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d78f2dda18
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@8218 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
143 lines
4.5 KiB
Fortran
143 lines
4.5 KiB
Fortran
subroutine gf64_osd(s3,cw)
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use jt65_generator_matrix
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real s3(64,63),xtmp(64),sympow_sorted(64,63),sympow(64,63)
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integer ideinterleave_indices(63),indxs(64),isymval_sorted(64,63),isymval(64,63)
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integer cw(63)
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integer indx(63)
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integer gmrb(12,63)
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integer correct(63)
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integer correctr(63)
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integer correct_sorted(63)
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integer candidate(63)
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integer candidater(63)
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integer itmp(63)
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logical mask(63),first
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data correct/ & ! K1ABC W9XYZ EN37
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41, 0, 54, 46, 55, 29, 57, 35, 35, 48, 48, 61, &
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21, 58, 25, 10, 50, 43, 28, 37, 10, 2, 61, 55, &
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25, 5, 5, 57, 28, 11, 32, 45, 16, 55, 31, 46, &
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44, 55, 34, 38, 50, 62, 52, 58, 17, 62, 35, 34, &
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28, 21, 15, 47, 33, 20, 15, 28, 58, 4, 58, 61, &
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59, 42, 2/
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data first/.true./
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save first,correctr
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if(first) then
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correctr=correct(63:1:-1)
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! find indices of deinterleaved symbols
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do i=1,63
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ideinterleave_indices(i)=i
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enddo
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call interleave63(ideinterleave_indices,-1)
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first=.false.
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endif
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! Sort the spectral powers in decreasing order, remove gray code
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do i=1,63
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xtmp=s3(:,i)
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call indexx(xtmp,64,indxs)
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sympow_sorted(:,i)=xtmp(indxs(64:1:-1))
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indxs=indxs-1
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call graycode65(indxs,64,-1)
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isymval_sorted(:,i)=indxs(64:1:-1)
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enddo
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! Deinterleave symbol powers.
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do i=1,63
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isymval(:,i)=isymval_sorted(:,ideinterleave_indices(i))
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sympow(:,i)=sympow_sorted(:,ideinterleave_indices(i))
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enddo
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! Now sort along the symbol index, using the largest spectral power at each index
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xtmp(1:63)=sympow(1,1:63)
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call indexx(xtmp(1:63),63,indx)
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! Calculate some statistics
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nhard=count(isymval(1,:).ne.correctr)
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nerrtop4=count(isymval(1,indx(60:63)).ne.correctr(indx(60:63)))
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nerrmid4=count(isymval(1,indx(56:59)).ne.correctr(indx(56:59)))
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nerrbot4=count(isymval(1,indx(52:55)).ne.correctr(indx(52:55)))
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do i=1,12
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if(isymval(1,indx(64-i)).ne.correctr(indx(64-i))) then
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write(*,'(i2,1x,64l1)') i,isymval(:,indx(64-i)).eq.correctr(indx(64-i))
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endif
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enddo
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write(*,*) 'nerr, nerrtop4, nerrmid4, nerrbot4',nhard,nerrtop4,nerrmid4,nerrbot4
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! The best 12 symbols will be used as the Most Reliable Basis
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! Reorder the columns of the generator matrix in order of decreasing quality.
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! do i=1,63
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! indx=isymval(64,63+1-i)+1
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! gmrb(:,i)=g(:,indx(63+1-i))
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! enddo
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! Put the generator matrix in standard form so that top 12 symbols are
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! encoded systematically.
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! call gf64_standardize_genmat(gmrb)
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! Add various error patterns to the 12 basis symbols and reencode each one
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! to get a list of codewords. For now, just find the zero'th order codeword.
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! call gf64_encode(gmrb,isymval(64,indx(63:52:-1)),candidate)
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! Undo the sorting to put the codeword symbols back into the "right" order.
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! candidater=candidate(63:1:-1)
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! candidate(indx)=candidater
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! nerr=count(correctr.ne.candidate)
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!write(*,*) 'Number of differences between candidate and correct codeword: ',nerr
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! if( nerr .eq. 0 ) write(*,*) 'Successful decode'
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return
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end subroutine gf64_osd
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subroutine gf64_standardize_genmat(gmrb)
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use gf64math
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integer gmrb(12,63),temp(63),gkk,gjk,gkkinv
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do k=1,12
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gkk=gmrb(k,k)
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if(gkk.eq.0) then ! zero pivot - swap with the first row with nonzero value
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do kk=k+1,12
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if(gmrb(kk,k).ne.0) then
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temp=gmrb(k,:)
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gmrb(k,:)=gmrb(kk,:)
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gmrb(kk,:)=temp
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gkk=gmrb(k,k)
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goto 20
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endif
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enddo
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endif
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20 gkkinv=gf64_inverse(gkk)
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do ic=1,63
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gmrb(k,ic)=gf64_product(gmrb(k,ic),gkkinv)
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enddo
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do j=1,12
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if(j.ne.k) then
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gjk=gmrb(j,k)
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do ic=1,63
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gmrb(j,ic)=gf64_sum(gmrb(j,ic),gf64_product(gmrb(k,ic),gjk))
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enddo
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endif
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enddo
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enddo
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return
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end subroutine gf64_standardize_genmat
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subroutine gf64_encode(gg,message,codeword)
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!
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! Encoder for a (63,12) Reed-Solomon code.
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! The generator matrix is supplied in array gg.
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!
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use gf64math
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integer message(12) !Twelve 6-bit data symbols
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integer codeword(63) !RS(63,12) codeword
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integer gg(12,63)
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codeword=0
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do j=1,12
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do i=1,63
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iprod=gf64_product(message(j),gg(j,i))
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codeword(i)=gf64_sum(codeword(i),iprod)
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enddo
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enddo
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return
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end subroutine gf64_encode
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