/**************************************************************************
 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
 *                                                                        *
 * Author: The ALICE Off-line Project.                                    *
 * Contributors are mentioned in the code where appropriate.              *
 *                                                                        *
 * Permission to use, copy, modify and distribute this software and its   *
 * documentation strictly for non-commercial purposes is hereby granted   *
 * without fee, provided that the above copyright notice appears in all   *
 * copies and that both the copyright notice and this permission notice   *
 * appear in the supporting documentation. The authors make no claims     *
 * about the suitability of this software for any purpose. It is          *
 * provided "as is" without express or implied warranty.                  *
 **************************************************************************/

/* $Id$ */

#include <Riostream.h>
#include <TRandom.h>
#include <TH1.h>
#include <TMath.h>
#include <TString.h>
#include <TParticle.h>

#include "AliRun.h"
#include "AliITS.h"
#include "AliITShit.h"
#include "AliITSdigit.h"
#include "AliITSmodule.h"
#include "AliITSMapA2.h"
#include "AliITSpList.h"
#include "AliITSsimulationSPD.h"
#include "AliITSsegmentation.h"
#include "AliITSresponse.h"
#include "AliITSsegmentationSPD.h"
#include "AliITSresponseSPD.h"

//#define DEBUG

ClassImp(AliITSsimulationSPD)
////////////////////////////////////////////////////////////////////////
// Version: 0
// Written by Rocco Caliandro
// from a model developed with T. Virgili and R.A. Fini
// June 15 2000
//
// AliITSsimulationSPD is the simulation of SPDs
//
//______________________________________________________________________
AliITSsimulationSPD::AliITSsimulationSPD(){
    // Default constructor

    fResponse     = 0;
    fSegmentation = 0;
    fHis          = 0;
    fMapA2        = 0;

/*
    fThresh       = 0.;
    fSigma        = 0.;
    fCouplCol     = 0.;
    fCouplRow     = 0.; */
}
//______________________________________________________________________
AliITSsimulationSPD::AliITSsimulationSPD(AliITSsegmentation *seg,
					 AliITSresponse *resp) {
    // Standard constructor

    fResponse     = 0;
    fSegmentation = 0;
    fHis          = 0;
    fMapA2        = 0;
    SetDebug(kFALSE);

/*
    fThresh       = 0.;
    fSigma        = 0.;
    fCouplCol     = 0.;
    fCouplRow     = 0.*/
    Init((AliITSsegmentationSPD*)seg,(AliITSresponseSPD*)resp);
}
//______________________________________________________________________
void AliITSsimulationSPD::Init(AliITSsegmentationSPD *seg,
			       AliITSresponseSPD *resp) {
    // Initilizes the variables of AliITSsimulation SPD.

    fHis = 0;
    fResponse     = resp;
    fSegmentation = seg;
    fMapA2  = new AliITSMapA2(fSegmentation);
    fpList  = new AliITSpList(GetNPixelsZ()+1,GetNPixelsX()+1);
/*
    fResponse->Thresholds(fThresh,fSigma);
    fResponse->GetNoiseParam(fCouplCol,fCouplRow);
    fNPixelsZ = fSegmentation->Npz();
    fNPixelsX = fSegmentation->Npx();
*/
}
//______________________________________________________________________
AliITSsimulationSPD::~AliITSsimulationSPD() { 
    // destructor

    delete fMapA2;
//    delete fpList;

    if (fHis) {
	fHis->Delete(); 
	delete fHis;     
    } // end if
}
//______________________________________________________________________
AliITSsimulationSPD::AliITSsimulationSPD(const AliITSsimulationSPD &source) :
    AliITSsimulation(source){
    // Copy Constructor

    if(&source == this) return;

    this->fMapA2    = source.fMapA2;
    this->fHis      = source.fHis;
/*
    this->fThresh   = source.fThresh;
    this->fSigma    = source.fSigma;
    this->fCouplCol = source.fCouplCol;
    this->fCouplRow = source.fCouplRow;
    this->fNPixelsX = source.fNPixelsX;
    this->fNPixelsZ = source.fNPixelsZ;
*/
    return;
}
//______________________________________________________________________
AliITSsimulationSPD& AliITSsimulationSPD::operator=(const AliITSsimulationSPD 
						    &source) {
    //    Assignment operator

    if(&source == this) return *this;

    this->fMapA2    = source.fMapA2;
    this->fHis      = source.fHis;
/*
    this->fThresh   = source.fThresh;
    this->fSigma    = source.fSigma;
    this->fCouplCol = source.fCouplCol;
    this->fCouplRow = source.fCouplRow;
    this->fNPixelsX = source.fNPixelsX;
    this->fNPixelsZ = source.fNPixelsZ;
*/
    return *this;
} 
//______________________________________________________________________
void AliITSsimulationSPD::InitSimulationModule(Int_t module,Int_t event){
    // Creates maps to build the list of tracks for each sumable digit
    // Inputs:
    //   Int_t module    // Module number to be simulated
    //   Int_t event     // Event number to be simulated
    // Outputs:
    //   none.
    // Return
    //    none.
 
    fModule = module;
    fEvent  = event;
    fMapA2->ClearMap();
    fpList->ClearMap();
}
//______________________________________________________________________
void AliITSsimulationSPD::FinishSDigitiseModule(){
    // Does the Sdigits to Digits work
    // Inputs:
    //   none.
    // Outputs:
    //   none.
    // Return:
    //   none.

    SDigitsToDigits(fModule,fpList);
}
//______________________________________________________________________
void AliITSsimulationSPD::SDigitiseModule(AliITSmodule *mod, Int_t dummy0,
                                             Int_t dummy1) {
    // Sum digitize module
    if (!(mod->GetNhits())) return; // if module has no hits then no Sdigits.
    Int_t    number     = 10000;
    Int_t    *frowpixel = new Int_t[number];
    Int_t    *fcolpixel = new Int_t[number];
    Double_t *fenepixel = new Double_t[number];

    dummy0 = dummy1; // remove unsued variable warning.
    fModule = mod->GetIndex();

    // Array of pointers to store the track index of the digits
    // leave +1, otherwise pList crashes when col=256, row=192

    HitsToAnalogDigits(mod,frowpixel,fcolpixel,fenepixel,fpList);

    WriteSDigits(fpList);

    // clean memory
    delete[] frowpixel;
    delete[] fcolpixel;
    delete[] fenepixel;
    fMapA2->ClearMap();
    fpList->ClearMap();
}
//______________________________________________________________________
void AliITSsimulationSPD::DigitiseModule(AliITSmodule *mod, Int_t dummy0,
                                             Int_t dummy1) {
    // digitize module. Also need to digitize modules with only noise.

    Int_t    number     = 10000;
    Int_t    *frowpixel = new Int_t[number];
    Int_t    *fcolpixel = new Int_t[number];
    Double_t *fenepixel = new Double_t[number];

    dummy0 = dummy1; // remove unsued variable warning.
    // Array of pointers to store the track index of the digits
    // leave +1, otherwise pList crashes when col=256, row=192
    fModule = mod->GetIndex();
    // noise setting
    SetFluctuations(fpList,fModule);

    HitsToAnalogDigits(mod,frowpixel,fcolpixel,fenepixel,fpList);

    // apply mask to SPD module
    SetMask();

    CreateDigit(fModule,fpList);

    // clean memory
    delete[] frowpixel;
    delete[] fcolpixel;
    delete[] fenepixel;
    fMapA2->ClearMap();
    fpList->ClearMap();
}
//______________________________________________________________________
void AliITSsimulationSPD::SDigitsToDigits(Int_t module,AliITSpList *pList) {
    // sum digits to Digits.

#ifdef DEBUG
    cout << "Entering AliITSsimulatinSPD::SDigitsToDigits for module=";
    cout << module << endl;
#endif
    fModule = module;

    // noise setting
    SetFluctuations(pList,module);

    fMapA2->ClearMap(); // since noise is in pList aready. Zero Map so that
    // noise is not doubled when calling FillMapFrompList.

    FillMapFrompList(pList);

    // apply mask to SPD module
    SetMask();

    CreateDigit(module,pList);

    fMapA2->ClearMap();
    pList->ClearMap();
}
//______________________________________________________________________
void AliITSsimulationSPD::UpdateMapSignal(Int_t row,Int_t col,Int_t trk,
					  Int_t hit,Int_t mod,Double_t ene,
					  AliITSpList *pList) {
    // updates the Map of signal, adding the energy  (ene) released by
    // the current track

    fMapA2->AddSignal(row,col,ene);
    pList->AddSignal(row,col,trk,hit,mod,ene);
}
//______________________________________________________________________
void AliITSsimulationSPD::UpdateMapNoise(Int_t row,Int_t col,Int_t mod,
					 Double_t ene,AliITSpList *pList) {
    // updates the Map of noise, adding the energy  (ene) give my noise

    fMapA2->AddSignal(row,col,ene);
    pList->AddNoise(row,col,mod,ene);
}
//______________________________________________________________________
void AliITSsimulationSPD::HitsToAnalogDigits(AliITSmodule *mod,
					     Int_t *frowpixel,Int_t *fcolpixel,
					     Double_t *fenepixel,
					     AliITSpList *pList) {
    // Loops over all hits to produce Analog/floting point digits. This
    // is also the first task in producing standard digits.
    
    // loop over hits in the module
    Int_t hitpos,nhits = mod->GetNhits();
    for (hitpos=0;hitpos<nhits;hitpos++) {
	HitToDigit(mod,hitpos,frowpixel,fcolpixel,fenepixel,pList);
    }// end loop over digits
}
//______________________________________________________________________
void AliITSsimulationSPD::HitToDigit(AliITSmodule *mod,Int_t hitpos,
				     Int_t *frowpixel,Int_t *fcolpixel,
				     Double_t *fenepixel,AliITSpList *pList) {
    //  Steering function to determine the digits associated to a given
    // hit (hitpos)
    // The digits are created by charge sharing (ChargeSharing) and by
    // capacitive coupling (SetCoupling). At all the created digits is
    // associated the track number of the hit (ntrack)
    Double_t x1l=0.0,y1l=0.0,z1l=0.0,x2l=0.0,y2l=0.0,z2l=0.0;
    Int_t r1,r2,c1,c2,row,col,npixel = 0;
    Int_t ntrack;
    Double_t ene=0.0,etot=0.0;
    const Float_t kconv = 10000.;     // cm -> microns
    const Float_t kconv1= 0.277e9;    // GeV -> electrons equivalent

    if(!(mod->LineSegmentL(hitpos,x1l,x2l,y1l,y2l,z1l,z2l,etot,ntrack)))return;

    x2l += x1l; y2l += y1l; z2l += z1l; // Convert to ending coordinate.
    // positions shifted and converted in microns
    x1l   = x1l*kconv + fSegmentation->Dx()/2.;
    z1l   = z1l*kconv + fSegmentation->Dz()/2.;
    // positions  shifted and converted in microns
    x2l   = x2l*kconv + fSegmentation->Dx()/2.;
    z2l   = z2l*kconv + fSegmentation->Dz()/2.;
    etot *= kconv1; // convert from GeV to electrons equivalent.
    Int_t module = mod->GetIndex();

    // to account for the effective sensitive area
    // introduced in geometry 
    if (z1l<0 || z1l>fSegmentation->Dz()) return;
    if (z2l<0 || z2l>fSegmentation->Dz()) return;
    if (x1l<0 || x1l>fSegmentation->Dx()) return;
    if (x2l<0 || x2l>fSegmentation->Dx()) return;

    //Get the col and row number starting from 1
    // the x direction is not inverted for the second layer!!!
    fSegmentation->GetPadIxz(x1l, z1l, c1, r1); 
    fSegmentation->GetPadIxz(x2l, z2l, c2, r2);

    // to account for unexpected equal entrance and 
    // exit coordinates
    if (x1l==x2l) x2l=x2l+x2l*0.1;
    if (z1l==z2l) z2l=z2l+z2l*0.1;

    if ((r1==r2) && (c1==c2)){
	// no charge sharing
	npixel = 1;		 
	frowpixel[npixel-1] = r1;
	fcolpixel[npixel-1] = c1;
	fenepixel[npixel-1] = etot;
    } else {
	// charge sharing
	ChargeSharing(x1l,z1l,x2l,z2l,c1,r1,c2,r2,etot,
		      npixel,frowpixel,fcolpixel,fenepixel);
    } // end if r1==r2 && c1==c2.

    for (Int_t npix=0;npix<npixel;npix++){
	row = frowpixel[npix];
	col = fcolpixel[npix];
	ene = fenepixel[npix];
	UpdateMapSignal(row,col,ntrack,hitpos,module,ene,pList); 
	// Starting capacitive coupling effect
	SetCoupling(row,col,ntrack,hitpos,module,pList); 
    } // end for npix
}
//______________________________________________________________________
void AliITSsimulationSPD::ChargeSharing(Float_t x1l,Float_t z1l,Float_t x2l,
					Float_t z2l,Int_t c1,Int_t r1,Int_t c2,
					Int_t r2,Float_t etot,
					Int_t &npixel,Int_t *frowpixel,
					Int_t *fcolpixel,Double_t *fenepixel){
    //  Take into account the geometrical charge sharing when the track
    //  crosses more than one pixel.
    //
    //Begin_Html
    /*
      <img src="picts/ITS/barimodel_2.gif">
      </pre>
      <br clear=left>
      <font size=+2 color=red>
      <a href="mailto:Rocco.Caliandro@ba.infn.it"></a>.
      </font>
      <pre>
    */
    //End_Html
    //Float_t dm;
    Float_t xa,za,xb,zb,dx,dz,dtot,refr,refm,refc;
    Float_t refn=0.;
    Float_t arefm, arefr, arefn, arefc, azb, az2l, axb, ax2l;
    Int_t   dirx,dirz,rb,cb;
    Int_t flag,flagrow,flagcol;
    Double_t epar;

    npixel = 0;
    xa     = x1l;
    za     = z1l;
//    dx     = x1l-x2l;
//    dz     = z1l-z2l;
    dx     = x2l-x1l;
    dz     = z2l-z1l;
    dtot   = TMath::Sqrt((dx*dx)+(dz*dz));   
    if (dtot==0.0) dtot = 0.01;
    dirx   = (Int_t) TMath::Sign((Float_t)1,dx);
    dirz   = (Int_t) TMath::Sign((Float_t)1,dz);

    // calculate the x coordinate of  the pixel in the next column    
    // and the z coordinate of  the pixel in the next row
    Float_t xpos, zpos;

    fSegmentation->GetPadCxz(c1, r1-1, xpos, zpos); 

    Float_t xsize = fSegmentation->Dpx(0);
    Float_t zsize = fSegmentation->Dpz(r1-1);
    
    if (dirx == 1) refr = xpos+xsize/2.;
    else refr = xpos-xsize/2.;

    if (dirz == 1) refn = zpos+zsize/2.;
    else refn = zpos-zsize/2.;

    flag = 0;
    flagrow = 0;
    flagcol = 0;
    do{
	// calculate the x coordinate of the intersection with the pixel
	// in the next cell in row  direction
      if(dz!=0)
        refm = dx*((refn - z1l)/dz) + x1l;
      else
        refm = refr+dirx*xsize;
   
	// calculate the z coordinate of the intersection with the pixel
	// in the next cell in column direction
      if (dx!=0)
        refc = dz*((refr - x1l)/dx) + z1l;
      else
        refc = refn+dirz*zsize;

	arefm = refm * dirx;
	arefr = refr * dirx;
	arefn = refn * dirz;
	arefc = refc * dirz;

	if ((arefm < arefr) && (arefn < arefc)){
	    // the track goes in the pixel in the next cell in row direction
	    xb = refm;
	    zb = refn;
	    cb = c1;
	    rb = r1 + dirz;
	    azb = zb * dirz;
	    az2l = z2l * dirz;
	    if (rb == r2) flagrow=1;
	    if (azb > az2l) {
	        zb = z2l;
	        xb = x2l;
	    } // end if
	    // shift to the pixel in the next cell in row direction
	    Float_t zsizeNext = fSegmentation->Dpz(rb-1);
	    //to account for cell at the borders of the detector
	    if(zsizeNext==0) zsizeNext = zsize;
	    refn += zsizeNext*dirz;
	}else {
	    // the track goes in the pixel in the next cell in column direction
	    xb = refr;
	    zb = refc;
	    cb = c1 + dirx;
	    rb = r1;
	    axb = xb * dirx;
	    ax2l = x2l * dirx;
	    if (cb == c2) flagcol=1;
	    if (axb > ax2l) {
	        zb = z2l;
	        xb = x2l;
	    } // end ifaxb > ax2l

	    // shift to the pixel in the next cell in column direction
	    Float_t xsizeNext = fSegmentation->Dpx(cb-1);
	    //to account for cell at the borders of the detector
	    if(xsizeNext==0) xsizeNext = xsize;
	    refr += xsizeNext*dirx;
	} // end if (arefm < arefr) && (arefn < arefc)

	//calculate the energy lost in the crossed pixel      
	epar = TMath::Sqrt((xb-xa)*(xb-xa)+(zb-za)*(zb-za)); 
	epar = etot*(epar/dtot);

	//store row, column and energy lost in the crossed pixel
	frowpixel[npixel] = r1;
	fcolpixel[npixel] = c1;
	fenepixel[npixel] = epar;
	npixel++;
 
	// the exit point of the track is reached
	if (epar == 0) flag = 1;
	if ((r1 == r2) && (c1 == c2)) flag = 1;
	if (flag!=1) {
	    r1 = rb;
	    c1 = cb;
	    xa = xb;
	    za = zb;
	} // end if flag!=1
    } while (flag==0);
}
//______________________________________________________________________
void AliITSsimulationSPD::SetCoupling(Int_t row, Int_t col, Int_t ntrack,
				      Int_t idhit,Int_t module,
				      AliITSpList *pList) {
    //  Take into account the coupling between adiacent pixels.
    //  The parameters probcol and probrow are the probability of the
    //  signal in one pixel shared in the two adjacent pixels along
    //  the column and row direction, respectively.
    //
    //Begin_Html
    /*
      <img src="picts/ITS/barimodel_3.gif">
      </pre>
      <br clear=left>
      <font size=+2 color=red>
      <a href="mailto:tiziano.virgili@cern.ch"></a>.
      </font>
      <pre>
    */
    //End_Html
    Int_t j1,j2,flag=0;
    Double_t pulse1,pulse2;
    Float_t couplR=0.0,couplC=0.0;
    Double_t xr=0.;

    GetCouplings(couplR,couplC);
    j1 = row;
    j2 = col;
    pulse1 = fMapA2->GetSignal(row,col);
    pulse2 = pulse1;
    for (Int_t isign=-1;isign<=1;isign+=2){// loop in row direction
	do{
	    j1 += isign;
	    //   pulse1 *= couplR; 
          xr = gRandom->Rndm();
	  //   if ((j1<0) || (j1>GetNPixelsZ()-1) || (pulse1<GetThreshold())){
	    if ((j1<0) || (j1>GetNPixelsZ()-1) || (xr>couplR)){
		j1 = row;
	       	flag = 1;
	    }else{
		UpdateMapSignal(j1,col,ntrack,idhit,module,pulse1,pList);
	      //  flag = 0;
	      flag = 1; // only first next!!
	    } // end if
	} while(flag == 0);
	// loop in column direction
      do{
	  j2 += isign;
	  // pulse2 *= couplC; 
          xr = gRandom->Rndm();
	  //  if ((j2<0) || (j2>(GetNPixelsX()-1)) || (pulse2<GetThreshold())){
	    if ((j2<0) || (j2>GetNPixelsX()-1) || (xr>couplC)){
	      j2 = col;
	      flag = 1;
	  }else{
	      UpdateMapSignal(row,j2,ntrack,idhit,module,pulse2,pList);
	      //  flag = 0;
	      flag = 1; // only first next!!
	  } // end if
      } while(flag == 0);
    } // for isign
}
//______________________________________________________________________
void AliITSsimulationSPD::SetCouplingOld(Int_t row, Int_t col, Int_t ntrack,
					 Int_t idhit,Int_t module,
					 AliITSpList *pList) {
    //  Take into account the coupling between adiacent pixels.
    //  The parameters probcol and probrow are the fractions of the
    //  signal in one pixel shared in the two adjacent pixels along
    //  the column and row direction, respectively.
    //
    //Begin_Html
    /*
      <img src="picts/ITS/barimodel_3.gif">
      </pre>
      <br clear=left>
      <font size=+2 color=red>
      <a href="mailto:Rocco.Caliandro@ba.infn.it"></a>.
      </font>
      <pre>
    */
    //End_Html
    Int_t j1,j2,flag=0;
    Double_t pulse1,pulse2;
    Float_t couplR=0.0,couplC=0.0;

    GetCouplings(couplR,couplC);
    j1 = row;
    j2 = col;
    pulse1 = fMapA2->GetSignal(row,col);
    pulse2 = pulse1;
    for (Int_t isign=-1;isign<=1;isign+=2){// loop in row direction
	do{
	    j1 += isign;
	    pulse1 *= couplR;
	    if ((j1<0) || (j1>GetNPixelsZ()-1) || (pulse1<GetThreshold())){
		pulse1 = fMapA2->GetSignal(row,col);
		j1 = row;
		flag = 1;
	    }else{
		UpdateMapSignal(j1,col,ntrack,idhit,module,pulse1,pList);
		flag = 0;
	    } // end if
	} while(flag == 0);
	// loop in column direction
      do{
	  j2 += isign;
	  pulse2 *= couplC;
	  if ((j2<0) || (j2>(GetNPixelsX()-1)) || (pulse2<GetThreshold())){
	      pulse2 = fMapA2->GetSignal(row,col);
	      j2 = col;
	      flag = 1;
	  }else{
	      UpdateMapSignal(row,j2,ntrack,idhit,module,pulse2,pList);
	      flag = 0;
	  } // end if
      } while(flag == 0);
    } // for isign
}
//______________________________________________________________________
void AliITSsimulationSPD::CreateDigit(Int_t module,AliITSpList *pList) {
    // The pixels are fired if the energy deposited inside them is above
    // the threshold parameter ethr. Fired pixed are interpreted as digits
    // and stored in the file digitfilename. One also needs to write out
    // cases when there is only noise (nhits==0).

    static AliITS *aliITS  = (AliITS*)gAlice->GetModule("ITS");

    Int_t size = AliITSdigitSPD::GetNTracks();
    Int_t * digits = new Int_t[size];
    Int_t * tracks = new Int_t[size];
    Int_t * hits = new Int_t[size];
    Float_t * charges = new Float_t[size]; 
    Int_t j1;

    module=0; // remove unused variable warning.
    for(j1=0;j1<size;j1++){tracks[j1]=-3;hits[j1]=-1;charges[j1]=0.0;}
    for (Int_t r=1;r<=GetNPixelsZ();r++) {
	for (Int_t c=1;c<=GetNPixelsX();c++) {
	    // check if the deposited energy in a pixel is above the
	    // threshold 
	    Float_t signal = (Float_t) fMapA2->GetSignal(r,c);
	    if ( signal > GetThreshold()) {
		digits[0] = r-1;  // digits starts from 0
		digits[1] = c-1;  // digits starts from 0
		//digits[2] = 1;  
		digits[2] =  (Int_t) signal;  // the signal is stored in
                                              //  electrons
		for(j1=0;j1<size;j1++){
		    if(j1<pList->GetNEnteries()){
			tracks[j1] = pList->GetTrack(r,c,j1);
			hits[j1]   = pList->GetHit(r,c,j1);
			//}else{
			//tracks[j1] = -3;
			//hits[j1]   = -1;
		    } // end if
		    //charges[j1] = 0;
		} // end for j1
		Float_t phys = 0;
		aliITS->AddSimDigit(0,phys,digits,tracks,hits,charges);
#ifdef DEBUG
		cout << " CreateSPDDigit mod=" << fModule << " r,c=" << r;
		cout <<","<<c<< " sig=" << fpList->GetSignalOnly(r,c);
		cout << " noise=" << fpList->GetNoise(r,c);
		cout << " Msig="<< signal << " Thres=" << GetThreshold()<<endl;
#endif
	    } // end if of threshold condition
	} // for c
    }// end do on pixels
    delete [] digits;
    delete [] tracks;
    delete [] hits;
    delete [] charges;

}
//______________________________________________________________________
void AliITSsimulationSPD::SetFluctuations(AliITSpList *pList,Int_t module) {
    //  Set the electronic noise and threshold non-uniformities to all the
    //  pixels in a detector.
    //  The parameter fSigma is the squared sum of the sigma due to noise
    //  and the sigma of the threshold distribution among pixels.
    //
    //Begin_Html
    /*
      <img src="picts/ITS/barimodel_1.gif">
      </pre>
      <br clear=left>
      <font size=+2 color=red>
      <a href="mailto:Rocco.Caliandro@ba.infn.it"></a>.
      </font>
      <pre>
    */
    //End_Html
    Float_t  thr=0.0,sigm=0.0;
    Double_t signal,sigma;
    Int_t iz,ix;

    GetThresholds(thr,sigm);
    sigma = (Double_t) sigm;
    for(iz=1;iz<=GetNPixelsZ();iz++){
	for(ix=1;ix<=GetNPixelsX();ix++){
	    signal = sigma*gRandom->Gaus(); 
	    fMapA2->SetHit(iz,ix,signal);
	    // insert in the label-signal-hit list the pixels fired
	    // only by noise
	    pList->AddNoise(iz,ix,module,signal);
	} // end of loop on pixels
    } // end of loop on pixels
}
//______________________________________________________________________
void AliITSsimulationSPD::SetMask() {
    //  Apply a mask to the SPD module. 1% of the pixel channels are
    //  masked. When the database will be ready, the masked pixels
    //  should be read from it.
    Double_t signal;
    Int_t iz,ix,im;
    Float_t totMask;
    Float_t perc = ((AliITSresponseSPD*)fResponse)->GetFractionDead();
    // in this way we get the same set of random numbers for all runs.
    // This is a cluge for now.
    static TRandom *rnd = new TRandom();

    totMask= perc*GetNPixelsZ()*GetNPixelsX();
    for(im=1;im<totMask;im++){
	do{
	    ix=(Int_t)(rnd->Rndm()*(GetNPixelsX()-1.) + 1.);
	} while(ix<=0 || ix>GetNPixelsX());
	do{
	    iz=(Int_t)(rnd->Rndm()*(GetNPixelsZ()-1.) + 1.);
	} while(iz<=0 || iz>GetNPixelsZ());
	signal = -1.;
	fMapA2->SetHit(iz,ix,signal);
    } // end loop on masked pixels
}
//______________________________________________________________________
void AliITSsimulationSPD::CreateHistograms() {
    // Create Histograms
    Int_t i;

    fHis=new TObjArray(GetNPixelsZ());
    for(i=0;i<GetNPixelsZ();i++) {
	TString spdname("spd_");
	Char_t candnum[4];
	sprintf(candnum,"%d",i+1);
	spdname.Append(candnum);
	(*fHis)[i] = new TH1F(spdname.Data(),"SPD maps",
			      GetNPixelsX(),0.,(Float_t) GetNPixelsX());
    } // end for i
}
//______________________________________________________________________
void AliITSsimulationSPD::ResetHistograms() {
    // Reset histograms for this detector
    Int_t i;

    for(i=0;i<GetNPixelsZ();i++ ) {
	if ((*fHis)[i])    ((TH1F*)(*fHis)[i])->Reset();
    } // end for i
}
//______________________________________________________________________
void AliITSsimulationSPD::WriteSDigits(AliITSpList *pList){
    // Fills the Summable digits Tree
    Int_t i,ni,j,nj;
    static AliITS *aliITS = (AliITS*)gAlice->GetModule("ITS");

    pList->GetMaxMapIndex(ni,nj);
    for(i=0;i<ni;i++)for(j=0;j<nj;j++){
	if(pList->GetSignalOnly(i,j)>0.0){
	    aliITS->AddSumDigit(*(pList->GetpListItem(i,j)));
#ifdef DEBUG
	    cout << "pListSPD: " << *(pList->GetpListItem(i,j)) << endl;
	    cout << " CreateSPDSDigit mod=" << fModule << " r,c=";
	    cout << i  <<","<< j << " sig=" << fpList->GetSignalOnly(i,j);
	    cout << " noise=" << fpList->GetNoise(i,j) <<endl;
#endif
	} // end if
    } // end for i,j
    return;
}
//______________________________________________________________________
void AliITSsimulationSPD::FillMapFrompList(AliITSpList *pList){
    // Fills fMap2A from the pList of Summable digits
    Int_t ix,iz;

    for(iz=0;iz<GetNPixelsZ();iz++)for(ix=0;ix<GetNPixelsX();ix++) 
        fMapA2->AddSignal(iz,ix,pList->GetSignal(iz,ix));
    return;
}