diff --git a/core/lib/gcr.c b/core/lib/gcr.c
new file mode 100644
index 000000000..3d89d073c
--- /dev/null
+++ b/core/lib/gcr.c
@@ -0,0 +1,163 @@
+/*
+ * Copyright (c) 2006, Swedish Institute of Computer Science
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. Neither the name of the Institute nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE 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 INSTITUTE 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.
+ *
+ * This file is part of the Contiki operating system.
+ *
+ * @(#)$Id: gcr.c,v 1.1 2006/10/05 09:23:41 adamdunkels Exp $
+ */
+
+/**
+ * \file
+ *         Implementation of GCR coding/decoding
+ * \author
+ *         Joakim Eriksson <joakime@sics.se>
+ *
+ */
+
+/* GCR conversion table - used for converting ordinary byte to 10-bits */
+/* (or 4 bits to 5) */
+static const unsigned char GCR_encode[16] = {
+    0x0a, 0x0b, 0x12, 0x13,
+    0x0e, 0x0f, 0x16, 0x17,
+    0x09, 0x19, 0x1a, 0x1b,
+    0x0d, 0x1d, 0x1e, 0x15
+};
+
+/*  5 bits > 4 bits (0xff => invalid) */
+static const unsigned char GCR_decode[32] = {
+    0xff, 0xff, 0xff, 0xff, // 0 - 3invalid...
+    0xff, 0xff, 0xff, 0xff, // 4 - 7 invalid...
+    0xff, 0x08, 0x00, 0x01, // 8 invalid... 9 = 8, a = 0, b = 1
+    0xff, 0x0c, 0x04, 0x05, // c invalid... d = c, e = 4, f = 5
+
+    0xff, 0xff, 0x02, 0x03, // 10-11 invalid...
+    0xff, 0x0f, 0x06, 0x07, // 14 invalid...
+    0xff, 0x09, 0x0a, 0x0b, // 18 invalid...
+    0xff, 0x0d, 0x0e, 0xff, // 1c, 1f invalid...
+  };
+
+static unsigned char gcr_bits = 0;
+static unsigned short gcr_val = 0;
+
+/* Call before starting encoding or decoding */
+void gcr_init() {
+  gcr_val = 0;
+  gcr_bits = 0;
+}
+
+/* Use this to check if encoding / decoding is complete for now */
+unsigned char gcr_finished() {
+  return gcr_bits == 0;
+}
+
+/* Encode one character - and store in bits - get encoded with get_encoded */
+void gcr_encode(unsigned char raw_data) {
+  gcr_val |=
+    ((GCR_encode[raw_data >> 4u] << 5u ) |
+     GCR_encode[raw_data & 0xf]) << gcr_bits;
+  gcr_bits += 10;
+}
+
+/* Gets the current char of the encoded stream */
+unsigned char gcr_get_encoded(unsigned char *raw_data) {
+  if (gcr_bits >= 8) {
+    *raw_data = (unsigned char) (gcr_val & 0xff);
+    gcr_val = gcr_val >> 8u;
+    gcr_bits = gcr_bits - 8;
+    return 1;
+  }
+  return 0;
+}
+
+/* Decode one char - result can be get from get_decoded */
+void gcr_decode(unsigned char gcr_data) {
+  gcr_val |= gcr_data << gcr_bits;
+  gcr_bits += 8;
+}
+
+/* check if the current decoded stream is correct */
+unsigned char gcr_valid() {
+  if (gcr_bits >= 10) {
+    unsigned short val = gcr_val & 0x3ff;
+    if ((GCR_decode[val >> 5u] << 4u) == 0xff ||
+	(GCR_decode[val & 0x1f]) == 0xff) {
+      return 0;
+    }
+  }
+  return 1;
+}
+
+/* gets the decoded stream - if any char is available */
+unsigned char gcr_get_decoded(unsigned char *raw_data) {
+  if (gcr_bits >= 10) {
+    unsigned short val = gcr_val & 0x3ff;
+    *raw_data = (unsigned char) ((GCR_decode[val >> 5] << 4) |
+				 (GCR_decode[val & 0x1f]));
+    gcr_val = gcr_val >> 10;
+    gcr_bits = gcr_bits - 10;
+    return 1;
+  }
+  return 0;
+}
+
+/*
+static const char encoded[] = {
+  0x4a, 0x25, 0xa5, 0xfc, 0x96, 0xff, 0xff, 0xb5, 0xd4, 0x5a, 0xea, 0xff, 0xff, 0xaa, 0xd3, 0xff
+};
+
+int main(int argc, char **argv) {
+  // unsigned char c[] = "testing gcr 1 2 3 4 5 6...";
+  unsigned char c[] = { 0, 8, 0xe0, 0x2b, 0xac, 0x10, 0x01, 0x11, 0x50, 0xff, 0xf4, 0xa4, 0x00 };
+  unsigned char c2[200];
+  int pos = 0, pos2 = 0, i = 0;
+
+  printf("Testing GCR on: %s \n", c);
+
+  gcr_init();
+  for (i = 0; i < sizeof(c); i++) {
+    gcr_encode(c[i]);
+    while(gcr_get_encoded(&c2[pos])) {
+      printf("%02x=>%02x ", c[i], c2[pos]);
+      pos++;
+    }
+  }
+  printf("\n");
+  printf("Encoded result %d chars (from %d) \n", pos, i);
+  gcr_init();
+  for (i = 0; i < pos; i++) {
+    gcr_decode(c2[i]);
+    if(!gcr_valid()) {
+      printf("GCR: not valid\n");
+    }
+    while(gcr_get_decoded(&c[pos2])) {
+      pos2++;
+    }
+  }
+  printf("GCR: %s\n",c);
+}
+*/
diff --git a/core/lib/gcr.h b/core/lib/gcr.h
new file mode 100644
index 000000000..c62ee0444
--- /dev/null
+++ b/core/lib/gcr.h
@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2006, Swedish Institute of Computer Science.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ * 3. Neither the name of the Institute nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE 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 INSTITUTE 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.
+ *
+ * $Id: gcr.h,v 1.1 2006/10/05 09:23:41 adamdunkels Exp $
+ *
+ * -----------------------------------------------------------------
+ *
+ * Author  : Adam Dunkels, Joakim Eriksson, Niclas Finne
+ * Created : 2006-10-02
+ * Updated : $Date: 2006/10/05 09:23:41 $
+ *           $Revision: 1.1 $
+ */
+
+#ifndef __GCR_H__
+#define __GCR_H__
+
+void gcr_init();
+unsigned char gcr_finished();
+
+void gcr_encode(unsigned char raw_data);
+
+void gcr_decode(unsigned char gcr_data);
+unsigned char gcr_get_encoded(unsigned char *raw_data);
+unsigned char gcr_get_decoded(unsigned char *raw_data);
+unsigned char gcr_valid();
+
+#endif /* __GCR_H__ */