Merge pull request #284 from YosysHQ/json_write

Initial support for writing to json files from nextpnr.

47 files changed, 1042 insertions, 804 deletions

diff --git a/common/command.cc b/common/command.cc
index 3eafdb17..8acbafd2 100644
--- a/common/command.cc
+++ b/common/command.cc
@@ -27,6 +27,7 @@
 #include "pybindings.h"
 #endif
 
+#include <boost/algorithm/string.hpp>
 #include <boost/algorithm/string/join.hpp>
 #include <boost/filesystem/convenience.hpp>
 #include <boost/program_options.hpp>
@@ -35,6 +36,7 @@
 #include "command.h"
 #include "design_utils.h"
 #include "jsonparse.h"
+#include "jsonwrite.h"
 #include "log.h"
 #include "timing.h"
 #include "util.h"
@@ -120,6 +122,7 @@ po::options_description CommandHandler::getGeneralOptions()
 
 #endif
     general.add_options()("json", po::value<std::string>(), "JSON design file to ingest");
+    general.add_options()("write", po::value<std::string>(), "JSON design file to write");
     general.add_options()("seed", po::value<int>(), "seed value for random number generator");
     general.add_options()("randomize-seed,r", "randomize seed value for random number generator");
 
@@ -135,6 +138,9 @@ po::options_description CommandHandler::getGeneralOptions()
     general.add_options()("placer-budgets", "use budget rather than criticality in placer timing weights");
 
     general.add_options()("pack-only", "pack design only without placement or routing");
+    general.add_options()("no-route", "process design without routing");
+    general.add_options()("no-place", "process design without placement");
+    general.add_options()("no-pack", "process design without packing");
 
     general.add_options()("ignore-loops", "ignore combinational loops in timing analysis");
 
@@ -143,13 +149,14 @@ po::options_description CommandHandler::getGeneralOptions()
     general.add_options()("freq", po::value<double>(), "set target frequency for design in MHz");
     general.add_options()("timing-allow-fail", "allow timing to fail in design");
     general.add_options()("no-tmdriv", "disable timing-driven placement");
-    general.add_options()("save", po::value<std::string>(), "project file to write");
-    general.add_options()("load", po::value<std::string>(), "project file to read");
     return general;
 }
 
 void CommandHandler::setupContext(Context *ctx)
 {
+    if (ctx->settings.find(ctx->id("seed")) != ctx->settings.end())
+        ctx->rngstate = ctx->setting<uint64_t>("seed");
+
     if (vm.count("verbose")) {
         ctx->verbose = true;
     }
@@ -177,9 +184,9 @@ void CommandHandler::setupContext(Context *ctx)
     }
 
     if (vm.count("slack_redist_iter")) {
-        ctx->slack_redist_iter = vm["slack_redist_iter"].as<int>();
+        ctx->settings[ctx->id("slack_redist_iter")] = vm["slack_redist_iter"].as<std::string>();
         if (vm.count("freq") && vm["freq"].as<double>() == 0) {
-            ctx->auto_freq = true;
+            ctx->settings[ctx->id("auto_freq")] = std::to_string(true);
 #ifndef NO_GUI
             if (!vm.count("gui"))
 #endif
@@ -188,11 +195,11 @@ void CommandHandler::setupContext(Context *ctx)
     }
 
     if (vm.count("ignore-loops")) {
-        settings->set("timing/ignoreLoops", true);
+        ctx->settings[ctx->id("timing/ignoreLoops")] = std::to_string(true);
     }
 
     if (vm.count("timing-allow-fail")) {
-        settings->set("timing/allowFail", true);
+        ctx->settings[ctx->id("timing/allowFail")] = std::to_string(true);
     }
 
     if (vm.count("placer")) {
@@ -201,30 +208,43 @@ void CommandHandler::setupContext(Context *ctx)
             Arch::availablePlacers.end())
             log_error("Placer algorithm '%s' is not supported (available options: %s)\n", placer.c_str(),
                       boost::algorithm::join(Arch::availablePlacers, ", ").c_str());
-        settings->set("placer", placer);
-    } else {
-        settings->set("placer", Arch::defaultPlacer);
+        ctx->settings[ctx->id("placer")] = placer;
     }
 
     if (vm.count("cstrweight")) {
-        settings->set("placer1/constraintWeight", vm["cstrweight"].as<float>());
+        ctx->settings[ctx->id("placer1/constraintWeight")] = std::to_string(vm["cstrweight"].as<float>());
     }
     if (vm.count("starttemp")) {
-        settings->set("placer1/startTemp", vm["starttemp"].as<float>());
+        ctx->settings[ctx->id("placer1/startTemp")] = std::to_string(vm["starttemp"].as<float>());
     }
 
     if (vm.count("placer-budgets")) {
-        settings->set("placer1/budgetBased", true);
+        ctx->settings[ctx->id("placer1/budgetBased")] = std::to_string(true);
     }
     if (vm.count("freq")) {
         auto freq = vm["freq"].as<double>();
         if (freq > 0)
-            ctx->target_freq = freq * 1e6;
+            ctx->settings[ctx->id("target_freq")] = std::to_string(freq * 1e6);
     }
 
-    ctx->timing_driven = true;
     if (vm.count("no-tmdriv"))
-        ctx->timing_driven = false;
+        ctx->settings[ctx->id("timing_driven")] = std::to_string(false);
+
+    // Setting default values
+    if (ctx->settings.find(ctx->id("target_freq")) == ctx->settings.end())
+        ctx->settings[ctx->id("target_freq")] = std::to_string(12e6);
+    if (ctx->settings.find(ctx->id("timing_driven")) == ctx->settings.end())
+        ctx->settings[ctx->id("timing_driven")] = std::to_string(true);
+    if (ctx->settings.find(ctx->id("slack_redist_iter")) == ctx->settings.end())
+        ctx->settings[ctx->id("slack_redist_iter")] = "0";
+    if (ctx->settings.find(ctx->id("auto_freq")) == ctx->settings.end())
+        ctx->settings[ctx->id("auto_freq")] = std::to_string(false);
+    if (ctx->settings.find(ctx->id("placer")) == ctx->settings.end())
+        ctx->settings[ctx->id("placer")] = Arch::defaultPlacer;
+
+    ctx->settings[ctx->id("arch.name")] = std::string(ctx->archId().c_str(ctx));
+    ctx->settings[ctx->id("arch.type")] = std::string(ctx->archArgsToId(ctx->archArgs()).c_str(ctx));
+    ctx->settings[ctx->id("seed")] = std::to_string(ctx->rngstate);
 }
 
 int CommandHandler::executeMain(std::unique_ptr<Context> ctx)
@@ -237,19 +257,17 @@ int CommandHandler::executeMain(std::unique_ptr<Context> ctx)
 #ifndef NO_GUI
     if (vm.count("gui")) {
         Application a(argc, argv, (vm.count("gui-no-aa") > 0));
-        MainWindow w(std::move(ctx), chipArgs);
+        MainWindow w(std::move(ctx), this);
         try {
             if (vm.count("json")) {
                 std::string filename = vm["json"].as<std::string>();
                 std::ifstream f(filename);
-                w.notifyChangeContext();
                 if (!parse_json_file(f, filename, w.getContext()))
                     log_error("Loading design failed.\n");
 
                 customAfterLoad(w.getContext());
-                w.updateLoaded();
-            } else if (vm.count("load")) {
-                w.projectLoad(vm["load"].as<std::string>());
+                w.notifyChangeContext();
+                w.updateActions();
             } else
                 w.notifyChangeContext();
         } catch (log_execution_error_exception) {
@@ -280,31 +298,42 @@ int CommandHandler::executeMain(std::unique_ptr<Context> ctx)
             execute_python_file(filename.c_str());
     } else
 #endif
-            if (vm.count("json") || vm.count("load")) {
-        run_script_hook("pre-pack");
-        if (!ctx->pack() && !ctx->force)
-            log_error("Packing design failed.\n");
+            if (vm.count("json")) {
+        bool do_pack = vm.count("pack-only") != 0 || vm.count("no-pack") == 0;
+        bool do_place = vm.count("pack-only") == 0 && vm.count("no-place") == 0;
+        bool do_route = vm.count("pack-only") == 0 && vm.count("no-route") == 0;
+
+        if (do_pack) {
+            run_script_hook("pre-pack");
+            if (!ctx->pack() && !ctx->force)
+                log_error("Packing design failed.\n");
+        }
         assign_budget(ctx.get());
         ctx->check();
         print_utilisation(ctx.get());
-        run_script_hook("pre-place");
 
-        if (!vm.count("pack-only")) {
+        if (do_place) {
+            run_script_hook("pre-place");
             if (!ctx->place() && !ctx->force)
                 log_error("Placing design failed.\n");
             ctx->check();
-            run_script_hook("pre-route");
+        }
 
+        if (do_route) {
+            run_script_hook("pre-route");
             if (!ctx->route() && !ctx->force)
                 log_error("Routing design failed.\n");
+            run_script_hook("post-route");
         }
-        run_script_hook("post-route");
 
         customBitstream(ctx.get());
     }
 
-    if (vm.count("save")) {
-        project.save(ctx.get(), vm["save"].as<std::string>());
+    if (vm.count("write")) {
+        std::string filename = vm["write"].as<std::string>();
+        std::ofstream f(filename);
+        if (!write_json_file(f, filename, ctx.get()))
+            log_error("Saving design failed.\n");
     }
 
 #ifndef NO_PYTHON
@@ -341,13 +370,14 @@ int CommandHandler::exec()
         if (executeBeforeContext())
             return 0;
 
-        std::unique_ptr<Context> ctx;
-        if (vm.count("load") && vm.count("gui") == 0) {
-            ctx = project.load(vm["load"].as<std::string>());
-        } else {
-            ctx = createContext();
+        std::unordered_map<std::string, Property> values;
+        if (vm.count("json")) {
+            std::string filename = vm["json"].as<std::string>();
+            std::ifstream f(filename);
+            if (!load_json_settings(f, filename, values))
+                log_error("Loading design failed.\n");
         }
-        settings = std::unique_ptr<Settings>(new Settings(ctx.get()));
+        std::unique_ptr<Context> ctx = createContext(values);
         setupContext(ctx.get());
         setupArchContext(ctx.get());
         int rc = executeMain(std::move(ctx));
@@ -359,6 +389,27 @@ int CommandHandler::exec()
     }
 }
 
+std::unique_ptr<Context> CommandHandler::load_json(std::string filename)
+{
+    vm.clear();
+    std::unordered_map<std::string, Property> values;
+    {
+        std::ifstream f(filename);
+        if (!load_json_settings(f, filename, values))
+            log_error("Loading design failed.\n");
+    }
+    std::unique_ptr<Context> ctx = createContext(values);
+    setupContext(ctx.get());
+    setupArchContext(ctx.get());
+    {
+        std::ifstream f(filename);
+        if (!parse_json_file(f, filename, ctx.get()))
+            log_error("Loading design failed.\n");
+    }
+    customAfterLoad(ctx.get());
+    return ctx;
+}
+
 void CommandHandler::run_script_hook(const std::string &name)
 {
 #ifndef NO_PYTHON
diff --git a/common/command.h b/common/command.h
index d0f1d328..e52b5a48 100644
--- a/common/command.h
+++ b/common/command.h
@@ -22,9 +22,9 @@
 #define COMMAND_H
 
 #include <boost/program_options.hpp>
+#include <fstream>
+#include "log.h"
 #include "nextpnr.h"
-#include "project.h"
-#include "settings.h"
 
 NEXTPNR_NAMESPACE_BEGIN
 
@@ -37,10 +37,11 @@ class CommandHandler
     virtual ~CommandHandler(){};
 
     int exec();
+    std::unique_ptr<Context> load_json(std::string filename);
 
   protected:
     virtual void setupArchContext(Context *ctx) = 0;
-    virtual std::unique_ptr<Context> createContext() = 0;
+    virtual std::unique_ptr<Context> createContext(std::unordered_map<std::string, Property> &values) = 0;
     virtual po::options_description getArchOptions() = 0;
     virtual void validate(){};
     virtual void customAfterLoad(Context *ctx){};
@@ -58,15 +59,12 @@ class CommandHandler
 
   protected:
     po::variables_map vm;
-    ArchArgs chipArgs;
-    std::unique_ptr<Settings> settings;
 
   private:
     po::options_description options;
     po::positional_options_description pos;
     int argc;
     char **argv;
-    ProjectHandler project;
     std::ofstream logfile;
 };
 
diff --git a/common/nextpnr.cc b/common/nextpnr.cc
index daaadf28..d4cc4917 100644
--- a/common/nextpnr.cc
+++ b/common/nextpnr.cc
@@ -18,6 +18,7 @@
  */
 
 #include "nextpnr.h"
+#include <boost/algorithm/string.hpp>
 #include "log.h"
 
 NEXTPNR_NAMESPACE_BEGIN
@@ -453,4 +454,118 @@ DecalXY BaseCtx::constructDecalXY(DecalId decal, float x, float y)
     return dxy;
 }
 
+void BaseCtx::archInfoToAttributes()
+{
+    for (auto &cell : cells) {
+        auto ci = cell.second.get();
+        if (ci->bel != BelId()) {
+            if (ci->attrs.find(id("BEL")) != ci->attrs.end()) {
+                ci->attrs.erase(ci->attrs.find(id("BEL")));
+            }
+            ci->attrs[id("NEXTPNR_BEL")] = getCtx()->getBelName(ci->bel).c_str(this);
+            ci->attrs[id("BEL_STRENGTH")] = std::to_string((int)ci->belStrength);
+        }
+        if (ci->constr_x != ci->UNCONSTR)
+            ci->attrs[id("CONSTR_X")] = std::to_string(ci->constr_x);
+        if (ci->constr_y != ci->UNCONSTR)
+            ci->attrs[id("CONSTR_Y")] = std::to_string(ci->constr_y);
+        if (ci->constr_z != ci->UNCONSTR) {
+            ci->attrs[id("CONSTR_Z")] = std::to_string(ci->constr_z);
+            ci->attrs[id("CONSTR_ABS_Z")] = std::to_string(ci->constr_abs_z ? 1 : 0);
+        }
+        if (ci->constr_parent != nullptr)
+            ci->attrs[id("CONSTR_PARENT")] = ci->constr_parent->name.c_str(this);
+        if (!ci->constr_children.empty()) {
+            std::string constr = "";
+            for (auto &item : ci->constr_children) {
+                if (!constr.empty())
+                    constr += std::string(";");
+                constr += item->name.c_str(this);
+            }
+            ci->attrs[id("CONSTR_CHILDREN")] = constr;
+        }
+    }
+    for (auto &net : getCtx()->nets) {
+        auto ni = net.second.get();
+        std::string routing;
+        bool first = true;
+        for (auto &item : ni->wires) {
+            if (!first)
+                routing += ";";
+            routing += getCtx()->getWireName(item.first).c_str(this);
+            routing += ";";
+            if (item.second.pip != PipId())
+                routing += getCtx()->getPipName(item.second.pip).c_str(this);
+            routing += ";" + std::to_string(item.second.strength);
+            first = false;
+        }
+        ni->attrs[id("ROUTING")] = routing;
+    }
+}
+
+void BaseCtx::attributesToArchInfo()
+{
+    for (auto &cell : cells) {
+        auto ci = cell.second.get();
+        auto val = ci->attrs.find(id("NEXTPNR_BEL"));
+        if (val != ci->attrs.end()) {
+            auto str = ci->attrs.find(id("BEL_STRENGTH"));
+            PlaceStrength strength = PlaceStrength::STRENGTH_USER;
+            if (str != ci->attrs.end())
+                strength = (PlaceStrength)std::stoi(str->second.str);
+
+            BelId b = getCtx()->getBelByName(id(val->second.str));
+            getCtx()->bindBel(b, ci, strength);
+        }
+        val = ci->attrs.find(id("CONSTR_X"));
+        if (val != ci->attrs.end())
+            ci->constr_x = std::stoi(val->second.str);
+
+        val = ci->attrs.find(id("CONSTR_Y"));
+        if (val != ci->attrs.end())
+            ci->constr_y = std::stoi(val->second.str);
+
+        val = ci->attrs.find(id("CONSTR_Z"));
+        if (val != ci->attrs.end())
+            ci->constr_z = std::stoi(val->second.str);
+
+        val = ci->attrs.find(id("CONSTR_ABS_Z"));
+        if (val != ci->attrs.end())
+            ci->constr_abs_z = std::stoi(val->second.str) == 1;
+
+        val = ci->attrs.find(id("CONSTR_PARENT"));
+        if (val != ci->attrs.end()) {
+            auto parent = cells.find(id(val->second.str));
+            if (parent != cells.end())
+                ci->constr_parent = parent->second.get();
+        }
+        val = ci->attrs.find(id("CONSTR_CHILDREN"));
+        if (val != ci->attrs.end()) {
+            std::vector<std::string> strs;
+            boost::split(strs, val->second.str, boost::is_any_of(";"));
+            for (auto val : strs) {
+                ci->constr_children.push_back(cells.find(id(val.c_str()))->second.get());
+            }
+        }
+    }
+    for (auto &net : getCtx()->nets) {
+        auto ni = net.second.get();
+        auto val = ni->attrs.find(id("ROUTING"));
+        if (val != ni->attrs.end()) {
+            std::vector<std::string> strs;
+            boost::split(strs, val->second.str, boost::is_any_of(";"));
+            for (size_t i = 0; i < strs.size() / 3; i++) {
+                std::string wire = strs[i * 3];
+                std::string pip = strs[i * 3 + 1];
+                PlaceStrength strength = (PlaceStrength)std::stoi(strs[i * 3 + 2]);
+                if (pip.empty())
+                    getCtx()->bindWire(getCtx()->getWireByName(id(wire)), ni, strength);
+                else
+                    getCtx()->bindPip(getCtx()->getPipByName(id(pip)), ni, strength);
+            }
+        }
+    }
+    getCtx()->assignArchInfo();
+}
+
 NEXTPNR_NAMESPACE_END
diff --git a/common/nextpnr.h b/common/nextpnr.h
index fc49300e..3f434580 100644
--- a/common/nextpnr.h
+++ b/common/nextpnr.h
@@ -32,6 +32,7 @@
 #include <vector>
 
 #include <boost/functional/hash.hpp>
+#include <boost/lexical_cast.hpp>
 
 #ifndef NEXTPNR_H
 #define NEXTPNR_H
@@ -286,6 +287,44 @@ struct PipMap
     PlaceStrength strength = STRENGTH_NONE;
 };
 
+struct Property
+{
+    bool is_string;
+
+    std::string str;
+    int num;
+
+    std::string::iterator begin() { return str.begin(); }
+    std::string::iterator end() { return str.end(); }
+
+    bool isString() const { return is_string; }
+
+    void setNumber(int val)
+    {
+        is_string = false;
+        num = val;
+        str = std::to_string(val);
+    }
+    void setString(std::string val)
+    {
+        is_string = true;
+        str = val;
+    }
+
+    const char *c_str() const { return str.c_str(); }
+    operator std::string() const { return str; }
+
+    bool operator==(const std::string other) const { return str == other; }
+    bool operator!=(const std::string other) const { return str != other; }
+
+    Property &operator=(std::string other)
+    {
+        is_string = true;
+        str = other;
+        return *this;
+    }
+};
+
 struct ClockConstraint;
 
 struct NetInfo : ArchNetInfo
@@ -295,7 +334,7 @@ struct NetInfo : ArchNetInfo
 
     PortRef driver;
     std::vector<PortRef> users;
-    std::unordered_map<IdString, std::string> attrs;
+    std::unordered_map<IdString, Property> attrs;
 
     // wire -> uphill_pip
     std::unordered_map<WireId, PipMap> wires;
@@ -328,7 +367,7 @@ struct CellInfo : ArchCellInfo
     int32_t udata;
 
     std::unordered_map<IdString, PortInfo> ports;
-    std::unordered_map<IdString, std::string> attrs, params;
+    std::unordered_map<IdString, Property> attrs, params;
 
     BelId bel;
     PlaceStrength belStrength = STRENGTH_NONE;
@@ -506,15 +545,21 @@ struct BaseCtx
     mutable std::vector<const std::string *> *idstring_idx_to_str;
 
     // Project settings and config switches
-    std::unordered_map<IdString, std::string> settings;
+    std::unordered_map<IdString, Property> settings;
 
     // Placed nets and cells.
     std::unordered_map<IdString, std::unique_ptr<NetInfo>> nets;
     std::unordered_map<IdString, std::unique_ptr<CellInfo>> cells;
 
+    // Top-level ports
+    std::unordered_map<IdString, PortInfo> ports;
+
     // Floorplanning regions
     std::unordered_map<IdString, std::unique_ptr<Region>> region;
 
+    // Context meta data
+    std::unordered_map<IdString, Property> attrs;
+
     BaseCtx()
     {
         idstring_str_to_idx = new std::unordered_map<std::string, int>;
@@ -646,6 +691,9 @@ struct BaseCtx
 
     // Workaround for lack of wrappable constructors
     DecalXY constructDecalXY(DecalId decal, float x, float y);
+
+    void archInfoToAttributes();
+    void attributesToArchInfo();
 };
 
 NEXTPNR_NAMESPACE_END
@@ -659,10 +707,6 @@ struct Context : Arch, DeterministicRNG
     bool verbose = false;
     bool debug = false;
     bool force = false;
-    bool timing_driven = true;
-    float target_freq = 12e6;
-    bool auto_freq = false;
-    int slack_redist_iter = 0;
 
     Context(ArchArgs args) : Arch(args) {}
 
@@ -683,6 +727,26 @@ struct Context : Arch, DeterministicRNG
 
     void check() const;
     void archcheck() const;
+
+    template <typename T> T setting(const char *name, T defaultValue)
+    {
+        IdString new_id = id(name);
+        if (settings.find(new_id) != settings.end())
+            return boost::lexical_cast<T>(settings.find(new_id)->second.str);
+        else
+            settings[id(name)] = std::to_string(defaultValue);
+
+        return defaultValue;
+    }
+
+    template <typename T> T setting(const char *name) const
+    {
+        IdString new_id = id(name);
+        if (settings.find(new_id) != settings.end())
+            return boost::lexical_cast<T>(settings.find(new_id)->second.str);
+        else
+            throw std::runtime_error("settings does not exists");
+    }
 };
 
 NEXTPNR_NAMESPACE_END
diff --git a/common/place_common.cc b/common/place_common.cc
index 73a320d0..cb9799b5 100644
--- a/common/place_common.cc
+++ b/common/place_common.cc
@@ -37,7 +37,7 @@ wirelen_t get_net_metric(const Context *ctx, const NetInfo *net, MetricType type
     if (driver_gb)
         return 0;
     int clock_count;
-    bool timing_driven = ctx->timing_driven && type == MetricType::COST &&
+    bool timing_driven = ctx->setting<bool>("timing_driven") && type == MetricType::COST &&
                          ctx->getPortTimingClass(driver_cell, net->driver.port, clock_count) != TMG_IGNORE;
     delay_t negative_slack = 0;
     delay_t worst_slack = std::numeric_limits<delay_t>::max();
diff --git a/common/placer1.cc b/common/placer1.cc
index a8ddd8a6..cb7ae847 100644
--- a/common/placer1.cc
+++ b/common/placer1.cc
@@ -219,7 +219,7 @@ class SAPlacer
             if ((placed_cells - constr_placed_cells) % 500 != 0)
                 log_info("  initial placement placed %d/%d cells\n", int(placed_cells - constr_placed_cells),
                          int(autoplaced.size()));
-            if (cfg.budgetBased && ctx->slack_redist_iter > 0)
+            if (cfg.budgetBased && cfg.slack_redist_iter > 0)
                 assign_budget(ctx);
             ctx->yield();
             auto iplace_end = std::chrono::high_resolution_clock::now();
@@ -370,16 +370,16 @@ class SAPlacer
                     ctx->shuffle(autoplaced);
 
                     // Legalisation is a big change so force a slack redistribution here
-                    if (ctx->slack_redist_iter > 0 && cfg.budgetBased)
+                    if (cfg.slack_redist_iter > 0 && cfg.budgetBased)
                         assign_budget(ctx, true /* quiet */);
                 }
                 require_legal = false;
-            } else if (cfg.budgetBased && ctx->slack_redist_iter > 0 && iter % ctx->slack_redist_iter == 0) {
+            } else if (cfg.budgetBased && cfg.slack_redist_iter > 0 && iter % cfg.slack_redist_iter == 0) {
                 assign_budget(ctx, true /* quiet */);
             }
 
             // Invoke timing analysis to obtain criticalities
-            if (!cfg.budgetBased && ctx->timing_driven)
+            if (!cfg.budgetBased && cfg.timing_driven)
                 get_criticalities(ctx, &net_crit);
             // Need to rebuild costs after criticalities change
             setup_costs();
@@ -804,7 +804,7 @@ class SAPlacer
             if (ignore_net(ni))
                 continue;
             net_bounds[ni->udata] = get_net_bounds(ni);
-            if (ctx->timing_driven && int(ni->users.size()) < cfg.timingFanoutThresh)
+            if (cfg.timing_driven && int(ni->users.size()) < cfg.timingFanoutThresh)
                 for (size_t i = 0; i < ni->users.size(); i++)
                     net_arc_tcost[ni->udata][i] = get_timing_cost(ni, i);
         }
@@ -1021,7 +1021,7 @@ class SAPlacer
                 }
             }
 
-            if (ctx->timing_driven && int(pn->users.size()) < cfg.timingFanoutThresh) {
+            if (cfg.timing_driven && int(pn->users.size()) < cfg.timingFanoutThresh) {
                 // Output ports - all arcs change timing
                 if (port.second.type == PORT_OUT) {
                     int cc;
@@ -1061,7 +1061,7 @@ class SAPlacer
             if (md.already_bounds_changed_x[bc] == MoveChangeData::NO_CHANGE)
                 md.wirelen_delta += md.new_net_bounds[bc].hpwl() - net_bounds[bc].hpwl();
 
-        if (ctx->timing_driven) {
+        if (cfg.timing_driven) {
             for (const auto &tc : md.changed_arcs) {
                 double old_cost = net_arc_tcost.at(tc.first).at(tc.second);
                 double new_cost = get_timing_cost(net_by_udata.at(tc.first), tc.second);
@@ -1131,13 +1131,15 @@ class SAPlacer
     Placer1Cfg cfg;
 };
 
-Placer1Cfg::Placer1Cfg(Context *ctx) : Settings(ctx)
+Placer1Cfg::Placer1Cfg(Context *ctx)
 {
-    constraintWeight = get<float>("placer1/constraintWeight", 10);
-    minBelsForGridPick = get<int>("placer1/minBelsForGridPick", 64);
-    budgetBased = get<bool>("placer1/budgetBased", false);
-    startTemp = get<float>("placer1/startTemp", 1);
+    constraintWeight = ctx->setting<float>("placer1/constraintWeight", 10);
+    minBelsForGridPick = ctx->setting<int>("placer1/minBelsForGridPick", 64);
+    budgetBased = ctx->setting<bool>("placer1/budgetBased", false);
+    startTemp = ctx->setting<float>("placer1/startTemp", 1);
     timingFanoutThresh = std::numeric_limits<int>::max();
+    timing_driven = ctx->setting<bool>("timing_driven");
+    slack_redist_iter = ctx->setting<int>("slack_redist_iter");
 }
 
 bool placer1(Context *ctx, Placer1Cfg cfg)
diff --git a/common/placer1.h b/common/placer1.h
index 4c7c7339..1356db3e 100644
--- a/common/placer1.h
+++ b/common/placer1.h
@@ -19,12 +19,12 @@
 #ifndef PLACE_H
 #define PLACE_H
 
+#include "log.h"
 #include "nextpnr.h"
-#include "settings.h"
 
 NEXTPNR_NAMESPACE_BEGIN
 
-struct Placer1Cfg : public Settings
+struct Placer1Cfg
 {
     Placer1Cfg(Context *ctx);
     float constraintWeight;
@@ -32,6 +32,8 @@ struct Placer1Cfg : public Settings
     bool budgetBased;
     float startTemp;
     int timingFanoutThresh;
+    bool timing_driven;
+    int slack_redist_iter;
 };
 
 extern bool placer1(Context *ctx, Placer1Cfg cfg);
diff --git a/common/placer_heap.cc b/common/placer_heap.cc
index f9b639f8..cd800085 100644
--- a/common/placer_heap.cc
+++ b/common/placer_heap.cc
@@ -234,7 +234,7 @@ class HeAPPlacer
                          std::chrono::duration<double>(run_stopt - run_startt).count());
             }
 
-            if (ctx->timing_driven)
+            if (cfg.timing_driven)
                 get_criticalities(ctx, &net_crit);
 
             if (legal_hpwl < best_hpwl) {
@@ -1516,11 +1516,12 @@ int HeAPPlacer::CutSpreader::seq = 0;
 
 bool placer_heap(Context *ctx, PlacerHeapCfg cfg) { return HeAPPlacer(ctx, cfg).place(); }
 
-PlacerHeapCfg::PlacerHeapCfg(Context *ctx) : Settings(ctx)
+PlacerHeapCfg::PlacerHeapCfg(Context *ctx)
 {
-    alpha = get<float>("placerHeap/alpha", 0.1);
-    criticalityExponent = get<int>("placerHeap/criticalityExponent", 2);
-    timingWeight = get<int>("placerHeap/timingWeight", 10);
+    alpha = ctx->setting<float>("placerHeap/alpha", 0.1);
+    criticalityExponent = ctx->setting<int>("placerHeap/criticalityExponent", 2);
+    timingWeight = ctx->setting<int>("placerHeap/timingWeight", 10);
+    timing_driven = ctx->setting<bool>("timing_driven");
 }
 
 NEXTPNR_NAMESPACE_END
@@ -1538,7 +1539,7 @@ bool placer_heap(Context *ctx, PlacerHeapCfg cfg)
     return false;
 }
 
-PlacerHeapCfg::PlacerHeapCfg(Context *ctx) : Settings(ctx) {}
+PlacerHeapCfg::PlacerHeapCfg(Context *ctx) {}
 
 NEXTPNR_NAMESPACE_END
 
diff --git a/common/placer_heap.h b/common/placer_heap.h
index 841aa0d9..a018aef8 100644
--- a/common/placer_heap.h
+++ b/common/placer_heap.h
@@ -26,18 +26,19 @@
 
 #ifndef PLACER_HEAP_H
 #define PLACER_HEAP_H
+#include "log.h"
 #include "nextpnr.h"
-#include "settings.h"
 
 NEXTPNR_NAMESPACE_BEGIN
 
-struct PlacerHeapCfg : public Settings
+struct PlacerHeapCfg
 {
     PlacerHeapCfg(Context *ctx);
 
     float alpha;
     float criticalityExponent;
     float timingWeight;
+    bool timing_driven;
 
     std::unordered_set<IdString> ioBufTypes;
 };
diff --git a/common/project.cc b/common/project.cc
deleted file mode 100644
index b0ebe961..00000000
--- a/common/project.cc
+++ /dev/null
@@ -1,144 +0,0 @@
-/*
- *  nextpnr -- Next Generation Place and Route
- *
- *  Copyright (C) 2018  Miodrag Milanovic <miodrag@symbioticeda.com>
- *
- *  Permission to use, copy, modify, and/or distribute this software for any
- *  purpose with or without fee is hereby granted, provided that the above
- *  copyright notice and this permission notice appear in all copies.
- *
- *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
- *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
- *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
- *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
- *
- */
-
-#include "project.h"
-#include <algorithm>
-#include <boost/filesystem/convenience.hpp>
-#include <boost/property_tree/json_parser.hpp>
-#include <fstream>
-#include "jsonparse.h"
-#include "log.h"
-
-NEXTPNR_NAMESPACE_BEGIN
-
-boost::filesystem::path make_relative(boost::filesystem::path child, boost::filesystem::path parent)
-{
-    boost::filesystem::path::const_iterator parentIter = parent.begin();
-    boost::filesystem::path::const_iterator childIter = child.begin();
-
-    while (parentIter != parent.end() && childIter != child.end() && (*childIter) == (*parentIter)) {
-        ++childIter;
-        ++parentIter;
-    }
-
-    boost::filesystem::path finalPath;
-    while (parentIter != parent.end()) {
-        finalPath /= "..";
-        ++parentIter;
-    }
-
-    while (childIter != child.end()) {
-        finalPath /= *childIter;
-        ++childIter;
-    }
-
-    return finalPath;
-}
-
-void ProjectHandler::save(Context *ctx, std::string filename)
-{
-    try {
-        boost::filesystem::path proj(filename);
-        std::ofstream f(filename);
-        pt::ptree root;
-
-        log_info("Saving project %s...\n", filename.c_str());
-        log_break();
-
-        root.put("project.version", 1);
-        root.put("project.name", boost::filesystem::basename(filename));
-        root.put("project.arch.name", ctx->archId().c_str(ctx));
-        root.put("project.arch.type", ctx->archArgsToId(ctx->archArgs()).c_str(ctx));
-        std::string fn = ctx->settings[ctx->id("input/json")];
-        root.put("project.input.json", make_relative(fn, proj.parent_path()).string());
-        root.put("project.params.freq", int(ctx->target_freq / 1e6));
-        root.put("project.params.seed", ctx->rngstate);
-        saveArch(ctx, root, proj.parent_path().string());
-        for (auto const &item : ctx->settings) {
-            std::string path = "project.settings.";
-            path += item.first.c_str(ctx);
-            std::replace(path.begin(), path.end(), '/', '.');
-            root.put(path, item.second);
-        }
-        pt::write_json(f, root);
-    } catch (...) {
-        log_error("Error saving project file.\n");
-    }
-}
-
-void addSettings(Context *ctx, std::string path, pt::ptree sub)
-{
-    for (pt::ptree::value_type &v : sub) {
-        const std::string &key = v.first;
-        const boost::property_tree::ptree &subtree = v.second;
-        if (subtree.empty()) {
-            ctx->settings.emplace(ctx->id(path + key), subtree.get_value<std::string>().c_str());
-        } else {
-            addSettings(ctx, path + key + "/", subtree);
-        }
-    }
-}
-
-std::unique_ptr<Context> ProjectHandler::load(std::string filename)
-{
-    std::unique_ptr<Context> ctx;
-    try {
-        pt::ptree root;
-        boost::filesystem::path proj(filename);
-        pt::read_json(filename, root);
-        log_info("Loading project %s...\n", filename.c_str());
-        log_break();
-
-        int version = root.get<int>("project.version");
-        if (version != 1)
-            log_error("Wrong project format version.\n");
-
-        ctx = createContext(root);
-
-        std::string arch_name = root.get<std::string>("project.arch.name");
-        if (arch_name != ctx->archId().c_str(ctx.get()))
-            log_error("Unsuported project architecture.\n");
-
-        auto project = root.get_child("project");
-        auto input = project.get_child("input");
-        std::string fn = input.get<std::string>("json");
-        boost::filesystem::path json = proj.parent_path() / fn;
-        std::ifstream f(json.string());
-        if (!parse_json_file(f, fn, ctx.get()))
-            log_error("Loading design failed.\n");
-
-        if (project.count("params")) {
-            auto params = project.get_child("params");
-            if (params.count("freq"))
-                ctx->target_freq = params.get<double>("freq") * 1e6;
-            if (params.count("seed"))
-                ctx->rngseed(params.get<uint64_t>("seed"));
-        }
-        if (project.count("settings")) {
-            addSettings(ctx.get(), "", project.get_child("settings"));
-        }
-
-        loadArch(ctx.get(), root, proj.parent_path().string());
-    } catch (...) {
-        log_error("Error loading project file.\n");
-    }
-    return ctx;
-}
-
-NEXTPNR_NAMESPACE_END
diff --git a/common/project.h b/common/project.h
deleted file mode 100644
index 03b4b7b5..00000000
--- a/common/project.h
+++ /dev/null
@@ -1,45 +0,0 @@
-/*
- *  nextpnr -- Next Generation Place and Route
- *
- *  Copyright (C) 2018  Miodrag Milanovic <miodrag@symbioticeda.com>
- *
- *  Permission to use, copy, modify, and/or distribute this software for any
- *  purpose with or without fee is hereby granted, provided that the above
- *  copyright notice and this permission notice appear in all copies.
- *
- *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
- *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
- *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
- *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
- *
- */
-
-#ifndef PROJECT_H
-#define PROJECT_H
-
-#include <boost/filesystem/convenience.hpp>
-#include <boost/property_tree/ptree.hpp>
-#include "nextpnr.h"
-
-NEXTPNR_NAMESPACE_BEGIN
-
-namespace pt = boost::property_tree;
-
-struct ProjectHandler
-{
-    void save(Context *ctx, std::string filename);
-    std::unique_ptr<Context> load(std::string filename);
-    // implemented per arch
-    void saveArch(Context *ctx, pt::ptree &root, std::string path);
-    std::unique_ptr<Context> createContext(pt::ptree &root);
-    void loadArch(Context *ctx, pt::ptree &root, std::string path);
-};
-
-boost::filesystem::path make_relative(boost::filesystem::path child, boost::filesystem::path parent);
-
-NEXTPNR_NAMESPACE_END
-
-#endif // PROJECT_H
diff --git a/common/pybindings.cc b/common/pybindings.cc
index 60f87e27..52dd9717 100644
--- a/common/pybindings.cc
+++ b/common/pybindings.cc
@@ -122,7 +122,7 @@ BOOST_PYTHON_MODULE(MODULE_NAME)
             .value("PORT_INOUT", PORT_INOUT)
             .export_values();
 
-    typedef std::unordered_map<IdString, std::string> AttrMap;
+    typedef std::unordered_map<IdString, Property> AttrMap;
     typedef std::unordered_map<IdString, PortInfo> PortMap;
     typedef std::unordered_map<IdString, IdString> PinMap;
     typedef std::unordered_map<IdString, std::unique_ptr<Region>> RegionMap;
diff --git a/common/router1.cc b/common/router1.cc
index 28a422c8..02c817c7 100644
--- a/common/router1.cc
+++ b/common/router1.cc
@@ -733,12 +733,12 @@ struct Router1
 
 NEXTPNR_NAMESPACE_BEGIN
 
-Router1Cfg::Router1Cfg(Context *ctx) : Settings(ctx)
+Router1Cfg::Router1Cfg(Context *ctx)
 {
-    maxIterCnt = get<int>("router1/maxIterCnt", 200);
-    cleanupReroute = get<bool>("router1/cleanupReroute", true);
-    fullCleanupReroute = get<bool>("router1/fullCleanupReroute", true);
-    useEstimate = get<bool>("router1/useEstimate", true);
+    maxIterCnt = ctx->setting<int>("router1/maxIterCnt", 200);
+    cleanupReroute = ctx->setting<bool>("router1/cleanupReroute", true);
+    fullCleanupReroute = ctx->setting<bool>("router1/fullCleanupReroute", true);
+    useEstimate = ctx->setting<bool>("router1/useEstimate", true);
 
     wireRipupPenalty = ctx->getRipupDelayPenalty();
     netRipupPenalty = 10 * ctx->getRipupDelayPenalty();
diff --git a/common/router1.h b/common/router1.h
index 80d7aa96..a37784f4 100644
--- a/common/router1.h
+++ b/common/router1.h
@@ -20,12 +20,11 @@
 #ifndef ROUTER1_H
 #define ROUTER1_H
 
+#include "log.h"
 #include "nextpnr.h"
-#include "settings.h"
-
 NEXTPNR_NAMESPACE_BEGIN
 
-struct Router1Cfg : Settings
+struct Router1Cfg
 {
     Router1Cfg(Context *ctx);
 
diff --git a/common/settings.h b/common/settings.h
deleted file mode 100644
index b57947c9..00000000
--- a/common/settings.h
+++ /dev/null
@@ -1,74 +0,0 @@
-/*
- *  nextpnr -- Next Generation Place and Route
- *
- *  Copyright (C) 2018  Miodrag Milanovic <miodrag@symbioticeda.com>
- *
- *  Permission to use, copy, modify, and/or distribute this software for any
- *  purpose with or without fee is hereby granted, provided that the above
- *  copyright notice and this permission notice appear in all copies.
- *
- *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
- *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
- *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
- *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
- *
- */
-#ifndef SETTINGS_H
-#define SETTINGS_H
-
-#include <boost/lexical_cast.hpp>
-#include "log.h"
-#include "nextpnr.h"
-
-NEXTPNR_NAMESPACE_BEGIN
-
-class Settings
-{
-  public:
-    explicit Settings(Context *ctx) : ctx(ctx) {}
-
-    template <typename T> T get(const char *name, T defaultValue)
-    {
-        try {
-            IdString id = ctx->id(name);
-            auto pair = ctx->settings.emplace(id, std::to_string(defaultValue));
-            if (!pair.second) {
-                return boost::lexical_cast<T>(pair.first->second);
-            }
-
-        } catch (boost::bad_lexical_cast &) {
-            log_error("Problem reading setting %s, using default value\n", name);
-        }
-        return defaultValue;
-    }
-
-    template <typename T> void set(const char *name, T value);
-
-  private:
-    Context *ctx;
-};
-
-template <typename T> inline void Settings::set(const char *name, T value)
-{
-    IdString id = ctx->id(name);
-    auto pair = ctx->settings.emplace(id, std::to_string(value));
-    if (!pair.second) {
-        ctx->settings[pair.first->first] = value;
-    }
-}
-
-template <> inline void Settings::set<std::string>(const char *name, std::string value)
-{
-    IdString id = ctx->id(name);
-    auto pair = ctx->settings.emplace(id, value);
-    if (!pair.second) {
-        ctx->settings[pair.first->first] = value;
-    }
-}
-
-NEXTPNR_NAMESPACE_END
-
-#endif // SETTINGS_H
diff --git a/common/timing.cc b/common/timing.cc
index e67ac231..599d6dbd 100644
--- a/common/timing.cc
+++ b/common/timing.cc
@@ -113,7 +113,7 @@ struct Timing
 
     Timing(Context *ctx, bool net_delays, bool update, CriticalPathMap *crit_path = nullptr,
            DelayFrequency *slack_histogram = nullptr, NetCriticalityMap *net_crit = nullptr)
-            : ctx(ctx), net_delays(net_delays), update(update), min_slack(1.0e12 / ctx->target_freq),
+            : ctx(ctx), net_delays(net_delays), update(update), min_slack(1.0e12 / ctx->setting<float>("target_freq")),
               crit_path(crit_path), slack_histogram(slack_histogram), net_crit(net_crit),
               async_clock(ctx->id("$async$"))
     {
@@ -121,7 +121,7 @@ struct Timing
 
     delay_t walk_paths()
     {
-        const auto clk_period = ctx->getDelayFromNS(1.0e9 / ctx->target_freq).maxDelay();
+        const auto clk_period = ctx->getDelayFromNS(1.0e9 / ctx->setting<float>("target_freq")).maxDelay();
 
         // First, compute the topographical order of nets to walk through the circuit, assuming it is a _acyclic_ graph
         // TODO(eddieh): Handle the case where it is cyclic, e.g. combinatorial loops
@@ -658,17 +658,18 @@ void assign_budget(Context *ctx, bool quiet)
 {
     if (!quiet) {
         log_break();
-        log_info("Annotating ports with timing budgets for target frequency %.2f MHz\n", ctx->target_freq / 1e6);
+        log_info("Annotating ports with timing budgets for target frequency %.2f MHz\n",
+                 ctx->setting<float>("target_freq") / 1e6);
     }
 
-    Timing timing(ctx, ctx->slack_redist_iter > 0 /* net_delays */, true /* update */);
+    Timing timing(ctx, ctx->setting<int>("slack_redist_iter") > 0 /* net_delays */, true /* update */);
     timing.assign_budget();
 
     if (!quiet || ctx->verbose) {
         for (auto &net : ctx->nets) {
             for (auto &user : net.second->users) {
                 // Post-update check
-                if (!ctx->auto_freq && user.budget < 0)
+                if (!ctx->setting<bool>("auto_freq") && user.budget < 0)
                     log_info("port %s.%s, connected to net '%s', has negative "
                              "timing budget of %fns\n",
                              user.cell->name.c_str(ctx), user.port.c_str(ctx), net.first.c_str(ctx),
@@ -684,13 +685,14 @@ void assign_budget(Context *ctx, bool quiet)
 
     // For slack redistribution, if user has not specified a frequency dynamically adjust the target frequency to be the
     // currently achieved maximum
-    if (ctx->auto_freq && ctx->slack_redist_iter > 0) {
-        delay_t default_slack = delay_t((1.0e9 / ctx->getDelayNS(1)) / ctx->target_freq);
-        ctx->target_freq = 1.0e9 / ctx->getDelayNS(default_slack - timing.min_slack);
+    if (ctx->setting<bool>("auto_freq") && ctx->setting<int>("slack_redist_iter") > 0) {
+        delay_t default_slack = delay_t((1.0e9 / ctx->getDelayNS(1)) / ctx->setting<float>("target_freq"));
+        ctx->settings[ctx->id("target_freq")] =
+                std::to_string(1.0e9 / ctx->getDelayNS(default_slack - timing.min_slack));
         if (ctx->verbose)
             log_info("minimum slack for this assign = %.2f ns, target Fmax for next "
                      "update = %.2f MHz\n",
-                     ctx->getDelayNS(timing.min_slack), ctx->target_freq / 1e6);
+                     ctx->getDelayNS(timing.min_slack), ctx->setting<float>("target_freq") / 1e6);
     }
 
     if (!quiet)
@@ -897,7 +899,7 @@ void timing_analysis(Context *ctx, bool print_histogram, bool print_fmax, bool p
         for (auto &clock : clock_reports) {
             const auto &clock_name = clock.first.str(ctx);
             const int width = max_width - clock_name.size();
-            float target = ctx->target_freq / 1e6;
+            float target = ctx->setting<float>("target_freq") / 1e6;
             if (ctx->nets.at(clock.first)->clkconstr)
                 target = 1000 / ctx->getDelayNS(ctx->nets.at(clock.first)->clkconstr->period.minDelay());
 
diff --git a/common/timing_opt.h b/common/timing_opt.h
index ceb35c71..775d9596 100644
--- a/common/timing_opt.h
+++ b/common/timing_opt.h
@@ -17,14 +17,14 @@
  *
  */
 
+#include "log.h"
 #include "nextpnr.h"
-#include "settings.h"
 
 NEXTPNR_NAMESPACE_BEGIN
 
-struct TimingOptCfg : public Settings
+struct TimingOptCfg
 {
-    TimingOptCfg(Context *ctx) : Settings(ctx) {}
+    TimingOptCfg(Context *ctx) {}
 
     // The timing optimiser will *only* optimise cells of these types
     // Normally these would only be logic cells (or tiles if applicable), the algorithm makes little sense
diff --git a/ecp5/arch.cc b/ecp5/arch.cc
index 91db8d81..5b3cc660 100644
--- a/ecp5/arch.cc
+++ b/ecp5/arch.cc
@@ -526,12 +526,15 @@ bool Arch::place()
     }
 
     permute_luts();
+    getCtx()->settings[getCtx()->id("place")] = "1";
+    archInfoToAttributes();
     return true;
 }
 
 bool Arch::route()
 {
     route_ecp5_globals(getCtx());
+    assignArchInfo();
     assign_budget(getCtx(), true);
 
     bool result = router1(getCtx(), Router1Cfg(getCtx()));
@@ -560,6 +563,8 @@ bool Arch::route()
     log_info("       base %d adder %d\n", speed_grade->pip_classes[locInfo(slowest_pip)->pip_data[slowest_pip.index].timing_class].max_base_delay,
              speed_grade->pip_classes[locInfo(slowest_pip)->pip_data[slowest_pip.index].timing_class].max_fanout_adder);
 #endif
+    getCtx()->settings[getCtx()->id("route")] = "1";
+    archInfoToAttributes();
     return result;
 }
 
diff --git a/ecp5/globals.cc b/ecp5/globals.cc
index fae2c683..026f3a85 100644
--- a/ecp5/globals.cc
+++ b/ecp5/globals.cc
@@ -382,7 +382,7 @@ class Ecp5GlobalRouter
         glbnet->name = ctx->id("$glbnet$" + net->name.str(ctx));
         glbnet->driver.cell = dcc.get();
         glbnet->driver.port = id_CLKO;
-        glbnet->is_global = true;
+        glbnet->attrs[ctx->id("ECP5_IS_GLOBAL")] = "1";
         dcc->ports[id_CLKO].net = glbnet.get();
 
         std::vector<PortRef> keep_users;
diff --git a/ecp5/lpf.cc b/ecp5/lpf.cc
index 4ac70fc9..ceb1d7ae 100644
--- a/ecp5/lpf.cc
+++ b/ecp5/lpf.cc
@@ -133,7 +133,7 @@ bool Arch::applyLPF(std::string filename, std::istream &in)
         }
         if (!isempty(linebuf))
             log_error("unexpected end of LPF file\n");
-        settings.emplace(id("input/lpf"), filename);
+        settings[id("input/lpf")] = filename;
         return true;
     } catch (log_execution_error_exception) {
         return false;
diff --git a/ecp5/main.cc b/ecp5/main.cc
index bb18aa58..75126cea 100644
--- a/ecp5/main.cc
+++ b/ecp5/main.cc
@@ -34,7 +34,7 @@ class ECP5CommandHandler : public CommandHandler
   public:
     ECP5CommandHandler(int argc, char **argv);
     virtual ~ECP5CommandHandler(){};
-    std::unique_ptr<Context> createContext() override;
+    std::unique_ptr<Context> createContext(std::unordered_map<std::string, Property> &values) override;
     void setupArchContext(Context *ctx) override{};
     void customAfterLoad(Context *ctx) override;
     void validate() override;
@@ -98,9 +98,25 @@ void ECP5CommandHandler::customBitstream(Context *ctx)
     write_bitstream(ctx, basecfg, textcfg);
 }
 
-std::unique_ptr<Context> ECP5CommandHandler::createContext()
+static std::string speedString(ArchArgs::SpeedGrade speed)
 {
-    chipArgs.type = ArchArgs::LFE5U_45F;
+    switch (speed) {
+    case ArchArgs::SPEED_6:
+        return "6";
+    case ArchArgs::SPEED_7:
+        return "7";
+    case ArchArgs::SPEED_8:
+        return "8";
+    case ArchArgs::SPEED_8_5G:
+        return "8";
+    }
+    return "";
+}
+
+std::unique_ptr<Context> ECP5CommandHandler::createContext(std::unordered_map<std::string, Property> &values)
+{
+    ArchArgs chipArgs;
+    chipArgs.type = ArchArgs::NONE;
 
     if (vm.count("25k"))
         chipArgs.type = ArchArgs::LFE5U_25F;
@@ -122,34 +138,96 @@ std::unique_ptr<Context> ECP5CommandHandler::createContext()
         chipArgs.type = ArchArgs::LFE5UM5G_85F;
     if (vm.count("package"))
         chipArgs.package = vm["package"].as<std::string>();
-    else
+
+    if (vm.count("speed")) {
+        int speed = vm["speed"].as<int>();
+        switch (speed) {
+        case 6:
+            chipArgs.speed = ArchArgs::SPEED_6;
+            break;
+        case 7:
+            chipArgs.speed = ArchArgs::SPEED_7;
+            break;
+        case 8:
+            chipArgs.speed = ArchArgs::SPEED_8;
+            break;
+        default:
+            log_error("Unsupported speed grade '%d'\n", speed);
+        }
+    } else {
+        if (chipArgs.type == ArchArgs::LFE5UM5G_25F || chipArgs.type == ArchArgs::LFE5UM5G_45F ||
+            chipArgs.type == ArchArgs::LFE5UM5G_85F) {
+            chipArgs.speed = ArchArgs::SPEED_8;
+        } else
+            chipArgs.speed = ArchArgs::SPEED_6;
+    }
+    if (values.find("arch.name") != values.end()) {
+        std::string arch_name = values["arch.name"].str;
+        if (arch_name != "ecp5")
+            log_error("Unsuported architecture '%s'.\n", arch_name.c_str());
+    }
+    if (values.find("arch.type") != values.end()) {
+        std::string arch_type = values["arch.type"].str;
+        if (chipArgs.type != ArchArgs::NONE)
+            log_error("Overriding architecture is unsuported.\n");
+
+        if (arch_type == "lfe5u_25f")
+            chipArgs.type = ArchArgs::LFE5U_25F;
+        if (arch_type == "lfe5u_45f")
+            chipArgs.type = ArchArgs::LFE5U_45F;
+        if (arch_type == "lfe5u_85f")
+            chipArgs.type = ArchArgs::LFE5U_85F;
+        if (arch_type == "lfe5um_25f")
+            chipArgs.type = ArchArgs::LFE5UM_25F;
+        if (arch_type == "lfe5um_45f")
+            chipArgs.type = ArchArgs::LFE5UM_45F;
+        if (arch_type == "lfe5um_85f")
+            chipArgs.type = ArchArgs::LFE5UM_85F;
+        if (arch_type == "lfe5um5g_25f")
+            chipArgs.type = ArchArgs::LFE5UM5G_25F;
+        if (arch_type == "lfe5um5g_45f")
+            chipArgs.type = ArchArgs::LFE5UM5G_45F;
+        if (arch_type == "lfe5um5g_85f")
+            chipArgs.type = ArchArgs::LFE5UM5G_85F;
+
+        if (chipArgs.type == ArchArgs::NONE)
+            log_error("Unsuported FPGA type '%s'.\n", arch_type.c_str());
+    }
+    if (values.find("arch.package") != values.end()) {
+        if (vm.count("package"))
+            log_error("Overriding architecture is unsuported.\n");
+        chipArgs.package = values["arch.package"].str;
+    }
+    if (values.find("arch.speed") != values.end()) {
+        std::string arch_speed = values["arch.speed"].str;
+        if (arch_speed == "6")
+            chipArgs.speed = ArchArgs::SPEED_6;
+        else if (arch_speed == "7")
+            chipArgs.speed = ArchArgs::SPEED_7;
+        else if (arch_speed == "8")
+            chipArgs.speed = ArchArgs::SPEED_8;
+        else
+            log_error("Unsuported speed '%s'.\n", arch_speed.c_str());
+    }
+    if (chipArgs.type == ArchArgs::NONE)
+        chipArgs.type = ArchArgs::LFE5U_45F;
+
+    if (chipArgs.package.empty())
         chipArgs.package = "CABGA381";
+
     if (chipArgs.type == ArchArgs::LFE5UM5G_25F || chipArgs.type == ArchArgs::LFE5UM5G_45F ||
         chipArgs.type == ArchArgs::LFE5UM5G_85F) {
-        if (vm.count("speed") && vm["speed"].as<int>() != 8)
+        if (chipArgs.speed != ArchArgs::SPEED_8)
             log_error("Only speed grade 8 is available for 5G parts\n");
-        chipArgs.speed = ArchArgs::SPEED_8_5G;
-    } else {
-        if (vm.count("speed")) {
-            int speed = vm["speed"].as<int>();
-            switch (speed) {
-            case 6:
-                chipArgs.speed = ArchArgs::SPEED_6;
-                break;
-            case 7:
-                chipArgs.speed = ArchArgs::SPEED_7;
-                break;
-            case 8:
-                chipArgs.speed = ArchArgs::SPEED_8;
-                break;
-            default:
-                log_error("Unsupported speed grade '%d'\n", speed);
-            }
-        } else {
-            chipArgs.speed = ArchArgs::SPEED_6;
-        }
+        else
+            chipArgs.speed = ArchArgs::SPEED_8_5G;
     }
+
     auto ctx = std::unique_ptr<Context>(new Context(chipArgs));
+    for (auto &val : values)
+        ctx->settings[ctx->id(val.first)] = val.second;
+    ctx->settings[ctx->id("arch.package")] = ctx->archArgs().package;
+    ctx->settings[ctx->id("arch.speed")] = speedString(ctx->archArgs().speed);
     return ctx;
 }
 
diff --git a/ecp5/pack.cc b/ecp5/pack.cc
index 7f00de1f..9e2bc326 100644
--- a/ecp5/pack.cc
+++ b/ecp5/pack.cc
@@ -1508,7 +1508,8 @@ class Ecp5Packer
 
                 std::unique_ptr<NetInfo> promoted_ecknet(new NetInfo);
                 promoted_ecknet->name = eckname;
-                promoted_ecknet->is_global = true; // Prevents router etc touching this special net
+                promoted_ecknet->attrs[ctx->id("ECP5_IS_GLOBAL")] =
+                        "1"; // Prevents router etc touching this special net
                 eclk.buf = promoted_ecknet.get();
                 NPNR_ASSERT(!ctx->nets.count(eckname));
                 ctx->nets[eckname] = std::move(promoted_ecknet);
@@ -1654,7 +1655,7 @@ class Ecp5Packer
                                       port.c_str(ctx), ci->name.c_str(ctx), usr.port.c_str(ctx),
                                       usr.cell->name.c_str(ctx));
                     }
-                    pn->is_global = true;
+                    pn->attrs[ctx->id("ECP5_IS_GLOBAL")] = "1";
                 }
 
                 for (auto zport :
@@ -1896,7 +1897,7 @@ class Ecp5Packer
                 iol->params[ctx->id("DELAY.DEL_VALUE")] =
                         std::to_string(lookup_delay(str_or_default(ci->params, ctx->id("DEL_MODE"), "USER_DEFINED")));
                 if (ci->params.count(ctx->id("DEL_VALUE")) &&
-                    ci->params.at(ctx->id("DEL_VALUE")).substr(0, 5) != "DELAY")
+                    std::string(ci->params.at(ctx->id("DEL_VALUE"))).substr(0, 5) != "DELAY")
                     iol->params[ctx->id("DELAY.DEL_VALUE")] = ci->params.at(ctx->id("DEL_VALUE"));
                 if (ci->ports.count(id_LOADN))
                     replace_port(ci, id_LOADN, iol, id_LOADN);
@@ -2428,6 +2429,8 @@ bool Arch::pack()
         Ecp5Packer(ctx).pack();
         log_info("Checksum: 0x%08x\n", ctx->checksum());
         assignArchInfo();
+        ctx->settings[ctx->id("pack")] = "1";
+        archInfoToAttributes();
         return true;
     } catch (log_execution_error_exception) {
         assignArchInfo();
@@ -2469,6 +2472,9 @@ void Arch::assignArchInfo()
                 ci->sliceInfo.has_l6mux = true;
         }
     }
+    for (auto net : sorted(nets)) {
+        net.second->is_global = bool_or_default(net.second->attrs, id("ECP5_IS_GLOBAL"));
+    }
 }
 
 NEXTPNR_NAMESPACE_END
diff --git a/ecp5/project.cc b/ecp5/project.cc
deleted file mode 100644
index 43318b1c..00000000
--- a/ecp5/project.cc
+++ /dev/null
@@ -1,55 +0,0 @@
-/*
- *  nextpnr -- Next Generation Place and Route
- *
- *  Copyright (C) 2018  Miodrag Milanovic <miodrag@symbioticeda.com>
- *
- *  Permission to use, copy, modify, and/or distribute this software for any
- *  purpose with or without fee is hereby granted, provided that the above
- *  copyright notice and this permission notice appear in all copies.
- *
- *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
- *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
- *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
- *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
- *
- */
-
-#include "project.h"
-#include <boost/filesystem/convenience.hpp>
-#include <boost/property_tree/json_parser.hpp>
-#include <fstream>
-#include "log.h"
-
-NEXTPNR_NAMESPACE_BEGIN
-
-void ProjectHandler::saveArch(Context *ctx, pt::ptree &root, std::string path)
-{
-    root.put("project.arch.package", ctx->archArgs().package);
-    root.put("project.arch.speed", ctx->archArgs().speed);
-}
-
-std::unique_ptr<Context> ProjectHandler::createContext(pt::ptree &root)
-{
-    ArchArgs chipArgs;
-    std::string arch_type = root.get<std::string>("project.arch.type");
-    if (arch_type == "25k") {
-        chipArgs.type = ArchArgs::LFE5U_25F;
-    }
-    if (arch_type == "45k") {
-        chipArgs.type = ArchArgs::LFE5U_45F;
-    }
-    if (arch_type == "85k") {
-        chipArgs.type = ArchArgs::LFE5U_85F;
-    }
-    chipArgs.package = root.get<std::string>("project.arch.package");
-    chipArgs.speed = ArchArgs::SpeedGrade(root.get<int>("project.arch.speed"));
-
-    return std::unique_ptr<Context>(new Context(chipArgs));
-}
-
-void ProjectHandler::loadArch(Context *ctx, pt::ptree &root, std::string path) {}
-
-NEXTPNR_NAMESPACE_END
diff --git a/generic/arch.cc b/generic/arch.cc
index 5617fa63..fa3c825d 100644
--- a/generic/arch.cc
+++ b/generic/arch.cc
@@ -496,13 +496,22 @@ bool Arch::place()
     std::string placer = str_or_default(settings, id("placer"), defaultPlacer);
     // FIXME: No HeAP because it needs a list of IO buffers
     if (placer == "sa") {
-        return placer1(getCtx(), Placer1Cfg(getCtx()));
+        bool retVal = placer1(getCtx(), Placer1Cfg(getCtx()));
+        getCtx()->settings[getCtx()->id("place")] = "1";
+        archInfoToAttributes();
+        return retVal;
     } else {
         log_error("Generic architecture does not support placer '%s'\n", placer.c_str());
     }
 }
 
-bool Arch::route() { return router1(getCtx(), Router1Cfg(getCtx())); }
+bool Arch::route()
+{
+    bool retVal = router1(getCtx(), Router1Cfg(getCtx()));
+    getCtx()->settings[getCtx()->id("route")] = "1";
+    archInfoToAttributes();
+    return retVal;
+}
 
 // ---------------------------------------------------------------
 
diff --git a/generic/main.cc b/generic/main.cc
index c203f35c..ce1a51c7 100644
--- a/generic/main.cc
+++ b/generic/main.cc
@@ -32,7 +32,7 @@ class GenericCommandHandler : public CommandHandler
   public:
     GenericCommandHandler(int argc, char **argv);
     virtual ~GenericCommandHandler(){};
-    std::unique_ptr<Context> createContext() override;
+    std::unique_ptr<Context> createContext(std::unordered_map<std::string, Property> &values) override;
     void setupArchContext(Context *ctx) override{};
     void customBitstream(Context *ctx) override;
 
@@ -51,8 +51,14 @@ po::options_description GenericCommandHandler::getArchOptions()
 
 void GenericCommandHandler::customBitstream(Context *ctx) {}
 
-std::unique_ptr<Context> GenericCommandHandler::createContext()
+std::unique_ptr<Context> GenericCommandHandler::createContext(std::unordered_map<std::string, Property> &values)
 {
+    ArchArgs chipArgs;
+    if (values.find("arch.name") != values.end()) {
+        std::string arch_name = values["arch.name"].str;
+        if (arch_name != "generic")
+            log_error("Unsuported architecture '%s'.\n", arch_name.c_str());
+    }
     return std::unique_ptr<Context>(new Context(chipArgs));
 }
 
diff --git a/generic/pack.cc b/generic/pack.cc
index 26ae9182..558eca7c 100644
--- a/generic/pack.cc
+++ b/generic/pack.cc
@@ -282,6 +282,7 @@ bool Arch::pack()
         pack_io(ctx);
         pack_lut_lutffs(ctx);
         pack_nonlut_ffs(ctx);
+        ctx->settings[ctx->id("pack")] = "1";
         ctx->assignArchInfo();
         log_info("Checksum: 0x%08x\n", ctx->checksum());
         return true;
diff --git a/gui/base.qrc b/gui/base.qrc
index 644b16a6..85d1432a 100644
--- a/gui/base.qrc
+++ b/gui/base.qrc
@@ -22,6 +22,7 @@
         <file>resources/route.png</file>
         <file>resources/time_add.png</file>
         <file>resources/open_json.png</file>
+        <file>resources/save_json.png</file>
 		<file>resources/py.png</file>
     </qresource>
 </RCC>
diff --git a/gui/basewindow.cc b/gui/basewindow.cc
index 346efb88..550a4b93 100644
--- a/gui/basewindow.cc
+++ b/gui/basewindow.cc
@@ -29,17 +29,17 @@
 #include "designwidget.h"

 #include "fpgaviewwidget.h"

 #include "jsonparse.h"

+#include "jsonwrite.h"

 #include "log.h"

 #include "mainwindow.h"

-#include "project.h"

 #include "pythontab.h"

 

 static void initBasenameResource() { Q_INIT_RESOURCE(base); }

 

 NEXTPNR_NAMESPACE_BEGIN

 

-BaseMainWindow::BaseMainWindow(std::unique_ptr<Context> context, ArchArgs args, QWidget *parent)

-        : QMainWindow(parent), chipArgs(args), ctx(std::move(context)), timing_driven(false)

+BaseMainWindow::BaseMainWindow(std::unique_ptr<Context> context, CommandHandler *handler, QWidget *parent)

+        : QMainWindow(parent), handler(handler), ctx(std::move(context)), timing_driven(false)

 {

     initBasenameResource();

     qRegisterMetaType<std::string>();

@@ -130,25 +130,6 @@ void BaseMainWindow::writeInfo(std::string text) { console->info(text); }
 void BaseMainWindow::createMenusAndBars()

 {

     // File menu / project toolbar actions

-    actionNew = new QAction("New", this);

-    actionNew->setIcon(QIcon(":/icons/resources/new.png"));

-    actionNew->setShortcuts(QKeySequence::New);

-    actionNew->setStatusTip("New project file");

-    connect(actionNew, &QAction::triggered, this, &BaseMainWindow::new_proj);

-

-    actionOpen = new QAction("Open", this);

-    actionOpen->setIcon(QIcon(":/icons/resources/open.png"));

-    actionOpen->setShortcuts(QKeySequence::Open);

-    actionOpen->setStatusTip("Open an existing project file");

-    connect(actionOpen, &QAction::triggered, this, &BaseMainWindow::open_proj);

-

-    actionSave = new QAction("Save", this);

-    actionSave->setIcon(QIcon(":/icons/resources/save.png"));

-    actionSave->setShortcuts(QKeySequence::Save);

-    actionSave->setStatusTip("Save existing project to disk");

-    actionSave->setEnabled(false);

-    connect(actionSave, &QAction::triggered, this, &BaseMainWindow::save_proj);

-

     QAction *actionExit = new QAction("Exit", this);

     actionExit->setIcon(QIcon(":/icons/resources/exit.png"));

     actionExit->setShortcuts(QKeySequence::Quit);

@@ -158,13 +139,26 @@ void BaseMainWindow::createMenusAndBars()
     // Help menu actions

     QAction *actionAbout = new QAction("About", this);

 

-    // Design menu options

+    // Gile menu options

+    actionNew = new QAction("New", this);

+    actionNew->setIcon(QIcon(":/icons/resources/new.png"));

+    actionNew->setShortcuts(QKeySequence::New);

+    actionNew->setStatusTip("New project");

+    connect(actionNew, &QAction::triggered, this, &BaseMainWindow::new_proj);

+

     actionLoadJSON = new QAction("Open JSON", this);

     actionLoadJSON->setIcon(QIcon(":/icons/resources/open_json.png"));

     actionLoadJSON->setStatusTip("Open an existing JSON file");

     actionLoadJSON->setEnabled(true);

     connect(actionLoadJSON, &QAction::triggered, this, &BaseMainWindow::open_json);

 

+    actionSaveJSON = new QAction("Save JSON", this);

+    actionSaveJSON->setIcon(QIcon(":/icons/resources/save_json.png"));

+    actionSaveJSON->setStatusTip("Write to JSON file");

+    actionSaveJSON->setEnabled(true);

+    connect(actionSaveJSON, &QAction::triggered, this, &BaseMainWindow::save_json);

+

+    // Design menu options

     actionPack = new QAction("Pack", this);

     actionPack->setIcon(QIcon(":/icons/resources/pack.png"));

     actionPack->setStatusTip("Pack current design");

@@ -244,13 +238,12 @@ void BaseMainWindow::createMenusAndBars()
 

     // Add File menu actions

     menuFile->addAction(actionNew);

-    menuFile->addAction(actionOpen);

-    menuFile->addAction(actionSave);

+    menuFile->addAction(actionLoadJSON);

+    menuFile->addAction(actionSaveJSON);

     menuFile->addSeparator();

     menuFile->addAction(actionExit);

 

     // Add Design menu actions

-    menuDesign->addAction(actionLoadJSON);

     menuDesign->addAction(actionPack);

     menuDesign->addAction(actionAssignBudget);

     menuDesign->addAction(actionPlace);

@@ -261,17 +254,13 @@ void BaseMainWindow::createMenusAndBars()
     // Add Help menu actions

     menuHelp->addAction(actionAbout);

 

-    // Project toolbar

-    QToolBar *projectToolBar = new QToolBar("Project");

-    addToolBar(Qt::TopToolBarArea, projectToolBar);

-    projectToolBar->addAction(actionNew);

-    projectToolBar->addAction(actionOpen);

-    projectToolBar->addAction(actionSave);

-

     // Main action bar

     mainActionBar = new QToolBar("Main");

     addToolBar(Qt::TopToolBarArea, mainActionBar);

+    mainActionBar->addAction(actionNew);

     mainActionBar->addAction(actionLoadJSON);

+    mainActionBar->addAction(actionSaveJSON);

+    mainActionBar->addSeparator();

     mainActionBar->addAction(actionPack);

     mainActionBar->addAction(actionAssignBudget);

     mainActionBar->addAction(actionPlace);

@@ -304,25 +293,29 @@ void BaseMainWindow::createMenusAndBars()
     setStatusBar(statusBar);

 }

 

-void BaseMainWindow::load_json(std::string filename)

+void BaseMainWindow::open_json()

 {

-    disableActions();

-    std::ifstream f(filename);

-    if (parse_json_file(f, filename, ctx.get())) {

-        log("Loading design successful.\n");

+    QString fileName = QFileDialog::getOpenFileName(this, QString("Open JSON"), QString(), QString("*.json"));

+    if (!fileName.isEmpty()) {

+        disableActions();

+        ctx = handler->load_json(fileName.toStdString());

+        Q_EMIT contextChanged(ctx.get());

         Q_EMIT updateTreeView();

-        updateLoaded();

-    } else {

-        actionLoadJSON->setEnabled(true);

-        log("Loading design failed.\n");

+        log("Loading design successful.\n");

+        updateActions();

     }

 }

 

-void BaseMainWindow::open_json()

+void BaseMainWindow::save_json()

 {

-    QString fileName = QFileDialog::getOpenFileName(this, QString("Open JSON"), QString(), QString("*.json"));

+    QString fileName = QFileDialog::getSaveFileName(this, QString("Save JSON"), QString(), QString("*.json"));

     if (!fileName.isEmpty()) {

-        load_json(fileName.toStdString());

+        std::string fn = fileName.toStdString();

+        std::ofstream f(fn);

+        if (write_json_file(f, fn, ctx.get()))

+            log("Saving JSON successful.\n");

+        else

+            log("Saving JSON failed.\n");

     }

 }

 

@@ -332,9 +325,7 @@ void BaseMainWindow::pack_finished(bool status)
     if (status) {

         log("Packing design successful.\n");

         Q_EMIT updateTreeView();

-        actionPlace->setEnabled(true);

-        actionAssignBudget->setEnabled(true);

-        onPackFinished();

+        updateActions();

     } else {

         log("Packing design failed.\n");

     }

@@ -345,8 +336,7 @@ void BaseMainWindow::budget_finish(bool status)
     disableActions();

     if (status) {

         log("Assigning timing budget successful.\n");

-        actionPlace->setEnabled(true);

-        onBudgetFinished();

+        updateActions();

     } else {

         log("Assigning timing budget failed.\n");

     }

@@ -358,8 +348,7 @@ void BaseMainWindow::place_finished(bool status)
     if (status) {

         log("Placing design successful.\n");

         Q_EMIT updateTreeView();

-        actionRoute->setEnabled(true);

-        onPlaceFinished();

+        updateActions();

     } else {

         log("Placing design failed.\n");

     }

@@ -370,7 +359,7 @@ void BaseMainWindow::route_finished(bool status)
     if (status) {

         log("Routing design successful.\n");

         Q_EMIT updateTreeView();

-        onRouteFinished();

+        updateActions();

     } else

         log("Routing design failed.\n");

 }

@@ -386,9 +375,6 @@ void BaseMainWindow::taskStarted()
     disableActions();

     actionPause->setEnabled(true);

     actionStop->setEnabled(true);

-

-    actionNew->setEnabled(false);

-    actionOpen->setEnabled(false);

 }

 

 void BaseMainWindow::taskPaused()

@@ -396,9 +382,6 @@ void BaseMainWindow::taskPaused()
     disableActions();

     actionPlay->setEnabled(true);

     actionStop->setEnabled(true);

-

-    actionNew->setEnabled(false);

-    actionOpen->setEnabled(false);

 }

 

 void BaseMainWindow::budget()

@@ -416,52 +399,32 @@ void BaseMainWindow::place() { Q_EMIT task->place(timing_driven); }
 

 void BaseMainWindow::disableActions()

 {

-    actionLoadJSON->setEnabled(false);

+    actionLoadJSON->setEnabled(true);

     actionPack->setEnabled(false);

     actionAssignBudget->setEnabled(false);

     actionPlace->setEnabled(false);

     actionRoute->setEnabled(false);

+

     actionExecutePy->setEnabled(true);

 

     actionPlay->setEnabled(false);

     actionPause->setEnabled(false);

     actionStop->setEnabled(false);

 

-    actionNew->setEnabled(true);

-    actionOpen->setEnabled(true);

-

-    if (ctx->settings.find(ctx->id("input/json")) != ctx->settings.end())

-        actionSave->setEnabled(true);

-    else

-        actionSave->setEnabled(false);

-

     onDisableActions();

 }

 

-void BaseMainWindow::updateLoaded()

-{

-    disableActions();

-    actionPack->setEnabled(true);

-    onJsonLoaded();

-    onProjectLoaded();

-}

-

-void BaseMainWindow::projectLoad(std::string filename)

+void BaseMainWindow::updateActions()

 {

-    ProjectHandler proj;

-    disableActions();

-    ctx = proj.load(filename);

-    Q_EMIT contextChanged(ctx.get());

-    log_info("Loaded project %s...\n", filename.c_str());

-    updateLoaded();

-}

+    if (ctx->settings.find(ctx->id("pack")) == ctx->settings.end())

+        actionPack->setEnabled(true);

+    else if (ctx->settings.find(ctx->id("place")) == ctx->settings.end()) {

+        actionAssignBudget->setEnabled(true);

+        actionPlace->setEnabled(true);

+    } else if (ctx->settings.find(ctx->id("route")) == ctx->settings.end())

+        actionRoute->setEnabled(true);

 

-void BaseMainWindow::open_proj()

-{

-    QString fileName = QFileDialog::getOpenFileName(this, QString("Open Project"), QString(), QString("*.proj"));

-    if (!fileName.isEmpty()) {

-        projectLoad(fileName.toStdString());

-    }

+    onUpdateActions();

 }

 

 void BaseMainWindow::execute_python()

@@ -473,18 +436,5 @@ void BaseMainWindow::execute_python()
 }

 

 void BaseMainWindow::notifyChangeContext() { Q_EMIT contextChanged(ctx.get()); }

-void BaseMainWindow::save_proj()

-{

-    if (currentProj.empty()) {

-        QString fileName = QFileDialog::getSaveFileName(this, QString("Save Project"), QString(), QString("*.proj"));

-        if (fileName.isEmpty())

-            return;

-        currentProj = fileName.toStdString();

-    }

-    if (!currentProj.empty()) {

-        ProjectHandler proj;

-        proj.save(ctx.get(), currentProj);

-    }

-}

 

 NEXTPNR_NAMESPACE_END

diff --git a/gui/basewindow.h b/gui/basewindow.h
index 0b2d3fbc..305cb6c9 100644
--- a/gui/basewindow.h
+++ b/gui/basewindow.h
@@ -20,6 +20,7 @@
 #ifndef BASEMAINWINDOW_H

 #define BASEMAINWINDOW_H

 

+#include "command.h"

 #include "nextpnr.h"

 #include "worker.h"

 

@@ -45,25 +46,19 @@ class BaseMainWindow : public QMainWindow
     Q_OBJECT

 

   public:

-    explicit BaseMainWindow(std::unique_ptr<Context> context, ArchArgs args, QWidget *parent = 0);

+    explicit BaseMainWindow(std::unique_ptr<Context> context, CommandHandler *handler, QWidget *parent = 0);

     virtual ~BaseMainWindow();

     Context *getContext() { return ctx.get(); }

-    void updateLoaded();

-    void projectLoad(std::string filename);

+    void updateActions();

+

     void notifyChangeContext();

 

   protected:

     void createMenusAndBars();

     void disableActions();

-    void load_json(std::string filename);

 

     virtual void onDisableActions(){};

-    virtual void onJsonLoaded(){};

-    virtual void onProjectLoaded(){};

-    virtual void onPackFinished(){};

-    virtual void onBudgetFinished(){};

-    virtual void onPlaceFinished(){};

-    virtual void onRouteFinished(){};

+    virtual void onUpdateActions(){};

 

   protected Q_SLOTS:

     void writeInfo(std::string text);

@@ -71,10 +66,8 @@ class BaseMainWindow : public QMainWindow
 

     virtual void new_proj() = 0;

 

-    void open_proj();

-    void save_proj();

-

     void open_json();

+    void save_json();

     void budget();

     void place();

 

@@ -95,7 +88,7 @@ class BaseMainWindow : public QMainWindow
 

   protected:

     // state variables

-    ArchArgs chipArgs;

+    CommandHandler *handler;

     std::unique_ptr<Context> ctx;

     TaskManager *task;

     bool timing_driven;

@@ -116,10 +109,9 @@ class BaseMainWindow : public QMainWindow
     QProgressBar *progressBar;

 

     QAction *actionNew;

-    QAction *actionOpen;

-    QAction *actionSave;

-

     QAction *actionLoadJSON;

+    QAction *actionSaveJSON;

+

     QAction *actionPack;

     QAction *actionAssignBudget;

     QAction *actionPlace;

diff --git a/gui/create_img.sh b/gui/create_img.sh
index 1508d023..2e7b1f87 100755
--- a/gui/create_img.sh
+++ b/gui/create_img.sh
@@ -2,5 +2,6 @@ convert -font helvetica -fill red -pointsize 8 -gravity center -draw "text 2,8 '
 convert -font helvetica -fill red -pointsize 8 -gravity center -draw "text 2,8 'PCF'" resources/open.png ice40/resources/open_pcf.png 
 convert -font helvetica -fill red -pointsize 8 -gravity center -draw "text 2,8 'BASE'" resources/open.png ecp5/resources/open_base.png 
 convert -font helvetica -fill red -pointsize 8 -gravity center -draw "text 2,8 'LPF'" resources/open.png ecp5/resources/open_lpf.png 
-convert -font helvetica -fill red -pointsize 8 -gravity center -draw "text 2,8 'ASC'" resources/save.png ice40/resources/save_asc.png 
-convert -font helvetica -fill red -pointsize 7 -gravity center -draw "text 2,8 'CONFIG'" resources/save.png ecp5/resources/save_config.png 
\ No newline at end of file
+convert -font helvetica -fill red -pointsize 8 -gravity center -draw "text 2,8 'ASC'" resources/save.png ice40/resources/save_asc.png
+convert -font helvetica -fill red -pointsize 7 -gravity center -draw "text 2,8 'CONFIG'" resources/save.png ecp5/resources/save_config.png
+convert -font helvetica -fill red -pointsize 8 -gravity center -draw "text 2,8 'JSON'" resources/save.png resources/save_json.png
diff --git a/gui/ecp5/mainwindow.cc b/gui/ecp5/mainwindow.cc
index c6c7bc97..880af047 100644
--- a/gui/ecp5/mainwindow.cc
+++ b/gui/ecp5/mainwindow.cc
@@ -30,8 +30,8 @@ static void initMainResource() { Q_INIT_RESOURCE(nextpnr); }
 

 NEXTPNR_NAMESPACE_BEGIN

 

-MainWindow::MainWindow(std::unique_ptr<Context> context, ArchArgs args, QWidget *parent)

-        : BaseMainWindow(std::move(context), args, parent)

+MainWindow::MainWindow(std::unique_ptr<Context> context, CommandHandler *handler, QWidget *parent)

+        : BaseMainWindow(std::move(context), handler, parent)

 {

     initMainResource();

 

@@ -47,7 +47,7 @@ MainWindow::~MainWindow() {}
 

 void MainWindow::newContext(Context *ctx)

 {

-    std::string title = "nextpnr-generic - " + ctx->getChipName() + " ( " + chipArgs.package + " )";

+    std::string title = "nextpnr-ecp5 - " + ctx->getChipName() + " ( " + ctx->archArgs().package + " )";

     setWindowTitle(title.c_str());

 }

 

@@ -60,12 +60,6 @@ void MainWindow::createMenu()
     actionLoadLPF->setEnabled(false);

     connect(actionLoadLPF, &QAction::triggered, this, &MainWindow::open_lpf);

 

-    actionLoadBase = new QAction("Open Base Config", this);

-    actionLoadBase->setIcon(QIcon(":/icons/resources/open_base.png"));

-    actionLoadBase->setStatusTip("Open Base Config file");

-    actionLoadBase->setEnabled(false);

-    connect(actionLoadBase, &QAction::triggered, this, &MainWindow::open_base);

-

     actionSaveConfig = new QAction("Save Bitstream", this);

     actionSaveConfig->setIcon(QIcon(":/icons/resources/save_config.png"));

     actionSaveConfig->setStatusTip("Save Bitstream config file");

@@ -75,12 +69,10 @@ void MainWindow::createMenu()
     // Add actions in menus

     mainActionBar->addSeparator();

     mainActionBar->addAction(actionLoadLPF);

-    mainActionBar->addAction(actionLoadBase);

     mainActionBar->addAction(actionSaveConfig);

 

     menuDesign->addSeparator();

     menuDesign->addAction(actionLoadLPF);

-    menuDesign->addAction(actionLoadBase);

     menuDesign->addAction(actionSaveConfig);

 }

 

@@ -121,7 +113,7 @@ void MainWindow::new_proj()
     bool ok;

     QString item = QInputDialog::getItem(this, "Select new context", "Chip:", arch.keys(), 0, false, &ok);

     if (ok && !item.isEmpty()) {

-

+        ArchArgs chipArgs;

         chipArgs.type = (ArchArgs::ArchArgsTypes)arch.value(item);

 

         QString package = QInputDialog::getItem(this, "Select package", "Package:", getSupportedPackages(chipArgs.type),

@@ -139,13 +131,6 @@ void MainWindow::new_proj()
     }

 }

 

-void MainWindow::load_base_config(std::string filename)

-{

-    disableActions();

-    currentBaseConfig = filename;

-    actionSaveConfig->setEnabled(true);

-}

-

 void MainWindow::open_lpf()

 {

     QString fileName = QFileDialog::getOpenFileName(this, QString("Open LPF"), QString(), QString("*.lpf"));

@@ -162,21 +147,13 @@ void MainWindow::open_lpf()
     }

 }

 

-void MainWindow::open_base()

-{

-    QString fileName = QFileDialog::getOpenFileName(this, QString("Open Base Config"), QString(), QString("*.config"));

-    if (!fileName.isEmpty()) {

-        load_base_config(fileName.toStdString());

-    }

-}

-

 void MainWindow::save_config()

 {

     QString fileName = QFileDialog::getSaveFileName(this, QString("Save Bitstream"), QString(), QString("*.config"));

     if (!fileName.isEmpty()) {

         std::string fn = fileName.toStdString();

         disableActions();

-        write_bitstream(ctx.get(), currentBaseConfig, fileName.toStdString());

+        write_bitstream(ctx.get(), "", fileName.toStdString());

         log("Saving Bitstream successful.\n");

     }

 }

@@ -184,18 +161,15 @@ void MainWindow::save_config()
 void MainWindow::onDisableActions()

 {

     actionLoadLPF->setEnabled(false);

-    actionLoadBase->setEnabled(false);

     actionSaveConfig->setEnabled(false);

 }

 

-void MainWindow::onJsonLoaded() { actionLoadLPF->setEnabled(true); }

-

-void MainWindow::onRouteFinished() { actionLoadBase->setEnabled(true); }

-

-void MainWindow::onProjectLoaded()

+void MainWindow::onUpdateActions()

 {

-    if (ctx->settings.find(ctx->id("input/lpf")) != ctx->settings.end())

-        actionLoadLPF->setEnabled(false);

+    if (ctx->settings.find(ctx->id("pack")) == ctx->settings.end())

+        actionLoadLPF->setEnabled(true);

+    if (ctx->settings.find(ctx->id("route")) != ctx->settings.end())

+        actionSaveConfig->setEnabled(true);

 }

 

 NEXTPNR_NAMESPACE_END

diff --git a/gui/ecp5/mainwindow.h b/gui/ecp5/mainwindow.h
index 721c6c0b..e60fc5b0 100644
--- a/gui/ecp5/mainwindow.h
+++ b/gui/ecp5/mainwindow.h
@@ -29,34 +29,25 @@ class MainWindow : public BaseMainWindow
     Q_OBJECT

 

   public:

-    explicit MainWindow(std::unique_ptr<Context> context, ArchArgs args, QWidget *parent = 0);

+    explicit MainWindow(std::unique_ptr<Context> context, CommandHandler *handler, QWidget *parent = 0);

     virtual ~MainWindow();

 

   public:

     void createMenu();

-    void load_base_config(std::string filename);

 

   protected:

     void onDisableActions() override;

-    void onJsonLoaded() override;

-    void onRouteFinished() override;

-    void onProjectLoaded() override;

+    void onUpdateActions() override;

 

   protected Q_SLOTS:

     void new_proj() override;

     void newContext(Context *ctx);

     void open_lpf();

-    void open_base();

     void save_config();

 

   private:

     QAction *actionLoadLPF;

-    QAction *actionLoadBase;

     QAction *actionSaveConfig;

-

-    ArchArgs chipArgs;

-

-    std::string currentBaseConfig;

 };

 

 NEXTPNR_NAMESPACE_END

diff --git a/gui/generic/mainwindow.cc b/gui/generic/mainwindow.cc
index 54d1f2c8..f616ca1a 100644
--- a/gui/generic/mainwindow.cc
+++ b/gui/generic/mainwindow.cc
@@ -26,9 +26,10 @@ static void initMainResource() { Q_INIT_RESOURCE(nextpnr); }
 

 NEXTPNR_NAMESPACE_BEGIN

 

-MainWindow::MainWindow(std::unique_ptr<Context> context, ArchArgs args, QWidget *parent)

-        : BaseMainWindow(std::move(context), args, parent)

+MainWindow::MainWindow(std::unique_ptr<Context> context, CommandHandler *handler, QWidget *parent)

+        : BaseMainWindow(std::move(context), handler, parent)

 {

+    initMainResource();

     QMessageBox::critical(0, "Error - FIXME", "No GUI support for nextpnr-generic");

     std::exit(1);

 }

diff --git a/gui/generic/mainwindow.h b/gui/generic/mainwindow.h
index bb6a4cf1..4d1cf598 100644
--- a/gui/generic/mainwindow.h
+++ b/gui/generic/mainwindow.h
@@ -29,7 +29,7 @@ class MainWindow : public BaseMainWindow
     Q_OBJECT

 

   public:

-    explicit MainWindow(std::unique_ptr<Context> context, ArchArgs args, QWidget *parent = 0);

+    explicit MainWindow(std::unique_ptr<Context> context, CommandHandler *handler, QWidget *parent = 0);

     virtual ~MainWindow();

 

   public:

diff --git a/gui/ice40/mainwindow.cc b/gui/ice40/mainwindow.cc
index f270b112..ccff2117 100644
--- a/gui/ice40/mainwindow.cc
+++ b/gui/ice40/mainwindow.cc
@@ -35,8 +35,8 @@ static void initMainResource() { Q_INIT_RESOURCE(nextpnr); }
 

 NEXTPNR_NAMESPACE_BEGIN

 

-MainWindow::MainWindow(std::unique_ptr<Context> context, ArchArgs args, QWidget *parent)

-        : BaseMainWindow(std::move(context), args, parent)

+MainWindow::MainWindow(std::unique_ptr<Context> context, CommandHandler *handler, QWidget *parent)

+        : BaseMainWindow(std::move(context), handler, parent)

 {

     initMainResource();

 

@@ -123,7 +123,7 @@ void MainWindow::new_proj()
     bool ok;

     QString item = QInputDialog::getItem(this, "Select new context", "Chip:", arch.keys(), 0, false, &ok);

     if (ok && !item.isEmpty()) {

-

+        ArchArgs chipArgs;

         chipArgs.type = (ArchArgs::ArchArgsTypes)arch.value(item);

 

         QString package = QInputDialog::getItem(this, "Select package", "Package:", getSupportedPackages(chipArgs.type),

@@ -156,7 +156,7 @@ void MainWindow::load_pcf(std::string filename)
 

 void MainWindow::newContext(Context *ctx)

 {

-    std::string title = "nextpnr-ice40 - " + ctx->getChipName() + " ( " + chipArgs.package + " )";

+    std::string title = "nextpnr-ice40 - " + ctx->getChipName() + " ( " + ctx->archArgs().package + " )";

     setWindowTitle(title.c_str());

 }

 

@@ -186,13 +186,12 @@ void MainWindow::onDisableActions()
     actionSaveAsc->setEnabled(false);

 }

 

-void MainWindow::onJsonLoaded() { actionLoadPCF->setEnabled(true); }

-void MainWindow::onRouteFinished() { actionSaveAsc->setEnabled(true); }

-

-void MainWindow::onProjectLoaded()

+void MainWindow::onUpdateActions()

 {

-    if (ctx->settings.find(ctx->id("input/pcf")) != ctx->settings.end())

-        actionLoadPCF->setEnabled(false);

+    if (ctx->settings.find(ctx->id("pack")) == ctx->settings.end())

+        actionLoadPCF->setEnabled(true);

+    if (ctx->settings.find(ctx->id("route")) != ctx->settings.end())

+        actionSaveAsc->setEnabled(true);

 }

 

 NEXTPNR_NAMESPACE_END

diff --git a/gui/ice40/mainwindow.h b/gui/ice40/mainwindow.h
index 4a9a7d8e..6e725a16 100644
--- a/gui/ice40/mainwindow.h
+++ b/gui/ice40/mainwindow.h
@@ -29,7 +29,7 @@ class MainWindow : public BaseMainWindow
     Q_OBJECT

 

   public:

-    explicit MainWindow(std::unique_ptr<Context> context, ArchArgs args, QWidget *parent = 0);

+    explicit MainWindow(std::unique_ptr<Context> context, CommandHandler *handler, QWidget *parent = 0);

     virtual ~MainWindow();

 

   public:

@@ -39,9 +39,7 @@ class MainWindow : public BaseMainWindow
     void load_pcf(std::string filename);

 

     void onDisableActions() override;

-    void onJsonLoaded() override;

-    void onRouteFinished() override;

-    void onProjectLoaded() override;

+    void onUpdateActions() override;

 

   protected Q_SLOTS:

     void new_proj() override;

diff --git a/gui/resources/save_json.png b/gui/resources/save_json.png
new file mode 100644
index 00000000..cbeb3243
--- /dev/null
+++ b/gui/resources/save_json.png
diff --git a/gui/worker.cc b/gui/worker.cc
index 900883d4..bd14771b 100644
--- a/gui/worker.cc
+++ b/gui/worker.cc
@@ -68,7 +68,7 @@ void Worker::budget(double freq)
 {
     Q_EMIT taskStarted();
     try {
-        ctx->target_freq = freq;
+        ctx->settings[ctx->id("target_freq")] = std::to_string(freq);
         assign_budget(ctx);
         Q_EMIT budget_finish(true);
     } catch (WorkerInterruptionRequested) {
@@ -80,7 +80,7 @@ void Worker::place(bool timing_driven)
 {
     Q_EMIT taskStarted();
     try {
-        ctx->timing_driven = timing_driven;
+        ctx->settings[ctx->id("timing_driven")] = std::to_string(timing_driven);
         Q_EMIT place_finished(ctx->place());
     } catch (WorkerInterruptionRequested) {
         Q_EMIT taskCanceled();
diff --git a/ice40/arch.cc b/ice40/arch.cc
index 80e1fb4c..0b1d280c 100644
--- a/ice40/arch.cc
+++ b/ice40/arch.cc
@@ -683,16 +683,24 @@ bool Arch::place()
     } else {
         log_error("iCE40 architecture does not support placer '%s'\n", placer.c_str());
     }
+    bool retVal = true;
     if (bool_or_default(settings, id("opt_timing"), false)) {
         TimingOptCfg tocfg(getCtx());
         tocfg.cellTypes.insert(id_ICESTORM_LC);
-        return timing_opt(getCtx(), tocfg);
-    } else {
-        return true;
+        retVal = timing_opt(getCtx(), tocfg);
     }
+    getCtx()->settings[getCtx()->id("place")] = "1";
+    archInfoToAttributes();
+    return retVal;
 }
 
-bool Arch::route() { return router1(getCtx(), Router1Cfg(getCtx())); }
+bool Arch::route()
+{
+    bool retVal = router1(getCtx(), Router1Cfg(getCtx()));
+    getCtx()->settings[getCtx()->id("route")] = "1";
+    archInfoToAttributes();
+    return retVal;
+}
 
 // -----------------------------------------------------------------------
 
diff --git a/ice40/main.cc b/ice40/main.cc
index 9b79a08c..83cb04b0 100644
--- a/ice40/main.cc
+++ b/ice40/main.cc
@@ -36,7 +36,7 @@ class Ice40CommandHandler : public CommandHandler
   public:
     Ice40CommandHandler(int argc, char **argv);
     virtual ~Ice40CommandHandler(){};
-    std::unique_ptr<Context> createContext() override;
+    std::unique_ptr<Context> createContext(std::unordered_map<std::string, Property> &values) override;
     void setupArchContext(Context *ctx) override;
     void validate() override;
     void customAfterLoad(Context *ctx) override;
@@ -116,8 +116,10 @@ void Ice40CommandHandler::setupArchContext(Context *ctx)
     }
 }
 
-std::unique_ptr<Context> Ice40CommandHandler::createContext()
+std::unique_ptr<Context> Ice40CommandHandler::createContext(std::unordered_map<std::string, Property> &values)
 {
+    ArchArgs chipArgs;
+    chipArgs.type = ArchArgs::NONE;
     if (vm.count("lp384")) {
         chipArgs.type = ArchArgs::LP384;
         chipArgs.package = "qn32";
@@ -153,6 +155,49 @@ std::unique_ptr<Context> Ice40CommandHandler::createContext()
         chipArgs.package = "sg48";
     }
 
+    if (vm.count("package"))
+        chipArgs.package = vm["package"].as<std::string>();
+
+    if (values.find("arch.name") != values.end()) {
+        std::string arch_name = values["arch.name"].str;
+        if (arch_name != "ice40")
+            log_error("Unsuported architecture '%s'.\n", arch_name.c_str());
+    }
+    if (values.find("arch.type") != values.end()) {
+        std::string arch_type = values["arch.type"].str;
+        if (chipArgs.type != ArchArgs::NONE)
+            log_error("Overriding architecture is unsuported.\n");
+
+        if (arch_type == "lp384") {
+            chipArgs.type = ArchArgs::LP384;
+        }
+        if (arch_type == "lp1k") {
+            chipArgs.type = ArchArgs::LP1K;
+        }
+        if (arch_type == "lp8k") {
+            chipArgs.type = ArchArgs::LP8K;
+        }
+        if (arch_type == "hx1k") {
+            chipArgs.type = ArchArgs::HX1K;
+        }
+        if (arch_type == "hx8k") {
+            chipArgs.type = ArchArgs::HX8K;
+        }
+        if (arch_type == "up5k") {
+            chipArgs.type = ArchArgs::UP5K;
+        }
+        if (arch_type == "u4k") {
+            chipArgs.type = ArchArgs::U4K;
+        }
+        if (chipArgs.type == ArchArgs::NONE)
+            log_error("Unsuported FPGA type '%s'.\n", arch_type.c_str());
+    }
+    if (values.find("arch.package") != values.end()) {
+        if (vm.count("package"))
+            log_error("Overriding architecture is unsuported.\n");
+        chipArgs.package = values["arch.package"].str;
+    }
+
     if (chipArgs.type == ArchArgs::NONE) {
         chipArgs.type = ArchArgs::HX1K;
         chipArgs.package = "tq144";
@@ -163,11 +208,11 @@ std::unique_ptr<Context> Ice40CommandHandler::createContext()
     }
 #endif
 
-    if (vm.count("package"))
-        chipArgs.package = vm["package"].as<std::string>();
-
     auto ctx = std::unique_ptr<Context>(new Context(chipArgs));
+    for (auto &val : values)
+        ctx->settings[ctx->id(val.first)] = val.second;
 
+    ctx->settings[ctx->id("arch.package")] = ctx->archArgs().package;
     if (vm.count("promote-logic"))
         ctx->settings[ctx->id("promote_logic")] = "1";
     if (vm.count("no-promote-globals"))
diff --git a/ice40/pack.cc b/ice40/pack.cc
index f520b295..d1366c9c 100644
--- a/ice40/pack.cc
+++ b/ice40/pack.cc
@@ -341,6 +341,11 @@ static void pack_constants(Context *ctx)
     gnd_net->driver.port = ctx->id("O");
     gnd_cell->ports.at(ctx->id("O")).net = gnd_net.get();
 
+    NetInfo *gnd_net_info = gnd_net.get();
+    if (ctx->nets.find(ctx->id("$PACKER_GND_NET")) != ctx->nets.end()) {
+        gnd_net_info = ctx->nets.find(ctx->id("$PACKER_GND_NET"))->second.get();
+    }
+
     std::unique_ptr<CellInfo> vcc_cell = create_ice_cell(ctx, ctx->id("ICESTORM_LC"), "$PACKER_VCC");
     vcc_cell->params[ctx->id("LUT_INIT")] = "1";
     std::unique_ptr<NetInfo> vcc_net = std::unique_ptr<NetInfo>(new NetInfo);
@@ -349,6 +354,11 @@ static void pack_constants(Context *ctx)
     vcc_net->driver.port = ctx->id("O");
     vcc_cell->ports.at(ctx->id("O")).net = vcc_net.get();
 
+    NetInfo *vcc_net_info = vcc_net.get();
+    if (ctx->nets.find(ctx->id("$PACKER_VCC_NET")) != ctx->nets.end()) {
+        vcc_net_info = ctx->nets.find(ctx->id("$PACKER_VCC_NET"))->second.get();
+    }
+
     std::vector<IdString> dead_nets;
 
     bool gnd_used = false;
@@ -357,26 +367,28 @@ static void pack_constants(Context *ctx)
         NetInfo *ni = net.second;
         if (ni->driver.cell != nullptr && ni->driver.cell->type == ctx->id("GND")) {
             IdString drv_cell = ni->driver.cell->name;
-            set_net_constant(ctx, ni, gnd_net.get(), false);
+            set_net_constant(ctx, ni, gnd_net_info, false);
             gnd_used = true;
             dead_nets.push_back(net.first);
             ctx->cells.erase(drv_cell);
         } else if (ni->driver.cell != nullptr && ni->driver.cell->type == ctx->id("VCC")) {
             IdString drv_cell = ni->driver.cell->name;
-            set_net_constant(ctx, ni, vcc_net.get(), true);
+            set_net_constant(ctx, ni, vcc_net_info, true);
             dead_nets.push_back(net.first);
             ctx->cells.erase(drv_cell);
         }
     }
 
-    if (gnd_used) {
+    if (gnd_used && (gnd_net_info == gnd_net.get())) {
         ctx->cells[gnd_cell->name] = std::move(gnd_cell);
         ctx->nets[gnd_net->name] = std::move(gnd_net);
     }
     // Vcc cell always inserted for now, as it may be needed during carry legalisation (TODO: trim later if actually
     // never used?)
-    ctx->cells[vcc_cell->name] = std::move(vcc_cell);
-    ctx->nets[vcc_net->name] = std::move(vcc_net);
+    if (vcc_net_info == vcc_net.get()) {
+        ctx->cells[vcc_cell->name] = std::move(vcc_cell);
+        ctx->nets[vcc_net->name] = std::move(vcc_net);
+    }
 
     for (auto dn : dead_nets) {
         ctx->nets.erase(dn);
@@ -1224,13 +1236,14 @@ static void pack_special(Context *ctx)
                 }
 
             auto feedback_path = packed->params[ctx->id("FEEDBACK_PATH")];
-            std::string fbp_value = feedback_path == "DELAY"
-                                            ? "0"
-                                            : feedback_path == "SIMPLE"
-                                                      ? "1"
-                                                      : feedback_path == "PHASE_AND_DELAY"
-                                                                ? "2"
-                                                                : feedback_path == "EXTERNAL" ? "6" : feedback_path;
+            std::string fbp_value =
+                    feedback_path == "DELAY"
+                            ? "0"
+                            : feedback_path == "SIMPLE"
+                                      ? "1"
+                                      : feedback_path == "PHASE_AND_DELAY"
+                                                ? "2"
+                                                : feedback_path == "EXTERNAL" ? "6" : std::string(feedback_path);
             if (!std::all_of(fbp_value.begin(), fbp_value.end(), isdigit))
                 log_error("PLL '%s' has unsupported FEEDBACK_PATH value '%s'\n", ci->name.c_str(ctx),
                           feedback_path.c_str());
@@ -1435,6 +1448,8 @@ bool Arch::pack()
         ctx->assignArchInfo();
         constrain_chains(ctx);
         ctx->assignArchInfo();
+        ctx->settings[ctx->id("pack")] = "1";
+        archInfoToAttributes();
         log_info("Checksum: 0x%08x\n", ctx->checksum());
         return true;
     } catch (log_execution_error_exception) {
diff --git a/ice40/pcf.cc b/ice40/pcf.cc
index 15132800..a854a780 100644
--- a/ice40/pcf.cc
+++ b/ice40/pcf.cc
@@ -119,7 +119,7 @@ bool apply_pcf(Context *ctx, std::string filename, std::istream &in)
                 }
             }
         }
-        ctx->settings.emplace(ctx->id("input/pcf"), filename);
+        ctx->settings[ctx->id("input/pcf")] = filename;
         return true;
     } catch (log_execution_error_exception) {
         return false;
diff --git a/ice40/project.cc b/ice40/project.cc
deleted file mode 100644
index bbd82fd7..00000000
--- a/ice40/project.cc
+++ /dev/null
@@ -1,76 +0,0 @@
-/*
- *  nextpnr -- Next Generation Place and Route
- *
- *  Copyright (C) 2018  Miodrag Milanovic <miodrag@symbioticeda.com>
- *
- *  Permission to use, copy, modify, and/or distribute this software for any
- *  purpose with or without fee is hereby granted, provided that the above
- *  copyright notice and this permission notice appear in all copies.
- *
- *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
- *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
- *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
- *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
- *
- */
-
-#include "project.h"
-#include <boost/filesystem/convenience.hpp>
-#include <fstream>
-#include "log.h"
-#include "pcf.h"
-
-NEXTPNR_NAMESPACE_BEGIN
-
-void ProjectHandler::saveArch(Context *ctx, pt::ptree &root, std::string path)
-{
-    root.put("project.arch.package", ctx->archArgs().package);
-    if (ctx->settings.find(ctx->id("input/pcf")) != ctx->settings.end()) {
-        std::string fn = ctx->settings[ctx->id("input/pcf")];
-        root.put("project.input.pcf", make_relative(fn, path).string());
-    }
-}
-
-std::unique_ptr<Context> ProjectHandler::createContext(pt::ptree &root)
-{
-    ArchArgs chipArgs;
-    std::string arch_type = root.get<std::string>("project.arch.type");
-    if (arch_type == "lp384") {
-        chipArgs.type = ArchArgs::LP384;
-    }
-    if (arch_type == "lp1k") {
-        chipArgs.type = ArchArgs::LP1K;
-    }
-    if (arch_type == "lp8k") {
-        chipArgs.type = ArchArgs::LP8K;
-    }
-    if (arch_type == "hx1k") {
-        chipArgs.type = ArchArgs::HX1K;
-    }
-    if (arch_type == "hx8k") {
-        chipArgs.type = ArchArgs::HX8K;
-    }
-    if (arch_type == "up5k") {
-        chipArgs.type = ArchArgs::UP5K;
-    }
-    if (arch_type == "u4k") {
-        chipArgs.type = ArchArgs::U4K;
-    }
-    chipArgs.package = root.get<std::string>("project.arch.package");
-
-    return std::unique_ptr<Context>(new Context(chipArgs));
-}
-
-void ProjectHandler::loadArch(Context *ctx, pt::ptree &root, std::string path)
-{
-    auto input = root.get_child("project").get_child("input");
-    boost::filesystem::path pcf = boost::filesystem::path(path) / input.get<std::string>("pcf");
-    std::ifstream f(pcf.string());
-    if (!apply_pcf(ctx, input.get<std::string>("pcf"), f))
-        log_error("Loading PCF failed.\n");
-}
-
-NEXTPNR_NAMESPACE_END
diff --git a/json/jsonparse.cc b/json/jsonparse.cc
index d463d8ce..caedbb5b 100644
--- a/json/jsonparse.cc
+++ b/json/jsonparse.cc
@@ -314,7 +314,7 @@ bool is_blackbox(JsonNode *node)
 }
 
 void json_import_cell_params(Context *ctx, string &modname, CellInfo *cell, JsonNode *param_node,
-                             std::unordered_map<IdString, std::string> *dest, int param_id)
+                             std::unordered_map<IdString, Property> *dest, int param_id)
 {
     //
     JsonNode *param;
@@ -324,9 +324,9 @@ void json_import_cell_params(Context *ctx, string &modname, CellInfo *cell, Json
 
     pId = ctx->id(param_node->data_dict_keys[param_id]);
     if (param->type == 'N') {
-        (*dest)[pId] = std::to_string(param->data_number);
+        (*dest)[pId].setNumber(param->data_number);
     } else if (param->type == 'S')
-        (*dest)[pId] = param->data_string;
+        (*dest)[pId].setString(param->data_string);
     else
         log_error("JSON parameter type of \"%s\' of cell \'%s\' not supported\n", pId.c_str(ctx),
                   cell->name.c_str(ctx));
@@ -337,6 +337,49 @@ void json_import_cell_params(Context *ctx, string &modname, CellInfo *cell, Json
                  pId.c_str(ctx), cell->params[pId].c_str(), cell->name.c_str(ctx), modname.c_str());
 }
 
+void json_import_net_attrib(Context *ctx, string &modname, NetInfo *net, JsonNode *param_node,
+                            std::unordered_map<IdString, Property> *dest, int param_id)
+{
+    //
+    JsonNode *param;
+    IdString pId;
+    //
+    param = param_node->data_dict.at(param_node->data_dict_keys[param_id]);
+
+    pId = ctx->id(param_node->data_dict_keys[param_id]);
+    if (param->type == 'N') {
+        (*dest)[pId].setNumber(param->data_number);
+    } else if (param->type == 'S')
+        (*dest)[pId].setString(param->data_string);
+    else
+        log_error("JSON parameter type of \"%s\' of net \'%s\' not supported\n", pId.c_str(ctx), net->name.c_str(ctx));
+    if (json_debug)
+        log_info("    Added parameter \'%s\'=%s to net \'%s\' "
+                 "of module \'%s\'\n",
+                 pId.c_str(ctx), net->attrs[pId].c_str(), net->name.c_str(ctx), modname.c_str());
+}
+
+void json_import_top_attrib(Context *ctx, string &modname, JsonNode *param_node,
+                            std::unordered_map<IdString, Property> *dest, int param_id)
+{
+    //
+    JsonNode *param;
+    IdString pId;
+    //
+    param = param_node->data_dict.at(param_node->data_dict_keys[param_id]);
+
+    pId = ctx->id(param_node->data_dict_keys[param_id]);
+    if (param->type == 'N') {
+        (*dest)[pId].setNumber(param->data_number);
+    } else if (param->type == 'S')
+        (*dest)[pId].setString(param->data_string);
+    else
+        log_error("JSON parameter type of \"%s\' of module not supported\n", pId.c_str(ctx));
+    if (json_debug)
+        log_info("    Added parameter \'%s\'=%s module \'%s\'\n", pId.c_str(ctx), (*dest)[pId].c_str(),
+                 modname.c_str());
+}
+
 static int const_net_idx = 0;
 
 template <typename F>
@@ -625,62 +668,70 @@ static void insert_iobuf(Context *ctx, NetInfo *net, PortType type, const string
     // During packing, this generic IO buffer will be converted to an
     // architecure primitive.
     //
-    std::unique_ptr<CellInfo> iobuf = std::unique_ptr<CellInfo>(new CellInfo());
-    iobuf->name = ctx->id(name);
-    std::copy(net->attrs.begin(), net->attrs.end(), std::inserter(iobuf->attrs, iobuf->attrs.begin()));
-    if (type == PORT_IN) {
-        if (ctx->verbose)
-            log_info("processing input port %s\n", name.c_str());
-        iobuf->type = ctx->id("$nextpnr_ibuf");
-        iobuf->ports[ctx->id("O")] = PortInfo{ctx->id("O"), net, PORT_OUT};
-        // Special case: input, etc, directly drives inout
-        if (net->driver.cell != nullptr) {
-            if (net->driver.cell->type != ctx->id("$nextpnr_iobuf"))
-                log_error("Top-level input '%s' also driven by %s.%s.\n", name.c_str(),
-                          net->driver.cell->name.c_str(ctx), net->driver.port.c_str(ctx));
-            net = net->driver.cell->ports.at(ctx->id("I")).net;
-        }
-        assert(net->driver.cell == nullptr);
-        net->driver.port = ctx->id("O");
-        net->driver.cell = iobuf.get();
-    } else if (type == PORT_OUT) {
-        if (ctx->verbose)
-            log_info("processing output port %s\n", name.c_str());
-        iobuf->type = ctx->id("$nextpnr_obuf");
-        iobuf->ports[ctx->id("I")] = PortInfo{ctx->id("I"), net, PORT_IN};
-        PortRef ref;
-        ref.cell = iobuf.get();
-        ref.port = ctx->id("I");
-        net->users.push_back(ref);
-    } else if (type == PORT_INOUT) {
-        if (ctx->verbose)
-            log_info("processing inout port %s\n", name.c_str());
-        iobuf->type = ctx->id("$nextpnr_iobuf");
-        iobuf->ports[ctx->id("I")] = PortInfo{ctx->id("I"), nullptr, PORT_IN};
-
-        // Split the input and output nets for bidir ports
-        std::unique_ptr<NetInfo> net2 = std::unique_ptr<NetInfo>(new NetInfo());
-        net2->name = ctx->id("$" + net->name.str(ctx) + "$iobuf_i");
-        net2->driver = net->driver;
-        if (net->driver.cell != nullptr) {
-            net2->driver.cell->ports[net2->driver.port].net = net2.get();
-            net->driver.cell = nullptr;
+    if (ctx->settings.find(ctx->id("synth")) == ctx->settings.end()) {
+        std::unique_ptr<CellInfo> iobuf = std::unique_ptr<CellInfo>(new CellInfo());
+        iobuf->name = ctx->id(name);
+        std::copy(net->attrs.begin(), net->attrs.end(), std::inserter(iobuf->attrs, iobuf->attrs.begin()));
+        if (type == PORT_IN) {
+            if (ctx->verbose)
+                log_info("processing input port %s\n", name.c_str());
+            iobuf->type = ctx->id("$nextpnr_ibuf");
+            iobuf->ports[ctx->id("O")] = PortInfo{ctx->id("O"), net, PORT_OUT};
+            // Special case: input, etc, directly drives inout
+            if (net->driver.cell != nullptr) {
+                if (net->driver.cell->type != ctx->id("$nextpnr_iobuf"))
+                    log_error("Top-level input '%s' also driven by %s.%s.\n", name.c_str(),
+                              net->driver.cell->name.c_str(ctx), net->driver.port.c_str(ctx));
+                net = net->driver.cell->ports.at(ctx->id("I")).net;
+            }
+            assert(net->driver.cell == nullptr);
+            net->driver.port = ctx->id("O");
+            net->driver.cell = iobuf.get();
+        } else if (type == PORT_OUT) {
+            if (ctx->verbose)
+                log_info("processing output port %s\n", name.c_str());
+            iobuf->type = ctx->id("$nextpnr_obuf");
+            iobuf->ports[ctx->id("I")] = PortInfo{ctx->id("I"), net, PORT_IN};
+            PortRef ref;
+            ref.cell = iobuf.get();
+            ref.port = ctx->id("I");
+            net->users.push_back(ref);
+        } else if (type == PORT_INOUT) {
+            if (ctx->verbose)
+                log_info("processing inout port %s\n", name.c_str());
+            iobuf->type = ctx->id("$nextpnr_iobuf");
+            iobuf->ports[ctx->id("I")] = PortInfo{ctx->id("I"), nullptr, PORT_IN};
+
+            // Split the input and output nets for bidir ports
+            std::unique_ptr<NetInfo> net2 = std::unique_ptr<NetInfo>(new NetInfo());
+            net2->name = ctx->id("$" + net->name.str(ctx) + "$iobuf_i");
+            net2->driver = net->driver;
+            if (net->driver.cell != nullptr) {
+                net2->driver.cell->ports[net2->driver.port].net = net2.get();
+                net->driver.cell = nullptr;
+            }
+            iobuf->ports[ctx->id("I")].net = net2.get();
+            PortRef ref;
+            ref.cell = iobuf.get();
+            ref.port = ctx->id("I");
+            net2->users.push_back(ref);
+            ctx->nets[net2->name] = std::move(net2);
+
+            iobuf->ports[ctx->id("O")] = PortInfo{ctx->id("O"), net, PORT_OUT};
+            assert(net->driver.cell == nullptr);
+            net->driver.port = ctx->id("O");
+            net->driver.cell = iobuf.get();
+        } else {
+            assert(false);
         }
-        iobuf->ports[ctx->id("I")].net = net2.get();
-        PortRef ref;
-        ref.cell = iobuf.get();
-        ref.port = ctx->id("I");
-        net2->users.push_back(ref);
-        ctx->nets[net2->name] = std::move(net2);
-
-        iobuf->ports[ctx->id("O")] = PortInfo{ctx->id("O"), net, PORT_OUT};
-        assert(net->driver.cell == nullptr);
-        net->driver.port = ctx->id("O");
-        net->driver.cell = iobuf.get();
-    } else {
-        assert(false);
+        ctx->cells[iobuf->name] = std::move(iobuf);
     }
-    ctx->cells[iobuf->name] = std::move(iobuf);
+
+    PortInfo pinfo;
+    pinfo.name = net->name;
+    pinfo.net = net;
+    pinfo.type = type;
+    ctx->ports[net->name] = pinfo;
 }
 
 void json_import_toplevel_port(Context *ctx, const string &modname, const std::vector<IdString> &netnames,
@@ -711,6 +762,11 @@ void json_import(Context *ctx, string modname, JsonNode *node)
         return;
 
     log_info("Importing module %s\n", modname.c_str());
+    ctx->attrs[ctx->id("module")] = modname;
+    JsonNode *attr_node = node->data_dict.at("attributes");
+    for (int attrid = 0; attrid < GetSize(attr_node->data_dict_keys); attrid++) {
+        json_import_top_attrib(ctx, modname, attr_node, &ctx->attrs, attrid);
+    }
 
     JsonNode *ports_parent = nullptr;
     if (node->data_dict.count("ports") > 0)
@@ -825,7 +881,43 @@ void json_import(Context *ctx, string modname, JsonNode *node)
             json_import_toplevel_port(ctx, modname, netids, ports_parent->data_dict_keys[portid], here);
         }
     }
+    if (node->data_dict.count("netnames")) {
+        JsonNode *net_parent = node->data_dict.at("netnames");
+        for (int nnid = 0; nnid < GetSize(net_parent->data_dict_keys); nnid++) {
+            JsonNode *here;
+
+            here = net_parent->data_dict.at(net_parent->data_dict_keys[nnid]);
+            std::string basename = net_parent->data_dict_keys[nnid];
+            if (here->data_dict.count("bits")) {
+                JsonNode *bits = here->data_dict.at("bits");
+                assert(bits->type == 'A');
+                size_t num_bits = bits->data_array.size();
+                for (size_t i = 0; i < num_bits; i++) {
+                    std::string name =
+                            basename + (num_bits == 1 ? "" : std::string("[") + std::to_string(i) + std::string("]"));
+                    IdString net_id = ctx->id(name);
+                    if (here->data_dict.count("attributes") && ctx->nets.find(net_id) != ctx->nets.end()) {
+                        NetInfo *this_net = ctx->nets[net_id].get();
+
+                        JsonNode *attr_node = here->data_dict.at("attributes");
+                        if (attr_node->type != 'D')
+                            log_error("JSON attribute list of \'%s\' is not a data dictionary\n",
+                                      this_net->name.c_str(ctx));
+
+                        //
+                        // Loop through all attributes, adding them into the
+                        // design to annotate the cell
+                        //
+                        for (int attrid = 0; attrid < GetSize(attr_node->data_dict_keys); attrid++) {
+                            json_import_net_attrib(ctx, modname, this_net, attr_node, &this_net->attrs, attrid);
+                        }
+                    }
+                }
+            }
+        }
+    }
     check_all_nets_driven(ctx);
+    ctx->settings[ctx->id("synth")] = "1";
 }
 }; // End Namespace JsonParser
 
@@ -856,7 +948,55 @@ bool parse_json_file(std::istream &f, std::string &filename, Context *ctx)
 
         log_info("Checksum: 0x%08x\n", ctx->checksum());
         log_break();
-        ctx->settings.emplace(ctx->id("input/json"), filename);
+        ctx->attributesToArchInfo();
+        return true;
+    } catch (log_execution_error_exception) {
+        return false;
+    }
+}
+
+bool load_json_settings(std::istream &f, std::string &filename, std::unordered_map<std::string, Property> &values)
+{
+    try {
+        using namespace JsonParser;
+
+        if (!f)
+            log_error("failed to open JSON file.\n");
+
+        int lineno = 1;
+
+        JsonNode root(f, lineno);
+
+        if (root.type != 'D')
+            log_error("JSON root node is not a dictionary.\n");
+
+        if (root.data_dict.count("modules") != 0) {
+            JsonNode *modules = root.data_dict.at("modules");
+
+            if (modules->type != 'D')
+                log_error("JSON modules node is not a dictionary.\n");
+
+            for (auto &it : modules->data_dict) {
+                JsonNode *node = it.second;
+                if (is_blackbox(node))
+                    continue;
+
+                if (node->data_dict.count("settings")) {
+                    JsonNode *attr_node = node->data_dict.at("settings");
+                    for (int attrid = 0; attrid < GetSize(attr_node->data_dict_keys); attrid++) {
+                        JsonNode *param = attr_node->data_dict.at(attr_node->data_dict_keys[attrid]);
+                        std::string pId = attr_node->data_dict_keys[attrid];
+                        if (param->type == 'N') {
+                            values[pId].setNumber(param->data_number);
+                        } else if (param->type == 'S')
+                            values[pId].setString(param->data_string);
+                        else
+                            log_error("JSON parameter type of \"%s\' of module not supported\n", pId.c_str());
+                    }
+                }
+            }
+        }
+
         return true;
     } catch (log_execution_error_exception) {
         return false;
diff --git a/json/jsonparse.h b/json/jsonparse.h
index fe71444f..65e3f02e 100644
--- a/json/jsonparse.h
+++ b/json/jsonparse.h
@@ -27,7 +27,8 @@
 NEXTPNR_NAMESPACE_BEGIN
 
 extern bool parse_json_file(std::istream &, std::string &, Context *);
-
+extern bool load_json_settings(std::istream &f, std::string &filename,
+                               std::unordered_map<std::string, Property> &values);
 NEXTPNR_NAMESPACE_END
 
 #endif
diff --git a/json/jsonwrite.cc b/json/jsonwrite.cc
new file mode 100644
index 00000000..0b7a5b25
--- /dev/null
+++ b/json/jsonwrite.cc
@@ -0,0 +1,180 @@
+/*
+ *  nextpnr -- Next Generation Place and Route
+ *
+ *  Copyright (C) 2018  Miodrag Milanovic <miodrag@symbioticeda.com>
+ *
+ *  Permission to use, copy, modify, and/or distribute this software for any
+ *  purpose with or without fee is hereby granted, provided that the above
+ *  copyright notice and this permission notice appear in all copies.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+#include "jsonwrite.h"
+#include <assert.h>
+#include <fstream>
+#include <iostream>
+#include <iterator>
+#include <log.h>
+#include <map>
+#include <string>
+#include "nextpnr.h"
+#include "version.h"
+
+NEXTPNR_NAMESPACE_BEGIN
+
+namespace JsonWriter {
+
+std::string get_string(std::string str)
+{
+    std::string newstr = "\"";
+    for (char c : str) {
+        if (c == '\\')
+            newstr += c;
+        newstr += c;
+    }
+    return newstr + "\"";
+}
+
+std::string get_name(IdString name, Context *ctx) { return get_string(name.c_str(ctx)); }
+
+void write_parameters(std::ostream &f, Context *ctx, const std::unordered_map<IdString, Property> &parameters,
+                      bool for_module = false)
+{
+    bool first = true;
+    for (auto &param : parameters) {
+        f << stringf("%s\n", first ? "" : ",");
+        f << stringf("        %s%s: ", for_module ? "" : "    ", get_name(param.first, ctx).c_str());
+        if (param.second.isString())
+            f << get_string(param.second);
+        else
+            f << param.second.num;
+        first = false;
+    }
+}
+
+void write_module(std::ostream &f, Context *ctx)
+{
+    auto val = ctx->attrs.find(ctx->id("module"));
+    if (val != ctx->attrs.end())
+        f << stringf("    %s: {\n", get_string(val->second.str).c_str());
+    else
+        f << stringf("    %s: {\n", get_string("top").c_str());
+    f << stringf("      \"settings\": {");
+    write_parameters(f, ctx, ctx->settings, true);
+    f << stringf("\n      },\n");
+    f << stringf("      \"attributes\": {");
+    write_parameters(f, ctx, ctx->attrs, true);
+    f << stringf("\n      },\n");
+    f << stringf("      \"ports\": {");
+    bool first = true;
+    for (auto &pair : ctx->ports) {
+        auto &c = pair.second;
+        f << stringf("%s\n", first ? "" : ",");
+        f << stringf("        %s: {\n", get_name(c.name, ctx).c_str());
+        f << stringf("          \"direction\": \"%s\",\n",
+                     c.type == PORT_IN ? "input" : c.type == PORT_INOUT ? "inout" : "output");
+        f << stringf("          \"bits\": [ %d ]\n", pair.first.index);
+        f << stringf("        }");
+        first = false;
+    }
+    f << stringf("\n      },\n");
+
+    f << stringf("      \"cells\": {");
+    first = true;
+    for (auto &pair : ctx->cells) {
+        auto &c = pair.second;
+        f << stringf("%s\n", first ? "" : ",");
+        f << stringf("        %s: {\n", get_name(c->name, ctx).c_str());
+        f << stringf("          \"hide_name\": %s,\n", c->name.c_str(ctx)[0] == '$' ? "1" : "0");
+        f << stringf("          \"type\": %s,\n", get_name(c->type, ctx).c_str());
+        f << stringf("          \"parameters\": {");
+        write_parameters(f, ctx, c->params);
+        f << stringf("\n          },\n");
+        f << stringf("          \"attributes\": {");
+        write_parameters(f, ctx, c->attrs);
+        f << stringf("\n          },\n");
+        f << stringf("          \"port_directions\": {");
+        bool first2 = true;
+        for (auto &conn : c->ports) {
+            auto &p = conn.second;
+            std::string direction = (p.type == PORT_IN) ? "input" : (p.type == PORT_OUT) ? "output" : "inout";
+            f << stringf("%s\n", first2 ? "" : ",");
+            f << stringf("            %s: \"%s\"", get_name(conn.first, ctx).c_str(), direction.c_str());
+            first2 = false;
+        }
+        f << stringf("\n          },\n");
+        f << stringf("          \"connections\": {");
+        first2 = true;
+        for (auto &conn : c->ports) {
+            auto &p = conn.second;
+            f << stringf("%s\n", first2 ? "" : ",");
+            if (p.net)
+                f << stringf("            %s: [ %d ]", get_name(conn.first, ctx).c_str(), p.net->name.index);
+            else
+                f << stringf("            %s: [ ]", get_name(conn.first, ctx).c_str());
+
+            first2 = false;
+        }
+        f << stringf("\n          }\n");
+
+        f << stringf("        }");
+        first = false;
+    }
+
+    f << stringf("\n      },\n");
+
+    f << stringf("      \"netnames\": {");
+    first = true;
+    for (auto &pair : ctx->nets) {
+        auto &w = pair.second;
+        f << stringf("%s\n", first ? "" : ",");
+        f << stringf("        %s: {\n", get_name(w->name, ctx).c_str());
+        f << stringf("          \"hide_name\": %s,\n", w->name.c_str(ctx)[0] == '$' ? "1" : "0");
+        f << stringf("          \"bits\": [ %d ] ,\n", pair.first.index);
+        f << stringf("          \"attributes\": {");
+        write_parameters(f, ctx, w->attrs);
+        f << stringf("\n          }\n");
+        f << stringf("        }");
+        first = false;
+    }
+
+    f << stringf("\n      }\n");
+    f << stringf("    }");
+}
+
+void write_context(std::ostream &f, Context *ctx)
+{
+    f << stringf("{\n");
+    f << stringf("  \"creator\": %s,\n",
+                 get_string("Next Generation Place and Route (git sha1 " GIT_COMMIT_HASH_STR ")").c_str());
+    f << stringf("  \"modules\": {\n");
+    write_module(f, ctx);
+    f << stringf("\n  }");
+    f << stringf("\n}\n");
+}
+
+}; // End Namespace JsonWriter
+
+bool write_json_file(std::ostream &f, std::string &filename, Context *ctx)
+{
+    try {
+        using namespace JsonWriter;
+        if (!f)
+            log_error("failed to open JSON file.\n");
+        write_context(f, ctx);
+        log_break();
+        return true;
+    } catch (log_execution_error_exception) {
+        return false;
+    }
+}
+
+NEXTPNR_NAMESPACE_END
diff --git a/generic/project.cc b/json/jsonwrite.h
index 342fcac3..9240bc96 100644
--- a/generic/project.cc
+++ b/json/jsonwrite.h
@@ -17,21 +17,17 @@
  *
  */
 
-#include "project.h"
-#include <boost/filesystem/convenience.hpp>
-#include <fstream>
-#include "log.h"
+#ifndef JSON_WRITER
+#define JSON_WRITER
 
-NEXTPNR_NAMESPACE_BEGIN
-
-void ProjectHandler::saveArch(Context *ctx, pt::ptree &root, std::string path) {}
+#include <ostream>
+#include <string>
+#include "nextpnr.h"
 
-std::unique_ptr<Context> ProjectHandler::createContext(pt::ptree &root)
-{
-    ArchArgs chipArgs;
-    return std::unique_ptr<Context>(new Context(chipArgs));
-}
+NEXTPNR_NAMESPACE_BEGIN
 
-void ProjectHandler::loadArch(Context *ctx, pt::ptree &root, std::string path) {}
+extern bool write_json_file(std::ostream &, std::string &, Context *);
 
 NEXTPNR_NAMESPACE_END
+
+#endif