#include "shared.h"

/* pre-computed binary sine 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 };

/* pre-computed binary cosine values */
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];

/* initialize cosine and sine tables */
int
inittables(void) 
{
  int i;
  double invpow2;

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

/* convert double to binary array */
int
dtobarr(double val) 
{
  double nval= val*2;
  int i;

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

  return 0;
}

double
cordic(double val) 
{
  int i, edge; 
  double sinval, cosval;

  /* check input */
  if (val < 0 || val > 1) {
    printf("usage: inputs should be between 0 and 1\n");
    exit(1);
  }

  /* convert val to a binary array */
  dtobarr(val);

  /* Deal with edge case first.  Once one known sine value
   * is found, trig addition takes over. */
  edge = 0;
  for (i = 0; i < N; i++)
  {
    if (bin[i] == 1) {
      if (edge != 0) {
        sinval=sinval*bcos[i]+cosval*bsin[i];
        cosval=cosval*bcos[i]-sinval*bsin[i];
      }
      else {
        sinval=bsin[i];
        cosval=bcos[i];
        edge = 1;
      }
    }
  }

  return sinval;
}