useful_functions.c

来自「详细的OFDM设计过程」· C语言 代码 · 共 51 行

// some useful functions

#include "useful_functions.h" 


void div_element(const float *x, const float *y, float *z, const int count)
{
	int i;
    
	for (i=0; i <= count-2; i+=2)
    {
    	z[i] = (x[i]*y[i]+x[i+1]*y[i+1])*(_rcpsp(y[i]*y[i]+y[i+1]*y[i+1]));
    	z[i+1] = (x[i+1]*y[i]-x[i]*y[i+1])*(_rcpsp(y[i]*y[i]+y[i+1]*y[i+1]));
       	
       	
       	  //Uncomment these lines and comment the two preceeding  
       	  //to increase precision. Execution time  will increase. 
       	/*  
       	  z[i]   = (x[i]*y[i]+x[i+1]*y[i+1])/(y[i]*y[i]+y[i+1]*y[i+1]);  
          z[i+1] = (x[i+1]*y[i]-x[i]*y[i+1])/(y[i]*y[i]+y[i+1]*y[i+1]);  
    	 */
    }
}


void prod_element_conj(const float *x, const float *y, float *z, const int count)
{
	int i;
    
    for (i=0; i <= count-2; i+=2)
    { 
    	float a=x[i];          				/* temporary variable */
    	float b=y[i];    	                /* temporary variable */
    	z[i] = x[i]*y[i]+x[i+1]*y[i+1];    	/* the real part */
    	z[i+1] = a*y[i+1]-x[i+1]*b;   		/* the imaginary part */
    }

}


void square_absolute(float *x, float *y, int count)
{
	int i;
    
    for (i=0; i < count; i++)			// count is the length of the output
    { 
    	y[i]=x[2*i]*x[2*i]+x[2*i+1]*x[2*i+1];

	}
}