log2.cpp

Digital filter designer s handbook C++ code source

//
//  File = log2.cpp
//

#include <stdlib.h>
#include "log2.h"

int ilog2(int value_inp)
{
 int log_base_2;
 int value; 
 int m, mx;

 log_base_2 = 0;
 value = value_inp;

 while(value >1)
   {
    value /=2;
    log_base_2++; 
   }  
 value = 1;
 int i;
 for(i=1; i<=log_base_2 ;i++)
   { 
    value *= 2;
   }
 if(value != value_inp) log_base_2 = -1;
 
 return(log_base_2);  
}

//++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++