diff --git a/src/tl/tl/tlProtocolBuffer.cc b/src/tl/tl/tlProtocolBuffer.cc
index e69de29bb..1f676e574 100644
--- a/src/tl/tl/tlProtocolBuffer.cc
+++ b/src/tl/tl/tlProtocolBuffer.cc
@@ -0,0 +1,479 @@
+
+/*
+
+  KLayout Layout Viewer
+  Copyright (C) 2006-2024 Matthias Koefferlein
+
+  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, write to the Free Software
+  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+
+*/
+
+#include "tlProtocolBuffer.h"
+
+namespace tl
+{
+
+// ----------------------------------------------------------------------------------
+
+ProtocolBufferReader::ProtocolBufferReader (tl::InputStream &input)
+  : mp_stream (&input), m_type (PBWireType (0)), m_pos (0), m_pos_before (0)
+{
+  //  .. nothing yet ..
+}
+
+int
+ProtocolBufferReader::read_tag ()
+{
+  uint32_t value = 0;
+  read (value);
+  m_type = PBWireType (value & 7);
+  return int (value >> 3);
+}
+
+void
+ProtocolBufferReader::skip ()
+{
+  if (m_type == PB_VARINT) {
+
+    while ((*get (1) & 0x80) != 0) {
+      //  continue reading until the byte's MSB is 0
+    }
+
+  } else if (m_type == PB_I64) {
+
+    get (8);
+
+  } else if (m_type == PB_I32) {
+
+    get (4);
+
+  } else if (m_type == PB_LEN) {
+
+    size_t value = 0;
+    read (value);
+    skip_bytes (value);
+
+  }
+}
+
+void
+ProtocolBufferReader::read (double &d)
+{
+  uint64_t value = 0;
+  read (value);
+  d = *reinterpret_cast<const double *> (&value);
+}
+
+void
+ProtocolBufferReader::read (float &f)
+{
+  uint32_t value = 0;
+  read (value);
+  f = *reinterpret_cast<const float *> (&value);
+}
+
+void
+ProtocolBufferReader::read (std::string &s)
+{
+  size_t value = 0;
+  read (value);
+
+  s = std::string ();
+  s.reserve (value);
+
+  const size_t chunk_size = 1024;
+  while (value > 0) {
+    size_t l = std::min (chunk_size, value);
+    s += std::string (get (l), l);
+    value -= l;
+  }
+}
+
+void
+ProtocolBufferReader::read (uint32_t &ui32, bool fixed)
+{
+  if (! fixed) {
+
+    pb_varint ui64 = read_varint ();
+    if (ui64 > std::numeric_limits<uint32_t>::max ()) {
+      error (tl::to_string (tr ("32 bit value overflow")));
+    }
+
+    ui32 = uint32_t (ui64);
+
+  } else {
+
+    ui32 = 0;
+    for (unsigned int i = 0; i < sizeof (ui32) && ! at_end (); ++i) {
+      ui32 <<= 8;
+      ui32 |= (unsigned char) *get (1);
+    }
+
+  }
+}
+
+void
+ProtocolBufferReader::read (int32_t &i32, bool fixed)
+{
+  uint32_t ui32;
+  read (ui32, fixed);
+
+  if (! fixed) {
+    if (ui32 & 1) {
+      i32 = -(int32_t (ui32 >> 1) + 1);
+    } else {
+      i32 = int32_t (ui32 >> 1);
+    }
+  } else {
+    i32 = int32_t (ui32);
+  }
+}
+
+void
+ProtocolBufferReader::read (uint64_t &ui64, bool fixed)
+{
+  if (! fixed) {
+
+    ui64 = read_varint ();
+
+  } else {
+
+    ui64 = 0;
+    for (unsigned int i = 0; i < sizeof (ui64) && ! at_end (); ++i) {
+      ui64 <<= 8;
+      ui64 |= (unsigned char) *get (1);
+    }
+
+  }
+}
+
+void
+ProtocolBufferReader::read (int64_t &i64, bool fixed)
+{
+  uint64_t ui64;
+  read (ui64, fixed);
+
+  if (! fixed) {
+    if (ui64 & 1) {
+      i64 = -(int64_t (ui64 >> 1) + 1);
+    } else {
+      i64 = int64_t (ui64 >> 1);
+    }
+  } else {
+    i64 = int64_t (ui64);
+  }
+}
+
+void
+ProtocolBufferReader::read (bool &b)
+{
+  uint32_t ui32;
+  read (ui32);
+  b = (ui32 != 0);
+}
+
+void
+ProtocolBufferReader::open ()
+{
+  size_t value = 0;
+  read (value);
+  m_seq_counts.push_back (value);
+}
+
+void
+ProtocolBufferReader::close ()
+{
+  if (! m_seq_counts.empty ()) {
+    skip_bytes (m_seq_counts.back ());
+    m_seq_counts.pop_back ();
+  }
+}
+
+bool
+ProtocolBufferReader::at_end () const
+{
+  if (m_seq_counts.empty ()) {
+    const char *cp = mp_stream->get (1);
+    if (cp) {
+      mp_stream->unget (1);
+      return false;
+    } else {
+      return true;
+    }
+  } else {
+    return m_seq_counts.back () == 0;
+  }
+}
+
+const char *
+ProtocolBufferReader::get (size_t n)
+{
+  m_pos_before = m_pos;
+  m_pos += n;
+  if (! m_seq_counts.empty ()) {
+    if (m_seq_counts.back () < n) {
+      error (tl::to_string (tr ("sequence underflow")));
+    }
+    m_seq_counts.back () -= n;
+  }
+
+  const char *cp = mp_stream->get (n);
+  if (! cp) {
+    error (tl::to_string (tr ("unexpected end of file")));
+  }
+
+  return cp;
+}
+
+pb_varint
+ProtocolBufferReader::read_varint ()
+{
+  pb_varint v = 0;
+
+  while (true) {
+    const char *cp = get (1);
+    if (! cp) {
+      error (tl::to_string (tr ("unexpected end of file")));
+    }
+    if ((v & 0xfe00000000000000l) != 0) {
+      error (tl::to_string (tr ("64 bit integer overflow")));
+    }
+    v <<= 7;
+    v |= (unsigned char) (*cp & 0x7f);
+    if ((*cp & 0x80) == 0) {
+      break;
+    }
+  }
+
+  return v;
+}
+
+void
+ProtocolBufferReader::skip_bytes (size_t n)
+{
+  const size_t chunk_size = 1024;
+  while (n > 0) {
+    size_t l = std::min (chunk_size, n);
+    if (! mp_stream->get (l)) {
+      error (tl::to_string (tr ("unexpected end of file")));
+    }
+    n -= l;
+  }
+}
+
+void
+ProtocolBufferReader::error (const std::string &msg)
+{
+  throw ProtocolBufferReaderError (msg + tl::to_string (tr (", in: ")) + mp_stream->source (), m_pos_before);
+}
+
+// ----------------------------------------------------------------------------------
+
+ProtocolBufferWriter::ProtocolBufferWriter (tl::OutputStream &stream)
+  : mp_stream (&stream), m_bytes_counted (0)
+{
+  //  .. nothing yet ..
+}
+
+void ProtocolBufferWriter::write (int tag, float v)
+{
+  write (tag, *reinterpret_cast<uint32_t *> (&v));
+}
+
+void ProtocolBufferWriter::write (int tag, double v)
+{
+  write (tag, *reinterpret_cast<uint64_t *> (&v));
+}
+
+void ProtocolBufferWriter::write (int tag, uint32_t v, bool fixed)
+{
+  if (fixed) {
+
+    write_varint (pb_varint ((tag << 3) + PB_I32));
+
+    if (is_counting ()) {
+
+      m_byte_counter_stack.back () += sizeof (v);
+
+    } else {
+
+      char b[sizeof (v)];
+      for (unsigned int i = 0; i < sizeof (v); ++i) {
+        b[sizeof (v) - 1 - i] = (char) v;
+        v >>= 8;
+      }
+
+      mp_stream->put (b, sizeof (v));
+
+    }
+
+  } else {
+
+    write_varint (pb_varint ((tag << 3) + PB_VARINT));
+    write_varint (pb_varint (v));
+
+  }
+}
+
+void ProtocolBufferWriter::write (int tag, int32_t v, bool fixed)
+{
+  if (fixed) {
+    write (tag, uint32_t (v), true);
+  } else {
+    if (v < 0) {
+      write (tag, ((uint32_t (-v) - 1) << 1) + 1, false);
+    } else {
+      write (tag, uint32_t (v), false);
+    }
+  }
+}
+
+void ProtocolBufferWriter::write (int tag, uint64_t v, bool fixed)
+{
+  if (fixed) {
+
+    write_varint (pb_varint ((tag << 3) + PB_I64));
+
+    if (is_counting ()) {
+
+      m_byte_counter_stack.back () += sizeof (v);
+
+    } else {
+
+      char b[sizeof (v)];
+      for (unsigned int i = 0; i < sizeof (v); ++i) {
+        b[sizeof (v) - 1 - i] = (char) v;
+        v >>= 8;
+      }
+
+      mp_stream->put (b, sizeof (v));
+
+    }
+
+  } else {
+
+    write_varint (pb_varint ((tag << 3) + PB_VARINT));
+    write_varint (pb_varint (v));
+
+  }
+}
+
+void ProtocolBufferWriter::write (int tag, int64_t v, bool fixed)
+{
+  if (fixed) {
+    write (tag, uint64_t (v), true);
+  } else {
+    if (v < 0) {
+      write (tag, ((uint64_t (-v) - 1) << 1) + 1, false);
+    } else {
+      write (tag, uint64_t (v), false);
+    }
+  }
+}
+
+void ProtocolBufferWriter::write (int tag, bool b)
+{
+  write (tag, uint32_t (b ? 1 : 0));
+}
+
+void ProtocolBufferWriter::write (int tag, const std::string &s)
+{
+  write_varint (pb_varint ((tag << 3) + PB_LEN));
+  write_varint (s.size ());
+
+  if (is_counting ()) {
+    m_byte_counter_stack.back () += s.size ();
+  } else {
+    mp_stream->put (s.c_str (), s.size ());
+  }
+}
+
+bool ProtocolBufferWriter::is_counting () const
+{
+  return ! m_byte_counter_stack.empty ();
+}
+
+void ProtocolBufferWriter::begin_seq (int tag, bool counting)
+{
+  if (counting) {
+
+    //  header only
+    m_byte_counter_stack.push_back (0);
+    write_varint (pb_varint ((tag << 3) + PB_LEN));
+
+    //  body only
+    m_byte_counter_stack.push_back (0);
+
+  } else {
+
+    write_varint (pb_varint ((tag << 3) + PB_LEN));
+    write_varint (m_bytes_counted);
+
+  }
+}
+
+void ProtocolBufferWriter::end_seq ()
+{
+  if (is_counting ()) {
+
+    m_bytes_counted = m_byte_counter_stack.back ();
+    m_byte_counter_stack.pop_back ();
+
+    //  just for adding the required bytes
+    write_varint (m_bytes_counted);
+
+    //  now add header bytes
+    m_bytes_counted += m_byte_counter_stack.back ();
+    m_byte_counter_stack.pop_back ();
+
+  }
+}
+
+void
+ProtocolBufferWriter::write_varint (pb_varint v)
+{
+  if (is_counting ()) {
+
+    size_t n = 0;
+    while (true) {
+      ++n;
+      if (v < 0x80) {
+        break;
+      }
+      v >>= 7;
+    }
+
+    m_byte_counter_stack.back () += n;
+
+  } else {
+
+    char b[16];
+    char *cp = b;
+    while (true) {
+      if (v < 0x80) {
+        *cp++ = char (v);
+        break;
+      } else {
+        *cp++ = (char (v) | 0x80);
+      }
+      v >>= 7;
+    }
+
+    m_byte_counter_stack.back () += (cp - b);
+
+  }
+}
+
+}
diff --git a/src/tl/tl/tlProtocolBuffer.h b/src/tl/tl/tlProtocolBuffer.h
index 1b461a3f2..011f3b7a7 100644
--- a/src/tl/tl/tlProtocolBuffer.h
+++ b/src/tl/tl/tlProtocolBuffer.h
@@ -30,7 +30,7 @@ namespace tl
 {
 
 //  Representation of VARINT values
-typedef size_t pb_varint;
+typedef uint64_t pb_varint;
 
 enum PBWireType
 {
@@ -55,7 +55,7 @@ public:
 
   virtual std::string msg () const
   {
-    return basic_msg () + tl::to_string (tr (", at position ") + tl::to_string (m_position));
+    return basic_msg () + tl::to_string (tr (", at position ")) + tl::to_string (m_position);
   }
 
 private:
@@ -97,7 +97,7 @@ public:
 
   /**
    *  @brief Reads a new tag
-   *
+   *  This method will also set the current write type.
    *  @returns The message ID
    */
   int read_tag ();
@@ -178,7 +178,7 @@ public:
    *  After calling "open", the parser will continue reading messages, but
    *  "at_end" will report true on the end of the sequence, not at the end of the
    *  file.
-   *  Thie method will throw an exception if not in a message of LEN type.
+   *  This method will throw an exception if not in a message of LEN type.
    */
   void open ();
 
@@ -195,15 +195,16 @@ public:
   bool at_end () const;
 
 private:
-  tl::InputStream m_stream;
+  tl::InputStream *mp_stream;
   PBWireType m_type;
   size_t m_pos;
-  std::vector<size_t> m_block_end;
+  size_t m_pos_before;
+  std::vector<size_t> m_seq_counts;
 
   pb_varint read_varint ();
-  bool has_bytes (size_t n);
   void skip_bytes (size_t n);
   void error (const std::string &msg);
+  const char *get (size_t n);
 };
 
 /**
@@ -259,10 +260,9 @@ public:
   void end_seq ();
 
 private:
-  size_t count_bytes_for (pb_varint v);
   void write_varint (pb_varint v);
 
-  tl::OutputStream m_stream;
+  tl::OutputStream *mp_stream;
   size_t m_bytes_counted;
   std::vector<size_t> m_byte_counter_stack;
 };