BSD 4_2 release

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

#ifndef lint
static char sccsid[] = "@(#)selunit.c   4.2     (Berkeley)      4/25/83";
#endif not lint

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

int     nsave   = 0;
int     review  = 0;

selunit()
{
       static char dobuff[50];
       static char saved[20];
       char fnam[80], s[80], zb[200];
       char posslev[20][20];
       int diff[20], i, k, m, n, best, alts;
       char *getlesson();
       FILE *f;

       if (again) {
               again = 0;
               if (todo=getlesson()) {
                       if (!review)
                               unsetdid(todo);
                       return;
               }
               wrapup(1);
       }
       while (ask) {
               printf("What lesson? ");
               fflush(stdout);
               gets(dobuff);
               if (strcmp(dobuff, "bye") == 0)
                       wrapup(1);
               level = dobuff;
               if (todo=getlesson())
                       return;
       }
       alts = 0;
retry:
       f = scrin;                      /* use old lesson to find next */
       if (f==NULL) {
               sprintf(fnam, "%s/%s/L%s", direct, sname, level);
               f = fopen(fnam, "r");
               if (f==NULL) {
                       perror(fnam);
                       fprintf(stderr, "Selunit:  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, 80, 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]))
                       continue;
               if (best<0)
                       best = m;
               alts++;                         /* real alternatives */
               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);
}