/*
 * jjmodel
 *
 * Ancient Josephson junction model generating program, slightly updated.
 * latest change 9/27/98 -- purge gets()
 *
 * S. R. Whiteley (stevew@srware.com)
 *
 * Usage:  Answer the questions and get a Jspice3/WRspice model.  Parameters
 * are based on the HYPRES process.
 *
 * To build:  cc -o jjmodel jjmodel.c -lm
 *
 * This is freeware -- use without restriction.
 */

#include <stdio.h>
#include <math.h>
#include <stdlib.h>

double C = 33.1;       /* fF/square micron at 1A/square cm    */
double VM = 30;        /* icrit * r0 in milivolts             */
double VG = 2.8;       /* gap voltage in millivolts           */
double DELV = .08;     /* gap spread in millivolts            */
double ICON = 10;
double ICR = 1.7;      /* crit current * normal resistance    */
int RTYPE = 1;
int CCT = 1;

int
main()
{
    char s[80];
    int i;
    double x = 0, y = 0, a, ic, j;
    FILE *fp, *fopen();
    printf("Josephson junction SPICE model generating program\n\n");
    printf("Enter critical current density in amps per square cm : ");
    j = atof(fgets(s, 80, stdin));
    while (j <= 0.0 || j > 1e6) {
        printf("\nerror: critical current density is out of bounds,\
 please reenter : ");
        j = atof(fgets(s, 80, stdin));
    }
    for (;;) {
        printf("\nEnter junction area in square microns (one number) \
or junction size\nin microns (two numbers separated by space) : ");
        i = sscanf(fgets(s, 80, stdin),"%lf %lf", &x, &y);
        switch (i) {
        case 1:
            a = x;
            break;
        case 2:
            a = x*y;
            break;
        default:
            printf("error: bogus input\n");
            continue;
        }
        if (a > 0 && a < 1e7)
            break;
        printf("error: out of bounds\n");
    }
    ic = j*a*1.0e-5;
    fp = fopen("jjmodel.out", "w");
    if (!fp) {
        fprintf(stderr, "Can't open \"jjmodel.out\".\n");
        return (1);
    }
    fprintf(fp, ".model XXXXX jj(rtype=%d, cct=%d, icon=%gm, vg=%gm, delv=%gm,\
\n+ icrit=%gm, r0=%g, rn=%g, cap=%gp)\n", RTYPE, CCT, ICON, VG, DELV, ic,
    VM/ic, VG/ic/ICR, C*a*(1+.05*log10(j))*1.0e-3);
    fprintf(fp,
"*Nb %g A/cm2   area = %g square microns (generated by JJMODEL)\n", j, a);
    fclose(fp);
    printf("\nModel created in file jjmodel.out.  Parasitic capacitance outside\
 of the\njunction area is not included.\n");
    return (0);
}