buffer reverse not working correctly

        -Incomplete function to reverse buffer, modified
        code to loop though bits and reverse them for all
        cases.

Change-Id: I1bca6a6f67a5aec7681d5b581b07e35c7e103dc0
RTC:137890
Reviewed-on: http://gfw160.aus.stglabs.ibm.com:8080/gerrit/20862
Tested-by: Jenkins Server
Reviewed-by: Brian Silver <bsilver@us.ibm.com>
Reviewed-by: Matt K. Light <mklight@us.ibm.com>
Reviewed-by: Jennifer A. Stofer <stofer@us.ibm.com>

1 files changed, 97 insertions, 62 deletions

diff --git a/import/hwpf/fapi2/include/buffer_traits.H b/import/hwpf/fapi2/include/buffer_traits.H
index 7585d135..f9e3bab5 100644
--- a/import/hwpf/fapi2/include/buffer_traits.H
+++ b/import/hwpf/fapi2/include/buffer_traits.H
@@ -36,31 +36,31 @@
 #include <buffer_parameters.H>
 
 #ifdef FAPI2_DEBUG
-#include <iostream>
+    #include <iostream>
 #endif
 
 #include <iterator>
 
 namespace fapi2
 {
-    /// @cond
-    /// Types representing a container of bits. Used to create
-    /// variable_buffer. container_unit must remain 32-bits
-    /// for now - there will be a lot of code to change if it
-    /// changes. There are assertions helping to enforce this
-    /// in places in the code.
-    typedef uint32_t container_unit;
-    typedef std::vector<container_unit> bits_container;
-
-    /// @brief Traits of buffers
-    // In general, we try to give buffers traits reflecting integral types. If
-    // this fails, the compiler will let someone know.
-    ///
-    /// @tparam T is the type of iv_data (std::vector, etc)
-    /// @tparam B is the type of the bit-specifier, typically uint32_t
-    template<typename T, typename B = uint32_t>
-    class bufferTraits
-    {
+/// @cond
+/// Types representing a container of bits. Used to create
+/// variable_buffer. container_unit must remain 32-bits
+/// for now - there will be a lot of code to change if it
+/// changes. There are assertions helping to enforce this
+/// in places in the code.
+typedef uint32_t container_unit;
+typedef std::vector<container_unit> bits_container;
+
+/// @brief Traits of buffers
+// In general, we try to give buffers traits reflecting integral types. If
+// this fails, the compiler will let someone know.
+///
+/// @tparam T is the type of iv_data (std::vector, etc)
+/// @tparam B is the type of the bit-specifier, typically uint32_t
+template<typename T, typename B = uint32_t>
+class bufferTraits
+{
     public:
 
 #if !defined(DOXYGEN) && defined(FAPI2_DEBUG)
@@ -87,11 +87,11 @@ namespace fapi2
         ///
         template<typename E>
         constexpr static B size(const T& i_buffer)
-            {
-                return (bit_length(i_buffer) +
-                        (parameterTraits<E>::bit_length() - 1)) /
-                    parameterTraits<E>::bit_length();
-            }
+        {
+            return (bit_length(i_buffer) +
+                    (parameterTraits<E>::bit_length() - 1)) /
+                   parameterTraits<E>::bit_length();
+        }
 
         ///
         /// @brief Return the size of the buffer itself
@@ -99,62 +99,86 @@ namespace fapi2
         /// @return The size of the buffer in bits (not units)
         ///
         constexpr static B bit_length(const T&)
-            { return sizeof(T) * 8; }
+        {
+            return sizeof(T) * 8;
+        }
 
         ///
         /// @brief Clear the buffer
         /// @param[in,out] io_buffer the buffer which to clear
         ///
         static inline void clear(T& io_buffer)
-            { io_buffer = static_cast<T>(0); }
+        {
+            io_buffer = static_cast<T>(0);
+        }
 
         ///
         /// @brief Set the buffer
         /// @param[in,out] io_buffer the buffer which to set
         ///
         static inline void set(T& io_buffer)
-            { io_buffer = static_cast<T>(~0); }
+        {
+            io_buffer = static_cast<T>(~0);
+        }
 
         ///
         /// @brief Invert the buffer
         /// @param[in,out] io_buffer the buffer which to invert
         ///
         static inline void invert(T& io_buffer)
-            { io_buffer = ~io_buffer; }
+        {
+            io_buffer = ~io_buffer;
+        }
 
         ///
         /// @brief Reverse the buffer
         /// @param[in,out] io_buffer the buffer which to reverse
+        //
+        //  @note from
+        //   http://stackoverflow.com/questions/746171/best-algorithm-for-bit-reversal-from-msb-lsb-to-lsb-msb-in-c
         ///
-        static inline void reverse(T& io_buffer)
+        static inline void reverse( T& io_buffer)
+        {
+            T l_result = io_buffer;
+            size_t l_s = sizeof(T) * 8 - 1;
+
+            for( io_buffer >>= 1; io_buffer; io_buffer >>= 1)
             {
-                io_buffer =
-                    ((io_buffer & 0xAAAAAAAAAAAAAAAA) >> 1) |
-                    ((io_buffer & 0x5555555555555555) << 1);
+                l_result <<= 1;
+                l_result |= io_buffer & 1;
+                l_s--;
             }
 
+            l_result <<= l_s;
+
+            io_buffer = l_result;
+        }
         ///
         /// @brief Get the address of the buffer as an array
         /// @param[in] i_buffer the buffer which to invert
         /// @return The address of the first element of the buffer
         ///
         static inline void* get_address(T& i_buffer)
-            { return (void*)&i_buffer; }
+        {
+            return (void*)&i_buffer;
+        }
 
         typedef B bits_type;
         typedef T unit_type;
         constexpr static uint32_t bits_per_unit(void)
-            { return sizeof(unit_type) * 8; }
-    };
-
-    //
-    //
-    /// @brief Traits for buffers which are a container of bits
-    //
-    //
-    template<>
-    class bufferTraits<bits_container, uint32_t>
-    {
+        {
+            return sizeof(unit_type) * 8;
+        }
+};
+
+//
+//
+/// @brief Traits for buffers which are a container of bits
+//
+//
+template<>
+class bufferTraits<bits_container, uint32_t>
+{
     public:
 #if !defined(DOXYGEN) && defined(FAPI2_DEBUG)
         ///
@@ -178,11 +202,11 @@ namespace fapi2
         ///
         template<typename E>
         constexpr static uint32_t size(const bits_container& i_buffer)
-            {
-                return (bit_length(i_buffer) +
-                        (parameterTraits<E>::bit_length() - 1)) /
-                    parameterTraits<E>::bit_length();
-            }
+        {
+            return (bit_length(i_buffer) +
+                    (parameterTraits<E>::bit_length() - 1)) /
+                   parameterTraits<E>::bit_length();
+        }
 
         ///
         /// @brief Return the size of the buffer itself
@@ -190,32 +214,41 @@ namespace fapi2
         /// @return The size of the buffer in bits (not units)
         ///
         static inline uint32_t bit_length(const bits_container& i_buffer)
-            { return i_buffer.size() * sizeof(container_unit) * 8; }
+        {
+            return i_buffer.size() * sizeof(container_unit) * 8;
+        }
 
         ///
         /// @brief Clear the buffer
         /// @param[in,out] io_buffer the buffer which to clear
         ///
         static inline void clear(bits_container& io_buffer)
-            { io_buffer.assign(io_buffer.size(), 0); }
+        {
+            io_buffer.assign(io_buffer.size(), 0);
+        }
 
         ///
         /// @brief Set the buffer
         /// @param[in,out] io_buffer the buffer which to set
         ///
         static inline void set(bits_container& io_buffer)
-            { io_buffer.assign(io_buffer.size(), ~0); }
+        {
+            io_buffer.assign(io_buffer.size(), ~0);
+        }
 
         ///
         /// @brief Invert the buffer
         /// @param[in,out] io_buffer the buffer which to invert
         ///
         static inline void invert(bits_container& io_buffer)
+        {
+            std::transform(io_buffer.begin(), io_buffer.end(),
+                           io_buffer.begin(),
+                           [](container_unit u)
             {
-                std::transform(io_buffer.begin(), io_buffer.end(),
-                               io_buffer.begin(),
-                               [](container_unit u) { return ~u; });
-            }
+                return ~u;
+            });
+        }
 
         ///
         /// @brief Get the address of the buffer as an array
@@ -223,16 +256,18 @@ namespace fapi2
         /// @return The address of the first element of the buffer
         ///
         static inline void* get_address(bits_container& i_buffer)
-            {
-                return (void*)&(i_buffer[0]);
-            }
+        {
+            return (void*) & (i_buffer[0]);
+        }
 
         typedef uint32_t bits_type;
         typedef container_unit unit_type;
         constexpr static uint32_t bits_per_unit(void)
-            { return sizeof(unit_type) * 8; }
-    };
-    /// @endcond
+        {
+            return sizeof(unit_type) * 8;
+        }
+};
+/// @endcond
 }