Add dynamic bitarray to common library.

Signed-off-by: Keith Rothman <537074+litghost@users.noreply.github.com>

common/dynamic_bitarray.h

@@ -0,0 +1,82 @@
+/*
+ *  nextpnr -- Next Generation Place and Route
+ *
+ *  Copyright (C) 2021  Symbiflow Authors
+ *
+ *  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 <cstdint>
+#include <limits>
+#include <vector>
+
+// This class implements a simple dynamic bitarray, backed by some resizable
+// random access storage.  The default is to use a std::vector<uint8_t>.
+
+#ifndef DYNAMIC_BITARRAY_H
+#define DYNAMIC_BITARRAY_H
+
+namespace nextpnr {
+
+template <typename Storage = std::vector<uint8_t>> class DynamicBitarray
+{
+  public:
+    static_assert(!std::numeric_limits<typename Storage::value_type>::is_signed, "Storage must be unsigned!");
+
+    void fill(bool value)
+    {
+        std::fill(storage.begin(), storage.end(), value ? std::numeric_limits<typename Storage::value_type>::max() : 0);
+    }
+
+    constexpr size_t bits_per_value() const
+    {
+        return sizeof(typename Storage::value_type) * std::numeric_limits<typename Storage::value_type>::digits;
+    }
+
+    bool get(size_t bit) const
+    {
+        size_t element_index = bit / bits_per_value();
+        size_t bit_offset = bit % bits_per_value();
+
+        auto element = storage.at(element_index);
+        return (element & (1 << bit_offset)) != 0;
+    }
+
+    void set(size_t bit, bool value)
+    {
+        size_t element_index = bit / bits_per_value();
+        size_t bit_offset = bit % bits_per_value();
+
+        if (value) {
+            storage.at(element_index) |= (1 << bit_offset);
+        } else {
+            storage.at(element_index) &= ~(1 << bit_offset);
+        }
+    }
+
+    void resize(size_t number_bits)
+    {
+        size_t required_storage = (number_bits + bits_per_value()) / bits_per_value();
+        storage.resize(required_storage);
+    }
+
+    size_t size() const { return storage.size() * bits_per_value(); }
+
+  private:
+    Storage storage;
+};
+
+}; // namespace nextpnr
+
+#endif /* DYNAMIC_BITARRAY_H */