// @(#)root/fft:$Id$
// Author: Anna Kreshuk   07/4/2006

/*************************************************************************
 * Copyright (C) 1995-2006, Rene Brun and Fons Rademakers.               *
 * All rights reserved.                                                  *
 *                                                                       *
 * For the licensing terms see $ROOTSYS/LICENSE.                         *
 * For the list of contributors see $ROOTSYS/README/CREDITS.             *
 *************************************************************************/

//////////////////////////////////////////////////////////////////////////
//                                                                      
// TFFTComplexReal                                                          
//                                                                      
// One of the interface classes to the FFTW package, can be used directly
// or via the TVirtualFFT class. Only the basic interface of FFTW is implemented.
//
// Computes the inverse of the real-to-complex transforms (class TFFTRealComplex)
// taking complex input (storing the non-redundant half of a logically Hermitian array)
// to real output (see FFTW manual for more details)
// 
// How to use it:
// 1) Create an instance of TFFTComplexReal - this will allocate input and output
//    arrays (unless an in-place transform is specified)
// 2) Run the Init() function with the desired flags and settings
// 3) Set the data (via SetPoints(), SetPoint() or SetPointComplex() functions)
// 4) Run the Transform() function
// 5) Get the output (via GetPoints(), GetPoint() or GetPointReal() functions)
// 6) Repeat steps 3)-5) as needed
//
// For a transform of the same size, but with different flags, rerun the Init()
// function and continue with steps 3)-5)
// NOTE: 1) running Init() function will overwrite the input array! Don't set any data
//          before running the Init() function
//       2) FFTW computes unnormalized transform, so doing a transform followed by 
//          its inverse will lead to the original array scaled by the transform size
//
//       3) In Complex to Real transform the input array is destroyed. It cannot then 
//          be retrieved when using the Get's methods. 
//                                                                      
//////////////////////////////////////////////////////////////////////////

#include "TFFTComplexReal.h"
#include "fftw3.h"
#include "TComplex.h"


ClassImp(TFFTComplexReal)

//_____________________________________________________________________________
TFFTComplexReal::TFFTComplexReal()
{
//default

   fIn   = 0;
   fOut  = 0;
   fPlan = 0;
   fN    = 0;
   fTotalSize = 0;
   fFlags = 0;
   fNdim = 0; 
}

//_____________________________________________________________________________
TFFTComplexReal::TFFTComplexReal(Int_t n, Bool_t inPlace)
{
//For 1d transforms
//Allocates memory for the input array, and, if inPlace = kFALSE, for the output array

   if (!inPlace){
      fIn = fftw_malloc(sizeof(fftw_complex)*(n/2+1));
      fOut = fftw_malloc(sizeof(Double_t)*n);

   } else {
      fIn = fftw_malloc(sizeof(fftw_complex)*(n/2+1));
      fOut = 0;
   }
   fNdim = 1;
   fN = new Int_t[1];
   fN[0] = n;
   fPlan = 0;
   fTotalSize = n;
   fFlags = 0;
}

//_____________________________________________________________________________
TFFTComplexReal::TFFTComplexReal(Int_t ndim, Int_t *n, Bool_t inPlace)
{
//For ndim-dimensional transforms
//Second argurment contains sizes of the transform in each dimension

   fNdim = ndim;
   fTotalSize = 1;
   fN = new Int_t[fNdim];
   for (Int_t i=0; i<fNdim; i++){
      fN[i] = n[i];
      fTotalSize*=n[i];
   }
   Int_t sizein = Int_t(Double_t(fTotalSize)*(n[ndim-1]/2+1)/n[ndim-1]);
   if (!inPlace){
      fIn = fftw_malloc(sizeof(fftw_complex)*sizein);
      fOut = fftw_malloc(sizeof(Double_t)*fTotalSize);
   } else {
      fIn = fftw_malloc(sizeof(fftw_complex)*sizein);
      fOut = 0;
   }
   fPlan = 0;
   fFlags = 0;
}


//_____________________________________________________________________________
TFFTComplexReal::~TFFTComplexReal()
{
//Destroys the data arrays and the plan. However, some plan information stays around
//until the root session is over, and is reused if other plans of the same size are
//created

   fftw_destroy_plan((fftw_plan)fPlan);
   fPlan = 0;
   fftw_free((fftw_complex*)fIn);
   if (fOut)
      fftw_free(fOut);
   fIn = 0;
   fOut = 0;
   if (fN)
      delete [] fN;
   fN = 0;
}

//_____________________________________________________________________________
void TFFTComplexReal::Init( Option_t *flags, Int_t /*sign*/,const Int_t* /*kind*/)
{
//Creates the fftw-plan
//
//NOTE:  input and output arrays are overwritten during initialisation,
//       so don't set any points, before running this function!!!!!
//
//Arguments sign and kind are dummy and not need to be specified
//Possible flag_options:
//"ES" (from "estimate") - no time in preparing the transform, but probably sub-optimal
//   performanc
//"M" (from "measure") - some time spend in finding the optimal way to do the transform
//"P" (from "patient") - more time spend in finding the optimal way to do the transform
//"EX" (from "exhaustive") - the most optimal way is found
//This option should be chosen depending on how many transforms of the same size and
//type are going to be done. Planning is only done once, for the first transform of this
//size and type.

   fFlags = flags;

   if (fOut)
      fPlan = (void*)fftw_plan_dft_c2r(fNdim, fN,(fftw_complex*)fIn,(Double_t*)fOut, MapFlag(flags));
   else
      fPlan = (void*)fftw_plan_dft_c2r(fNdim, fN, (fftw_complex*)fIn, (Double_t*)fIn, MapFlag(flags));
}

//_____________________________________________________________________________
void TFFTComplexReal::Transform()
{
//Computes the transform, specified in Init() function

   if (fPlan)
      fftw_execute((fftw_plan)fPlan);
   else {
      Error("Transform", "transform was not initialized");
      return;
   }
}

//_____________________________________________________________________________
void TFFTComplexReal::GetPoints(Double_t *data, Bool_t fromInput) const
{
//Fills the argument array with the computed transform
// Works only for output (input array is destroyed in a C2R transform)

   if (fromInput){
      Error("GetPoints", "Input array has been destroyed");
      return;
   }
   const Double_t * array =  (const Double_t*) ( (fOut) ?  fOut :  fIn );  
   std::copy(array,array+fTotalSize, data);
}

//_____________________________________________________________________________
Double_t TFFTComplexReal::GetPointReal(Int_t ipoint, Bool_t fromInput) const
{
//Returns the point #ipoint
// Works only for output (input array is destroyed in a C2R transform)

   if (fromInput){
      Error("GetPointReal", "Input array has been destroyed");
      return 0;
   }
   const Double_t * array =  (const Double_t*) ( (fOut) ?  fOut :  fIn );  
   return array[ipoint];
}

//_____________________________________________________________________________
Double_t TFFTComplexReal::GetPointReal(const Int_t *ipoint, Bool_t fromInput) const
{
//For multidimensional transforms. Returns the point #ipoint
// Works only for output (input array is destroyed in a C2R transform)

   if (fromInput){
      Error("GetPointReal", "Input array has been destroyed");
      return 0;
   }
   Int_t ireal = ipoint[0];
   for (Int_t i=0; i<fNdim-1; i++)
      ireal=fN[i+1]*ireal + ipoint[i+1];

   const Double_t * array =  (const Double_t*) ( (fOut) ?  fOut :  fIn );  
   return array[ireal];
}


//_____________________________________________________________________________
void TFFTComplexReal::GetPointComplex(Int_t ipoint, Double_t &re, Double_t &im, Bool_t fromInput) const
{
// Works only for output (input array is destroyed in a C2R transform)

   if (fromInput){
      Error("GetPointComplex", "Input array has been destroyed");
      return;
   }
   const Double_t * array =  (const Double_t*) ( (fOut) ?  fOut :  fIn );  
   re = array[ipoint];
   im = 0;         
}

//_____________________________________________________________________________
void TFFTComplexReal::GetPointComplex(const Int_t *ipoint, Double_t &re, Double_t &im, Bool_t fromInput) const
{
//For multidimensional transforms. Returns the point #ipoint
// Works only for output (input array is destroyed in a C2R transform)

   if (fromInput){
      Error("GetPointComplex", "Input array has been destroyed");
      return;
   }
   const Double_t * array =  (const Double_t*) ( (fOut) ?  fOut :  fIn );  

   Int_t ireal = ipoint[0];
   for (Int_t i=0; i<fNdim-1; i++)
      ireal=fN[i+1]*ireal + ipoint[i+1];

   re = array[ireal];
   im = 0;
}
//_____________________________________________________________________________
Double_t* TFFTComplexReal::GetPointsReal(Bool_t fromInput) const
{
//Returns the array of computed transform
// Works only for output (input array is destroyed in a C2R transform)
   
   // we have 2 different cases
   // fromInput = false; fOut = !NULL (transformed is not in place) : return fOut 
   // fromInput = false; fOut = NULL (transformed is in place) : return fIn

   if (fromInput) { 
      Error("GetPointsReal","Input array was destroyed"); 
      return 0; 
   }
   return  (Double_t*) ( (fOut) ?  fOut :  fIn );  
}

//_____________________________________________________________________________
void TFFTComplexReal::GetPointsComplex(Double_t *re, Double_t *im, Bool_t fromInput) const
{
//Fills the argument array with the computed transform
// Works only for output (input array is destroyed in a C2R transform)

   if (fromInput){
      Error("GetPointsComplex", "Input array has been destroyed");
      return;
   }
   const Double_t * array =  (const Double_t*) ( (fOut) ?  fOut :  fIn );  
   for (Int_t i=0; i<fTotalSize; i++){
      re[i] = array[i];
      im[i] = 0;
   }
}

//_____________________________________________________________________________
void TFFTComplexReal::GetPointsComplex(Double_t *data, Bool_t fromInput) const
{
//Fills the argument array with the computed transform. 
// Works only for output (input array is destroyed in a C2R transform)

   if (fromInput){
      Error("GetPointsComplex", "Input array has been destroyed");
      return;
   }
   const Double_t * array =  (const Double_t*) ( (fOut) ?  fOut :  fIn );  
   for (Int_t i=0; i<fTotalSize; i+=2){
      data[i] = array[i/2];
      data[i+1]=0;
   }
}

//_____________________________________________________________________________
void TFFTComplexReal::SetPoint(Int_t ipoint, Double_t re, Double_t im)
{
//since the input must be complex-Hermitian, if the ipoint > n/2, the according
//point before n/2 is set to (re, -im)

   if (ipoint <= fN[0]/2){
      ((fftw_complex*)fIn)[ipoint][0] = re;
      ((fftw_complex*)fIn)[ipoint][1] = im;
   } else {
      ((fftw_complex*)fOut)[2*(fN[0]/2)-ipoint][0] = re;
      ((fftw_complex*)fOut)[2*(fN[0]/2)-ipoint][1] = -im;
   }
}

//_____________________________________________________________________________
void TFFTComplexReal::SetPoint(const Int_t *ipoint, Double_t re, Double_t im)
{
//Set the point #ipoint. Since the input is Hermitian, only the first (roughly)half of
//the points have to be set.

   Int_t ireal = ipoint[0];
   for (Int_t i=0; i<fNdim-2; i++){
      ireal=fN[i+1]*ireal + ipoint[i+1];
   } 
   ireal = (fN[fNdim-1]/2+1)*ireal+ipoint[fNdim-1];
   Int_t realN = Int_t(Double_t(fTotalSize)*(fN[fNdim-1]/2+1)/fN[fNdim-1]);

   if (ireal > realN){
      Error("SetPoint", "Illegal index value");
      return;
   }
   ((fftw_complex*)fIn)[ireal][0] = re;
   ((fftw_complex*)fIn)[ireal][1] = im;
}

//_____________________________________________________________________________
void TFFTComplexReal::SetPointComplex(Int_t ipoint, TComplex &c)
{
//since the input must be complex-Hermitian, if the ipoint > n/2, the according
//point before n/2 is set to (re, -im)

   if (ipoint <= fN[0]/2){
      ((fftw_complex*)fIn)[ipoint][0] = c.Re();
      ((fftw_complex*)fIn)[ipoint][1] = c.Im();
   } else {
      ((fftw_complex*)fIn)[2*(fN[0]/2)-ipoint][0] = c.Re();
      ((fftw_complex*)fIn)[2*(fN[0]/2)-ipoint][1] = -c.Im();
   }
}

//_____________________________________________________________________________
void TFFTComplexReal::SetPoints(const Double_t *data)
{
//set all points. the values are copied. points should be ordered as follows:
//[re_0, im_0, re_1, im_1, ..., re_n, im_n)

   Int_t sizein = Int_t(Double_t(fTotalSize)*(fN[fNdim-1]/2+1)/fN[fNdim-1]);

   for (Int_t i=0; i<2*(sizein); i+=2){
      ((fftw_complex*)fIn)[i/2][0]=data[i];
      ((fftw_complex*)fIn)[i/2][1]=data[i+1];
   }
}

//_____________________________________________________________________________
void TFFTComplexReal::SetPointsComplex(const Double_t *re, const Double_t *im)
{
//Set all points. The values are copied.

   Int_t sizein = Int_t(Double_t(fTotalSize)*(fN[fNdim-1]/2+1)/fN[fNdim-1]);
   for (Int_t i=0; i<sizein; i++){
      ((fftw_complex*)fIn)[i][0]=re[i];
      ((fftw_complex*)fIn)[i][1]=im[i];
   }
}

//_____________________________________________________________________________
UInt_t TFFTComplexReal::MapFlag(Option_t *flag)
{
//allowed options:
//"ES" - FFTW_ESTIMATE
//"M" - FFTW_MEASURE
//"P" - FFTW_PATIENT
//"EX" - FFTW_EXHAUSTIVE

   TString opt = flag;
   opt.ToUpper();
   if (opt.Contains("ES"))
      return FFTW_ESTIMATE;
   if (opt.Contains("M"))
      return FFTW_MEASURE;
   if (opt.Contains("P"))
      return FFTW_PATIENT;
   if (opt.Contains("EX"))
      return FFTW_EXHAUSTIVE;
   return FFTW_ESTIMATE;
}