static inline double interpolate_product_double()

in subprojects/speex/resample_sse.h [100:126]

• 26 lines of code
• 2 McCabe index (conditional complexity)

static inline double interpolate_product_double(const float *a, const float *b, unsigned int len, const spx_uint32_t oversample, float *frac) {
  int i;
  double ret;
  __m128d sum;
  __m128d sum1 = _mm_setzero_pd();
  __m128d sum2 = _mm_setzero_pd();
  __m128 f = _mm_loadu_ps(frac);
  __m128d f1 = _mm_cvtps_pd(f);
  __m128d f2 = _mm_cvtps_pd(_mm_movehl_ps(f,f));
  __m128 t;
  for(i=0;i<len;i+=2)
  {
    t = _mm_mul_ps(_mm_load1_ps(a+i), _mm_loadu_ps(b+i*oversample));
    sum1 = _mm_add_pd(sum1, _mm_cvtps_pd(t));
    sum2 = _mm_add_pd(sum2, _mm_cvtps_pd(_mm_movehl_ps(t, t)));

    t = _mm_mul_ps(_mm_load1_ps(a+i+1), _mm_loadu_ps(b+(i+1)*oversample));
    sum1 = _mm_add_pd(sum1, _mm_cvtps_pd(t));
    sum2 = _mm_add_pd(sum2, _mm_cvtps_pd(_mm_movehl_ps(t, t)));
  }
  sum1 = _mm_mul_pd(f1, sum1);
  sum2 = _mm_mul_pd(f2, sum2);
  sum = _mm_add_pd(sum1, sum2);
  sum = _mm_add_sd(sum, _mm_unpackhi_pd(sum, sum));
  _mm_store_sd(&ret, sum);
  return ret;
}