nexus: Initial PDC parser integration

Signed-off-by: David Shah <dave@ds0.me>

nexus/arch.h

@@ -1444,7 +1444,7 @@ struct Arch : BaseCtx
     // List of IO constraints, used by PDC parser
     std::unordered_map<IdString, std::unordered_map<IdString, Property>> io_attr;
 
-    void parse_pdc(std::istream &in) const;
+    void read_pdc(std::istream &in);
 
     // -------------------------------------------------
     void write_fasm(std::ostream &out) const;

nexus/main.cc

@@ -50,6 +50,7 @@ po::options_description NexusCommandHandler::getArchOptions()
     specific.add_options()("chipdb", po::value<std::string>(), "name of chip database binary");
     specific.add_options()("device", po::value<std::string>(), "device name");
     specific.add_options()("fasm", po::value<std::string>(), "fasm file to write");
+    specific.add_options()("pdc", po::value<std::string>(), "physical constraints file");
     return specific;
 }
 
@@ -72,7 +73,16 @@ std::unique_ptr<Context> NexusCommandHandler::createContext(std::unordered_map<s
     return std::unique_ptr<Context>(new Context(chipArgs));
 }
 
-void NexusCommandHandler::customAfterLoad(Context *ctx) {}
+void NexusCommandHandler::customAfterLoad(Context *ctx)
+{
+    if (vm.count("pdc")) {
+        std::string filename = vm["pdc"].as<std::string>();
+        std::ifstream in(filename);
+        if (!in)
+            log_error("Failed to open input PDC file %s.\n", filename.c_str());
+        ctx->read_pdc(in);
+    }
+}
 
 int main(int argc, char *argv[])
 {

nexus/pdc.cc

@@ -21,6 +21,8 @@
 #include "log.h"
 #include "nextpnr.h"
 
+#include <iterator>
+
 NEXTPNR_NAMESPACE_BEGIN
 
 struct TCLEntity
@@ -76,6 +78,8 @@ struct PDCParser
     int lineno = 1;
     Context *ctx;
 
+    PDCParser(const std::string &buf, Context *ctx) : buf(buf), ctx(ctx){};
+
     inline bool eof() const { return pos == int(buf.size()); }
 
     inline char peek() const { return buf.at(pos); }
@@ -193,10 +197,14 @@ struct PDCParser
         const std::string &cmd = arg0.str;
         if (cmd == "get_ports")
             return cmd_get_ports(arguments);
+        else if (cmd == "get_cells")
+            return cmd_get_cells(arguments);
         else if (cmd == "ldc_set_location")
             return cmd_ldc_set_location(arguments);
         else if (cmd == "ldc_set_port")
             return cmd_ldc_set_port(arguments);
+        else
+            log_error("Unsupported PDC command '%s'\n", cmd.c_str());
     }
 
     std::vector<TCLValue> get_arguments()
@@ -208,6 +216,8 @@ struct PDCParser
                 auto result = evaluate(get_arguments());
                 NPNR_ASSERT(check_get(']'));
                 args.push_back(result);
+            } else if (peek() == ']') {
+                break;
             } else {
                 args.push_back(get_str());
             }
@@ -233,6 +243,23 @@ struct PDCParser
         return ports;
     }
 
+    TCLValue cmd_get_cells(const std::vector<TCLValue> &arguments)
+    {
+        std::vector<TCLEntity> cells;
+        for (int i = 1; i < int(arguments.size()); i++) {
+            auto &arg = arguments.at(i);
+            if (!arg.is_string)
+                log_error("get_cells expected string arguments (line %d)\n", lineno);
+            std::string s = arg.str;
+            if (s.at(0) == '-')
+                log_error("unsupported argument '%s' to get_cells (line %d)\n", s.c_str(), lineno);
+            IdString id = ctx->id(s);
+            if (ctx->cells.count(id))
+                cells.emplace_back(TCLEntity::ENTITY_CELL, id);
+        }
+        return cells;
+    }
+
     TCLValue cmd_ldc_set_location(const std::vector<TCLValue> &arguments)
     {
         std::string site;
@@ -296,6 +323,23 @@ struct PDCParser
         }
         return std::string{};
     }
+
+    void operator()()
+    {
+        while (!eof()) {
+            skip_blank(true);
+            auto args = get_arguments();
+            if (args.empty())
+                continue;
+            evaluate(args);
+        }
+    }
 };
 
+void Arch::read_pdc(std::istream &in)
+{
+    std::string buf(std::istreambuf_iterator<char>(in), {});
+    PDCParser(buf, getCtx())();
+}
+
 NEXTPNR_NAMESPACE_END