diff --git a/src/main/c/HybiPacketDecoder.cpp b/src/main/c/HybiPacketDecoder.cpp
new file mode 100644
index 0000000..f0fdefe
--- /dev/null
+++ b/src/main/c/HybiPacketDecoder.cpp
@@ -0,0 +1,102 @@
+// Copyright (c) 2013, Matt Godbolt
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without 
+// modification, are permitted provided that the following conditions are met:
+// 
+// Redistributions of source code must retain the above copyright notice, this 
+// list of conditions and the following disclaimer.
+// 
+// Redistributions in binary form must reproduce the above copyright notice, 
+// this list of conditions and the following disclaimer in the documentation 
+// and/or other materials provided with the distribution.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 
+// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
+// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE 
+// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 
+// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 
+// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 
+// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
+// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
+// POSSIBILITY OF SUCH DAMAGE.
+
+#include "internal/HybiPacketDecoder.h"
+#include "internal/LogStream.h"
+
+#include <arpa/inet.h>
+
+namespace seasocks {
+
+HybiPacketDecoder::HybiPacketDecoder(Logger& logger, const std::vector<uint8_t>& buffer) :
+    _logger(logger),
+    _buffer(buffer),
+    _messageStart(0) {
+}
+
+HybiPacketDecoder::MessageState HybiPacketDecoder::decodeNextMessage(std::vector<uint8_t>& messageOut) {
+    if (_messageStart + 1 >= _buffer.size()) {
+        return NoMessage;
+    }
+    if ((_buffer[_messageStart] & 0x80) == 0) {
+        // FIN bit is not clear...
+        // TODO: support
+        LS_WARNING(&_logger, "Received hybi frame without FIN bit set - unsupported");
+        return Error;
+    }
+    if ((_buffer[_messageStart] & (7<<4)) != 0) {
+        LS_WARNING(&_logger, "Received hybi frame with reserved bits set - error");
+        return Error;
+    }
+    auto opcode = _buffer[_messageStart] & 0xf;
+    size_t payloadLength = _buffer[_messageStart + 1] & 0x7f;
+    auto maskBit = _buffer[_messageStart + 1] & 0x80;
+    auto ptr = _messageStart + 2;
+    if (payloadLength == 126) {
+        if (_buffer.size() < 4) { return NoMessage; }
+        payloadLength = htons(*reinterpret_cast<const uint16_t*>(&_buffer[ptr]));
+        ptr += 2;
+    } else if (payloadLength == 127) {
+        if (_buffer.size() < 10) { return NoMessage; }
+        payloadLength = __bswap_64(*reinterpret_cast<const uint64_t*>(&_buffer[ptr]));
+        ptr += 8;
+    }
+    uint32_t mask = 0;
+    if (maskBit) {
+        // MASK is set.
+        if (_buffer.size() < ptr + 4) { return NoMessage; }
+        mask = htonl(*reinterpret_cast<const uint32_t*>(&_buffer[ptr]));
+        ptr += 4;
+    }
+    auto bytesLeftInBuffer = _buffer.size() - ptr;
+    if (payloadLength > bytesLeftInBuffer) { return NoMessage; }
+
+    messageOut.clear();
+    messageOut.reserve(payloadLength);
+    for (auto i = 0u; i < payloadLength; ++i) {
+        auto byteShift = (3 - (i & 3)) * 8;
+        messageOut.push_back(static_cast<char>((_buffer[ptr++] ^ (mask >> byteShift)) & 0xff));
+    }
+    _messageStart = ptr;
+    switch (opcode) {
+    default:
+        LS_WARNING(&_logger, "Received hybi frame with unknown opcode " << opcode);
+        return Error;
+    case OPCODE_TEXT:
+        return TextMessage;
+    case OPCODE_BINARY:
+        return BinaryMessage;
+    case OPCODE_PING:
+        return Ping;
+    case OPCODE_CLOSE:
+        return Close;
+    }
+}
+
+size_t HybiPacketDecoder::numBytesDecoded() const {
+    return _messageStart;
+}
+
+}