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+/**
+ * Alee Forth: A portable and concise Forth implementation in modern C++.
+ * Copyright (C) 2023  Clyne Sullivan <clyne@bitgloo.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef ALEEFORTH_SPLITMEMDICT_HPP
+#define ALEEFORTH_SPLITMEMDICT_HPP
+
+#include "dictionary.hpp"
+
+#include <cstring>
+
+#ifndef MEMDICTSIZE
+#define MEMDICTSIZE (65536)
+#endif
+constexpr unsigned long int MemDictSize = MEMDICTSIZE;
+
+template<unsigned long int RON>
+class SplitMemDict : public Dictionary
+{
+    const uint8_t *rodict;
+    uint8_t rwdict[MemDictSize];
+    uint8_t extra[Dictionary::Begin];
+
+public:
+    constexpr SplitMemDict(const uint8_t *rod):
+        rodict(rod)
+    {
+        std::memcpy(extra, rodict, sizeof(extra));
+    }
+
+    virtual Cell read(Addr addr) const noexcept final {
+        const uint8_t *dict;
+        if (addr < RON) {
+            dict = addr < Dictionary::Begin ? extra : rodict;
+        } else {
+            dict = rwdict;
+            addr -= RON;
+        }
+
+        return *reinterpret_cast<const Cell *>(dict + addr);
+    }
+
+    virtual void write(Addr addr, Cell value) noexcept final {
+        if (addr >= RON)
+            *reinterpret_cast<Cell *>(rwdict + addr - RON) = value;
+        else if (addr < Dictionary::Begin)
+            *reinterpret_cast<Cell *>(extra + addr) = value;
+    }
+
+    virtual uint8_t readbyte(Addr addr) const noexcept final {
+        const uint8_t *dict;
+        if (addr < RON) {
+            dict = addr < Dictionary::Begin ? extra : rodict;
+        } else {
+            dict = rwdict;
+            addr -= RON;
+        }
+
+        return dict[addr];
+    }
+
+    virtual void writebyte(Addr addr, uint8_t value) noexcept final {
+        if (addr >= RON)
+            rwdict[addr - RON] = value;
+        else if (addr < Dictionary::Begin)
+            extra[addr] = value;
+    }
+};
+
+#endif // ALEEFORTH_SPLITMEMDICT_HPP
+