Trying to speed up STIR acquisition data algebra by avoiding unnecessary 0-fill of newly created data.

src/buildblock/ProjDataInMemory.cxx

@@ -73,14 +73,8 @@ ProjDataInMemory::ProjDataInMemory(shared_ptr<const ExamInfo> const& exam_info_s
 void
 ProjDataInMemory::create_buffer(const bool initialise_with_0)
 {
-#if 0  
-  float *b = new float[this->size_all()];
-  if (initialise_with_0)
-    memset(b, 0, this->size_all()*sizeof(float));
-  return b;
-#else
-  this->buffer = Array<1, float>(static_cast<int>(this->size_all()));
-#endif
+  // this->buffer.set_initialise_with_zeros(initialise_with_0);
+  this->buffer.grow(0, this->size_all() - 1, initialise_with_0);
 }
 
 ///////////////// /set functions

src/include/stir/Array.h

@@ -451,13 +451,13 @@ class Array<1, elemT> : public NumericVectorWithOffset<elemT, elemT>
   inline virtual void grow(const IndexRange<1>& range);
 
   // Array::grow initialises new elements to 0
-  inline void grow(const int min_index, const int max_index) override;
+  inline virtual void grow(const int min_index, const int max_index, bool initialise_with_0 = true);
 
   //! Array::resize initialises new elements to 0
   inline virtual void resize(const IndexRange<1>& range);
 
   // Array::resize initialises new elements to 0
-  inline void resize(const int min_index, const int max_index) override;
+  inline virtual void resize(const int min_index, const int max_index, bool initialise_with_0 = true);
 
   //! \name access to the data via a pointer
   //@{
@@ -569,6 +569,15 @@ class Array<1, elemT> : public NumericVectorWithOffset<elemT, elemT>
   inline const elemT& at(const BasicCoordinate<1, int>& c) const;
   //@}
 
+  void set_initialise_with_zeros(bool iwz)
+  {
+    init_with_zeros_ = iwz;
+  }
+  bool get_initialise_with_zeros() const
+  {
+    return init_with_zeros_;
+  }
+
 private:
   // Make sure we can call init() recursively.
   template <int num_dimensions2, class elemT2>
@@ -579,6 +588,8 @@ class Array<1, elemT> : public NumericVectorWithOffset<elemT, elemT>
     \arg data_ptr should start to a contiguous block of correct size
   */
   inline void init(const IndexRange<1>& range, elemT* const data_ptr, bool copy_data);
+
+  bool init_with_zeros_ = true;
 };
 
 END_NAMESPACE_STIR

src/include/stir/Array.inl

@@ -576,13 +576,21 @@ Array<1, elemT>::init(const IndexRange<1>& range, elemT* const data_ptr, bool co
 
 template <class elemT>
 void
-Array<1, elemT>::resize(const int min_index, const int max_index)
+Array<1, elemT>::resize(const int min_index, const int max_index, bool initialise_with_0)
 {
   this->check_state();
   const int oldstart = this->get_min_index();
   const size_type oldlength = this->size();
 
-  base_type::resize(min_index, max_index);
+  base_type::resize(min_index, max_index, initialise_with_0);
+
+  // if (!get_initialise_with_zeros())
+  if (!initialise_with_0)
+    {
+      this->check_state();
+      return;
+    }
+
   if (oldlength == 0)
     {
       for (int i = this->get_min_index(); i <= this->get_max_index(); i++)
@@ -607,9 +615,9 @@ Array<1, elemT>::resize(const IndexRange<1>& range)
 
 template <class elemT>
 void
-Array<1, elemT>::grow(const int min_index, const int max_index)
+Array<1, elemT>::grow(const int min_index, const int max_index, bool initialise_with_0)
 {
-  resize(min_index, max_index);
+  resize(min_index, max_index, initialise_with_0);
 }
 
 template <class elemT>

src/include/stir/VectorWithOffset.h

@@ -194,7 +194,7 @@ class VectorWithOffset
       resize() in a derived class, it is probably safest to overload
       grow() as well.
   */
-  inline virtual void grow(const int min_index, const int max_index);
+  inline virtual void grow(const int min_index, const int max_index, bool initialise_with_0 = true);
 
   //! grow the range of the vector from 0 to new_size-1, new elements are set to \c T()
   inline void grow(const unsigned int new_size);
@@ -207,7 +207,7 @@ class VectorWithOffset
       \todo in principle reallocation could be avoided when the new range would fit in the
       old one by shifting.
     */
-  inline virtual void resize(const int min_index, const int max_index);
+  inline virtual void resize(const int min_index, const int max_index, bool initialise_with_0 = true);
 
   //! change the range of the vector from 0 to new_size-1, new elements are set to \c T()
   inline void resize(const unsigned int new_size);

src/include/stir/VectorWithOffset.inl

@@ -416,7 +416,7 @@ VectorWithOffset<T>::reserve(const unsigned int new_size)
 // the new members will be initialised with the default constructor for T
 template <class T>
 void
-VectorWithOffset<T>::resize(const int min_index, const int max_index)
+VectorWithOffset<T>::resize(const int min_index, const int max_index, bool initialise_with_0)
 {
   this->check_state();
   if (min_index > max_index)
@@ -482,11 +482,11 @@ VectorWithOffset<T>::resize(const unsigned new_size)
 // the new members will be initialised with the default constructor for T
 template <class T>
 void
-VectorWithOffset<T>::grow(const int min_index, const int max_index)
+VectorWithOffset<T>::grow(const int min_index, const int max_index, bool initialise_with_0)
 {
   // allow grow arbitrary when it's zero length
   assert(length == 0 || (min_index <= this->get_min_index() && max_index >= this->get_max_index()));
-  this->resize(min_index, max_index);
+  this->resize(min_index, max_index, initialise_with_0);
 }
 
 template <class T>