The C code

void preQsBc(char *x, int m, int qsBc[]) {
  int i;

  for (i = 0; i < ASIZE; ++i)
     qsBc[i] = m + 1;
  for (i = 0; i < m; ++i)
     qsBc[x[i]] = m - i;
}


void QS(char *x, int m, char *y, int n) {
  int j, qsBc[ASIZE];

  /* Preprocessing */
  preQsBc(x, m, qsBc);

  /* Searching */
  j = 0;
  while (j <= n - m) {
     if (memcmp(x, y + j, m) == 0)
        OUTPUT(j);
     j += qsBc[y[j + m]];               /* shift */
  }
}