, { + test_op(&sub_t, { + .state = &state, .name = "0x100-0x0200", .A = 0x100, .B = 0x200, .op = 0b001, .O = 0xffffff00, .overflow = true, }); - test_op(valu, &sub_t, { + test_op(&sub_t, { + .state = &state, .name = "0x21-0x9", .A = 0x21, .B = 0x9, .op = 0b001, .O = 0x18, .overflow = false, .zero = false, }); - test_op(valu, &sub_t, { + test_op(&sub_t, { + .state = &state, .name = "0x20-0x20", .A = 0x20, .B = 0x20, .op = 0b001, .O = 0x0, .overflow = false, .zero = true, @@ -145,38 +244,43 @@ int main(int argc, char **argv) { Tester bitwise_t(&alu_t, "bitwise", true); // 0x3 = 0b0011, 0x5 = 0b0101 - test_op(valu, &bitwise_t, { + test_op(&bitwise_t, { + .state = &state, .name = "0x3&0x5", .A = 0x3, .B = 0x5, .op = 0b100, .O = 0x1, .zero = false, }); - test_op(valu, &bitwise_t, { + test_op(&bitwise_t, { + .state = &state, .name = "0x3|0x5", .A = 0x3, .B = 0x5, .op = 0b101, .O = 0x7, .zero = false, }); - test_op(valu, &bitwise_t, { + test_op(&bitwise_t, { + .state = &state, .name = "0x3^0x5", .A = 0x3, .B = 0x5, .op = 0b110, .O = 0x6, .zero = false, }); - test_op(valu, &bitwise_t, { + test_op(&bitwise_t, { + .state = &state, .name = "~0xa5a5a5a5", .A = 0xa5a5a5a5, .B = 0x0, .op = 0b111, .O = 0x5a5a5a5a, .zero = false, }); - test_op(valu, &bitwise_t, { + test_op(&bitwise_t, { + .state = &state, .name = "~0xffffffff", .A = 0xffffffff, .B = 0x0, .op = 0b111, .O = 0x0, .zero = true, }); } - { + if (DO_AUTO) { Tester auto_t(&alu_t, "auto", true); std::default_random_engine eng; @@ -194,7 +298,8 @@ int main(int argc, char **argv) { name.append("+"); name.append(fmt_hex(B)); - test_op(valu, &auto_t, { + test_op(&auto_t, { + .state = &state, .name = name, .A = A, .B = B, .op = 0b000, .O = A + B, .overflow = (A + B < A), .zero = (A + B == 0), @@ -206,7 +311,8 @@ int main(int argc, char **argv) { name.append("-"); name.append(fmt_hex(B)); - test_op(valu, &auto_t, { + test_op(&auto_t, { + .state = &state, .name = name, .A = A, .B = B, .op = 0b001, .O = A - B, .overflow = (B > A), .zero = (A == B), @@ -218,7 +324,8 @@ int main(int argc, char **argv) { name.append("&"); name.append(fmt_hex(B)); - test_op(valu, &auto_t, { + test_op(&auto_t, { + .state = &state, .name = name, .A = A, .B = B, .op = 0b100, .O = A & B, .overflow = 0, .zero = ((A & B) == 0), @@ -230,7 +337,8 @@ int main(int argc, char **argv) { name.append("|"); name.append(fmt_hex(B)); - test_op(valu, &auto_t, { + test_op(&auto_t, { + .state = &state, .name = name, .A = A, .B = B, .op = 0b101, .O = A | B, .overflow = 0, .zero = ((A | B) == 0), @@ -242,7 +350,8 @@ int main(int argc, char **argv) { name.append("^"); name.append(fmt_hex(B)); - test_op(valu, &auto_t, { + test_op(&auto_t, { + .state = &state, .name = name, .A = A, .B = B, .op = 0b110, .O = A ^ B, .overflow = 0, .zero = ((A ^ B) == 0), @@ -253,7 +362,8 @@ int main(int argc, char **argv) { name.append("~"); name.append(fmt_hex(A)); - test_op(valu, &auto_t, { + test_op(&auto_t, { + .state = &state, .name = name, .A = A, .B = B, .op = 0b111, .O = ~A, .overflow = 0, .zero = (A == 0xffffffff), @@ -263,4 +373,7 @@ int main(int argc, char **argv) { } } } + #ifdef TRACE + state.trace->close(); + #endif } diff --git a/src/alu/alu.v b/src/alu/alu.v index be2db09..0535a16 100644 --- a/src/alu/alu.v +++ b/src/alu/alu.v @@ -12,44 +12,99 @@ 111 = not A */ module alu( + input CLK, + input EN, + output reg RDY, + input [31:0] A, input [31:0] B, input [2:0] op, - output [31:0] O, - output Fflow, - output Fzero + output reg [31:0] O, + output reg Fflow, + output reg Fzero ); -wire [31:0] adder_out; +// Constants +localparam OP_ADD = 3'b000; +localparam OP_SUB = 3'b001; +localparam OP_AND = 3'b100; +localparam OP_OR = 3'b101; +localparam OP_XOR = 3'b110; +localparam OP_NOT = 3'b111; -begin : addsub - wire addition = op == 3'b000; - wire subtraction = op == 3'b001; - wire [31:0] adder_B = subtraction ? ~B : B; - wire adder_cout; +localparam ST_IDLE = 0; - carry_select_adder a(A, adder_B, subtraction, adder_out, adder_cout); - assign Fflow = - addition ? adder_cout : - subtraction ? ~adder_cout : - 0; -end +// State -wire [31:0] mult_out_hi; -wire [31:0] mult_out_lo; -multiplier mult(A, B, mult_out_hi, mult_out_lo); +reg [8:0] state = ST_IDLE; +reg [2:0] selected_out; + +assign RDY = state == ST_IDLE; + +reg [31:0] bitwise_out; + +// Outputs assign O = - op == 3'b000 ? adder_out : - op == 3'b001 ? adder_out : - op == 3'b010 ? mult_out_hi : - op == 3'b011 ? mult_out_lo : - op == 3'b100 ? A & B : - op == 3'b101 ? A | B : - op == 3'b110 ? A ^ B : - op == 3'b111 ? ~A : - '0; + (selected_out == OP_ADD || selected_out == OP_SUB) ? adder_out : + bitwise_out; -assign Fzero = ~ (| O); +assign Fflow = + selected_out == OP_ADD ? adder_carry_out : + selected_out == OP_SUB ? ~adder_carry_out : + 0; + +assign Fzero = ~(| O); + +// Modules + +reg [31:0] adder_A, adder_B; +reg adder_carry_in, adder_carry_out; +wire [31:0] adder_out; + +carry_select_adder adder(adder_A, adder_B, adder_carry_in, adder_out, adder_carry_out); + +// Clocking + +always @(posedge CLK) begin + case (state) + ST_IDLE: begin + if (EN) begin + case (op) + OP_ADD: begin + adder_A <= A; + adder_B <= B; + adder_carry_in <= 0; + selected_out <= OP_ADD; + end + OP_SUB: begin + adder_A <= A; + adder_B <= ~B; + adder_carry_in <= 1; + selected_out <= OP_SUB; + end + OP_AND: begin + bitwise_out <= A & B; + selected_out <= OP_AND; + end + OP_OR: begin + bitwise_out <= A | B; + selected_out <= OP_OR; + end + OP_XOR: begin + bitwise_out <= A ^ B; + selected_out <= OP_XOR; + end + OP_NOT: begin + bitwise_out <= ~A; + selected_out <= OP_NOT; + end + default: begin end // TODO: this should be $stop in verilator, no-op in synthesis + endcase + end + end + default: $stop; + endcase +end endmodule