5 files changed, 94 insertions, 2 deletions

diff --git a/nexus/arch.cc b/nexus/arch.cc
index eadfaa4b..95b409bf 100644
--- a/nexus/arch.cc
+++ b/nexus/arch.cc
@@ -171,6 +171,19 @@ Arch::Arch(ArchArgs args) : args(args)
     }
     if (!speed_grade)
         log_error("Unknown speed grade '%s'.\n", speed.c_str());
+
+    std::unordered_set<IdString> bel_types;
+    for (BelId bel : getBels()) {
+        bel_types.insert(getBelType(bel));
+    }
+
+    for (IdString bel_type : bel_types) {
+        cell_types.push_back(bel_type);
+
+        BelBucketId bucket;
+        bucket.name = bel_type;
+        buckets.push_back(bucket);
+    }
 }
 
 // -----------------------------------------------------------------------
@@ -635,8 +648,8 @@ bool Arch::place()
         cfg.ioBufTypes.insert(id_SEIO18_CORE);
         cfg.ioBufTypes.insert(id_OSC_CORE);
         cfg.cellGroups.emplace_back();
-        cfg.cellGroups.back().insert(id_OXIDE_COMB);
-        cfg.cellGroups.back().insert(id_OXIDE_FF);
+        cfg.cellGroups.back().insert({id_OXIDE_COMB});
+        cfg.cellGroups.back().insert({id_OXIDE_FF});
 
         cfg.beta = 0.5;
         cfg.criticalityExponent = 7;
diff --git a/nexus/arch.h b/nexus/arch.h
index 56b48bf3..ee66599a 100644
--- a/nexus/arch.h
+++ b/nexus/arch.h
@@ -1335,6 +1335,47 @@ struct Arch : BaseCtx
     // Perform placement validity checks, returning false on failure (all
     // implemented in arch_place.cc)
 
+    // Whether this cell type can be placed at this BEL.
+    bool isValidBelForCellType(IdString cell_type, BelId bel) const { return cell_type == getBelType(bel); }
+
+    const std::vector<IdString> &getCellTypes() const { return cell_types; }
+
+    std::vector<BelBucketId> getBelBuckets() const { return buckets; }
+
+    IdString getBelBucketName(BelBucketId bucket) const { return bucket.name; }
+
+    BelBucketId getBelBucketByName(IdString name) const
+    {
+        BelBucketId bucket;
+        bucket.name = name;
+        return bucket;
+    }
+
+    BelBucketId getBelBucketForBel(BelId bel) const
+    {
+        BelBucketId bucket;
+        bucket.name = getBelType(bel);
+        return bucket;
+    }
+
+    BelBucketId getBelBucketForCellType(IdString cell_type) const
+    {
+        BelBucketId bucket;
+        bucket.name = cell_type;
+        return bucket;
+    }
+
+    std::vector<BelId> getBelsInBucket(BelBucketId bucket) const
+    {
+        std::vector<BelId> bels;
+        for (BelId bel : getBels()) {
+            if (getBelType(bel) == bucket.name) {
+                bels.push_back(bel);
+            }
+        }
+        return bels;
+    }
+
     // Whether or not a given cell can be placed at a given Bel
     // This is not intended for Bel type checks, but finer-grained constraints
     // such as conflicting set/reset signals, etc
@@ -1536,6 +1577,9 @@ struct Arch : BaseCtx
 
     // -------------------------------------------------
     void write_fasm(std::ostream &out) const;
+
+    std::vector<IdString> cell_types;
+    std::vector<BelBucketId> buckets;
 };
 
 NEXTPNR_NAMESPACE_END
diff --git a/nexus/arch_pybindings.cc b/nexus/arch_pybindings.cc
index 1a3890ff..b07031f7 100644
--- a/nexus/arch_pybindings.cc
+++ b/nexus/arch_pybindings.cc
@@ -55,6 +55,9 @@ void arch_wrap_python(py::module &m)
     typedef UpDownhillPipRange DownhillPipRange;
     typedef WireBelPinRange BelPinRange;
 
+    typedef const std::vector<BelBucketId> &BelBucketRange;
+    typedef const std::vector<BelId> &BelRangeForBelBucket;
+
 #include "arch_pybindings_shared.h"
 
     WRAP_RANGE(m, Bel, conv_to_str<BelId>);
diff --git a/nexus/arch_pybindings.h b/nexus/arch_pybindings.h
index 326af306..7694090b 100644
--- a/nexus/arch_pybindings.h
+++ b/nexus/arch_pybindings.h
@@ -76,6 +76,18 @@ template <> struct string_converter<PipId>
     }
 };
 
+template <> struct string_converter<BelBucketId>
+{
+    BelBucketId from_str(Context *ctx, std::string name) { return ctx->getBelBucketByName(ctx->id(name)); }
+
+    std::string to_str(Context *ctx, BelBucketId id)
+    {
+        if (id == BelBucketId())
+            throw bad_wrap();
+        return ctx->getBelBucketName(id).str(ctx);
+    }
+};
+
 template <> struct string_converter<BelPin>
 {
     BelPin from_str(Context *ctx, std::string name)
diff --git a/nexus/archdefs.h b/nexus/archdefs.h
index adc1342c..7e427e06 100644
--- a/nexus/archdefs.h
+++ b/nexus/archdefs.h
@@ -114,6 +114,15 @@ struct PipId
     }
 };
 
+struct BelBucketId
+{
+    IdString name;
+
+    bool operator==(const BelBucketId &other) const { return (name == other.name); }
+    bool operator!=(const BelBucketId &other) const { return (name != other.name); }
+    bool operator<(const BelBucketId &other) const { return name < other.name; }
+};
+
 struct GroupId
 {
     enum : int8_t
@@ -250,4 +259,15 @@ template <> struct hash<NEXTPNR_NAMESPACE_PREFIX DecalId>
         return seed;
     }
 };
+
+template <> struct hash<NEXTPNR_NAMESPACE_PREFIX BelBucketId>
+{
+    std::size_t operator()(const NEXTPNR_NAMESPACE_PREFIX BelBucketId &bucket) const noexcept
+    {
+        std::size_t seed = 0;
+        boost::hash_combine(seed, hash<NEXTPNR_NAMESPACE_PREFIX IdString>()(bucket.name));
+        return seed;
+    }
+};
+
 } // namespace std