Fix: do not transpose data in Tensor if current or new format is Default

include/aidge/data/Tensor.hpp

@@ -431,7 +431,7 @@ public:
      * @brief Get the data format enum.
      * @return constexpr DataFormat
      */
-    constexpr DataFormat dataFormat() const noexcept { return mDataFormat; }
+    const DataFormat& dataFormat() const noexcept { return mDataFormat; }
 
     /**
      * @brief Set the DataType of the Tensor and converts data
@@ -462,13 +462,13 @@ public:
      *                  data is copy-transposed.
      */
     void setDataFormat(const DataFormat df, bool copyTrans = true) {
-        if (!copyTrans || df == dataFormat()) {
+        if (!copyTrans || df == dataFormat() || df == DataFormat::Default || dataFormat() == DataFormat::Default) {
             mDataFormat = df;
             return;
         }
-    
-        const auto transpose = getDataFormatTranspose(dataFormat(), df);
-        
+
+        const auto transpose = getPermutationMapping(dataFormat(), df);
+
         if (mImpl) {
             copyTranspose(*this, transpose);
         } else {
@@ -476,7 +476,7 @@ public:
             for (std::size_t i = 0; i < dims().size(); ++i) {
                 newDims.push_back(dims()[transpose[i]]);
             }
-    
+
             std::vector<std::size_t> newStrides(dims().size(), 1);
             for (size_t i = 0; i < dims().size(); ++i) {
                 for (size_t j = i + 1; j < dims().size(); ++j) {
@@ -486,9 +486,10 @@ public:
             mDims = std::move(newDims);
             mStrides = std::move(newStrides);
         }
-    
+
         mDataFormat = df;
     }
+
     /**
      * @brief Get the Impl object
      * @return constexpr const std::shared_ptr<TensorImpl>&