initial commit

.envrc

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+use flake

.gitignore

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+.direnv

flake.lock

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+{
+  "nodes": {
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1694529238,
+        "narHash": "sha256-zsNZZGTGnMOf9YpHKJqMSsa0dXbfmxeoJ7xHlrt+xmY=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "ff7b65b44d01cf9ba6a71320833626af21126384",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1697009197,
+        "narHash": "sha256-viVRhBTFT8fPJTb1N3brQIpFZnttmwo3JVKNuWRVc3s=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "01441e14af5e29c9d27ace398e6dd0b293e25a54",
+        "type": "github"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "type": "indirect"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

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+{
+  description = "ice40 testing";
+
+  inputs = {
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, flake-utils }:
+    flake-utils.lib.eachDefaultSystem (sys:
+      let pkgs = nixpkgs.legacyPackages.${sys};
+
+          verilator = import ./verilator.nix pkgs ;
+
+          rot-sim = pkgs.runCommandCC "rot-sim" {} ''
+            cp "${./rot.v}" rot.v
+            ${verilator}/bin/verilator --cc -O3 --exe --build --trace ${./sim_main.cpp} rot.v
+            mv obj_dir "$out"
+          '';
+
+          rot-trace = pkgs.runCommand "rot-trace" {} ''
+            mkdir "$out"
+            ${rot-sim}/Vrot $out/trace.vcd
+          '';
+
+          rot-trace-view = pkgs.writeScriptBin "rot-view" ''
+            ${pkgs.gtkwave}/bin/gtkwave ${rot-trace}/trace.vcd
+          '';
+
+          rot-synth = pkgs.runCommand "rot-synth" {} ''
+            mkdir "$out"
+            ${pkgs.yosys}/bin/yosys -p "read -vlog95 ${./rot.v} ; synth_ice40 -json $out/synth.json"
+          '';
+
+          rot-route = pkgs.runCommand "rot-route" {} ''
+            mkdir "$out"
+            ${pkgs.nextpnr}/bin/nextpnr-ice40 --pcf ${./rot.pcf} --json ${rot-synth}/synth.json --asc $out/routed.asc --up5k --top rot --freq 12
+          '';
+
+          rot-pack = pkgs.runCommand "rot-pack" {} ''
+            mkdir "$out"
+            ${pkgs.icestorm}/bin/icepack ${rot-route}/routed.asc $out/packed.bin
+          '';
+
+          rot-upload = pkgs.writeScriptBin "rot-upload" ''
+            ${pkgs.icestorm}/bin/iceprog ${rot-pack}/packed.bin
+          '';
+
+          deps = with pkgs; [
+            yosys nextpnrWithGui icestorm verilator
+          ];
+      in rec {
+        packages.verilator = verilator;
+
+        packages.rot-sim = rot-sim;
+        packages.rot-trace = rot-trace;
+        packages.rot-trace-view = rot-trace-view;
+
+        packages.rot-synth = rot-synth;
+        packages.rot-route = rot-route;
+        packages.rot-pack = rot-pack;
+        packages.rot-upload = rot-upload;
+
+        devShells.default = pkgs.mkShell {
+          packages = deps;
+        };
+      }
+    );
+}

rot.pcf

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+set_io D0 23
+set_io D1 27
+set_io D2 21
+set_io D3 25
+set_io clk 35

rot.v

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+module rot (input clk, output D0, output D1, output D2, output D3);
+
+reg ready = 0;
+reg [23:0] divider;
+reg [3:0] rot;
+
+always @(posedge clk) begin
+    if (ready)
+        begin
+        if (divider == 12_000_000)
+            begin
+            divider <= 0;
+            rot <= {rot[2], rot[1], rot[0], rot[3]};
+            end
+        else
+            divider <= divider + 1;
+        end
+    else begin
+        ready <= 1;
+        rot <= 4'b1;
+        divider <= 0;
+    end
+end
+
+assign D0 = rot[0];
+assign D1 = rot[1];
+assign D2 = rot[2];
+assign D3 = rot[3];
+
+endmodule

sim_main.cpp

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+#include "Vrot.h"
+#include "verilated.h"
+#include "verilated_vcd_c.h"
+
+int main(int argc, char** argv) {
+    VerilatedContext* contextp = new VerilatedContext;
+    contextp->commandArgs(argc, argv);
+
+    Vrot* rot = new Vrot{contextp};
+
+    Verilated::traceEverOn(true);
+    VerilatedVcdC* tracer = new VerilatedVcdC;
+
+    if (argc == 2) {
+        rot->trace(tracer, 10);
+        tracer->open(argv[1]);
+    }
+
+
+    while (!contextp->gotFinish() && contextp->time() < 100000) {
+        contextp->timeInc(1);
+        rot->clk = 1;
+        rot->eval();
+        tracer->dump(contextp->time());
+
+        contextp->timeInc(1);
+        rot->clk = 0;
+        rot->eval();
+        tracer->dump(contextp->time());
+    }
+
+    tracer->close();
+
+    delete rot;
+    delete contextp;
+    return 0;
+}

verilator.nix

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+pkgs: with pkgs;
+
+# From https://github.com/NixOS/nixpkgs/blob/nixos-23.11/pkgs/applications/science/electronics/verilator/default.nix
+# Patches out SystemC-support, as the SystemC does not build on Darwin
+stdenv.mkDerivation rec {
+  pname = "verilator";
+  version = "5.018";
+
+  src = fetchFromGitHub {
+    owner = pname;
+    repo = pname;
+    rev = "v${version}";
+    hash = "sha256-f06UzNw2MQ5me03EPrVFhkwxKum/GLDzQbDNTBsJMJs=";
+  };
+
+  enableParallelBuilding = true;
+  buildInputs = [ perl python3 ];  # ccache
+  nativeBuildInputs = [ makeWrapper flex bison autoconf help2man git ];
+  nativeCheckInputs = [ which numactl ];  # cmake
+
+  doCheck = stdenv.isLinux; # darwin tests are broken for now...
+  checkTarget = "test";
+
+  preConfigure = "autoconf";
+
+  postPatch = ''
+    patchShebangs bin/* src/* nodist/* docs/bin/* examples/xml_py/* \
+    test_regress/{driver.pl,t/*.{pl,pf}} \
+    ci/* ci/docker/run/* ci/docker/run/hooks/* ci/docker/buildenv/build.sh
+  '';
+  # grep '^#!/' -R . | grep -v /nix/store | less
+  # (in nix-shell after patchPhase)
+
+  postInstall = lib.optionalString stdenv.isLinux ''
+    for x in $(ls $out/bin/verilator*); do
+      wrapProgram "$x" --set LOCALE_ARCHIVE "${glibcLocales}/lib/locale/locale-archive"
+    done
+  '';
+
+  meta = with lib; {
+    description = "Fast and robust (System)Verilog simulator/compiler and linter";
+    homepage    = "https://www.veripool.org/verilator";
+    license     = with licenses; [ lgpl3Only artistic2 ];
+    platforms   = platforms.unix;
+    maintainers = with maintainers; [ thoughtpolice amiloradovsky ];
+  };
+}