/*
 * Speed Fraction
 * by: Charlton Harrison
 * Computes the best approximate fractions for a decimal
 */

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <gmp.h>

/*---------------------------------------------*/
/* for kbhit() */
#include <sys/time.h>
#include <unistd.h>

/* Function for kbhit() - the gcc way */
/* Only works for the <return> key though... */
int kbhit()
{
    struct timeval wait;
    int ret;
    fd_set readfd;

    FD_ZERO(&readfd);
    FD_SET(0, &readfd);
    wait.tv_sec  = 0;   /* Wait zero seconds */
    wait.tv_usec = 0;
				    
    ret = select(1, &readfd, NULL, NULL, &wait);
    return(ret);
}
/*---------------------------------------------*/

int main(int argc, char *argv[])
{
    int kcount=0;
    mpz_t lpa, lasta, lastb, a, b, c, e, t, tai, tbi, last10;
    mpf_t m, p, lastp, x, h, fe, ft, taf, tbf;

    mpf_set_default_prec(128);

    mpz_init(e);  mpz_init(tai);  mpz_init(tbi);  mpz_init(last10);
    mpz_init(lpa);    mpz_set_ui(lpa, 0);
    mpz_init(lasta);  mpz_set_ui(lasta, 0);
    mpz_init(lastb);  mpz_set_ui(lastb, 0);
    mpz_init(a);      mpz_set_ui(a, 0);
    mpz_init(b);      mpz_set_ui(b, 0);
    mpz_init(c);      mpz_set_ui(c, 1);
    mpz_init(t);      mpz_set_ui(t, 0);

    mpf_init(x);  mpf_init(h);  mpf_init(fe);  mpf_init(ft);
    mpf_init(taf);  mpf_init(tbf);
    mpf_init(m);      mpf_set_d(m, 0.5);
    mpf_init(p);      mpf_set_d(p, 0.0);
    mpf_init(lastp);  mpf_set_d(lastp, 0.0);

    /* Initializations */
    if (argc != 2) {
	printf("Usage: spfrcn <decimal>\n");
	exit(1);
    }

    printf("\nHit return at any time to stop...\n");

    mpf_init_set_str(x, argv[1], 10);

    mpf_out_str(stdout, 10, 0, x); printf("\n");

    while (1) {						/* Main Loop */

	mpz_add_ui(t, t, 1);  mpf_add(m, m, x);
	mpz_set_f(e, m);

	mpf_set_z(fe, e);  mpf_set_z(ft, t);
	mpf_div(h, fe, ft);

	mpf_sub(taf, h, x);  mpf_sub(tbf, p, x);
	mpf_abs(taf, taf);  mpf_abs(tbf, tbf);

	if ((mpf_cmp(taf, tbf)) < 0) {
	    mpf_set(p, h);  mpz_set(a, e);  mpz_set(b, t);
	}

	if ((mpz_cmp(a, lpa)) != 0) {
	    if ((mpf_cmp(h, x)) == 0) {
		mpz_out_str(stdout, 10, a);  printf(" / ");
		mpz_out_str(stdout, 10, b);  printf("  :  ");
		mpf_out_str(stdout, 10, 0, p);  printf("\n");
		exit(1);
	    }
	    mpz_ui_pow_ui(last10, 10, (mpz_sizeinbase(e, 10) - 1));

	    mpz_tdiv_q(tai, e, last10);  mpz_tdiv_q(tbi, a, last10);

	    if ((mpz_cmp(tai, tbi)) != 0) {
		mpz_out_str(stdout, 10, a);  printf(" / ");
		mpz_out_str(stdout, 10, b);  printf("  :  ");
		mpf_out_str(stdout, 10, 0, p);  printf("\n");
		mpz_set(lpa, a);
	    }
	}

	kcount++;
	if (kcount==1000) {     /* every 1000 loops check to see if kbhit */
	    kcount=0;
	    if (kbhit()) {
		exit(1);
	    }
	}

    }						/* End of Main Loop */

}