[feat](trx-rs): add ft8 decoder

Co-authored-by: Codex <codex@openai.com>
Signed-off-by: Stanislaw Grams <stanislawgrams@gmail.com>

external/ft8_lib/ft4_ft8_public/hashcodes.f90

@@ -0,0 +1,34 @@
+program hashcodes
+
+  parameter (NTOKENS=2063592)
+  integer*8 nprime,n8(3)
+  integer nbits(3),ihash(3)
+  character*11 callsign
+  character*38 c
+  data c/' 0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ/'/
+  data nprime/47055833459_8/,nbits/10,12,22/
+
+  nargs=iargc()
+  if(nargs.ne.1) then
+     print*,'Usage:    hashcodes <callsign>'
+     print*,'Examples: hashcodes PJ4/K1ABC'
+     print*,'          hashcodes YW18FIFA'
+     go to 999
+  endif
+  call getarg(1,callsign)
+  callsign=adjustl(callsign)
+
+  do k=1,3
+     n8(k)=0
+     do i=1,11
+        j=index(c,callsign(i:i)) - 1
+        n8(k)=38*n8(k) + j
+     enddo
+     ihash(k)=ishft(nprime*n8(k),nbits(k)-64)
+  enddo
+  ih22_biased=ihash(3) + NTOKENS
+  write(*,1000) callsign,ihash,ih22_biased
+1000 format('Callsign',9x,'h10',7x,'h12',7x,'h22'/41('-')/        &
+          a11,i9,2i10,/'Biased for storage in c28:',i14)
+
+999 end program hashcodes