#include"header.h"



// Precompute 32 basic sine xues and 32 basic cosine values. 
double bsin[] = { 0.479426, 0.247404, 0.124675, 0.062459, 
                  0.031245, 0.015624, 0.007812, 0.003906, 
                  0.001953, 0.000977, 0.000488, 0.000244,
                  0.000122, 0.000061, 0.000031, 0.000015, 
                  0.000008, 0.000004, 0.000002, 0.000001, 
                  0.000000, 0.000000, 0.000000, 0.000000, 
                  0.000000, 0.000000, 0.000000, 0.000000, 
                  0.000000, 0.000000, 0.000000, 0.000000 };


double bcos[] = { 0.877583, 0.968912, 0.992198, 0.998048, 
                  0.999512, 0.999878, 0.999969, 0.999992, 
                  0.999998, 1.000000, 1.000000, 1.000000, 
                  1.000000, 1.000000, 1.000000, 1.000000, 
                  1.000000, 1.000000, 1.000000, 1.000000, 
                  1.000000, 1.000000, 1.000000, 1.000000, 
                  1.000000, 1.000000, 1.000000, 1.000000, 
                  1.000000, 1.000000, 1.000000, 1.000000 };



 int bin[N];
//Initializing the 64 basic sine and cosine values.
int initial(void) {
  int i;
  double invpow2;

  for (i = 0; i < N; i++) {
    invpow2 = pow(2,-(i+1));
    bsin[i] = sin(invpow2);
    bcos[i] = cos(invpow2);
  }
  return 0;
}



//Convert double numbers between 0 and 1 to a binary array.
int dtob(double x) {
  double nx= x*2;
  int i;

  for (i = 0; i < N; i++) {
    bin[i] = (int) nx;
    nx = 2*(nx - floor(nx)); 
  }

  return 0;
}



// The CORDIC part.
double cordic(double x) {
  int i, edge; 
  double sinx, cosx;

  //Make sure x is between 0.0 and 1.0, if x is out of range, the function stops.
  if (x < 0 || x > 1) {
    return 0;
  }

  //Convert x to a binary array.
  dtob(x);

// Use addition formula.
  edge = 0;
  for (i = 0; i < N; i++){
    if (bin[i] == 1) {
      if (edge != 0) {
        sinx=sinx*bcos[i]+cosx*bsin[i];
        cosx=cosx*bcos[i]-sinx*bsin[i];
      }
      else {
        sinx=bsin[i];
        cosx=bcos[i];
        edge = 1;
      }
    }
  }

  return sinx;
}