117 lines
2.7 KiB
Plaintext
117 lines
2.7 KiB
Plaintext
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subroutine encode120(message,codeword)
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! Encode an 60-bit message and return a 120-bit codeword.
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! The generator matrix has dimensions (60,60).
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! The code is a (120,60) regular ldpc code with column weight 3.
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! The code was generated using the PEG algorithm.
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! After creating the codeword, the columns are re-ordered according to
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! "colorder" to make the codeword compatible with the parity-check matrix
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!
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character*15 g(60)
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integer*1 codeword(120)
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integer colorder(120)
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integer*1 gen(60,60)
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integer*1 itmp(120)
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integer*1 message(60)
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integer*1 pchecks(60)
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logical first
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data first/.true./
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data g/ &
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"65541ad98feab6e",&
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"27249940a5895a3",&
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"c80eac7506bf794",&
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"aa50393e3e18d3f",&
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"28527e87d47dced",&
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"5da0dcaf8db048c",&
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"d6509a43ca9b01a",&
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"9a7dadd9c94f1d4",&
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"bb673d3ba07cf29",&
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"65e190f2fbed447",&
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"bc2062a4e520969",&
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"9e357f3feed059b",&
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"aa6b59212036a57",&
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"f78a326722d6565",&
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"416754bc34c6405",&
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"f77000b3f04ff67",&
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"d48fbd7d48c5ab9",&
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"031ffb5db3a70cb",&
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"125964e358c4df5",&
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"bd02c32a5a241ea",&
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"4c15ecdd8561abd",&
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"7f0f1b352c7413e",&
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"26edb94dfd0ae79",&
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"ca1ba1ee0f8fb24",&
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"49878a58cb4544c",&
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"3dbcd0ff821b203",&
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"c1f4440160d5345",&
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"b5ea9dc7a5a70ab",&
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"cebcf7d94976be4",&
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"0968265f5977c88",&
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"c5a36937faa78c3",&
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"f0d4fef11e01c10",&
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"e35fc0c779bebfe",&
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"cf49c3eb41a31d5",&
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"3f0b19352c7013e",&
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"0e15eccd8521abd",&
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"dda8dcaf9d3048c",&
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"fee31438fba59ed",&
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"ad74a27e939189c",&
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"736ac01b439106e",&
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"ab5d2729b29bfa1",&
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"edf11fb02e5a426",&
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"5f38be1c93ecc83",&
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"1e4b3b8dc516b3e",&
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"84443d8bee614c6",&
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"d854d9f355ceac4",&
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"a476b5ece51f0ea",&
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"831c2b36c4c2f68",&
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"f485c97a91615ae",&
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"e9376d828ade9ba",&
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"cac586f089d3185",&
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"b8f8c67613dafe2",&
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"1a3142b401b315d",&
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"87dbedc43265d2e",&
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"bb64ec6e652e7da",&
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"e71bfd4c95dfd38",&
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"31209af07ad4f75",&
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"cff1a8ccc5f4978",&
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"742eded1e1dfefd",&
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"1cd7154a904dac4"/
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data colorder/ &
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0,1,2,21,3,4,5,6,7,8,20,10,9,11,12,23,13,28,14,31, &
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15,16,22,26,17,30,18,29,25,32,41,34,19,33,27,36,38,43,42,24, &
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37,39,45,40,35,44,47,46,50,51,53,48,52,56,54,57,55,49,58,61, &
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60,59,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79, &
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80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99, &
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100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119/
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save first,gen
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if( first ) then ! fill the generator matrix
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gen=0
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do i=1,60
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do j=1,15
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read(g(i)(j:j),"(Z1)") istr
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do jj=1, 4
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icol=(j-1)*4+jj
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if( btest(istr,4-jj) ) gen(i,icol)=1
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enddo
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enddo
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enddo
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first=.false.
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endif
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do i=1, 60
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nsum=0
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do j=1, 60
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nsum=nsum+message(j)*gen(i,j)
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enddo
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pchecks(i)=mod(nsum,2)
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enddo
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itmp(1:60)=pchecks
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itmp(61:120)=message(1:60)
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codeword(colorder+1)=itmp(1:120)
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return
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end subroutine encode120
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