142 lines
4.0 KiB
Fortran
142 lines
4.0 KiB
Fortran
subroutine encode168(message,codeword)
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! Encode an 84-bit message and return a 168-bit codeword.
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! The generator matrix has dimensions (84,84).
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! The code is a (168,84) 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*21 g(84)
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integer*1 codeword(168)
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integer colorder(168)
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integer*1 gen(84,168)
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integer*1 itmp(168)
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integer*1 message(84)
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integer*1 pchecks(84)
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logical first
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data first/.true./
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data g/ & !parity generator matrix for (168,84) code
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"25c5bf31ef6710fde9a5a", &
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"18038ef7899cd97a77d96", &
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"270dde504dad076c02b1f", &
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"ed37fe12616565bd7d500", &
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"12b99aa49b5367aff3838", &
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"41cc27f2fac8b228aac21", &
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"2265b233a3cff0b9cee24", &
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"292760cd4f7f4a526a2f1", &
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"2b3db4c8bd831911680cc", &
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"cef2b24ce203bdc60b266", &
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"5045a24f9340915d807ab", &
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"3592b7fc60ba85139502e", &
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"9318023145637bd798f0e", &
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"ad796023c3d58d1e6509c", &
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"3da5eab57f040e75d7413", &
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"27466d1d2734d0ff64830", &
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"2ed50bb1ce313bbfb1ab0", &
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"9a616bda01b25b7e6eeaf", &
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"a84c8c1e9df103169d10d", &
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"a40da29b4aca9234a8942", &
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"dd258d02d79a5f209d3d0", &
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"bdfdc06713511997b5621", &
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"25c58f12f4096cd8ead1a", &
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"b2638a478f21e10fe97de", &
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"4051020f43c605d458156", &
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"f651aad14322a526dae35", &
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"a1c147e31bcc9d87330bf", &
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"7524b53d996d48284647b", &
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"a72e7d25ce31b27282e56", &
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"a97f53b019022350b7519", &
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"56106c6340c0810790984", &
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"c63b8e03a57208635992b", &
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"43a3de2aa3a2b1afb65dc", &
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"9baa64847ead03b77fecc", &
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"251cbd1895c8839c46b0d", &
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"2858107dde2d173e13530", &
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"20096f6a870f636b704e7", &
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"7f833ccbceec52dd6eb79", &
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"a9108dd77b8015b75242a", &
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"689666a79e5579c916236", &
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"aa5dff46459787f69911f", &
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"794558c13138d08171089", &
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"c937042857b291cee8dfd", &
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"6f0bf3248bb9a231366b8", &
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"1c09e756ef1656c96f2d2", &
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"073b875b6774e71fba549", &
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"f7d840aafc037febd2d5c", &
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"dcc0e7d0da5fe17c99ad3", &
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"98238ef7819cd97a77d94", &
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"177c2594743477421a262", &
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"7d01a833c19374fbaaa6e", &
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"7bb800216660482ffd1c4", &
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"39a92e2dba0d4cfda98d2", &
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"44b8d88622698816456a8", &
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"791db2334d6d86639229b", &
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"ba6004b086bd38559ea48", &
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"f94558e13138d18170089", &
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"08ba145302cfbed7845ae", &
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"fb8e64b6da3602168ed38", &
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"1045a2cf1340915d8072b", &
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"7592b6fc64ba85139582e", &
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"3eb238a11bc6654452bae", &
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"b69d8d23b1ea170f70214", &
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"0123dfae84fb20462a614", &
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"4131066ad52a339b3c0d7", &
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"fd2cc26850951c43ed737", &
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"a644d4eb7e56c40f0d050", &
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"0c3bd9d5dab7c9ee2c8fc", &
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"4a198b37af56d7ceffb56", &
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"b6e946c429294cf0eed8b", &
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"98384d75e758774f5ff3b", &
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"5c58e5d9a4d0531d37384", &
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"7a0af02719afed521fd06", &
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"8cd5b2e694e7854abbc70", &
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"1a2f061912d0ea19702d3", &
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"6ffbce557d8fa691a50e8", &
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"d43438e2e2ed5d9f14011", &
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"8d502106083b809adba00", &
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"67e22f9b9983aa715964d", &
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"b31f3a3f3c1f406b1fd58", &
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"529f60ac291f827d97331", &
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"476a815424f2e2cbe641f", &
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"81c82c89bcc3feec42458", &
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"2c882d0e281b178e80364"/
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data colorder/0,1,2,3,28,4,5,6,7,8,9,10,11,34,12,32,13,14,15,16,17, &
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18,36,29,42,31,20,21,41,40,30,38,22,19,47,37,46,35,44,33,49,24, &
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43,51,25,26,27,50,52,57,69,54,55,45,59,58,56,61,60,53,48,23,62, &
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63,64,67,66,65,68,39,70,71,72,74,73,75,76,77,80,81,78,82,79,83, &
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84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104, &
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105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125, &
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126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,144,145,146, &
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147,148,149,150,151,152,153,154,155,156,157,158,159,160,161,162,163,164,165,166,167/
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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=1,84
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do j=1,21
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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, 84
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nsum=0
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do j=1, 84
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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(1:84)=pchecks
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itmp(85:168)=message(1:84)
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codeword(colorder+1)=itmp(1:168)
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return
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end subroutine encode168
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