diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 2d2122a..368d074 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -144,12 +144,12 @@ jobs:
           - name: "TOOLSET=clang CXXSTD=03,11,14,1z Job 2"
             buildtype: "boost"
             packages: ""
-            os: "macos-10.15"
+            os: "macos-12"
             cxx: "clang++"
             sources: ""
             llvm_os: ""
             llvm_ver: ""
-            xcode_version: 11.7
+            xcode_version: 14.2
             toolset: "clang"
             cxxstd: "03,11,14,1z"
 
diff --git a/README.md b/README.md
index c7588c2..49aa16e 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,6 @@
-<h1>BOOST SORT</H1>
+# BOOST SORT
 
-<H2>Introduction</h2>
+## Introduction
 
 The goal of the Boost Sort Library is provide to the users, the most modern and fast sorting algorithms.
 
@@ -8,72 +8,74 @@ This library provides stable and not stable sorting algorithms, in single thread
 
 These algorithms do not use any other library or utility. The parallel algorithms need a C++11 compliant compiler.
 
-<h2>Single Thread Algorithms</h2>
+Detailed [boost API documentation](https://www.boost.org/doc/libs/release/libs/sort/) also available.
 
+## Single Thread Algorithms
 
-                      |       |                            |                               |                     |
-    Algorithm         |Stable |   Additional memory        |Best, average, and worst case  | Comparison method   |
-    ------------------|-------|----------------------------|-------------------------------|---------------------|
-    spreadsort        |  no   |      key_length            | N, N sqrt(LogN),              | Hybrid radix sort   |
-                      |       |                            | min(N logN, N key_length)     |                     |
-    pdqsort           |  no   |      Log N                 | N, N LogN, N LogN             | Comparison operator |
-    spinsort          |  yes  |      N / 2                 | N, N LogN, N LogN             | Comparison operator |
-    flat_stable_sort  |  yes  |size of the data / 256 + 8K | N, N LogN, N LogN             | Comparison operator |
-                      |       |                            |                               |                     |
 
+  | Algorithm         |Stable |   Additional memory        |Best, average, and worst case  | Comparison method   |
+  |-------------------|-------|----------------------------|-------------------------------|---------------------|
+  | spreadsort        |  no   |      key_length            | N, N sqrt(LogN),              | Hybrid radix sort   |
+  |                   |       |                            | min(N logN, N key_length)     |                     |
+  | pdqsort           |  no   |      Log N                 | N, N LogN, N LogN             | Comparison operator |
+  | spinsort          |  yes  |      N / 2                 | N, N LogN, N LogN             | Comparison operator |
+  | flat_stable_sort  |  yes  |size of the data / 256 + 8K | N, N LogN, N LogN             | Comparison operator |
 
-- **spreadsort** is a novel hybrid radix sort algorithm, extremely fast, designed and developed by Steven Ross.
 
-- **pdqsort** is a improvement of the quick sort algorithm, designed and developed by Orson Peters.
+- **spreadsort** is a [novel hybrid radix sort algorithm](https://en.wikipedia.org/wiki/Spreadsort), extremely fast, designed and developed by Steven Ross.
+  [(paper)](doc/papers/original_spreadsort06_2002.pdf)
+
+- **pdqsort** is a [improvement of the quick sort algorithm](https://en.wikipedia.org/wiki/Introsort#pdqsort), designed and developed by Orson Peters.
+  [(paper)](https://arxiv.org/pdf/2106.05123.pdf)
 
 - **spinsort** is a stable sort, fast with random and with near sorted data, designed and developed by Francisco Tapia.
 
 - **flat_stable_sort** stable sort with a small additional memory (around 1% of the size of the data), provide the 80% - 90% of the speed of spinsort, being fast with random and with near sorted data, designed and developed by Francisco Tapia.
+  [(paper)](doc/papers/flat_stable_sort_eng.pdf)
 
 
-<h2>Parallel Algorithms</h2>
+## Parallel Algorithms
 
 
-                          |       |                        |                              |
-    Algorithm             |Stable |   Additional memory    |Best, average, and worst case |
-    ----------------------|-------|------------------------|------------------------------|
-    block_indirect_sort   |  no   |block_size * num_threads| N, N LogN , N LogN           |
-    sample_sort           |  yes  |        N               | N, N LogN , N LogN           |
-    parallel_stable_sort  |  yes  |      N / 2             | N, N LogN , N LogN           |
-                          |       |                        |                              |
+  | Algorithm             |Stable |   Additional memory    |Best, average, and worst case |
+  |-----------------------|-------|------------------------|------------------------------|
+  | block_indirect_sort   |  no   |block_size * num_threads| N, N LogN , N LogN           |
+  | sample_sort           |  yes  |        N               | N, N LogN , N LogN           |
+  | parallel_stable_sort  |  yes  |      N / 2             | N, N LogN , N LogN           |
 
 
-- **Sample_sort** is a implementation of the [Samplesort algorithm](https://en.wikipedia.org/wiki/Samplesort)  done by Francisco Tapia.
+- **Sample_sort** is a implementation of the [Samplesort algorithm](https://en.wikipedia.org/wiki/Samplesort) done by Francisco Tapia.
 
 - **Parallel_stable_sort** is based on the samplesort algorithm, but using a half of the memory used by sample_sort, conceived and implemented by Francisco Tapia.
 
 - **Block_indirect_sort** is a novel parallel sort algorithm, very fast, with low additional memory consumption, conceived and implemented by Francisco Tapia.
+  [(paper)](doc/papers/block_indirect_sort_en.pdf)
 
 The **block_size** is an internal parameter of the algorithm, which in order to achieve the
 highest speed, changes according to the size of the objects to sort according to the next table. The strings use a block_size of 128.
 
 
-                                    |        |         |         |         |         |         |          |
-    object size (bytes)             | 1 - 15 | 16 - 31 | 32 - 63 | 64 - 127|128 - 255|256 - 511| 512 -    |
-    --------------------------------|--------|---------|---------|---------|---------|---------|----------|
-    block_size (number of elements) |  4096  |  2048   |   1024  |   768   |   512   |   256   |  128     |
-                                    |        |         |         |         |         |         |          |
+  | object size (bytes)             | 1 - 15 | 16 - 31 | 32 - 63 | 64 - 127|128 - 255|256 - 511| 512 -    |
+  |---------------------------------|--------|---------|---------|---------|---------|---------|----------|
+  | block_size (number of elements) |  4096  |  2048   |   1024  |   768   |   512   |   256   |  128     |
+
 
+## Installation
 
-<h2>Installation </h2>
 - This library is **include only**.
 - Don't need to link with any static or dynamic library. Only need a C++11 compiler
 - Only need to include the file boost/sort/sort.hpp
 
 
-<h2>Author and Copyright</h2>
-This library is integrated in the [Boost Library](https://boost.org) .
+## Author and Copyright
+
+This library is integrated in the [Boost Library](https://boost.org).
 
 
 Copyright 2017
 
-- [Steven Ross *(spreadsort@gmail.com)* ](mail:spreadsort@gmail.com)
-- [Francisco Tapia *(fjtapia@gmail.com)* ](mail:fjtapia@gmail.com)
-- [Orson Peters *(orsonpeters@gmail.com)* ](mail:orsonpeters@gmail.com)
+- [Steven Ross](mailto:spreadsort@gmail.com)
+- [Francisco Tapia](mailto:fjtapia@gmail.com)
+- [Orson Peters](mailto:orsonpeters@gmail.com)
 
-Distributed under the [Boost Software License, Version 1.0. ](http://www.boost.org/LICENSE_1_0.txt)  (See http://www.boost.org/LICENSE_1_0.txt)
+Distributed under the [Boost Software License, Version 1.0](https://www.boost.org/LICENSE_1_0.txt).
diff --git a/doc/Jamfile.v2 b/doc/Jamfile.v2
index adc100b..672a200 100644
--- a/doc/Jamfile.v2
+++ b/doc/Jamfile.v2
@@ -52,6 +52,7 @@ doxygen autodoc
   :
     [ glob $(here)/../include/boost/sort.hpp ]
     [ glob $(here)/../include/boost/sort/spreadsort/*.hpp ]
+    [ glob $(here)/../include/boost/sort/pdqsort/pdqsort.hpp ]
     # [ glob $(here)/../include/boost/sort/detail/spreadsort/*.hpp ] # Hide implementation/detail for now.
     # but could also include this and switch Boost.Sort C++ reference info to include implementation/detail or not using Doxygen macro DETAIL.
     # See http://www.stack.nl/~dimitri/doxygen/manual/commands.html#cmdcond
diff --git a/doc/introduction.qbk b/doc/introduction.qbk
index 714b751..1967934 100644
--- a/doc/introduction.qbk
+++ b/doc/introduction.qbk
@@ -14,7 +14,8 @@ The goal of the Boost Sort Library is provide to the users, the most modern, fas
 
 This library provides stable and unstable sorting algorithms, in single threaded and parallel versions.
 
-These algorithms do not use any other library or utility. The parallel algorithms need a C++11 compliant compiler.
+These algorithms do not use any other library or utility, you only need to include boost/sort/sort.hpp 
+or one of the more specific headers.  The parallel algorithms need a C++11 compliant compiler.
 
 [h4[_Single Thread Algorithms]]
 
diff --git a/doc/pdqsort.qbk b/doc/pdqsort.qbk
index fc94ed1..adf4750 100644
--- a/doc/pdqsort.qbk
+++ b/doc/pdqsort.qbk
@@ -32,7 +32,8 @@ introsort. It is identical in usage to __std_sort.
 
 Pattern-defeating quicksort is available through two calls, __pdqsort and __pdqsort_branchless. Both
 have identical guarantees, behavior and overloads as __std_sort, with the exception of the C++17
-parallel execution policy argument. Thus you can simply replace a call to __std_sort with __pdqsort,
+parallel execution policy argument. Thus you can replace a call to __std_sort with
+boost::sort::pdqsort, available from boost/sort/pdqsort/pdqsort.hpp,
 it is simply a faster implementation. It is almost always appropriate to simply call __pdqsort and
 ignore __pdqsort_branchless.
 
diff --git a/doc/sort.idx b/doc/sort.idx
index 4492743..b44406b 100644
--- a/doc/sort.idx
+++ b/doc/sort.idx
@@ -1,37 +1,38 @@
-# sort.idx for Boost.Sort/Spreadsort Quickbook, Doxygen and Auto-index.
-
-# Note needs more customization to be useful in practice! TODO?
-
-#!debug "\<\w*\>"
-
-# Sort Header files.
-#!scan-path "/boost/sort/" ".*\.*pp" true
-!scan-path "../include/boost/sort" ".*\.hpp" false
-!scan-path "../include/boost/sort/spreadsort" ".*\.hpp" false
-
-# All example source files, assuming no sub-folders.
-# sort example files.
-!scan-path "../example" ".*\.cpp" true
-
-# Allow alternative spellings colour | color, and plurals etc.
-color  \<\w*(colour|color)\w*\>
-container \<contain\w*\>
-data
-deque \<deque\w*\>
-example \<example\w*\>
-font  \<font\w*\>
-greek
-quartile \<quartile\w*\>
-histogram
-ioflags
-origin
-outlier
-maximum \<max\w*\>
-minimum \<min\w*\>
-precision
-range  \<\w*\range\w*\>
-scaling \<\w*\scal\w*\>
-tick \<\w*\tick\w*\>
-title
-Unicode \<unicode\w*\>
-vector \<\w*\vector\w*\>
+# sort.idx for Boost.Sort/Spreadsort Quickbook, Doxygen and Auto-index.
+
+# Note needs more customization to be useful in practice! TODO?
+
+#!debug "\<\w*\>"
+
+# Sort Header files.
+#!scan-path "/boost/sort/" ".*\.*pp" true
+!scan-path "../include/boost/sort" ".*\.hpp" false
+!scan-path "../include/boost/sort/spreadsort" ".*\.hpp" false
+!scan-path "../include/boost/sort/pdqsort" ".*\.hpp" false
+
+# All example source files, assuming no sub-folders.
+# sort example files.
+!scan-path "../example" ".*\.cpp" true
+
+# Allow alternative spellings colour | color, and plurals etc.
+color  \<\w*(colour|color)\w*\>
+container \<contain\w*\>
+data
+deque \<deque\w*\>
+example \<example\w*\>
+font  \<font\w*\>
+greek
+quartile \<quartile\w*\>
+histogram
+ioflags
+origin
+outlier
+maximum \<max\w*\>
+minimum \<min\w*\>
+precision
+range  \<\w*\range\w*\>
+scaling \<\w*\scal\w*\>
+tick \<\w*\tick\w*\>
+title
+Unicode \<unicode\w*\>
+vector \<\w*\vector\w*\>
diff --git a/include/boost/sort/block_indirect_sort/blk_detail/parallel_sort.hpp b/include/boost/sort/block_indirect_sort/blk_detail/parallel_sort.hpp
index 71c74e6..69dfa5b 100644
--- a/include/boost/sort/block_indirect_sort/blk_detail/parallel_sort.hpp
+++ b/include/boost/sort/block_indirect_sort/blk_detail/parallel_sort.hpp
@@ -134,6 +134,7 @@ parallel_sort<Block_size, Iter_t, Compare>
 ::parallel_sort(backbone_t &bkbn, Iter_t first, Iter_t last)
  : bk(bkbn), counter(0)
 {
+    using std::swap;
     assert((last - first) >= 0);
     size_t nelem = size_t(last - first);
 
@@ -153,7 +154,7 @@ ::parallel_sort(backbone_t &bkbn, Iter_t first, Iter_t last)
         size_t nelem2 = nelem >> 1;
         Iter_t it1 = first, it2 = last - 1;
         for (size_t i = 0; i < nelem2; ++i)
-            std::swap(*(it1++), *(it2--));
+            swap(*(it1++), *(it2--));
         return;
     };
 
@@ -188,6 +189,7 @@ template<uint32_t Block_size, class Iter_t, class Compare>
 void parallel_sort<Block_size, Iter_t, Compare>
 ::divide_sort(Iter_t first, Iter_t last, uint32_t level)
 {
+    using std::swap;
     //------------------- check if sort -----------------------------------
     bool sorted = true;
     for (Iter_t it1 = first, it2 = first + 1;
@@ -211,14 +213,14 @@ ::divide_sort(Iter_t first, Iter_t last, uint32_t level)
 
     while (c_first < c_last)
     {
-        std::swap(*(c_first++), *(c_last--));
+        swap(*(c_first++), *(c_last--));
         while (bk.cmp(*c_first, val))
             ++c_first;
         while (bk.cmp(val, *c_last))
             --c_last;
     };
 
-    std::swap(*first, *c_last);
+    swap(*first, *c_last);
 
     // insert  the work of the second half in the stack of works
     function_divide_sort(c_first, last, level - 1, counter, bk.error);
diff --git a/include/boost/sort/block_indirect_sort/block_indirect_sort.hpp b/include/boost/sort/block_indirect_sort/block_indirect_sort.hpp
index 04ea42f..5e03b28 100644
--- a/include/boost/sort/block_indirect_sort/block_indirect_sort.hpp
+++ b/include/boost/sort/block_indirect_sort/block_indirect_sort.hpp
@@ -216,7 +216,8 @@ ::block_indirect_sort(Iter_t first, Iter_t last, Compare cmp, uint32_t nthr)
             Iter_t it1 = first, it2 = last - 1;
             for (size_t i = 0; i < nelem2; ++i)
             {
-                std::swap(*(it1++), *(it2--));
+		using std::swap;
+                swap(*(it1++), *(it2--));
             };
             return;
         };
diff --git a/include/boost/sort/common/file_vector.hpp b/include/boost/sort/common/file_vector.hpp
index ec2bb0e..642ccf3 100644
--- a/include/boost/sort/common/file_vector.hpp
+++ b/include/boost/sort/common/file_vector.hpp
@@ -89,7 +89,7 @@ inline int fill_vector_uint64(const std::string & filename,
     size_t uCount = length / 8;
     if (uCount < NElem)
     {
-        throw std::ios_base::failure("incorrect lenght of the file\n");
+        throw std::ios_base::failure("incorrect length of the file\n");
     };
     V.clear();
     V.reserve(NElem);
diff --git a/include/boost/sort/common/merge_four.hpp b/include/boost/sort/common/merge_four.hpp
index 6b791be..ce3f5e5 100644
--- a/include/boost/sort/common/merge_four.hpp
+++ b/include/boost/sort/common/merge_four.hpp
@@ -76,6 +76,7 @@ range<Iter1_t> full_merge4(const range<Iter1_t> &rdest,
                            range<Iter2_t> vrange_input[4],
                            uint32_t nrange_input, Compare comp)
 {
+    using std::swap;
     typedef range<Iter1_t> range1_t;
     typedef util::value_iter<Iter1_t> type1;
     typedef util::value_iter<Iter2_t> type2;
@@ -120,28 +121,28 @@ range<Iter1_t> full_merge4(const range<Iter1_t> &rdest,
     if (less_range(vrange_input[pos[1]].first, pos[1],
                     vrange_input[pos[0]].first, pos[0], comp))
     {
-        std::swap(pos[0], pos[1]);
+        swap(pos[0], pos[1]);
     };
     if (npos == 4 and less_range(vrange_input[pos[3]].first, pos[3],
                                  vrange_input[pos[2]].first, pos[2], comp))
     {
-        std::swap(pos[3], pos[2]);
+        swap(pos[3], pos[2]);
     };
     if (less_range (vrange_input[pos[2]].first, pos[2],
                     vrange_input[pos[0]].first, pos[0], comp))
     {
-        std::swap(pos[0], pos[2]);
+        swap(pos[0], pos[2]);
     };
     if (npos == 4
                     and less_range (vrange_input[pos[3]].first, pos[3],
                                     vrange_input[pos[1]].first, pos[1], comp))
     {
-        std::swap(pos[1], pos[3]);
+        swap(pos[1], pos[3]);
     };
     if (less_range (vrange_input[pos[2]].first, pos[2],
                     vrange_input[pos[1]].first, pos[1], comp))
     {
-        std::swap(pos[1], pos[2]);
+        swap(pos[1], pos[2]);
     };
 
     Iter1_t it_dest = rdest.first;
@@ -160,18 +161,18 @@ range<Iter1_t> full_merge4(const range<Iter1_t> &rdest,
             if (less_range(vrange_input[pos[1]].first, pos[1],
                             vrange_input[pos[0]].first, pos[0], comp))
             {
-                std::swap(pos[0], pos[1]);
+                swap(pos[0], pos[1]);
                 if (less_range(vrange_input[pos[2]].first, pos[2],
                                 vrange_input[pos[1]].first, pos[1], comp))
                 {
-                    std::swap(pos[1], pos[2]);
+                    swap(pos[1], pos[2]);
                     if (npos == 4
                                     and less_range(vrange_input[pos[3]].first,
                                                     pos[3],
                                                     vrange_input[pos[2]].first,
                                                     pos[2], comp))
                     {
-                        std::swap(pos[2], pos[3]);
+                        swap(pos[2], pos[3]);
                     };
                 };
             };
@@ -208,6 +209,7 @@ range<Value_t *> uninit_full_merge4(const range<Value_t *> &dest,
                                     range<Iter_t> vrange_input[4],
                                     uint32_t nrange_input, Compare comp)
 {
+    using std::swap;
     typedef util::value_iter<Iter_t> type1;
     static_assert (std::is_same< type1, Value_t >::value,
                     "Incompatible iterators\n");
@@ -248,27 +250,27 @@ range<Value_t *> uninit_full_merge4(const range<Value_t *> &dest,
     if (less_range(vrange_input[pos[1]].first, pos[1],
                     vrange_input[pos[0]].first, pos[0], comp))
     {
-        std::swap(pos[0], pos[1]);
+        swap(pos[0], pos[1]);
     };
     if (npos == 4  and less_range(vrange_input[pos[3]].first, pos[3],
                                   vrange_input[pos[2]].first, pos[2], comp))
     {
-        std::swap(pos[3], pos[2]);
+        swap(pos[3], pos[2]);
     };
     if (less_range(vrange_input[pos[2]].first, pos[2],
                     vrange_input[pos[0]].first, pos[0], comp))
     {
-        std::swap(pos[0], pos[2]);
+        swap(pos[0], pos[2]);
     };
     if (npos == 4 and less_range(vrange_input[pos[3]].first, pos[3],
                                  vrange_input[pos[1]].first, pos[1], comp))
     {
-        std::swap(pos[1], pos[3]);
+        swap(pos[1], pos[3]);
     };
     if (less_range(vrange_input[pos[2]].first, pos[2],
                     vrange_input[pos[1]].first, pos[1], comp))
     {
-        std::swap(pos[1], pos[2]);
+        swap(pos[1], pos[2]);
     };
 
     Value_t *it_dest = dest.first;
@@ -288,17 +290,17 @@ range<Value_t *> uninit_full_merge4(const range<Value_t *> &dest,
             if (less_range (vrange_input[pos[1]].first, pos[1],
                             vrange_input[pos[0]].first, pos[0], comp))
             {
-                std::swap(pos[0], pos[1]);
+                swap(pos[0], pos[1]);
                 if (less_range (vrange_input[pos[2]].first, pos[2],
                                 vrange_input[pos[1]].first, pos[1], comp))
                 {
-                    std::swap(pos[1], pos[2]);
+                    swap(pos[1], pos[2]);
                     if (npos == 4 and less_range(vrange_input[pos[3]].first,
                                                  pos[3],
                                                  vrange_input[pos[2]].first,
                                                  pos[2], comp))
                     {
-                        std::swap(pos[2], pos[3]);
+                        swap(pos[2], pos[3]);
                     };
                 };
             };
diff --git a/include/boost/sort/common/pivot.hpp b/include/boost/sort/common/pivot.hpp
index 6422a34..7b10385 100644
--- a/include/boost/sort/common/pivot.hpp
+++ b/include/boost/sort/common/pivot.hpp
@@ -43,10 +43,11 @@ namespace common
 template < typename Iter_t, typename Compare >
 inline Iter_t mid3 (Iter_t iter_1, Iter_t iter_2, Iter_t iter_3, Compare comp)
 {
-	if (comp (*iter_2, *iter_1)) std::swap ( *iter_2, *iter_1);
+    using std::swap;
+	if (comp (*iter_2, *iter_1)) swap ( *iter_2, *iter_1);
 	if (comp (*iter_3, *iter_2))
-	{	std::swap ( *iter_3, *iter_2);
-		if (comp (*iter_2, *iter_1)) std::swap ( *iter_2, *iter_1);
+	{	swap ( *iter_3, *iter_2);
+		if (comp (*iter_2, *iter_1)) swap ( *iter_2, *iter_1);
 	};
 	return iter_2;
 };
@@ -64,9 +65,10 @@ inline Iter_t mid3 (Iter_t iter_1, Iter_t iter_2, Iter_t iter_3, Compare comp)
 template < class Iter_t, class Compare >
 inline void pivot3 (Iter_t first, Iter_t last, Compare comp)
 {
+    using std::swap;
     auto N2 = (last - first) >> 1;
     Iter_t it_val = mid3 (first + 1, first + N2, last - 1, comp);
-    std::swap (*first, *it_val);
+    swap (*first, *it_val);
 };
 
 //
@@ -110,11 +112,12 @@ inline Iter_t mid9 (Iter_t iter_1, Iter_t iter_2, Iter_t iter_3, Iter_t iter_4,
 template < class Iter_t, class Compare >
 inline void pivot9 (Iter_t first, Iter_t last, Compare comp)
 {
+    using std::swap;
     size_t cupo = (last - first) >> 3;
     Iter_t itaux = mid9 (first + 1, first + cupo, first + 2 * cupo,
                          first + 3 * cupo, first + 4 * cupo, first + 5 * cupo,
                          first + 6 * cupo, first + 7 * cupo, last - 1, comp);
-    std::swap (*first, *itaux);
+    swap (*first, *itaux);
 };
 //****************************************************************************
 };//    End namespace common
diff --git a/include/boost/sort/common/rearrange.hpp b/include/boost/sort/common/rearrange.hpp
index fe48ee6..d32db09 100644
--- a/include/boost/sort/common/rearrange.hpp
+++ b/include/boost/sort/common/rearrange.hpp
@@ -92,8 +92,9 @@ void rearrange(Iter_data global_first, Iter_index itx_first,
 
         while ((pos_src = pos(itx_src)) != pos_ini)
         {
+	    using std::swap;
             data[pos_dest] = std::move(data[pos_src]);
-            std::swap(itx_src, index[pos_src]);
+            swap(itx_src, index[pos_src]);
             pos_dest = pos_src;
         };
 
diff --git a/include/boost/sort/common/stack_cnc.hpp b/include/boost/sort/common/stack_cnc.hpp
index e040b1d..ca2039f 100644
--- a/include/boost/sort/common/stack_cnc.hpp
+++ b/include/boost/sort/common/stack_cnc.hpp
@@ -99,7 +99,7 @@ class stack_cnc
     {
         std::lock_guard < spinlock_t > guard(spl);
         v_t.emplace_back(std::forward< Args > (args)...);
-    };
+    }
 
     //
     //-------------------------------------------------------------------------
@@ -116,7 +116,7 @@ class stack_cnc
         P = std::move(v_t.back());
         v_t.pop_back();
         return true;
-    };
+    }
     //-------------------------------------------------------------------------
     //  function : push_back
     /// @brief Insert one vector at the end of the container
@@ -132,7 +132,7 @@ class stack_cnc
             v_t.push_back(v_other[i]);
         }
         return *this;
-    };
+    }
 };
 // end class stack_cnc
 
diff --git a/include/boost/sort/common/util/insert.hpp b/include/boost/sort/common/util/insert.hpp
index 485e25b..150ef26 100644
--- a/include/boost/sort/common/util/insert.hpp
+++ b/include/boost/sort/common/util/insert.hpp
@@ -22,7 +22,6 @@
 #include <type_traits>
 #include <vector>
 #include <cstddef>
-#include <boost/sort/common/util/insert.hpp>
 #include <boost/sort/common/util/traits.hpp>
 #include <boost/sort/common/util/algorithm.hpp>
 
diff --git a/include/boost/sort/common/util/traits.hpp b/include/boost/sort/common/util/traits.hpp
index 622a99c..d4237b8 100644
--- a/include/boost/sort/common/util/traits.hpp
+++ b/include/boost/sort/common/util/traits.hpp
@@ -112,7 +112,7 @@ struct constructor
     void operator()(Args && ... args)
     {
         T(std::forward<Args> (args) ...);
-    };
+    }
 };
 //
 //****************************************************************************
diff --git a/include/boost/sort/flat_stable_sort/flat_stable_sort.hpp b/include/boost/sort/flat_stable_sort/flat_stable_sort.hpp
index 8ebfdfb..340b9ff 100644
--- a/include/boost/sort/flat_stable_sort/flat_stable_sort.hpp
+++ b/include/boost/sort/flat_stable_sort/flat_stable_sort.hpp
@@ -87,6 +87,9 @@ class flat_stable_sort: public bsc::merge_block<Iter_t, Compare, Power2>
                      circular_t *ptr_circ)
                     : merge_block_t(first, last, comp, ptr_circ)
     {
+        auto nelem = last - first;
+        assert (nelem >= 0);
+        if (nelem < 2) return;
         divide(index.begin(), index.end());
         rearrange_with_index();
     };
diff --git a/include/boost/sort/insert_sort/insert_sort.hpp b/include/boost/sort/insert_sort/insert_sort.hpp
index c03a96f..e7fe6f6 100644
--- a/include/boost/sort/insert_sort/insert_sort.hpp
+++ b/include/boost/sort/insert_sort/insert_sort.hpp
@@ -19,7 +19,6 @@
 #include <algorithm>
 #include <utility> // std::swap
 #include <boost/sort/common/util/traits.hpp>
-#include <boost/sort/common/util/insert.hpp>
 
 namespace boost
 {
@@ -61,56 +60,6 @@ static void insert_sort (Iter_t first, Iter_t last,
     };
 };
 
-/*
-//
-//-----------------------------------------------------------------------------
-//  function : insert_partial_sort
-/// @brief : Insertion sort of elements sorted
-/// @param first: iterator to the first element of the range
-/// @param mid : last pointer of the sorted data, and first pointer to the
-///               elements to insert
-/// @param last : iterator to the next element of the last in the range
-/// @param comp : object for to do the comparison between the elements
-/// @remarks This algorithm is O(N^2)
-//-----------------------------------------------------------------------------
-template < class Iter_t, typename Compare = compare_iter < Iter_t > >
-void insert_partial_sort (Iter_t first, Iter_t mid, Iter_t last,
-                          Compare comp = Compare())
-{
-    //--------------------------------------------------------------------
-    //                   DEFINITIONS
-    //--------------------------------------------------------------------
-    typedef value_iter< Iter_t > value_t;
-
-    if ( mid == last ) return ;
-    insert_sort ( mid, last, comp);
-    if (first == mid) return ;
-
-    // creation of the vector of elements to insert and their position in the
-    // sorted part
-    std::vector<Iter_t> viter ;
-    std::vector<value_t> vdata ;
-
-    for ( Iter_t alpha = mid ; alpha != last ; ++alpha)
-        vdata.push_back ( std::move ( *alpha));
-
-    Iter_t linf = first , lsup = mid ;
-    for ( uint32_t i= 0 ; i < vdata.size() ; ++i)
-    {   Iter_t it1 = std::upper_bound ( linf, lsup , vdata[i], comp);
-        viter.push_back ( it1 );
-        linf = it1 ;
-    };
-
-    // moving the elements
-    viter.push_back ( mid) ;
-    for ( uint32_t i = viter.size() -1 ; i!= 0 ; --i)
-    {   Iter_t src = viter[i], limit = viter[i-1];
-        Iter_t dest = src + ( i);
-        while ( src != limit) * (--dest) = std::move ( *(--src));
-        *(viter[i-1] + (i -1)) = std::move (vdata[i-1]);
-    };
-}
-*/
 //
 //****************************************************************************
 }; //    End namespace sort
diff --git a/include/boost/sort/parallel_stable_sort/parallel_stable_sort.hpp b/include/boost/sort/parallel_stable_sort/parallel_stable_sort.hpp
index 9f1ada1..cd68557 100644
--- a/include/boost/sort/parallel_stable_sort/parallel_stable_sort.hpp
+++ b/include/boost/sort/parallel_stable_sort/parallel_stable_sort.hpp
@@ -150,10 +150,11 @@ ::parallel_stable_sort (Iter_t first, Iter_t last, Compare comp,
          it2 != last and (sw = comp(*it2, *it1)); it1 = it2++);
     if (sw)
     {
+	using std::swap;
         size_t nelem2 = nelem >> 1;
         Iter_t it1 = first, it2 = last - 1;
         for (size_t i = 0; i < nelem2; ++i)
-            std::swap(*(it1++), *(it2--));
+            swap(*(it1++), *(it2--));
         return;
     };
 
diff --git a/include/boost/sort/pdqsort/pdqsort.hpp b/include/boost/sort/pdqsort/pdqsort.hpp
index 8352e39..fd447ce 100644
--- a/include/boost/sort/pdqsort/pdqsort.hpp
+++ b/include/boost/sort/pdqsort/pdqsort.hpp
@@ -232,7 +232,7 @@ namespace pdqsort_detail {
 
                 // Fill the offset blocks.
                 if (left_split >= block_size) {
-                    for (size_t i = 0; i < block_size;) {
+                    for (unsigned char i = 0; i < static_cast<unsigned char>(block_size);) {
                         offsets_l[num_l] = i++; num_l += !comp(*first, pivot); ++first;
                         offsets_l[num_l] = i++; num_l += !comp(*first, pivot); ++first;
                         offsets_l[num_l] = i++; num_l += !comp(*first, pivot); ++first;
@@ -243,13 +243,13 @@ namespace pdqsort_detail {
                         offsets_l[num_l] = i++; num_l += !comp(*first, pivot); ++first;
                     }
                 } else {
-                    for (size_t i = 0; i < left_split;) {
+                    for (unsigned char i = 0; i < static_cast<unsigned char>(left_split);) {
                         offsets_l[num_l] = i++; num_l += !comp(*first, pivot); ++first;
                     }
                 }
 
                 if (right_split >= block_size) {
-                    for (size_t i = 0; i < block_size;) {
+                    for (unsigned char i = 0; i < static_cast<unsigned char>(block_size);) {
                         offsets_r[num_r] = ++i; num_r += comp(*--last, pivot);
                         offsets_r[num_r] = ++i; num_r += comp(*--last, pivot);
                         offsets_r[num_r] = ++i; num_r += comp(*--last, pivot);
@@ -260,7 +260,7 @@ namespace pdqsort_detail {
                         offsets_r[num_r] = ++i; num_r += comp(*--last, pivot);
                     }
                 } else {
-                    for (size_t i = 0; i < right_split;) {
+                    for (unsigned char i = 0; i < static_cast<unsigned char>(right_split);) {
                         offsets_r[num_r] = ++i; num_r += comp(*--last, pivot);
                     }
                 }
diff --git a/include/boost/sort/sample_sort/sample_sort.hpp b/include/boost/sort/sample_sort/sample_sort.hpp
index c5b4cb9..e52e2dd 100644
--- a/include/boost/sort/sample_sort/sample_sort.hpp
+++ b/include/boost/sort/sample_sort/sample_sort.hpp
@@ -273,10 +273,11 @@ ::sample_sort (Iter_t first, Iter_t last, Compare cmp, uint32_t num_thread,
                     it2 != last and (sw = comp(*it2, *it1)); it1 = it2++);
     if (sw)
     {
+	using std::swap;
         size_t nelem2 = nelem >> 1;
         Iter_t it1 = first, it2 = last - 1;
         for (size_t i = 0; i < nelem2; ++i)
-            std::swap(*(it1++), *(it2--));
+            swap(*(it1++), *(it2--));
         return;
     };
 
diff --git a/include/boost/sort/spinsort/spinsort.hpp b/include/boost/sort/spinsort/spinsort.hpp
index 726341b..b8d0fdf 100644
--- a/include/boost/sort/spinsort/spinsort.hpp
+++ b/include/boost/sort/spinsort/spinsort.hpp
@@ -209,8 +209,10 @@ static bool check_stable_sort(const range<Iter1_t> &rng_data,
     size_t nreverse = it2 - rng_data.first;
     Iter1_t alpha(rng_data.first), beta(it2 - 1), mid(
                     rng_data.first + (nreverse >> 1));
-    while (alpha != mid)
-        std::swap(*(alpha++), *(beta--));
+    while (alpha != mid) {
+	using std::swap;
+        swap(*(alpha++), *(beta--));
+    }
 
     // insert the elements between it1 and last
     if (it2 != rng_data.last)
@@ -470,10 +472,11 @@ ::spinsort (Iter_t first, Iter_t last, Compare comp, value_t *paux, size_t naux)
          it2 != last and (sw = comp(*it2, *it1)); it1 = it2++);
     if (sw)
     {
+	using std::swap;
         size_t nelem2 = nelem >> 1;
         Iter_t it1 = first, it2 = last - 1;
         for (size_t i = 0; i < nelem2; ++i)
-            std::swap(*(it1++), *(it2--));
+            swap(*(it1++), *(it2--));
         return;
     };
 
diff --git a/include/boost/sort/spreadsort/detail/float_sort.hpp b/include/boost/sort/spreadsort/detail/float_sort.hpp
index 8682afd..2fb903f 100644
--- a/include/boost/sort/spreadsort/detail/float_sort.hpp
+++ b/include/boost/sort/spreadsort/detail/float_sort.hpp
@@ -410,7 +410,7 @@ namespace spreadsort {
                                                                 max, min))
         return;
       unsigned log_divisor = get_log_divisor<float_log_mean_bin_size>(
-          last - first, rough_log_2_size(Size_type(max - min)));
+          last - first, rough_log_2_size(Size_type(max/2 - min/2)) + 1);
       Div_type div_min = min >> log_divisor;
       Div_type div_max = max >> log_divisor;
       unsigned bin_count = unsigned(div_max - div_min) + 1;
@@ -507,7 +507,7 @@ namespace spreadsort {
       if (is_sorted_or_find_extremes(first, last, max, min, rshift))
         return;
       unsigned log_divisor = get_log_divisor<float_log_mean_bin_size>(
-          last - first, rough_log_2_size(Size_type(max - min)));
+          last - first, rough_log_2_size(Size_type(max/2 - min/2)) + 1);
       Div_type div_min = min >> log_divisor;
       Div_type div_max = max >> log_divisor;
       unsigned bin_count = unsigned(div_max - div_min) + 1;
@@ -605,7 +605,7 @@ namespace spreadsort {
       if (is_sorted_or_find_extremes(first, last, max, min, rshift, comp))
         return;
       unsigned log_divisor = get_log_divisor<float_log_mean_bin_size>(
-          last - first, rough_log_2_size(Size_type(max - min)));
+          last - first, rough_log_2_size(Size_type(max/2 - min/2)) + 1);
       Div_type div_min = min >> log_divisor;
       Div_type div_max = max >> log_divisor;
       unsigned bin_count = unsigned(div_max - div_min) + 1;
diff --git a/test/test_block_indirect_sort.cpp b/test/test_block_indirect_sort.cpp
index b03f00f..05f63cf 100644
--- a/test/test_block_indirect_sort.cpp
+++ b/test/test_block_indirect_sort.cpp
@@ -37,8 +37,11 @@ void test1 (void)
     std::vector< uint64_t > V1;
     V1.reserve (NElem);
     
+    //------------------- sort 0 elements ------------------------------------
+    block_indirect_sort ( V1.end (), V1.end ( ), 4);
+    
     //------------------ sorted elements  4 threads --------------------------
-    V1.clear ( );
+    V1.clear ();
     for (uint32_t i = 0; i < NElem; ++i) V1.push_back (i);
 
     block_indirect_sort ( V1.begin ( ), V1.end ( ), 4);
diff --git a/test/test_flat_stable_sort.cpp b/test/test_flat_stable_sort.cpp
index 83aaaad..d1df52c 100644
--- a/test/test_flat_stable_sort.cpp
+++ b/test/test_flat_stable_sort.cpp
@@ -53,6 +53,8 @@ void test1 ( )
             V1.push_back (G);
         };
     };
+    //check sort 0 elements
+    flat_stable_sort< iter_t, compare_t > (V1.begin ( ), V1.begin ( ), compare_t ( ));
     V2 = V1;
     flat_stable_sort< iter_t, compare_t > (V1.begin ( ), V1.end ( ), compare_t ( ));
     std::stable_sort (V2.begin ( ), V2.end ( ));
diff --git a/test/test_insert_sort.cpp b/test/test_insert_sort.cpp
index c2b93db..4027edc 100644
--- a/test/test_insert_sort.cpp
+++ b/test/test_insert_sort.cpp
@@ -23,7 +23,6 @@
 
 using namespace boost::sort;
 using namespace std;
-using boost::sort::common::util::insert_sorted;
 
 void test01 (void)
 {
@@ -31,6 +30,10 @@ void test01 (void)
                     16, 6, 14, 21, 5,  1, 12, 19, 22, 25, 8};
 
     std::less< unsigned > comp;
+    
+    // Insertion Sort  sort an empty range
+    insert_sort (&A[ 0 ], &A[ 0 ], comp);
+    
     // Insertion Sort  Unordered, not repeated
     insert_sort (&A[ 0 ], &A[ 22 ], comp);
     for (unsigned i = 0; i < 21; i++) {
@@ -117,47 +120,9 @@ void test02 (void)
                  A[ 1001 + NELEM ] == 999999999);
 };
 
-
-void test03 ( void)
-{
-    std::vector<uint32_t> V {1,3,5,2,4};
-    std::less<uint32_t> comp ;
-    uint32_t aux[10] ;
-
-    insert_sorted ( V.begin() , V.begin()+3, V.end(), comp, aux);
-    //insert_partial_sort ( V.begin() , V.begin()+3, V.end() , comp);
-    for ( uint32_t i =0 ; i < V.size() ; ++i)
-        std::cout<<V[i]<<", ";
-    std::cout<<std::endl;
-
-    V ={3,5,7,9,11,13,15,17,19,8,6,10,4,2};
-    insert_sorted ( V.begin() , V.begin()+9, V.end() , comp, aux);
-    //insert_partial_sort ( V.begin() , V.begin()+9, V.end() , comp);
-    for ( uint32_t i =0 ; i < V.size() ; ++i)
-        std::cout<<V[i]<<", ";
-    std::cout<<std::endl;
-
-    V ={13,15,17,19,21,23,35,27,29,8,6,10,4,2};
-    insert_sorted ( V.begin() , V.begin()+9, V.end() , comp, aux);
-    //insert_partial_sort ( V.begin() , V.begin()+9, V.end() , comp);
-    for ( uint32_t i =0 ; i < V.size() ; ++i)
-        std::cout<<V[i]<<", ";
-    std::cout<<std::endl;
-
-    V ={3,5,7,9,11,13,15,17,19,28,26,30,24,22};
-    insert_sorted ( V.begin() , V.begin()+9, V.end() , comp, aux);
-    //insert_partial_sort ( V.begin() , V.begin()+9, V.end() , comp);
-    for ( uint32_t i =0 ; i < V.size() ; ++i)
-        std::cout<<V[i]<<", ";
-    std::cout<<std::endl;
-
-
-
-}
 int test_main (int, char *[])
 {
     test01 ( );
     test02 ( );
-    test03 ( );
     return 0;
 }
diff --git a/test/test_parallel_stable_sort.cpp b/test/test_parallel_stable_sort.cpp
index 6c1dace..f790677 100644
--- a/test/test_parallel_stable_sort.cpp
+++ b/test/test_parallel_stable_sort.cpp
@@ -51,6 +51,10 @@ void test1()
         };
     };
     V3 = V2 = V1;
+    
+    // check to sort with 0 elements
+    bss::parallel_stable_sort(V1.end(), V1.end());
+    
     bss::parallel_stable_sort(V1.begin(), V1.end());
     std::stable_sort(V2.begin(), V2.end());
     bss::parallel_stable_sort(V3.begin(), V3.end(), 0);
diff --git a/test/test_sample_sort.cpp b/test/test_sample_sort.cpp
index a83634f..c23b56f 100644
--- a/test/test_sample_sort.cpp
+++ b/test/test_sample_sort.cpp
@@ -50,6 +50,9 @@ void test1()
         };
     };
     V3 = V2 = V1;
+    // sort 0 elements
+    bss::sample_sort(V1.end(), V1.end());
+    
     bss::sample_sort(V1.begin(), V1.end());
     std::stable_sort(V2.begin(), V2.end());
     bss::sample_sort(V3.begin(), V3.end(), 0);
diff --git a/test/test_spinsort.cpp b/test/test_spinsort.cpp
index b8e2f26..91b5a43 100644
--- a/test/test_spinsort.cpp
+++ b/test/test_spinsort.cpp
@@ -61,6 +61,10 @@ void test1 ( )
         };
     };
     V2 = V1;
+    // test with 0 elements
+    spinsort (V1.end ( ), V1.end ( ), compare_t ( ));
+    
+    
     spinsort (V1.begin ( ), V1.end ( ), compare_t ( ));
     std::stable_sort (V2.begin ( ), V2.end ( ));
 
diff --git a/tune.pl b/tune.pl
index 598f1a9..4f83ce7 100755
--- a/tune.pl
+++ b/tune.pl
@@ -19,7 +19,7 @@
 $verifycorrect = 0;
 $verbose = 0;
 $exename = "spreadsort";
-$makename = "../../b2 \-\-tune";
+$makename = "b2 \-\-tune";
 $all = "";
 $iter_count = 1;
 $debug = 0;