text: #include "poly.h"
  
  void PQCLEAN_NTRUHPS2048509_CLEAN_poly_Rq_mul(poly *r, const poly *a, const poly *b) {
      int k, i;
  
      for (k = 0; k < NTRU_N; k++) {
          r->coeffs[k] = 0;
          for (i = 1; i < NTRU_N - k; i++) {
              r->coeffs[k] += a->coeffs[k + i] * b->coeffs[NTRU_N - i];
          }
          for (i = 0; i < k + 1; i++) {
              r->coeffs[k] += a->coeffs[k - i] * b->coeffs[i];
          }
      }
  }
  