BSD 3 development

[unix-history] / usr / src / cmd / learn / selunit.c

#include "stdio.h"
#include "lrnref"

int     nsave   = 0;

selunit()
{
       char fnam[20], s[50];
       static char dobuff[50];
       char posslev[20][20];
       int diff[20], i, k, m, n, best, alts;
       FILE *f;
       char zb[200];
       static char saved[20];

       while (ask) {
               printf("What lesson? ");
               fflush(stdout);
               gets(dobuff);
               if (strcmp(dobuff, "bye") == 0)
                       wrapup(0);
               level = todo = dobuff;
               sprintf(s, "../../%s/L%s", sname, dobuff);
               if (access(s, 04) == 0)
                       return;
               printf("no such lesson\n");
       }
       alts = 0;
retry:
       f=scrin;
       if (f==NULL) {
               sprintf(fnam, "../../%s/L%s", sname, level);
               f = fopen(fnam, "r");
               if (f==NULL) {
                       fprintf(stderr, "No script for lesson %s.\n", level);
                       wrapup(1);
               }
               while (fgets(zb, 200, f)) {
                       trim(zb);
                       if (strcmp(zb, "#next")==0)
                               break;
               }
       }
       if (feof(f)) {
               printf("Congratulations; you have finished this sequence.\n");
               fflush(stdout);
               todo = 0;
               return;
       }
       for(i=0; fgets(s, 50, f); i++) {
               sscanf(s, "%s %d", posslev[i], &diff[i]);
       }
       best = -1;
       /* cycle through lessons from random start */
       /* first try the current place, failing that back up to
            last place there are untried alternatives (but only one backup) */
       n = grand()%i;
       for(k=0; k<i; k++) {
               m = (n+k)%i;
               if (already(posslev[m],0)) continue;
               if (best<0) best=m;
               /* real alternatives */
               alts++;
               if (abs(diff[m]-speed) < abs(diff[best]-speed))
                       best=m;
       }
       if (best < 0 && nsave) {
               nsave--;
               strcpy(level, saved);
               goto retry;
       }
       if (best <0) {
               /* lessons exhausted or missing */
               printf("Sorry, there are no alternative lessons at this stage.\n");
               printf("See someone for help.\n");
               fflush(stdout);
               todo = 0;
               return;
       }
       strcpy (dobuff, posslev[best]);
       if (alts>1) {
               nsave=1;
               strcpy (saved, level);
       }
       todo = dobuff;
       fclose(f);
}

abs(x)
{
       return(x>=0? x: -x);
}

grand()
{
       static int garbage;
       int a[2], b;

       time(a);
       b = a[1]+10*garbage++;
       return(b&077777);
}