mot-encoder: Add charset converter for EBU Latin

7 files changed, 1135 insertions, 42 deletions

diff --git a/src/charset-test.cpp b/src/charset-test.cpp
new file mode 100644
index 0000000..d65fcc7
--- /dev/null
+++ b/src/charset-test.cpp
@@ -0,0 +1,57 @@
+/*
+    Copyright (C) 2015 Matthias P. Braendli (http://opendigitalradio.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 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 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/>.
+
+    charset.cpp
+         This is test code for the character set conversion. It does not
+         get compiled by default.
+         Please use
+         g++ -Wall -Wextra -std=c++11 -o charset-test charset-test.cpp
+         to compile this, and create a input.txt file with test data.
+
+    Authors:
+         Matthias P. Braendli <matthias@mpb.li>
+*/
+
+#include "charset.h"
+#include <iostream>
+#include <fstream>
+
+#include <cstdio>
+
+using namespace std;
+
+int main(int argc, char** argv)
+{
+    string test_file_path("input.txt");
+
+    ifstream fs8(test_file_path);
+    if (!fs8.is_open()) {
+        cerr << "Could not open " << test_file_path << endl;
+        return 1;
+    }
+
+    CharsetConverter conv;
+
+    string line;
+    // Play with all the lines in the file
+    while (getline(fs8, line)) {
+        cout << conv.convert(line) << endl;
+    }
+
+    return 0;
+}
+
+
diff --git a/src/charset.h b/src/charset.h
new file mode 100644
index 0000000..0eb1edf
--- /dev/null
+++ b/src/charset.h
@@ -0,0 +1,104 @@
+/*
+    Copyright (C) 2015 Matthias P. Braendli (http://opendigitalradio.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 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 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/>.
+
+    charset.h
+         Define the EBU charsets for DLS encoding
+
+    Authors:
+         Matthias P. Braendli <matthias@mpb.li>
+*/
+
+#ifndef __CHARSET_H_
+#define __CHARSET_H_
+
+#include "utf8.h"
+#include <string>
+#include <vector>
+#include <algorithm>
+
+// The first 32 entries are control characters and are not specified in
+// the table.
+#define CHARSET_TABLE_OFFSET 32
+#define CHARSET_TABLE_ENTRIES (255 - CHARSET_TABLE_OFFSET)
+const char* utf8_encoded_EBU_Latin[CHARSET_TABLE_ENTRIES] = {
+" ", "!", "\"","#", "¤", "%", "&", "'", "(", ")", "*", "+", ",", "-", ".", "/",
+"0", "1", "2", "3", "4", "5", "6", "7", "8", "9", ":", ";", "<", "=", ">", "?",
+"@", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O",
+"P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z", "[", "\\","]", "—", "_",
+"‖", "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o",
+"p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", "{", "|", "}", "⎺", " ",
+"á", "à", "é", "è", "í", "ì", "ó", "ò", "ú", "ù", "Ñ", "Ç", "Ş", "ß", "¡", "IJ",
+"â", "ä", "ê", "ë", "î", "ï", "ô", "ö", "û", "ü", "ñ", "ç", "ş", "ǧ", "ı", "ij",
+"ª", "α", "©", "‰", "Ǧ", "ě", "ň", "ő", "π", "€", "£", "$", "←", "↑", "→", "↓",
+"º", "¹", "²", "³", "±", "İ", "ń", "ű", "μ", "¿", "÷", "°", "¼", "½", "¾", "§",
+"Á", "À", "Ê", "È", "Í", "Ì", "Ó", "Ò", "Ú", "Ù", "Ř", "Č", "Š", "Ž", "Ð", "Ŀ",
+"Â", "Ä", "Ê", "Ë", "Î", "Ï", "Ô", "Ö", "Û", "Ü", "ř", "č", "š", "ž", "đ", "ŀ",
+"Ã", "Å", "Æ", "Œ", "ŷ", "Ý", "Õ", "Ø", "Þ", "Ŋ", "Ŕ", "Ć", "Ś", "Ź", "∓", "ð",
+"ã", "å", "æ", "œ", "ŵ", "ý", "õ", "ø", "þ", "ŋ", "ŕ", "ć", "ś", "ź", "ł"};
+
+class CharsetConverter
+{
+    public:
+        CharsetConverter() {
+            /* Build the converstion table that contains the known code points,
+             * at the indices corresponding to the EBU Latin table
+             */
+            using namespace std;
+            for (size_t i = 0; i < CHARSET_TABLE_ENTRIES; i++) {
+                string table_entry(utf8_encoded_EBU_Latin[i]);
+                string::iterator it = table_entry.begin();
+                uint32_t code_point = utf8::next(it, table_entry.end());
+                m_conversion_table.push_back(code_point);
+            }
+        }
+
+        /* Convert a UTF-8 encoded text line into a EBU Latin 1 encoded byte stream
+         */
+        std::string convert(std::string line_utf8) {
+            using namespace std;
+
+            // check for invalid utf-8, we only convert up to the first error
+            string::iterator end_it = utf8::find_invalid(line_utf8.begin(), line_utf8.end());
+
+            // Convert it to utf-32
+            vector<uint32_t> utf32line;
+            utf8::utf8to32(line_utf8.begin(), end_it, back_inserter(utf32line));
+
+            string encoded_line(utf32line.size(), '0');
+
+            // Try to convert each codepoint
+            for (size_t i = 0; i < utf32line.size(); i++) {
+                vector<uint32_t>::iterator iter = find(m_conversion_table.begin(),
+                        m_conversion_table.end(), utf32line[i]);
+                if (iter != m_conversion_table.end()) {
+                    size_t index = std::distance(m_conversion_table.begin(), iter);
+
+                    encoded_line[i] = (char)(index + CHARSET_TABLE_OFFSET);
+                }
+                else {
+                    encoded_line[i] = ' ';
+                }
+            }
+            return encoded_line;
+        }
+
+    private:
+
+        std::vector<uint32_t> m_conversion_table;
+};
+
+#endif
+
diff --git a/src/mot-encoder.cpp b/src/mot-encoder.cpp
index 8422514..6ddfcb8 100644
--- a/src/mot-encoder.cpp
+++ b/src/mot-encoder.cpp
@@ -1,7 +1,7 @@
 /*
     Copyright (C) 2014 CSP Innovazione nelle ICT s.c.a r.l. (http://rd.csp.it/)
 
-    Copyright (C) 2014 Matthias P. Braendli (http://opendigitalradio.org)
+    Copyright (C) 2014, 2015 Matthias P. Braendli (http://opendigitalradio.org)
 
     Copyright (C) 2015 Stefan Pöschel (http://opendigitalradio.org)
 
@@ -33,6 +33,10 @@
 #include <unistd.h>
 #include <cstring>
 #include <string>
+#include <sstream>
+#include <iostream>
+#include <fstream>
+#include <algorithm>
 #include <vector>
 #include <deque>
 #include <list>
@@ -43,6 +47,7 @@
 #include <wand/magick_wand.h>
 #include <getopt.h>
 #include "config.h"
+#include "charset.h"
 
 #define DEBUG 0
 
@@ -225,8 +230,8 @@ void writeMotPAD(int output_fd,
         unsigned short int mscdgsize,
         unsigned short int padlen);
 
-void create_dls_pads(const char* text, const int padlen, const uint8_t charset);
-void writeDLS(int output_fd, const char* dls_file, int padlen, uint8_t charset);
+void create_dls_pads(const std::string& text, const int padlen, const uint8_t charset);
+void writeDLS(int output_fd, const std::string& dls_file, int padlen, uint8_t charset);
 
 
 int get_xpadlengthmask(int padlen);
@@ -247,10 +252,12 @@ static int cindex_body = 0;
 #define DLS_SEG_LEN_CRC          2
 #define DLS_SEG_LEN_MAX         (DLS_SEG_LEN_PREFIX + DLS_SEG_LEN_CHAR_MAX + DLS_SEG_LEN_CRC)
 
+CharsetConverter charset_converter;
+
 typedef std::vector<uint8_t> pad_t;
 static std::deque<pad_t> dls_pads;
 static bool dls_toggle = false;
-static char dlstext_prev[MAXDLS + 1];
+std::string dlstext_prev(MAXDLS + 1, ' ');
 
 
 static int verbose = 0;
@@ -311,7 +318,7 @@ int main(int argc, char *argv[])
 
     const char* dir = NULL;
     const char* output = "/tmp/pad.fifo";
-    const char* dls_file = NULL;
+    std::string dls_file;
 
     const struct option longopts[] = {
         {"charset",    required_argument,  0, 'c'},
@@ -377,17 +384,17 @@ int main(int argc, char *argv[])
         return 1;
     }
 
-    if (dir && dls_file) {
+    if (dir && not dls_file.empty()) {
         fprintf(stderr, "mot-encoder encoding Slideshow from %s and DLS from %s to %s\n",
-                dir, dls_file, output);
+                dir, dls_file.c_str(), output);
     }
     else if (dir) {
         fprintf(stderr, "mot-encoder encoding Slideshow from %s to %s. No DLS.\n",
                 dir, output);
     }
-    else if (dls_file) {
+    else if (not dls_file.empty()) {
         fprintf(stderr, "mot-encoder encoding DLS from %s to %s. No Slideshow.\n",
-                dls_file, output);
+                dls_file.c_str(), output);
     }
     else {
         fprintf(stderr, "mot-encoder Error: No DLS nor slideshow to encode !\n");
@@ -471,7 +478,7 @@ int main(int argc, char *argv[])
             // Sort the list in fidx order
             slides_to_transmit.sort();
 
-            if (dls_file) {
+            if (not dls_file.empty()) {
                 // Maybe we have no slides, always update DLS
                 writeDLS(output_fd, dls_file, padlen, charset);
                 sleep(sleepdelay);
@@ -496,7 +503,7 @@ int main(int argc, char *argv[])
                 }
 
                 // Always retransmit DLS after each slide, we want it to be updated frequently
-                if (dls_file) {
+                if (not dls_file.empty()) {
                     writeDLS(output_fd, dls_file, padlen, charset);
                 }
 
@@ -509,7 +516,7 @@ int main(int argc, char *argv[])
 
             slides_to_transmit.resize(0);
         }
-        else if (dls_file) { // only DLS
+        else if (not dls_file.empty()) { // only DLS
             // Always retransmit DLS, we want it to be updated frequently
             writeDLS(output_fd, dls_file, padlen, charset);
 
@@ -893,58 +900,65 @@ void packMscDG(unsigned char* b, MSCDG* msc, unsigned short int* bsize)
 }
 
 
-void writeDLS(int output_fd, const char* dls_file, int padlen, uint8_t charset)
+void writeDLS(int output_fd, const std::string& dls_file, int padlen, uint8_t charset)
 {
-    char dlstext[MAXDLS + 1];
-    int dlslen;
-    int i;
-    bool dlstext_new;
-
-    int dlsfd = open(dls_file, O_RDONLY);
-    if (dlsfd == -1) {
-        fprintf(stderr, "mot-encoder Error: Cannot open dls file\n");
+    std::ifstream dls_fstream(dls_file.c_str());
+    if (!dls_fstream.is_open()) {
+        std::cerr << "Could not open " << dls_file << std::endl;
         return;
     }
 
-    dlslen = read(dlsfd, dlstext, MAXDLS);
+    std::vector<std::string> dls_lines;
 
-    close(dlsfd);
-
-    dlstext[dlslen] = 0x00;
+    std::string line;
+    // Read and convert lines one by one because the converter doesn't understand
+    // line endings
+    while (std::getline(dls_fstream, line)) {
+        if (not line.empty()) {
+            if (charset == CHARSET_COMPLETE_EBU_LATIN) {
+                dls_lines.push_back(charset_converter.convert(line));
+            }
+            else {
+                dls_lines.push_back(line);
+            }
+            // TODO handle the other charsets accordingly
+        }
+    }
 
-    // Remove trailing line breaks from the file
-    char* endp = dlstext + dlslen;
-    while (   endp > dlstext &&
-            (*endp == '\0' || *endp == '\n')) {
-        if (*endp == '\n') {
-            *endp = '\0';
+    std::stringstream ss;
+    for (size_t i = 0; i < dls_lines.size(); i++) {
+        if (i != 0) {
+            ss << "\n";
         }
-        endp--;
+        ss << dls_lines[i];
     }
+    std::string dlstext = ss.str();
+    using namespace std;
+
 
     // (Re)Create data groups (and thereby toggle the toggle bit) only on (first call or) new text
-    dlstext_new = dls_pads.empty() || strcmp(dlstext, dlstext_prev);
+    bool dlstext_is_new = dls_pads.empty() || (dlstext != dlstext_prev);
     if (verbose) {
-        fprintf(stderr, "mot-encoder writing %s DLS text \"%s\"\n", dlstext_new ? "new" : "old", dlstext);
+        fprintf(stderr, "mot-encoder writing %s DLS text \"%s\"\n", dlstext_is_new ? "new" : "old", dlstext.c_str());
     }
-    if (dlstext_new) {
+    if (dlstext_is_new) {
         create_dls_pads(dlstext, padlen, charset);
-        strcpy(dlstext_prev, dlstext);
+        dlstext_prev = dlstext;
     }
 
-    for (i = 0; i < dls_pads.size(); i++) {
+    for (size_t i = 0; i < dls_pads.size(); i++) {
         size_t dummy = write(output_fd, &dls_pads[i].front(), dls_pads[i].size());
     }
 }
 
 
-int dls_count(const char* text) {
-    size_t text_len = strlen(text);
+int dls_count(const std::string& text) {
+    size_t text_len = text.size();
     return text_len / DLS_SEG_LEN_CHAR_MAX + (text_len % DLS_SEG_LEN_CHAR_MAX ? 1 : 0);
 }
 
 
-size_t dls_get(const char* text, const uint8_t charset, const unsigned int seg_index, uint8_t *seg_data) {
+size_t dls_get(const std::string& text, const uint8_t charset, const unsigned int seg_index, uint8_t *seg_data) {
     int seg_count = dls_count(text);
     if (seg_index >= seg_count)
         return 0;
@@ -952,7 +966,7 @@ size_t dls_get(const char* text, const uint8_t charset, const unsigned int seg_i
     bool first_seg = seg_index == 0;
     bool last_seg  = seg_index == seg_count - 1;
 
-    const char *seg_text_start = text + seg_index * DLS_SEG_LEN_CHAR_MAX;
+    const char *seg_text_start = text.c_str() + seg_index * DLS_SEG_LEN_CHAR_MAX;
     size_t seg_text_len = strnlen(seg_text_start, DLS_SEG_LEN_CHAR_MAX);
     size_t seg_len = DLS_SEG_LEN_PREFIX + seg_text_len + DLS_SEG_LEN_CRC;
 
@@ -991,7 +1005,7 @@ size_t dls_get(const char* text, const uint8_t charset, const unsigned int seg_i
 }
 
 
-void create_dls_pads(const char* text, const int padlen, const uint8_t charset) {
+void create_dls_pads(const std::string& text, const int padlen, const uint8_t charset) {
     uint8_t seg_data[DLS_SEG_LEN_MAX];
     int xpadlengthmask = get_xpadlengthmask(padlen);
 
diff --git a/src/utf8.h b/src/utf8.h
new file mode 100644
index 0000000..4e44514
--- /dev/null
+++ b/src/utf8.h
@@ -0,0 +1,34 @@
+// Copyright 2006 Nemanja Trifunovic

+

+/*

+Permission is hereby granted, free of charge, to any person or organization

+obtaining a copy of the software and accompanying documentation covered by

+this license (the "Software") to use, reproduce, display, distribute,

+execute, and transmit the Software, and to prepare derivative works of the

+Software, and to permit third-parties to whom the Software is furnished to

+do so, all subject to the following:

+

+The copyright notices in the Software and this entire statement, including

+the above license grant, this restriction and the following disclaimer,

+must be included in all copies of the Software, in whole or in part, and

+all derivative works of the Software, unless such copies or derivative

+works are solely in the form of machine-executable object code generated by

+a source language processor.

+

+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

+FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT

+SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE

+FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,

+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER

+DEALINGS IN THE SOFTWARE.

+*/

+

+

+#ifndef UTF8_FOR_CPP_2675DCD0_9480_4c0c_B92A_CC14C027B731

+#define UTF8_FOR_CPP_2675DCD0_9480_4c0c_B92A_CC14C027B731

+

+#include "utf8/checked.h"

+#include "utf8/unchecked.h"

+

+#endif // header guard

diff --git a/src/utf8/checked.h b/src/utf8/checked.h
new file mode 100644
index 0000000..1331155
--- /dev/null
+++ b/src/utf8/checked.h
@@ -0,0 +1,327 @@
+// Copyright 2006 Nemanja Trifunovic
+
+/*
+Permission is hereby granted, free of charge, to any person or organization
+obtaining a copy of the software and accompanying documentation covered by
+this license (the "Software") to use, reproduce, display, distribute,
+execute, and transmit the Software, and to prepare derivative works of the
+Software, and to permit third-parties to whom the Software is furnished to
+do so, all subject to the following:
+
+The copyright notices in the Software and this entire statement, including
+the above license grant, this restriction and the following disclaimer,
+must be included in all copies of the Software, in whole or in part, and
+all derivative works of the Software, unless such copies or derivative
+works are solely in the form of machine-executable object code generated by
+a source language processor.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
+*/
+
+
+#ifndef UTF8_FOR_CPP_CHECKED_H_2675DCD0_9480_4c0c_B92A_CC14C027B731
+#define UTF8_FOR_CPP_CHECKED_H_2675DCD0_9480_4c0c_B92A_CC14C027B731
+
+#include "core.h"
+#include <stdexcept>
+
+namespace utf8
+{
+    // Base for the exceptions that may be thrown from the library
+    class exception : public ::std::exception {
+    };
+
+    // Exceptions that may be thrown from the library functions.
+    class invalid_code_point : public exception {
+        uint32_t cp;
+    public:
+        invalid_code_point(uint32_t cp) : cp(cp) {}
+        virtual const char* what() const throw() { return "Invalid code point"; }
+        uint32_t code_point() const {return cp;}
+    };
+
+    class invalid_utf8 : public exception {
+        uint8_t u8;
+    public:
+        invalid_utf8 (uint8_t u) : u8(u) {}
+        virtual const char* what() const throw() { return "Invalid UTF-8"; }
+        uint8_t utf8_octet() const {return u8;}
+    };
+
+    class invalid_utf16 : public exception {
+        uint16_t u16;
+    public:
+        invalid_utf16 (uint16_t u) : u16(u) {}
+        virtual const char* what() const throw() { return "Invalid UTF-16"; }
+        uint16_t utf16_word() const {return u16;}
+    };
+
+    class not_enough_room : public exception {
+    public:
+        virtual const char* what() const throw() { return "Not enough space"; }
+    };
+
+    /// The library API - functions intended to be called by the users
+
+    template <typename octet_iterator>
+    octet_iterator append(uint32_t cp, octet_iterator result)
+    {
+        if (!utf8::internal::is_code_point_valid(cp))
+            throw invalid_code_point(cp);
+
+        if (cp < 0x80)                        // one octet
+            *(result++) = static_cast<uint8_t>(cp);
+        else if (cp < 0x800) {                // two octets
+            *(result++) = static_cast<uint8_t>((cp >> 6)            | 0xc0);
+            *(result++) = static_cast<uint8_t>((cp & 0x3f)          | 0x80);
+        }
+        else if (cp < 0x10000) {              // three octets
+            *(result++) = static_cast<uint8_t>((cp >> 12)           | 0xe0);
+            *(result++) = static_cast<uint8_t>(((cp >> 6) & 0x3f)   | 0x80);
+            *(result++) = static_cast<uint8_t>((cp & 0x3f)          | 0x80);
+        }
+        else {                                // four octets
+            *(result++) = static_cast<uint8_t>((cp >> 18)           | 0xf0);
+            *(result++) = static_cast<uint8_t>(((cp >> 12) & 0x3f)  | 0x80);
+            *(result++) = static_cast<uint8_t>(((cp >> 6) & 0x3f)   | 0x80);
+            *(result++) = static_cast<uint8_t>((cp & 0x3f)          | 0x80);
+        }
+        return result;
+    }
+
+    template <typename octet_iterator, typename output_iterator>
+    output_iterator replace_invalid(octet_iterator start, octet_iterator end, output_iterator out, uint32_t replacement)
+    {
+        while (start != end) {
+            octet_iterator sequence_start = start;
+            internal::utf_error err_code = utf8::internal::validate_next(start, end);
+            switch (err_code) {
+                case internal::UTF8_OK :
+                    for (octet_iterator it = sequence_start; it != start; ++it)
+                        *out++ = *it;
+                    break;
+                case internal::NOT_ENOUGH_ROOM:
+                    throw not_enough_room();
+                case internal::INVALID_LEAD:
+                    out = utf8::append (replacement, out);
+                    ++start;
+                    break;
+                case internal::INCOMPLETE_SEQUENCE:
+                case internal::OVERLONG_SEQUENCE:
+                case internal::INVALID_CODE_POINT:
+                    out = utf8::append (replacement, out);
+                    ++start;
+                    // just one replacement mark for the sequence
+                    while (start != end && utf8::internal::is_trail(*start))
+                        ++start;
+                    break;
+            }
+        }
+        return out;
+    }
+
+    template <typename octet_iterator, typename output_iterator>
+    inline output_iterator replace_invalid(octet_iterator start, octet_iterator end, output_iterator out)
+    {
+        static const uint32_t replacement_marker = utf8::internal::mask16(0xfffd);
+        return utf8::replace_invalid(start, end, out, replacement_marker);
+    }
+
+    template <typename octet_iterator>
+    uint32_t next(octet_iterator& it, octet_iterator end)
+    {
+        uint32_t cp = 0;
+        internal::utf_error err_code = utf8::internal::validate_next(it, end, cp);
+        switch (err_code) {
+            case internal::UTF8_OK :
+                break;
+            case internal::NOT_ENOUGH_ROOM :
+                throw not_enough_room();
+            case internal::INVALID_LEAD :
+            case internal::INCOMPLETE_SEQUENCE :
+            case internal::OVERLONG_SEQUENCE :
+                throw invalid_utf8(*it);
+            case internal::INVALID_CODE_POINT :
+                throw invalid_code_point(cp);
+        }
+        return cp;
+    }
+
+    template <typename octet_iterator>
+    uint32_t peek_next(octet_iterator it, octet_iterator end)
+    {
+        return utf8::next(it, end);
+    }
+
+    template <typename octet_iterator>
+    uint32_t prior(octet_iterator& it, octet_iterator start)
+    {
+        // can't do much if it == start
+        if (it == start)
+            throw not_enough_room();
+
+        octet_iterator end = it;
+        // Go back until we hit either a lead octet or start
+        while (utf8::internal::is_trail(*(--it)))
+            if (it == start)
+                throw invalid_utf8(*it); // error - no lead byte in the sequence
+        return utf8::peek_next(it, end);
+    }
+
+    /// Deprecated in versions that include "prior"
+    template <typename octet_iterator>
+    uint32_t previous(octet_iterator& it, octet_iterator pass_start)
+    {
+        octet_iterator end = it;
+        while (utf8::internal::is_trail(*(--it)))
+            if (it == pass_start)
+                throw invalid_utf8(*it); // error - no lead byte in the sequence
+        octet_iterator temp = it;
+        return utf8::next(temp, end);
+    }
+
+    template <typename octet_iterator, typename distance_type>
+    void advance (octet_iterator& it, distance_type n, octet_iterator end)
+    {
+        for (distance_type i = 0; i < n; ++i)
+            utf8::next(it, end);
+    }
+
+    template <typename octet_iterator>
+    typename std::iterator_traits<octet_iterator>::difference_type
+    distance (octet_iterator first, octet_iterator last)
+    {
+        typename std::iterator_traits<octet_iterator>::difference_type dist;
+        for (dist = 0; first < last; ++dist)
+            utf8::next(first, last);
+        return dist;
+    }
+
+    template <typename u16bit_iterator, typename octet_iterator>
+    octet_iterator utf16to8 (u16bit_iterator start, u16bit_iterator end, octet_iterator result)
+    {
+        while (start != end) {
+            uint32_t cp = utf8::internal::mask16(*start++);
+            // Take care of surrogate pairs first
+            if (utf8::internal::is_lead_surrogate(cp)) {
+                if (start != end) {
+                    uint32_t trail_surrogate = utf8::internal::mask16(*start++);
+                    if (utf8::internal::is_trail_surrogate(trail_surrogate))
+                        cp = (cp << 10) + trail_surrogate + internal::SURROGATE_OFFSET;
+                    else
+                        throw invalid_utf16(static_cast<uint16_t>(trail_surrogate));
+                }
+                else
+                    throw invalid_utf16(static_cast<uint16_t>(cp));
+
+            }
+            // Lone trail surrogate
+            else if (utf8::internal::is_trail_surrogate(cp))
+                throw invalid_utf16(static_cast<uint16_t>(cp));
+
+            result = utf8::append(cp, result);
+        }
+        return result;
+    }
+
+    template <typename u16bit_iterator, typename octet_iterator>
+    u16bit_iterator utf8to16 (octet_iterator start, octet_iterator end, u16bit_iterator result)
+    {
+        while (start != end) {
+            uint32_t cp = utf8::next(start, end);
+            if (cp > 0xffff) { //make a surrogate pair
+                *result++ = static_cast<uint16_t>((cp >> 10)   + internal::LEAD_OFFSET);
+                *result++ = static_cast<uint16_t>((cp & 0x3ff) + internal::TRAIL_SURROGATE_MIN);
+            }
+            else
+                *result++ = static_cast<uint16_t>(cp);
+        }
+        return result;
+    }
+
+    template <typename octet_iterator, typename u32bit_iterator>
+    octet_iterator utf32to8 (u32bit_iterator start, u32bit_iterator end, octet_iterator result)
+    {
+        while (start != end)
+            result = utf8::append(*(start++), result);
+
+        return result;
+    }
+
+    template <typename octet_iterator, typename u32bit_iterator>
+    u32bit_iterator utf8to32 (octet_iterator start, octet_iterator end, u32bit_iterator result)
+    {
+        while (start != end)
+            (*result++) = utf8::next(start, end);
+
+        return result;
+    }
+
+    // The iterator class
+    template <typename octet_iterator>
+    class iterator : public std::iterator <std::bidirectional_iterator_tag, uint32_t> {
+      octet_iterator it;
+      octet_iterator range_start;
+      octet_iterator range_end;
+      public:
+      iterator () {}
+      explicit iterator (const octet_iterator& octet_it,
+                         const octet_iterator& range_start,
+                         const octet_iterator& range_end) :
+               it(octet_it), range_start(range_start), range_end(range_end)
+      {
+          if (it < range_start || it > range_end)
+              throw std::out_of_range("Invalid utf-8 iterator position");
+      }
+      // the default "big three" are OK
+      octet_iterator base () const { return it; }
+      uint32_t operator * () const
+      {
+          octet_iterator temp = it;
+          return utf8::next(temp, range_end);
+      }
+      bool operator == (const iterator& rhs) const
+      {
+          if (range_start != rhs.range_start || range_end != rhs.range_end)
+              throw std::logic_error("Comparing utf-8 iterators defined with different ranges");
+          return (it == rhs.it);
+      }
+      bool operator != (const iterator& rhs) const
+      {
+          return !(operator == (rhs));
+      }
+      iterator& operator ++ ()
+      {
+          utf8::next(it, range_end);
+          return *this;
+      }
+      iterator operator ++ (int)
+      {
+          iterator temp = *this;
+          utf8::next(it, range_end);
+          return temp;
+      }
+      iterator& operator -- ()
+      {
+          utf8::prior(it, range_start);
+          return *this;
+      }
+      iterator operator -- (int)
+      {
+          iterator temp = *this;
+          utf8::prior(it, range_start);
+          return temp;
+      }
+    }; // class iterator
+
+} // namespace utf8
+
+#endif //header guard
+
+
diff --git a/src/utf8/core.h b/src/utf8/core.h
new file mode 100644
index 0000000..693d388
--- /dev/null
+++ b/src/utf8/core.h
@@ -0,0 +1,329 @@
+// Copyright 2006 Nemanja Trifunovic
+
+/*
+Permission is hereby granted, free of charge, to any person or organization
+obtaining a copy of the software and accompanying documentation covered by
+this license (the "Software") to use, reproduce, display, distribute,
+execute, and transmit the Software, and to prepare derivative works of the
+Software, and to permit third-parties to whom the Software is furnished to
+do so, all subject to the following:
+
+The copyright notices in the Software and this entire statement, including
+the above license grant, this restriction and the following disclaimer,
+must be included in all copies of the Software, in whole or in part, and
+all derivative works of the Software, unless such copies or derivative
+works are solely in the form of machine-executable object code generated by
+a source language processor.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
+*/
+
+
+#ifndef UTF8_FOR_CPP_CORE_H_2675DCD0_9480_4c0c_B92A_CC14C027B731
+#define UTF8_FOR_CPP_CORE_H_2675DCD0_9480_4c0c_B92A_CC14C027B731
+
+#include <iterator>
+
+namespace utf8
+{
+    // The typedefs for 8-bit, 16-bit and 32-bit unsigned integers
+    // You may need to change them to match your system.
+    // These typedefs have the same names as ones from cstdint, or boost/cstdint
+    typedef unsigned char   uint8_t;
+    typedef unsigned short  uint16_t;
+    typedef unsigned int    uint32_t;
+
+// Helper code - not intended to be directly called by the library users. May be changed at any time
+namespace internal
+{
+    // Unicode constants
+    // Leading (high) surrogates: 0xd800 - 0xdbff
+    // Trailing (low) surrogates: 0xdc00 - 0xdfff
+    const uint16_t LEAD_SURROGATE_MIN  = 0xd800u;
+    const uint16_t LEAD_SURROGATE_MAX  = 0xdbffu;
+    const uint16_t TRAIL_SURROGATE_MIN = 0xdc00u;
+    const uint16_t TRAIL_SURROGATE_MAX = 0xdfffu;
+    const uint16_t LEAD_OFFSET         = LEAD_SURROGATE_MIN - (0x10000 >> 10);
+    const uint32_t SURROGATE_OFFSET    = 0x10000u - (LEAD_SURROGATE_MIN << 10) - TRAIL_SURROGATE_MIN;
+
+    // Maximum valid value for a Unicode code point
+    const uint32_t CODE_POINT_MAX      = 0x0010ffffu;
+
+    template<typename octet_type>
+    inline uint8_t mask8(octet_type oc)
+    {
+        return static_cast<uint8_t>(0xff & oc);
+    }
+    template<typename u16_type>
+    inline uint16_t mask16(u16_type oc)
+    {
+        return static_cast<uint16_t>(0xffff & oc);
+    }
+    template<typename octet_type>
+    inline bool is_trail(octet_type oc)
+    {
+        return ((utf8::internal::mask8(oc) >> 6) == 0x2);
+    }
+
+    template <typename u16>
+    inline bool is_lead_surrogate(u16 cp)
+    {
+        return (cp >= LEAD_SURROGATE_MIN && cp <= LEAD_SURROGATE_MAX);
+    }
+
+    template <typename u16>
+    inline bool is_trail_surrogate(u16 cp)
+    {
+        return (cp >= TRAIL_SURROGATE_MIN && cp <= TRAIL_SURROGATE_MAX);
+    }
+
+    template <typename u16>
+    inline bool is_surrogate(u16 cp)
+    {
+        return (cp >= LEAD_SURROGATE_MIN && cp <= TRAIL_SURROGATE_MAX);
+    }
+
+    template <typename u32>
+    inline bool is_code_point_valid(u32 cp)
+    {
+        return (cp <= CODE_POINT_MAX && !utf8::internal::is_surrogate(cp));
+    }
+
+    template <typename octet_iterator>
+    inline typename std::iterator_traits<octet_iterator>::difference_type
+    sequence_length(octet_iterator lead_it)
+    {
+        uint8_t lead = utf8::internal::mask8(*lead_it);
+        if (lead < 0x80)
+            return 1;
+        else if ((lead >> 5) == 0x6)
+            return 2;
+        else if ((lead >> 4) == 0xe)
+            return 3;
+        else if ((lead >> 3) == 0x1e)
+            return 4;
+        else
+            return 0;
+    }
+
+    template <typename octet_difference_type>
+    inline bool is_overlong_sequence(uint32_t cp, octet_difference_type length)
+    {
+        if (cp < 0x80) {
+            if (length != 1) 
+                return true;
+        }
+        else if (cp < 0x800) {
+            if (length != 2) 
+                return true;
+        }
+        else if (cp < 0x10000) {
+            if (length != 3) 
+                return true;
+        }
+
+        return false;
+    }
+
+    enum utf_error {UTF8_OK, NOT_ENOUGH_ROOM, INVALID_LEAD, INCOMPLETE_SEQUENCE, OVERLONG_SEQUENCE, INVALID_CODE_POINT};
+
+    /// Helper for get_sequence_x
+    template <typename octet_iterator>
+    utf_error increase_safely(octet_iterator& it, octet_iterator end)
+    {
+        if (++it == end)
+            return NOT_ENOUGH_ROOM;
+
+        if (!utf8::internal::is_trail(*it))
+            return INCOMPLETE_SEQUENCE;
+        
+        return UTF8_OK;
+    }
+
+    #define UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR(IT, END) {utf_error ret = increase_safely(IT, END); if (ret != UTF8_OK) return ret;}    
+
+    /// get_sequence_x functions decode utf-8 sequences of the length x
+    template <typename octet_iterator>
+    utf_error get_sequence_1(octet_iterator& it, octet_iterator end, uint32_t& code_point)
+    {
+        if (it == end)
+            return NOT_ENOUGH_ROOM;
+
+        code_point = utf8::internal::mask8(*it);
+
+        return UTF8_OK;
+    }
+
+    template <typename octet_iterator>
+    utf_error get_sequence_2(octet_iterator& it, octet_iterator end, uint32_t& code_point)
+    {
+        if (it == end) 
+            return NOT_ENOUGH_ROOM;
+        
+        code_point = utf8::internal::mask8(*it);
+
+        UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR(it, end)
+
+        code_point = ((code_point << 6) & 0x7ff) + ((*it) & 0x3f);
+
+        return UTF8_OK;
+    }
+
+    template <typename octet_iterator>
+    utf_error get_sequence_3(octet_iterator& it, octet_iterator end, uint32_t& code_point)
+    {
+        if (it == end)
+            return NOT_ENOUGH_ROOM;
+            
+        code_point = utf8::internal::mask8(*it);
+
+        UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR(it, end)
+
+        code_point = ((code_point << 12) & 0xffff) + ((utf8::internal::mask8(*it) << 6) & 0xfff);
+
+        UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR(it, end)
+
+        code_point += (*it) & 0x3f;
+
+        return UTF8_OK;
+    }
+
+    template <typename octet_iterator>
+    utf_error get_sequence_4(octet_iterator& it, octet_iterator end, uint32_t& code_point)
+    {
+        if (it == end)
+           return NOT_ENOUGH_ROOM;
+
+        code_point = utf8::internal::mask8(*it);
+
+        UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR(it, end)
+
+        code_point = ((code_point << 18) & 0x1fffff) + ((utf8::internal::mask8(*it) << 12) & 0x3ffff);
+
+        UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR(it, end)
+
+        code_point += (utf8::internal::mask8(*it) << 6) & 0xfff;
+
+        UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR(it, end)
+
+        code_point += (*it) & 0x3f;
+
+        return UTF8_OK;
+    }
+
+    #undef UTF8_CPP_INCREASE_AND_RETURN_ON_ERROR
+
+    template <typename octet_iterator>
+    utf_error validate_next(octet_iterator& it, octet_iterator end, uint32_t& code_point)
+    {
+        // Save the original value of it so we can go back in case of failure
+        // Of course, it does not make much sense with i.e. stream iterators
+        octet_iterator original_it = it;
+
+        uint32_t cp = 0;
+        // Determine the sequence length based on the lead octet
+        typedef typename std::iterator_traits<octet_iterator>::difference_type octet_difference_type;
+        const octet_difference_type length = utf8::internal::sequence_length(it);
+
+        // Get trail octets and calculate the code point
+        utf_error err = UTF8_OK;
+        switch (length) {
+            case 0: 
+                return INVALID_LEAD;
+            case 1:
+                err = utf8::internal::get_sequence_1(it, end, cp);
+                break;
+            case 2:
+                err = utf8::internal::get_sequence_2(it, end, cp);
+            break;
+            case 3:
+                err = utf8::internal::get_sequence_3(it, end, cp);
+            break;
+            case 4:
+                err = utf8::internal::get_sequence_4(it, end, cp);
+            break;
+        }
+
+        if (err == UTF8_OK) {
+            // Decoding succeeded. Now, security checks...
+            if (utf8::internal::is_code_point_valid(cp)) {
+                if (!utf8::internal::is_overlong_sequence(cp, length)){
+                    // Passed! Return here.
+                    code_point = cp;
+                    ++it;
+                    return UTF8_OK;
+                }
+                else
+                    err = OVERLONG_SEQUENCE;
+            }
+            else 
+                err = INVALID_CODE_POINT;
+        }
+
+        // Failure branch - restore the original value of the iterator
+        it = original_it;
+        return err;
+    }
+
+    template <typename octet_iterator>
+    inline utf_error validate_next(octet_iterator& it, octet_iterator end) {
+        uint32_t ignored;
+        return utf8::internal::validate_next(it, end, ignored);
+    }
+
+} // namespace internal
+
+    /// The library API - functions intended to be called by the users
+
+    // Byte order mark
+    const uint8_t bom[] = {0xef, 0xbb, 0xbf};
+
+    template <typename octet_iterator>
+    octet_iterator find_invalid(octet_iterator start, octet_iterator end)
+    {
+        octet_iterator result = start;
+        while (result != end) {
+            utf8::internal::utf_error err_code = utf8::internal::validate_next(result, end);
+            if (err_code != internal::UTF8_OK)
+                return result;
+        }
+        return result;
+    }
+
+    template <typename octet_iterator>
+    inline bool is_valid(octet_iterator start, octet_iterator end)
+    {
+        return (utf8::find_invalid(start, end) == end);
+    }
+
+    template <typename octet_iterator>
+    inline bool starts_with_bom (octet_iterator it, octet_iterator end)
+    {
+        return (
+            ((it != end) && (utf8::internal::mask8(*it++)) == bom[0]) &&
+            ((it != end) && (utf8::internal::mask8(*it++)) == bom[1]) &&
+            ((it != end) && (utf8::internal::mask8(*it))   == bom[2])
+           );
+    }
+	
+    //Deprecated in release 2.3 
+    template <typename octet_iterator>
+    inline bool is_bom (octet_iterator it)
+    {
+        return (
+            (utf8::internal::mask8(*it++)) == bom[0] &&
+            (utf8::internal::mask8(*it++)) == bom[1] &&
+            (utf8::internal::mask8(*it))   == bom[2]
+           );
+    }
+} // namespace utf8
+
+#endif // header guard
+
+
diff --git a/src/utf8/unchecked.h b/src/utf8/unchecked.h
new file mode 100644
index 0000000..cb24271
--- /dev/null
+++ b/src/utf8/unchecked.h
@@ -0,0 +1,228 @@
+// Copyright 2006 Nemanja Trifunovic
+
+/*
+Permission is hereby granted, free of charge, to any person or organization
+obtaining a copy of the software and accompanying documentation covered by
+this license (the "Software") to use, reproduce, display, distribute,
+execute, and transmit the Software, and to prepare derivative works of the
+Software, and to permit third-parties to whom the Software is furnished to
+do so, all subject to the following:
+
+The copyright notices in the Software and this entire statement, including
+the above license grant, this restriction and the following disclaimer,
+must be included in all copies of the Software, in whole or in part, and
+all derivative works of the Software, unless such copies or derivative
+works are solely in the form of machine-executable object code generated by
+a source language processor.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
+SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
+FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+DEALINGS IN THE SOFTWARE.
+*/
+
+
+#ifndef UTF8_FOR_CPP_UNCHECKED_H_2675DCD0_9480_4c0c_B92A_CC14C027B731
+#define UTF8_FOR_CPP_UNCHECKED_H_2675DCD0_9480_4c0c_B92A_CC14C027B731
+
+#include "core.h"
+
+namespace utf8
+{
+    namespace unchecked 
+    {
+        template <typename octet_iterator>
+        octet_iterator append(uint32_t cp, octet_iterator result)
+        {
+            if (cp < 0x80)                        // one octet
+                *(result++) = static_cast<uint8_t>(cp);  
+            else if (cp < 0x800) {                // two octets
+                *(result++) = static_cast<uint8_t>((cp >> 6)          | 0xc0);
+                *(result++) = static_cast<uint8_t>((cp & 0x3f)        | 0x80);
+            }
+            else if (cp < 0x10000) {              // three octets
+                *(result++) = static_cast<uint8_t>((cp >> 12)         | 0xe0);
+                *(result++) = static_cast<uint8_t>(((cp >> 6) & 0x3f) | 0x80);
+                *(result++) = static_cast<uint8_t>((cp & 0x3f)        | 0x80);
+            }
+            else {                                // four octets
+                *(result++) = static_cast<uint8_t>((cp >> 18)         | 0xf0);
+                *(result++) = static_cast<uint8_t>(((cp >> 12) & 0x3f)| 0x80);
+                *(result++) = static_cast<uint8_t>(((cp >> 6) & 0x3f) | 0x80);
+                *(result++) = static_cast<uint8_t>((cp & 0x3f)        | 0x80);
+            }
+            return result;
+        }
+
+        template <typename octet_iterator>
+        uint32_t next(octet_iterator& it)
+        {
+            uint32_t cp = utf8::internal::mask8(*it);
+            typename std::iterator_traits<octet_iterator>::difference_type length = utf8::internal::sequence_length(it);
+            switch (length) {
+                case 1:
+                    break;
+                case 2:
+                    it++;
+                    cp = ((cp << 6) & 0x7ff) + ((*it) & 0x3f);
+                    break;
+                case 3:
+                    ++it; 
+                    cp = ((cp << 12) & 0xffff) + ((utf8::internal::mask8(*it) << 6) & 0xfff);
+                    ++it;
+                    cp += (*it) & 0x3f;
+                    break;
+                case 4:
+                    ++it;
+                    cp = ((cp << 18) & 0x1fffff) + ((utf8::internal::mask8(*it) << 12) & 0x3ffff);                
+                    ++it;
+                    cp += (utf8::internal::mask8(*it) << 6) & 0xfff;
+                    ++it;
+                    cp += (*it) & 0x3f; 
+                    break;
+            }
+            ++it;
+            return cp;        
+        }
+
+        template <typename octet_iterator>
+        uint32_t peek_next(octet_iterator it)
+        {
+            return utf8::unchecked::next(it);    
+        }
+
+        template <typename octet_iterator>
+        uint32_t prior(octet_iterator& it)
+        {
+            while (utf8::internal::is_trail(*(--it))) ;
+            octet_iterator temp = it;
+            return utf8::unchecked::next(temp);
+        }
+
+        // Deprecated in versions that include prior, but only for the sake of consistency (see utf8::previous)
+        template <typename octet_iterator>
+        inline uint32_t previous(octet_iterator& it)
+        {
+            return utf8::unchecked::prior(it);
+        }
+
+        template <typename octet_iterator, typename distance_type>
+        void advance (octet_iterator& it, distance_type n)
+        {
+            for (distance_type i = 0; i < n; ++i)
+                utf8::unchecked::next(it);
+        }
+
+        template <typename octet_iterator>
+        typename std::iterator_traits<octet_iterator>::difference_type
+        distance (octet_iterator first, octet_iterator last)
+        {
+            typename std::iterator_traits<octet_iterator>::difference_type dist;
+            for (dist = 0; first < last; ++dist) 
+                utf8::unchecked::next(first);
+            return dist;
+        }
+
+        template <typename u16bit_iterator, typename octet_iterator>
+        octet_iterator utf16to8 (u16bit_iterator start, u16bit_iterator end, octet_iterator result)
+        {       
+            while (start != end) {
+                uint32_t cp = utf8::internal::mask16(*start++);
+            // Take care of surrogate pairs first
+                if (utf8::internal::is_lead_surrogate(cp)) {
+                    uint32_t trail_surrogate = utf8::internal::mask16(*start++);
+                    cp = (cp << 10) + trail_surrogate + internal::SURROGATE_OFFSET;
+                }
+                result = utf8::unchecked::append(cp, result);
+            }
+            return result;         
+        }
+
+        template <typename u16bit_iterator, typename octet_iterator>
+        u16bit_iterator utf8to16 (octet_iterator start, octet_iterator end, u16bit_iterator result)
+        {
+            while (start < end) {
+                uint32_t cp = utf8::unchecked::next(start);
+                if (cp > 0xffff) { //make a surrogate pair
+                    *result++ = static_cast<uint16_t>((cp >> 10)   + internal::LEAD_OFFSET);
+                    *result++ = static_cast<uint16_t>((cp & 0x3ff) + internal::TRAIL_SURROGATE_MIN);
+                }
+                else
+                    *result++ = static_cast<uint16_t>(cp);
+            }
+            return result;
+        }
+
+        template <typename octet_iterator, typename u32bit_iterator>
+        octet_iterator utf32to8 (u32bit_iterator start, u32bit_iterator end, octet_iterator result)
+        {
+            while (start != end)
+                result = utf8::unchecked::append(*(start++), result);
+
+            return result;
+        }
+
+        template <typename octet_iterator, typename u32bit_iterator>
+        u32bit_iterator utf8to32 (octet_iterator start, octet_iterator end, u32bit_iterator result)
+        {
+            while (start < end)
+                (*result++) = utf8::unchecked::next(start);
+
+            return result;
+        }
+
+        // The iterator class
+        template <typename octet_iterator>
+          class iterator : public std::iterator <std::bidirectional_iterator_tag, uint32_t> { 
+            octet_iterator it;
+            public:
+            iterator () {}
+            explicit iterator (const octet_iterator& octet_it): it(octet_it) {}
+            // the default "big three" are OK
+            octet_iterator base () const { return it; }
+            uint32_t operator * () const
+            {
+                octet_iterator temp = it;
+                return utf8::unchecked::next(temp);
+            }
+            bool operator == (const iterator& rhs) const 
+            { 
+                return (it == rhs.it);
+            }
+            bool operator != (const iterator& rhs) const
+            {
+                return !(operator == (rhs));
+            }
+            iterator& operator ++ () 
+            {
+                ::std::advance(it, utf8::internal::sequence_length(it));
+                return *this;
+            }
+            iterator operator ++ (int)
+            {
+                iterator temp = *this;
+                ::std::advance(it, utf8::internal::sequence_length(it));
+                return temp;
+            }  
+            iterator& operator -- ()
+            {
+                utf8::unchecked::prior(it);
+                return *this;
+            }
+            iterator operator -- (int)
+            {
+                iterator temp = *this;
+                utf8::unchecked::prior(it);
+                return temp;
+            }
+          }; // class iterator
+
+    } // namespace utf8::unchecked
+} // namespace utf8 
+
+
+#endif // header guard
+