#include "header.h"

float Cordic ( float x)	
{
	int i;
	unsigned int bin=0,bit;
	float remainder=x, resultSin;
	int a[L];
	float Trig[L][2], Cos[L], Sin[L];

	for ( i=0; i<L; i++)  // creat a matrix Trig to store the basic sine and cosine values
	{
		Trig[i][0]=cos( pow(0.5,i+1) );  // the first column of Trig is the cosine values
		Trig[i][1]=sin( pow(0.5,i+1) );  // the second column of Trig is the sine values
	}

	for ( i=0; i<L; i++)  // change a float number to a binary number
	{
		remainder *= 2.0;
		bit = (int) remainder;
		bin *= 2;
		bin += bit;
		a[i] = bit;	// a[0]~a[L-1] are used to store a binary number 0 or 1.
//		printf("a[%d]=%u\n",i,a[i]);
		remainder -= bit;
	}

	if ( a[0]==1)
	{
		Cos[0]=Trig[0][0];  // cos( 0.1 in binary )
		Sin[0]=Trig[0][1];  // sin( 0.1 in binary )
	}
	else
	{
		Cos[0]=1;  // cos( 0 )=1
		Sin[0]=0;  // sin( 0 )=0
	}


	
	for  ( i=0; i<L-1; i++)  // L=32 iterations
	{

			if (a[i+1]==1)
			{
				Cos[i+1]=Cos[i]*Trig[i+1][0]-Sin[i]*Trig[i+1][1];	// using the cordic algorithm
				Sin[i+1]=Sin[i]*Trig[i+1][0]+Cos[i]*Trig[i+1][1];
			}
			else
			{
				Cos[i+1]=Cos[i];  // if (a[i+1]==0), the values of cosine and sine don't change
				Sin[i+1]=Sin[i];
			}

	}
	resultSin=Sin[L-1];  // Sin[L-1] should be around sin(x)

	return resultSin;
}