WSJT-X/lib/fsk4hf/gf64_osd.f90
Steven Franke 207aefb8d0 Changes to a test program.
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@8209 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
2017-11-02 16:11:07 +00:00

143 lines
4.5 KiB
Fortran

subroutine gf64_osd(s3,cw)
use jt65_generator_matrix
real s3(64,63),xtmp(64),sympow_sorted(64,63),sympow(64,63)
integer ideinterleave_indices(63),indxs(64),isymval_sorted(64,63),isymval(64,63)
integer cw(63)
integer indx(63)
integer gmrb(12,63)
integer correct(63)
integer correctr(63)
integer correct_sorted(63)
integer candidate(63)
integer candidater(63)
integer itmp(63)
logical mask(63),first
data correct/ & ! K1ABC W9XYZ EN37
41, 0, 54, 46, 55, 29, 57, 35, 35, 48, 48, 61, &
21, 58, 25, 10, 50, 43, 28, 37, 10, 2, 61, 55, &
25, 5, 5, 57, 28, 11, 32, 45, 16, 55, 31, 46, &
44, 55, 34, 38, 50, 62, 52, 58, 17, 62, 35, 34, &
28, 21, 15, 47, 33, 20, 15, 28, 58, 4, 58, 61, &
59, 42, 2/
data first/.true./
save first,correctr
if(first) then
correctr=correct(63:1:-1)
! find indices of deinterleaved symbols
do i=1,63
ideinterleave_indices(i)=i
enddo
call interleave63(ideinterleave_indices,-1)
first=.false.
endif
! Sort the spectral powers in decreasing order, remove gray code
do i=1,63
xtmp=s3(:,i)
call indexx(xtmp,64,indxs)
sympow_sorted(:,i)=xtmp(indxs(64:1:-1))
indxs=indxs-1
call graycode65(indxs,64,-1)
isymval_sorted(:,i)=indxs(64:1:-1)
enddo
! Deinterleave symbols symbol powers.
do i=1,63
isymval(:,i)=isymval_sorted(:,ideinterleave_indices(i))
sympow(:,i)=sympow_sorted(:,ideinterleave_indices(i))
enddo
! Now sort along the symbol index, using the largest spectral power at each index
xtmp(1:63)=sympow(1,1:63)
call indexx(xtmp(1:63),63,indx)
! Calculate some statistics
nhard=count(isymval(1,:).ne.correctr)
nerrtop4=count(isymval(1,indx(60:63)).ne.correctr(indx(60:63)))
nerrmid4=count(isymval(1,indx(56:59)).ne.correctr(indx(56:59)))
nerrbot4=count(isymval(1,indx(52:55)).ne.correctr(indx(52:55)))
do i=1,12
if(isymval(1,indx(64-i)).ne.correctr(indx(64-i))) then
write(*,'(i2,1x,64l1)') i,isymval(:,indx(64-i)).eq.correctr(indx(64-i))
endif
enddo
write(*,*) 'nerr, nerrtop4, nerrmid4, nerrbot4',nhard,nerrtop4,nerrmid4,nerrbot4
! The best 12 symbols will be used as the Most Reliable Basis
! Reorder the columns of the generator matrix in order of decreasing quality.
! do i=1,63
! indx=isymval(64,63+1-i)+1
! gmrb(:,i)=g(:,indx(63+1-i))
! enddo
! Put the generator matrix in standard form so that top 12 symbols are
! encoded systematically.
! call gf64_standardize_genmat(gmrb)
! Add various error patterns to the 12 basis symbols and reencode each one
! to get a list of codewords. For now, just find the zero'th order codeword.
! call gf64_encode(gmrb,isymval(64,indx(63:52:-1)),candidate)
! Undo the sorting to put the codeword symbols back into the "right" order.
! candidater=candidate(63:1:-1)
! candidate(indx)=candidater
! nerr=count(correctr.ne.candidate)
!write(*,*) 'Number of differences between candidate and correct codeword: ',nerr
! if( nerr .eq. 0 ) write(*,*) 'Successful decode'
return
end subroutine gf64_osd
subroutine gf64_standardize_genmat(gmrb)
use gf64math
integer gmrb(12,63),temp(63),gkk,gjk,gkkinv
do k=1,12
gkk=gmrb(k,k)
if(gkk.eq.0) then ! zero pivot - swap with the first row with nonzero value
do kk=k+1,12
if(gmrb(kk,k).ne.0) then
temp=gmrb(k,:)
gmrb(k,:)=gmrb(kk,:)
gmrb(kk,:)=temp
gkk=gmrb(k,k)
goto 20
endif
enddo
endif
20 gkkinv=gf64_inverse(gkk)
do ic=1,63
gmrb(k,ic)=gf64_product(gmrb(k,ic),gkkinv)
enddo
do j=1,12
if(j.ne.k) then
gjk=gmrb(j,k)
do ic=1,63
gmrb(j,ic)=gf64_sum(gmrb(j,ic),gf64_product(gmrb(k,ic),gjk))
enddo
endif
enddo
enddo
return
end subroutine gf64_standardize_genmat
subroutine gf64_encode(gg,message,codeword)
!
! Encoder for a (63,12) Reed-Solomon code.
! The generator matrix is supplied in array gg.
!
use gf64math
integer message(12) !Twelve 6-bit data symbols
integer codeword(63) !RS(63,12) codeword
integer gg(12,63)
codeword=0
do j=1,12
do i=1,63
iprod=gf64_product(message(j),gg(j,i))
codeword(i)=gf64_sum(codeword(i),iprod)
enddo
enddo
return
end subroutine gf64_encode