Magnus Lundmark

See PR that implements this.

I just noticed there's a NaN test as well... https://github.com/gnuradio/volk/pull/731 Need to update this PR with this as well for AVX512!

> @Ka-zam #731 is essential for airspy-fmradion, and I've spent a few weeks solving the NaN issue. Please add the NaN test before completing your implementation. I think it's already...

Here's some special values and a sanity check: ``` magnus@r7950x3d:~/src/kazam/scratch$ ./a.out y : 1.00 -1.00 1.00 -1.00 nan nan 0.00 -0.00 1.00 -1.00 x : 1.00 1.00 -1.00 -1.00 1.00...

I ran all kernels for special values: ``` magnus@r7950x3d:~/src/kazam/scratch$ ./a.out x: -0.0000e+00 0.0000e+00 inf -inf nan -nan 1.0000e-30 1.0000e+30 generic: -inf inf 0.0000e+00 -0.0000e+00 nan -nan 1.0000e+30 1.0000e-30 a_sse: -inf...

I looked at this as well and I wrote a new kernel based on the rsqrt() intrinsic. It's faster and more accurate than this kernel. Should I submit a PR...

Fixed in fcch_detector.cc L318 fft[i] = complex(m_out[i][0], m_out[i][1]); Also should use constexpr in fcch_detector.h static constexpr double GSM_RATE = 1625000.0 / 6.0;

I also have this issue using GR 3.7.13.4 built from source.