1 files changed, 160 insertions, 0 deletions
diff --git a/src/common/Encoding/BaseEncoding.h b/src/common/Encoding/BaseEncoding.h
new file mode 100644
index 00000000000..d8b1453f271
--- /dev/null
+++ b/src/common/Encoding/BaseEncoding.h
@@ -0,0 +1,160 @@
+/*
+ * Copyright (C) 2008-2019 TrinityCore <https://www.trinitycore.org/>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 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 General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+ 
+#ifndef TRINITY_BASE_ENCODING_HPP
+#define TRINITY_BASE_ENCODING_HPP
+
+#include "advstd.h"
+#include "Define.h"
+#include "Optional.h"
+#include <string>
+#include <vector>
+
+namespace Trinity
+{
+namespace Impl
+{
+template <typename Encoding>
+struct GenericBaseEncoding
+{
+    static constexpr std::size_t BITS_PER_CHAR = Encoding::BITS_PER_CHAR;
+    static constexpr std::size_t PAD_TO = advstd::lcm(8u, BITS_PER_CHAR);
+
+    static_assert(BITS_PER_CHAR < 8, "Encoding parameters are invalid");
+
+    static constexpr uint8 DECODE_ERROR = Encoding::DECODE_ERROR;
+    static constexpr char PADDING = Encoding::PADDING;
+
+    static constexpr std::size_t EncodedSize(std::size_t size)
+    {
+        size *= 8; // bits in input
+        if (size % PAD_TO) // pad to boundary
+            size += (PAD_TO - (size % PAD_TO));
+        return (size / BITS_PER_CHAR);
+    }
+
+    static constexpr std::size_t DecodedSize(std::size_t size)
+    {
+        size *= BITS_PER_CHAR; // bits in input
+        if (size % PAD_TO) // pad to boundary
+            size += (PAD_TO - (size % PAD_TO));
+        return (size / 8);
+    }
+
+    static std::string Encode(std::vector<uint8> const& data)
+    {
+        auto it = data.begin(), end = data.end();
+        if (it == end)
+            return "";
+
+        std::string s;
+        s.reserve(EncodedSize(data.size()));
+
+        uint8 bitsLeft = 8; // in current byte
+        do
+        {
+            uint8 thisC = 0;
+            if (bitsLeft >= BITS_PER_CHAR)
+            {
+                bitsLeft -= BITS_PER_CHAR;
+                thisC = ((*it >> bitsLeft) & ((1 << BITS_PER_CHAR)-1));
+                if (!bitsLeft)
+                {
+                    ++it;
+                    bitsLeft = 8;
+                }
+            }
+            else
+            {
+                thisC = (*it & ((1 << bitsLeft) - 1)) << (BITS_PER_CHAR - bitsLeft);
+                bitsLeft += (8 - BITS_PER_CHAR);
+                if ((++it) != end)
+                    thisC |= (*it >> bitsLeft);
+            }
+            s.append(1, Encoding::Encode(thisC));
+        } while (it != end);
+
+        while (bitsLeft != 8)
+        {
+            if (bitsLeft > BITS_PER_CHAR)
+                bitsLeft -= BITS_PER_CHAR;
+            else
+                bitsLeft += (8 - BITS_PER_CHAR);
+            s.append(1, PADDING);
+        }
+
+        return s;
+    }
+
+    static Optional<std::vector<uint8>> Decode(std::string const& data)
+    {
+        auto it = data.begin(), end = data.end();
+        if (it == end)
+            return std::vector<uint8>();
+
+        std::vector<uint8> v;
+        v.reserve(DecodedSize(data.size()));
+
+        uint8 currentByte = 0;
+        uint8 bitsLeft = 8; // in current byte
+        while ((it != end) && (*it != PADDING))
+        {
+            uint8 cur = Encoding::Decode(*(it++));
+            if (cur == DECODE_ERROR)
+                return {};
+
+            if (bitsLeft > BITS_PER_CHAR)
+            {
+                bitsLeft -= BITS_PER_CHAR;
+                currentByte |= (cur << bitsLeft);
+            }
+            else
+            {
+                bitsLeft = BITS_PER_CHAR - bitsLeft; // in encoded char
+                currentByte |= (cur >> bitsLeft);
+                v.push_back(currentByte);
+                currentByte = (cur & ((1 << bitsLeft) - 1));
+                bitsLeft = 8 - bitsLeft; // in byte again
+                currentByte <<= bitsLeft;
+            }
+        }
+
+        if (currentByte)
+            return {}; // decode error, trailing non-zero bits
+
+        // process padding
+        while ((it != end) && (*it == PADDING) && (bitsLeft != 8))
+        {
+            if (bitsLeft > BITS_PER_CHAR)
+                bitsLeft -= BITS_PER_CHAR;
+            else
+                bitsLeft += (8 - BITS_PER_CHAR);
+            ++it;
+        }
+
+        // ok, all padding should be consumed, and we should be at end of string
+        if (it == end)
+            return v;
+
+        // anything else is an error
+        return {};
+    }
+};
+}
+}
+
+#endif