mc2coda_random.cc

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#include <stdint.h>
#include <cmath>
using namespace std;

#include <TRandom2.h>

static TRandom2 randgen;
bool NO_PEDESTAL = true;              // flag to completely disable pedestal generation
bool NO_RANDOM_PEDESTAL = false;       // turn off random components of pedestals
float MEAN_PEDESTAL = 100.0;           // mean pedestal in single sample fADC counts
float SIGMA_COMMON_PEDESTAL = 4.0;     // common mode noise in single sample fADC counts
float SIGMA_INDIVIDUAL_PEDESTAL = 3.0; // stochastic noise in single sample fADC counts


extern "C" {
   void GetPedestals(uint32_t *peds, uint32_t Npeds);
}

void GetPedestals(uint32_t *peds, uint32_t Npeds)
{
   /// Generate a set of pedestal values based on the global variables.
   /// Ths will fill in the first Npeds-1 values in "peds" with a pedestal
   /// near zero and Npeds-th value will be near the mean pedestal setting.
   /// The idea is that the last value delivered will contain the mean
   /// pedestal for all channels in the module plus common mode noise.
   /// The first set of values will contain individual pedestal fluctuations
   /// for each channel. The f250 and f125 will use the one common pedestal
   /// to adjust the pulse integral and pulse peak values. For the measured
   /// pedestals output in Pulse Pedestal words, the stochastic part is added
   /// in as well to represent the inaccuracy of that measurement. Note that 
   /// this means the actual pedestal value used is not actually written
   /// to the output file anywhere.
   ///
   /// If the global boolean NO_PEDESTAL is set to true, then all values
   /// will be set to zero.
   ///
   /// If the global NO_RANDOM_PEDESTAL is set to true, then the first
   /// Npeds-1 values will be set to zero and the last value to the mean
   /// pedestal (=MEAN_PEDESTAL) with no random variation.
   ///
   /// The values MEAN_PEDESTAL, SIGMA_COMMON_PEDESTAL, and
   /// SIGMA_INDIVIDUAL_PEDESTAL are used to calculate the values. Random
   /// sampling is done from Gaussian's with the specified sigmas.

   if(NO_PEDESTAL){
      for(uint32_t i=0; i<Npeds; i++) peds[i] = 0;
   }else if(NO_RANDOM_PEDESTAL){
      for(uint32_t i=0; i<Npeds-1; i++) peds[i] = 0;  
      peds[Npeds - 1] = (uint32_t)MEAN_PEDESTAL;
   }else{
      for(uint32_t i=0; i<Npeds-1; i++) peds[i] = round(randgen.Gaus(0.0, SIGMA_INDIVIDUAL_PEDESTAL));
      peds[Npeds - 1] = round(randgen.Gaus(MEAN_PEDESTAL, SIGMA_COMMON_PEDESTAL));
   }

}