/* strlen:  return length of s */
   int strlen(char s[])
   {
       int i;

       while (s[i] != '\0')
           ++i;
       return i;
   }

   /* atoi:  convert s to integer */
   int atoi(char s[])
   {
       int i, n;

       n = 0;
       for (i = 0; s[i] >= '0' && s[i] <= '9'; ++i)
           n = 10 * n + (s[i] - '0');
       return n;
   }

   /* lower:  convert c to lower case; ASCII only */
   int lower(int c)
   {
       if (c >= 'A' && c <= 'Z')
           return c + 'a' - 'A';
       else
           return c;
   }

   unsigned long int next = 1;

   /* rand:  return pseudo-random integer on 0..32767 */
   int rand(void)
   {
       next = next * 1103515245 + 12345;
       return (unsigned int)(next/65536) % 32768;
   }

   /* srand:  set seed for rand() */
   void srand(unsigned int seed)
   {
       next = seed;
   }

   /* squeeze:  delete all c from s */
   void squeeze(char s[], int c)
   {
      int i, j;

      for (i = j = 0; s[i] != '\0'; i++)
          if (s[i] != c)
              s[j++] = s[i];
      s[j] = '\0';
   }

   /* strcat:  concatenate t to end of s; s must be big enough */
   void strcat(char s[], char t[])
   {
       int i, j;

       i = j = 0;
       while (s[i] != '\0') /* find end of s */
           i++;
       while ((s[i++] = t[j++]) != '\0') /* copy t */
           ;
   }

   /* getbits:  get n bits from position p */
   unsigned getbits(unsigned x, int p, int n)
   {
       return (x >> (p+1-n)) & ~(~0 << n);
   }