nexus: Add iterator types based on nextpnr-xilinx

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

nexus/arch.h

@@ -162,6 +162,7 @@ NPNR_PACKED_STRUCT(struct ChipInfoPOD {
     RelPtr<char> device_name;
     uint16_t width;
     uint16_t height;
+    uint32_t num_tiles;
     RelPtr<GridLocationPOD> grid;
 });
 
@@ -174,6 +175,330 @@ NPNR_PACKED_STRUCT(struct DatabasePOD {
     RelPtr<LocTypePOD> loctypes;
 });
 
+// -----------------------------------------------------------------------
+
+// Helper functions for database access
+namespace {
+template <typename Id> const LocTypePOD &chip_loc_data(const DatabasePOD *db, const ChipInfoPOD *chip, Id &id)
+{
+    return db->loctypes[chip->grid[id.tile].loc_type];
+}
+
+template <typename Id> const LocNeighourhoodPOD &chip_nh_data(const DatabasePOD *db, const ChipInfoPOD *chip, Id &id)
+{
+    auto &t = chip->grid[id.tile];
+    return db->loctypes[t.loc_type].neighbourhoods[t.neighbourhood_type];
+}
+
+inline const BelInfoPOD &chip_bel_data(const DatabasePOD *db, const ChipInfoPOD *chip, BelId id)
+{
+    return chip_loc_data(db, chip, id).bels[id.index];
+}
+inline const LocWireInfoPOD &chip_wire_data(const DatabasePOD *db, const ChipInfoPOD *chip, WireId &id)
+{
+    return chip_loc_data(db, chip, id).wires[id.index];
+}
+inline const PipInfoPOD &chip_pip_data(const DatabasePOD *db, const ChipInfoPOD *chip, PipId &id)
+{
+    return chip_loc_data(db, chip, id).pips[id.index];
+}
+inline bool chip_rel_tile(const ChipInfoPOD *chip, int32_t base, int16_t rel_x, int16_t rel_y, int32_t &next)
+{
+    int32_t curr_x = base % chip->width;
+    int32_t curr_y = base / chip->width;
+    int32_t new_x = curr_x + rel_x;
+    int32_t new_y = curr_y + rel_y;
+    if (new_x < 0 || new_x >= chip->width)
+        return false;
+    if (new_y < 0 || new_y >= chip->height)
+        return false;
+    next = new_y * chip->width + new_x;
+    return true;
+}
+inline WireId chip_canonical_wire(const DatabasePOD *db, const ChipInfoPOD *chip, int32_t tile, uint16_t index)
+{
+    WireId wire{tile, index};
+    // `tile` is the primary location for the wire, so ID is already canonical
+    if (chip_wire_data(db, chip, wire).flags & WIRE_PRIMARY)
+        return wire;
+    // Not primary; find the primary location which forms the canonical ID
+    auto &nd = chip_nh_data(db, chip, wire);
+    auto &wn = nd.wire_neighbours[index];
+    for (size_t i = 0; i < wn.num_nwires; i++) {
+        auto &nw = wn.neigh_wires[i];
+        if (nw.arc_flags & LOGICAL_TO_PRIMARY) {
+            if (chip_rel_tile(chip, tile, nw.rel_x, nw.rel_y, wire.tile)) {
+                wire.index = nw.wire_index;
+                break;
+            }
+        }
+    }
+    return wire;
+}
+inline bool chip_wire_is_primary(const DatabasePOD *db, const ChipInfoPOD *chip, int32_t tile, uint16_t index)
+{
+    WireId wire{tile, index};
+    // `tile` is the primary location for the wire, so ID is already canonical
+    if (chip_wire_data(db, chip, wire).flags & WIRE_PRIMARY)
+        return true;
+    // Not primary; find the primary location which forms the canonical ID
+    auto &nd = chip_nh_data(db, chip, wire);
+    auto &wn = nd.wire_neighbours[index];
+    for (size_t i = 0; i < wn.num_nwires; i++) {
+        auto &nw = wn.neigh_wires[i];
+        if (nw.arc_flags & LOGICAL_TO_PRIMARY) {
+            if (chip_rel_tile(chip, tile, nw.rel_x, nw.rel_y, wire.tile)) {
+                return false;
+            }
+        }
+    }
+    return true;
+}
+} // namespace
+
+// -----------------------------------------------------------------------
+
+struct BelIterator
+{
+    const DatabasePOD *db;
+    const ChipInfoPOD *chip;
+    int cursor_index;
+    int cursor_tile;
+
+    BelIterator operator++()
+    {
+        cursor_index++;
+        while (cursor_tile < int(chip->num_tiles) &&
+               cursor_index >= int(db->loctypes[chip->grid[cursor_tile].loc_type].num_bels)) {
+            cursor_index = 0;
+            cursor_tile++;
+        }
+        return *this;
+    }
+    BelIterator operator++(int)
+    {
+        BelIterator prior(*this);
+        ++(*this);
+        return prior;
+    }
+
+    bool operator!=(const BelIterator &other) const
+    {
+        return cursor_index != other.cursor_index || cursor_tile != other.cursor_tile;
+    }
+
+    bool operator==(const BelIterator &other) const
+    {
+        return cursor_index == other.cursor_index && cursor_tile == other.cursor_tile;
+    }
+
+    BelId operator*() const
+    {
+        BelId ret;
+        ret.tile = cursor_tile;
+        ret.index = cursor_index;
+        return ret;
+    }
+};
+
+struct BelRange
+{
+    BelIterator b, e;
+    BelIterator begin() const { return b; }
+    BelIterator end() const { return e; }
+};
+
+// -----------------------------------------------------------------------
+
+struct WireIterator
+{
+    const DatabasePOD *db;
+    const ChipInfoPOD *chip;
+    int cursor_index;
+    int cursor_tile = 0;
+
+    WireIterator operator++()
+    {
+        // Iterate over nodes first, then tile wires that aren't nodes
+        do {
+            cursor_index++;
+            while (cursor_tile < int(chip->num_tiles) &&
+                   cursor_index >= int(db->loctypes[chip->grid[cursor_tile].loc_type].num_wires)) {
+                cursor_index = 0;
+                cursor_tile++;
+            }
+        } while (cursor_tile < int(chip->num_tiles) && !chip_wire_is_primary(db, chip, cursor_tile, cursor_index));
+
+        return *this;
+    }
+    WireIterator operator++(int)
+    {
+        WireIterator prior(*this);
+        ++(*this);
+        return prior;
+    }
+
+    bool operator!=(const WireIterator &other) const
+    {
+        return cursor_index != other.cursor_index || cursor_tile != other.cursor_tile;
+    }
+
+    bool operator==(const WireIterator &other) const
+    {
+        return cursor_index == other.cursor_index && cursor_tile == other.cursor_tile;
+    }
+
+    WireId operator*() const
+    {
+        WireId ret;
+        ret.tile = cursor_tile;
+        ret.index = cursor_index;
+        return ret;
+    }
+};
+
+struct WireRange
+{
+    WireIterator b, e;
+    WireIterator begin() const { return b; }
+    WireIterator end() const { return e; }
+};
+
+// Iterate over all neighour wires for a wire
+struct TileWireIterator
+{
+    const DatabasePOD *db;
+    const ChipInfoPOD *chip;
+    WireId baseWire;
+    int cursor = -1;
+
+    void operator++()
+    {
+        auto &wn = chip_nh_data(db, chip, baseWire).wire_neighbours[baseWire.index];
+        int32_t tile;
+        do
+            cursor++;
+        while (cursor < int(wn.num_nwires) &&
+               ((wn.neigh_wires[cursor].arc_flags & LOGICAL_TO_PRIMARY) ||
+                !chip_rel_tile(chip, baseWire.tile, wn.neigh_wires[cursor].rel_x, wn.neigh_wires[cursor].rel_y, tile)));
+    }
+    bool operator!=(const TileWireIterator &other) const { return cursor != other.cursor; }
+
+    // Returns a *denormalised* identifier that may be a non-primary wire (and thus should _not_ be used
+    // as a WireId in general as it will break invariants)
+    WireId operator*() const
+    {
+        if (cursor == -1) {
+            return baseWire;
+        } else {
+            auto &nw = chip_nh_data(db, chip, baseWire).wire_neighbours[baseWire.index].neigh_wires[cursor];
+            WireId result;
+            result.index = nw.wire_index;
+            if (!chip_rel_tile(chip, baseWire.tile, nw.rel_x, nw.rel_y, result.tile))
+                return WireId();
+            return result;
+        }
+    }
+};
+
+// -----------------------------------------------------------------------
+
+struct AllPipIterator
+{
+    const DatabasePOD *db;
+    const ChipInfoPOD *chip;
+    int cursor_index;
+    int cursor_tile;
+
+    AllPipIterator operator++()
+    {
+        cursor_index++;
+        while (cursor_tile < int(chip->num_tiles) &&
+               cursor_index >= int(db->loctypes[chip->grid[cursor_tile].loc_type].num_pips)) {
+            cursor_index = 0;
+            cursor_tile++;
+        }
+        return *this;
+    }
+    AllPipIterator operator++(int)
+    {
+        AllPipIterator prior(*this);
+        ++(*this);
+        return prior;
+    }
+
+    bool operator!=(const AllPipIterator &other) const
+    {
+        return cursor_index != other.cursor_index || cursor_tile != other.cursor_tile;
+    }
+
+    bool operator==(const AllPipIterator &other) const
+    {
+        return cursor_index == other.cursor_index && cursor_tile == other.cursor_tile;
+    }
+
+    PipId operator*() const
+    {
+        PipId ret;
+        ret.tile = cursor_tile;
+        ret.index = cursor_index;
+        return ret;
+    }
+};
+
+struct AllPipRange
+{
+    AllPipIterator b, e;
+    AllPipIterator begin() const { return b; }
+    AllPipIterator end() const { return e; }
+};
+
+// -----------------------------------------------------------------------
+
+struct UpDownhillPipIterator
+{
+    const DatabasePOD *db;
+    const ChipInfoPOD *chip;
+    TileWireIterator twi, twi_end;
+    int cursor = -1;
+    bool uphill = false;
+
+    void operator++()
+    {
+        cursor++;
+        while (true) {
+            if (!(twi != twi_end))
+                break;
+            WireId w = *twi;
+            auto &tile = db->loctypes[chip->grid[w.tile].loc_type];
+            if (cursor < int(uphill ? tile.wires[w.index].num_uphill : tile.wires[w.index].num_downhill))
+                break;
+            ++twi;
+            cursor = 0;
+        }
+    }
+    bool operator!=(const UpDownhillPipIterator &other) const { return twi != other.twi || cursor != other.cursor; }
+
+    PipId operator*() const
+    {
+        PipId ret;
+        WireId w = *twi;
+        ret.tile = w.tile;
+        auto &tile = db->loctypes[chip->grid[w.tile].loc_type];
+        ret.index = uphill ? tile.wires[w.index].pips_uh[cursor] : tile.wires[w.index].pips_dh[cursor];
+        return ret;
+    }
+};
+
+struct UpDownhillPipRange
+{
+    UpDownhillPipIterator b, e;
+    UpDownhillPipIterator begin() const { return b; }
+    UpDownhillPipIterator end() const { return e; }
+};
+
+// -----------------------------------------------------------------------
+
 const int bba_version =
 #include "bba_version.inc"
         ;
@@ -205,52 +530,20 @@ struct Arch : BaseCtx
     int getTileBelDimZ(int, int) const { return 256; }
     int getTilePipDimZ(int, int) const { return 1; }
 
-    template <typename Id> const LocTypePOD &loc_data(Id &id) const
+    template <typename Id> const LocTypePOD &loc_data(Id &id) const { return chip_loc_data(db, chip_info, id); }
-    {
-        return db->loctypes[chip_info->grid[id.tile].loc_type];
-    }
 
-    template <typename Id> const LocNeighourhoodPOD &nh_data(Id &id) const
+    template <typename Id> const LocNeighourhoodPOD &nh_data(Id &id) const { return chip_nh_data(db, chip_info, id); }
-    {
-        auto &t = chip_info->grid[id.tile];
-        return db->loctypes[t.loc_type].neighbourhoods[t.neighbourhood_type];
-    }
 
-    inline const BelInfoPOD &bel_data(BelId id) const { return loc_data(id).bels[id.index]; }
+    inline const BelInfoPOD &bel_data(BelId id) const { return chip_bel_data(db, chip_info, id); }
-    inline const LocWireInfoPOD &wire_data(WireId &id) const { return loc_data(id).wires[id.index]; }
+    inline const LocWireInfoPOD &wire_data(WireId &id) const { return chip_wire_data(db, chip_info, id); }
-    inline const PipInfoPOD &pip_data(PipId &id) const { return loc_data(id).pips[id.index]; }
+    inline const PipInfoPOD &pip_data(PipId &id) const { return chip_pip_data(db, chip_info, id); }
     inline bool rel_tile(int32_t base, int16_t rel_x, int16_t rel_y, int32_t &next)
     {
-        int32_t curr_x = base % chip_info->width;
+        return chip_rel_tile(chip_info, base, rel_x, rel_y, next);
-        int32_t curr_y = base / chip_info->width;
-        int32_t new_x = curr_x + rel_x;
-        int32_t new_y = curr_y + rel_y;
-        if (new_x < 0 || new_x >= chip_info->width)
-            return false;
-        if (new_y < 0 || new_y >= chip_info->height)
-            return false;
-        next = new_y * chip_info->width + new_x;
-        return true;
     }
     inline const WireId canonical_wire(int32_t tile, uint16_t index)
     {
-        WireId wire{tile, index};
+        return chip_canonical_wire(db, chip_info, tile, index);
-        // `tile` is the primary location for the wire, so ID is already canonical
-        if (wire_data(wire).flags & WIRE_PRIMARY)
-            return wire;
-        // Not primary; find the primary location which forms the canonical ID
-        auto &nd = nh_data(wire);
-        auto &wn = nd.wire_neighbours[index];
-        for (size_t i = 0; i < wn.num_nwires; i++) {
-            auto &nw = wn.neigh_wires[i];
-            if (nw.arc_flags & LOGICAL_TO_PRIMARY) {
-                if (rel_tile(tile, nw.rel_x, nw.rel_y, wire.tile)) {
-                    wire.index = nw.wire_index;
-                    break;
-                }
-            }
-        }
-        return wire;
     }
 };