[Libre-soc-dev] [RFC] REMAP, SHAPE, complex (full) FFT

[Luke Kenneth Casson Leighton]

On Fri, Jul 23, 2021 at 7:13 PM Luke Kenneth Casson Leighton
<lkcl at lkcl.net> wrote:

> joining the two together should be easy:

done.

> my next concern is how to easily generate the cosine table,

got the pieces done, the normal loop is:
  while size >= 2
     for j in range(0, n, size):
        for i in range(half):
            t1, t2 = vector[i], vector[n-i-1]
            k = (math.cos((i + 0.5) * math.pi / n) * 2.0)

i had to first check that it was possible to calculate k from scalar
(it is), and second add schedules where both n and i may be
first scheduled and second *extracted as integers*.

with those two pieces in place it's straightforward to stitch
them together to create a Vectorised schedule of cosine
coefficients.

> although this is only needed for a
> Vertical-First variant which i will get to in a couple of days.

.... and then a Vertical-First variant can be done afterwards.

l.