TDA4VM: Be careful，Correction of possible errors in dsplib source code

void DSPF_dp_mat_mul_gemm(double *x1, double const a, const int r1, const int c1,
    double *x2, const int c2, double *restrict y)
{
    int    i, j, k, xoff1, xoff2;
    double sum0, sum1, sum2, sum3;
    double x00, x01, y00, y01, y10, y11, x10, x11;
    double *ptr_x, *ptr_y, *restrict y1, *restrict y2;

    _nassert(r1 > 0);
    _nassert(c1 > 0);
    _nassert(c2 > 0);
    _nassert((int)x1 % 8 == 0);
    _nassert((int)x2 % 8 == 0);
    _nassert((int)y  % 8 == 0);
    _nassert(c1 % 2 == 0 );
    _nassert(r1 % 2 == 0 );
    _nassert(c2 % 2 == 0 );

    #pragma MUST_ITERATE(1,,)
    for (j = 0; j < c2; j+=2) {
      xoff2 = j * c1;
      y1 = &y[(j + 0) * r1];
      y2 = &y[(j + 1) * r1];

      #pragma MUST_ITERATE(1,,)
      for (i = 0; i < r1; i+=2) {                         
        xoff1 = i * c1;                            
        sum0  = 0;
        sum1  = 0;
        sum2  = 0;
        sum3  = 0;
        ptr_x = &x1[xoff1];
        ptr_y = &x2[xoff2];

        #pragma MUST_ITERATE(1,,)
        for (k = 0; k < c1; k+=2,ptr_x+=2,ptr_y+=2) {
          x00 = ptr_x[0];
          x01 = ptr_x[1];
          x10 = ptr_x[c1];
          x11 = ptr_x[c1 + 1];
          y00 = ptr_y[0];
          y01 = ptr_y[c1];
          y10 = ptr_y[1];
          y11 = ptr_y[c1 + 1];

          sum0 += x00 * y00 + x01 * y10;
          sum1 += x00 * y01 + x01 * y11;
          sum2 += x10 * y00 + x11 * y10;
          sum3 += x10 * y01 + x11 * y11;
        }
        y1[(i + 0)] += a*sum0;
        y2[(i + 0)] += a*sum1;
        y1[(i + 1)] += a*sum2;
        y2[(i + 1)] += a*sum3;        
      }
    }                        
}