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Add routines that will implement 77-bit messages for MSK144. Initial tests will use a (128,90) code.
This commit is contained in:
Steve Franke
parent
a5837bd5c7
commit
41920af89a
113
lib/bpdecode128_90.f90
Normal file
113
lib/bpdecode128_90.f90
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@ -0,0 +1,113 @@
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subroutine bpdecode128_90(llr,apmask,maxiterations,decoded,cw,nharderror,iter)
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!
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! A log-domain belief propagation decoder for the (128,90) code.
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!
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integer, parameter:: N=128, K=90, M=N-K
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integer*1 codeword(N),cw(N),apmask(N)
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integer*1 decoded(K)
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integer Nm(11,M)
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integer Mn(3,N) ! 3 checks per bit
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integer synd(M)
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real tov(3,N)
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real toc(11,M)
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real tanhtoc(11,M)
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real zn(N)
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real llr(N)
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real Tmn
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integer nrw(M),ncw
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include "ldpc_128_90_reordered_parity.f90"
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decoded=0
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toc=0
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tov=0
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tanhtoc=0
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! initialize messages to checks
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do j=1,M
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do i=1,nrw(j)
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toc(i,j)=llr((Nm(i,j)))
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enddo
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enddo
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ncnt=0
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do iter=0,maxiterations
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! Update bit log likelihood ratios (tov=0 in iteration 0).
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do i=1,N
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if( apmask(i) .ne. 1 ) then
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zn(i)=llr(i)+sum(tov(1:ncw,i))
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else
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zn(i)=llr(i)
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endif
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enddo
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! Check to see if we have a codeword (check before we do any iteration).
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cw=0
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where( zn .gt. 0. ) cw=1
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ncheck=0
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do i=1,M
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synd(i)=sum(cw(Nm(1:nrw(i),i)))
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if( mod(synd(i),2) .ne. 0 ) ncheck=ncheck+1
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! if( mod(synd(i),2) .ne. 0 ) write(*,*) 'check ',i,' unsatisfied'
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enddo
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! write(*,*) 'number of unsatisfied parity checks ',ncheck
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if( ncheck .eq. 0 ) then ! we have a codeword - reorder the columns and return it
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codeword=cw
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decoded=codeword(1:K)
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nerr=0
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do i=1,N
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if( (2*cw(i)-1)*llr(i) .lt. 0.0 ) nerr=nerr+1
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enddo
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nharderror=nerr
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return
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endif
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if( iter.gt.0 ) then ! this code block implements an early stopping criterion
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! if( iter.gt.10000 ) then ! this code block implements an early stopping criterion
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nd=ncheck-nclast
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if( nd .lt. 0 ) then ! # of unsatisfied parity checks decreased
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ncnt=0 ! reset counter
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else
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ncnt=ncnt+1
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endif
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! write(*,*) iter,ncheck,nd,ncnt
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if( ncnt .ge. 5 .and. iter .ge. 10 .and. ncheck .gt. 15) then
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nharderror=-1
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return
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endif
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endif
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nclast=ncheck
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! Send messages from bits to check nodes
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do j=1,M
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do i=1,nrw(j)
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ibj=Nm(i,j)
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toc(i,j)=zn(ibj)
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do kk=1,ncw ! subtract off what the bit had received from the check
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if( Mn(kk,ibj) .eq. j ) then
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toc(i,j)=toc(i,j)-tov(kk,ibj)
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endif
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enddo
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enddo
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enddo
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! send messages from check nodes to variable nodes
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do i=1,M
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tanhtoc(1:7,i)=tanh(-toc(1:7,i)/2)
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enddo
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do j=1,N
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do i=1,ncw
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ichk=Mn(i,j) ! Mn(:,j) are the checks that include bit j
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Tmn=product(tanhtoc(1:nrw(ichk),ichk),mask=Nm(1:nrw(ichk),ichk).ne.j)
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call platanh(-Tmn,y)
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! y=atanh(-Tmn)
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tov(i,j)=2*y
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enddo
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enddo
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enddo
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nharderror=-1
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return
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end subroutine bpdecode128_90
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31
lib/crc13.cpp
Normal file
31
lib/crc13.cpp
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@ -0,0 +1,31 @@
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#include <boost/crc.hpp>
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#include <boost/config.hpp>
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extern "C"
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{
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short crc13 (unsigned char const * data, int length);
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bool crc13_check (unsigned char const * data, int length);
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}
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#define POLY 0x15D7
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#ifdef BOOST_NO_CXX11_CONSTEXPR
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#define TRUNCATED_POLYNOMIAL POLY
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#else
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namespace
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{
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unsigned long constexpr TRUNCATED_POLYNOMIAL = POLY;
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}
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#endif
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// assumes CRC is last 13 bits of the data and is set to zero
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// caller should assign the returned CRC into the message in big endian byte order
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short crc13 (unsigned char const * data, int length)
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{
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return boost::augmented_crc<13, TRUNCATED_POLYNOMIAL> (data, length);
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}
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bool crc13_check (unsigned char const * data, int length)
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{
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return !boost::augmented_crc<13, TRUNCATED_POLYNOMIAL> (data, length);
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}
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46
lib/encode128_90.f90
Normal file
46
lib/encode128_90.f90
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@ -0,0 +1,46 @@
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subroutine encode128_90(message,codeword)
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! Encode an 90-bit message and return a 128-bit codeword.
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! The generator matrix has dimensions (38,90).
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! The code is a (128,90) regular ldpc code with column weight 3.
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!
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integer, parameter:: N=128, K=90, M=N-K
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integer*1 codeword(N)
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integer*1 gen(M,K)
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integer*1 message(K)
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integer*1 pchecks(M)
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include "ldpc_128_90_generator.f90"
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logical first
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data first/.true./
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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,M
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do j=1,23
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read(g(i)(j:j),"(Z1)") istr
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ibmax=4
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if(j.eq.23) ibmax=2
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do jj=1, ibmax
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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,M
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nsum=0
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do j=1,K
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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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codeword(1:K)=message
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codeword(K+1:N)=pchecks
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return
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end subroutine encode128_90
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34
lib/extractmessage128_90.f90
Normal file
34
lib/extractmessage128_90.f90
Normal file
@ -0,0 +1,34 @@
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subroutine extractmessage128_90(decoded,msgreceived,ncrcflag)
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use iso_c_binding, only: c_loc,c_size_t
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use crc
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use packjt
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character*22 msgreceived
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character*90 cbits
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integer*1 decoded(90)
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integer*1, target:: i1Dec8BitBytes(12)
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integer*4 i4Dec6BitWords(12)
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! Write decoded bits into cbits: 77-bit message plus 13-bit CRC
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write(cbits,1000) decoded
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1000 format(90i1)
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read(cbits,1001) i1Dec8BitBytes
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1001 format(12b8)
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read(cbits,1002) ncrc13 !Received CRC12
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1002 format(77x,b13)
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i1Dec8BitBytes(10)=iand(i1Dec8BitBytes(10),128+64+32+16+8)
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i1Dec8BitBytes(11:12)=0
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icrc13=crc13(c_loc(i1Dec8BitBytes),12) !CRC13 computed from 77 msg bits
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if(ncrc13.eq.icrc13 .or. sum(decoded(57:87)).eq.0) then !### Kludge ### ???
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! CRC13 checks out --- unpack 72-bit message
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read(cbits,'(12b6)') i4Dec6BitWords
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call unpackmsg(i4Dec6BitWords,msgreceived,.false.,' ')
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ncrcflag=1
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else
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msgreceived=' '
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ncrcflag=-1
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endif
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return
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end subroutine extractmessage128_90
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41
lib/ldpc_128_90_generator.f90
Normal file
41
lib/ldpc_128_90_generator.f90
Normal file
@ -0,0 +1,41 @@
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character*23 g(38)
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data g/ &
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"a08ea80879050a5e94da994", &
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"59f3b48040ca089c81ee880", &
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"e4070262802e31b7b17d3dc", &
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"95cbcbaf032dc3d960bacc8", &
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"c4d79b5dcc21161a254ffbc", &
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"93fde9cdbf2622a70868424", &
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"e73b888bb1b01167379ba28", &
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"45a0d0a0f39a7ad2439949c", &
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"759acef19444bcad79c4964", &
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"71eb4dddf4f5ed9e2ea17e0", &
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"80f0ad76fb247d6b4ca8d38", &
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"184fff3aa1b82dc66640104", &
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"ca4e320bb382ed14cbb1094", &
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"52514447b90e25b9e459e28", &
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"dd10c1666e071956bd0df38", &
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"99c332a0b792a2da8ef1ba8", &
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"7bd9f688e7ed402e231aaac", &
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"00fcad76eb647d6a0ca8c38", &
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"6ac8d0499c43b02eed78d70", &
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"2c2c764baf795b4788db010", &
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"0e907bf9e280d2624823dd0", &
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"b857a6e315afd8c1c925e64", &
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"8deb58e22d73a141cae3778", &
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"22d3cb80d92d6ac132dfe08", &
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"754763877b28c187746855c", &
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"1d1bb7cf6953732e04ebca4", &
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"2c65e0ea4466ab9f5e1deec", &
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"6dc530ca37fc916d1f84870", &
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"49bccbbee152355be7ac984", &
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"e8387f3f4367cf45a150448", &
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"8ce25e03d67d51091c81884", &
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"b798012ffa40a93852752c8", &
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"2e43307933adfca37adc3c8", &
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"ca06e0a42ca1ec782d6c06c", &
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"c02b762927556a7039e638c", &
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"4a3e9b7d08b6807f8619fac", &
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"45e8030f68997bb68544424", &
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"7e79362c16773efc6482e30"/
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176
lib/ldpc_128_90_reordered_parity.f90
Normal file
176
lib/ldpc_128_90_reordered_parity.f90
Normal file
@ -0,0 +1,176 @@
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data Mn/ &
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21, 34, 36, &
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1, 8, 28, &
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2, 9, 37, &
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3, 7, 19, &
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4, 16, 32, &
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2, 5, 22, &
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6, 13, 25, &
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10, 31, 33, &
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11, 24, 27, &
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12, 15, 23, &
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14, 18, 26, &
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17, 20, 29, &
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17, 30, 34, &
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6, 34, 35, &
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1, 10, 30, &
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3, 18, 23, &
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4, 12, 25, &
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5, 28, 36, &
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7, 14, 21, &
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8, 15, 31, &
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9, 27, 32, &
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11, 19, 35, &
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13, 16, 37, &
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20, 24, 38, &
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21, 22, 26, &
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12, 29, 33, &
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1, 17, 35, &
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2, 28, 30, &
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3, 10, 32, &
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4, 8, 36, &
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5, 19, 29, &
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6, 20, 27, &
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7, 22, 37, &
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9, 11, 33, &
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13, 24, 26, &
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14, 31, 34, &
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15, 16, 25, &
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13, 18, 38, &
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8, 20, 23, &
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1, 32, 33, &
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2, 17, 19, &
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3, 24, 34, &
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4, 7, 38, &
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5, 11, 31, &
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6, 18, 21, &
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9, 15, 36, &
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10, 16, 28, &
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12, 26, 30, &
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14, 27, 29, &
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22, 25, 35, &
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23, 30, 32, &
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4, 11, 37, &
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1, 14, 23, &
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2, 8, 25, &
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3, 13, 27, &
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5, 10, 37, &
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6, 16, 31, &
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7, 15, 18, &
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9, 22, 24, &
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12, 19, 36, &
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17, 26, 38, &
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20, 21, 33, &
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20, 28, 35, &
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4, 29, 34, &
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1, 26, 36, &
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2, 23, 34, &
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3, 9, 38, &
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5, 6, 17, &
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7, 27, 35, &
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8, 14, 32, &
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10, 15, 22, &
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11, 18, 29, &
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12, 13, 28, &
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16, 19, 33, &
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21, 25, 31, &
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24, 30, 37, &
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1, 3, 21, &
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2, 18, 31, &
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4, 6, 9, &
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5, 8, 33, &
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7, 29, 32, &
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10, 13, 19, &
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11, 22, 23, &
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12, 27, 34, &
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14, 15, 30, &
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16, 27, 38, &
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17, 28, 37, &
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20, 25, 26, &
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5, 24, 35, &
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3, 6, 36, &
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1, 12, 31, &
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2, 4, 33, &
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3, 16, 30, &
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1, 2, 24, &
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5, 23, 27, &
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6, 28, 32, &
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7, 17, 36, &
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8, 22, 38, &
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9, 18, 20, &
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10, 21, 29, &
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11, 13, 34, &
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4, 14, 20, &
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11, 30, 38, &
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14, 35, 37, &
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15, 19, 26, &
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3, 28, 29, &
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7, 8, 9, &
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5, 18, 34, &
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13, 15, 17, &
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12, 16, 35, &
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10, 23, 25, &
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19, 21, 37, &
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17, 27, 31, &
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24, 25, 36, &
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1, 18, 19, &
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6, 26, 33, &
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22, 31, 32, &
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3, 20, 22, &
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4, 21, 27, &
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2, 13, 29, &
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6, 7, 12, &
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15, 24, 32, &
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9, 25, 30, &
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23, 37, 38, &
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5, 16, 26, &
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11, 14, 28, &
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33, 36, 38, &
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8, 10, 35/
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data Nm/ &
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2, 15, 27, 40, 53, 65, 77, 91, 94, 115, 0, &
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3, 6, 28, 41, 54, 66, 78, 92, 94, 120, 0, &
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4, 16, 29, 42, 55, 67, 77, 90, 93, 106, 118, &
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5, 17, 30, 43, 52, 64, 79, 92, 102, 119, 0, &
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6, 18, 31, 44, 56, 68, 80, 89, 95, 108, 125, &
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7, 14, 32, 45, 57, 68, 79, 90, 96, 116, 121, &
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4, 19, 33, 43, 58, 69, 81, 97, 107, 121, 0, &
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2, 20, 30, 39, 54, 70, 80, 98, 107, 128, 0, &
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3, 21, 34, 46, 59, 67, 79, 99, 107, 123, 0, &
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8, 15, 29, 47, 56, 71, 82, 100, 111, 128, 0, &
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9, 22, 34, 44, 52, 72, 83, 101, 103, 126, 0, &
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10, 17, 26, 48, 60, 73, 84, 91, 110, 121, 0, &
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7, 23, 35, 38, 55, 73, 82, 101, 109, 120, 0, &
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11, 19, 36, 49, 53, 70, 85, 102, 104, 126, 0, &
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10, 20, 37, 46, 58, 71, 85, 105, 109, 122, 0, &
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5, 23, 37, 47, 57, 74, 86, 93, 110, 125, 0, &
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12, 13, 27, 41, 61, 68, 87, 97, 109, 113, 0, &
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11, 16, 38, 45, 58, 72, 78, 99, 108, 115, 0, &
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4, 22, 31, 41, 60, 74, 82, 105, 112, 115, 0, &
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12, 24, 32, 39, 62, 63, 88, 99, 102, 118, 0, &
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1, 19, 25, 45, 62, 75, 77, 100, 112, 119, 0, &
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6, 25, 33, 50, 59, 71, 83, 98, 117, 118, 0, &
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10, 16, 39, 51, 53, 66, 83, 95, 111, 124, 0, &
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9, 24, 35, 42, 59, 76, 89, 94, 114, 122, 0, &
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7, 17, 37, 50, 54, 75, 88, 111, 114, 123, 0, &
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11, 25, 35, 48, 61, 65, 88, 105, 116, 125, 0, &
|
||||
9, 21, 32, 49, 55, 69, 84, 86, 95, 113, 119, &
|
||||
2, 18, 28, 47, 63, 73, 87, 96, 106, 126, 0, &
|
||||
12, 26, 31, 49, 64, 72, 81, 100, 106, 120, 0, &
|
||||
13, 15, 28, 48, 51, 76, 85, 93, 103, 123, 0, &
|
||||
8, 20, 36, 44, 57, 75, 78, 91, 113, 117, 0, &
|
||||
5, 21, 29, 40, 51, 70, 81, 96, 117, 122, 0, &
|
||||
8, 26, 34, 40, 62, 74, 80, 92, 116, 127, 0, &
|
||||
1, 13, 14, 36, 42, 64, 66, 84, 101, 108, 0, &
|
||||
14, 22, 27, 50, 63, 69, 89, 104, 110, 128, 0, &
|
||||
1, 18, 30, 46, 60, 65, 90, 97, 114, 127, 0, &
|
||||
3, 23, 33, 52, 56, 76, 87, 104, 112, 124, 0, &
|
||||
24, 38, 43, 61, 67, 86, 98, 103, 124, 127, 0/
|
||||
|
||||
data nrw/ &
|
||||
10,10,11,10,11,11,10,10,10,10,10,10,10,10,10,10,10,10, &
|
||||
10,10,10,10,10,10,10,10,11,10,10,10,10,10,10,10,10,10, &
|
||||
10,10/
|
||||
|
||||
ncw=3
|
||||
169
lib/ldpcsim128_90.f90
Normal file
169
lib/ldpcsim128_90.f90
Normal file
@ -0,0 +1,169 @@
|
||||
program ldpcsim
|
||||
|
||||
use, intrinsic :: iso_c_binding
|
||||
use iso_c_binding, only: c_loc,c_size_t
|
||||
use crc
|
||||
use packjt
|
||||
integer, parameter:: NRECENT=10, N=128, K=90, M=N-K
|
||||
character*12 recent_calls(NRECENT)
|
||||
character*22 msg,msgsent,msgreceived
|
||||
character*96 tmpchar
|
||||
character*8 arg
|
||||
integer*1, allocatable :: codeword(:), decoded(:), message(:)
|
||||
integer*1, target:: i1Msg8BitBytes(12)
|
||||
integer*1 i1hash(4)
|
||||
integer*1 msgbits(80)
|
||||
integer*4 i4Msg6BitWords(13)
|
||||
integer ihash
|
||||
integer nerrtot(N),nerrdec(N),nmpcbad(K)
|
||||
real*8, allocatable :: lratio(:), rxdata(:), rxavgd(:)
|
||||
real, allocatable :: yy(:), llr(:)
|
||||
equivalence(ihash,i1hash)
|
||||
|
||||
do i=1,NRECENT
|
||||
recent_calls(i)=' '
|
||||
enddo
|
||||
nerrtot=0
|
||||
nerrdec=0
|
||||
|
||||
nargs=iargc()
|
||||
if(nargs.ne.4) then
|
||||
print*,'Usage: ldpcsim niter navg #trials s '
|
||||
print*,'eg: ldpcsim 10 1 1000 0.75'
|
||||
return
|
||||
endif
|
||||
call getarg(1,arg)
|
||||
read(arg,*) max_iterations
|
||||
call getarg(2,arg)
|
||||
read(arg,*) navg
|
||||
call getarg(3,arg)
|
||||
read(arg,*) ntrials
|
||||
call getarg(4,arg)
|
||||
read(arg,*) s
|
||||
|
||||
! don't count hash bits as data bits
|
||||
rate=real(K)/real(N)
|
||||
|
||||
write(*,*) "rate: ",rate
|
||||
|
||||
write(*,*) "niter= ",max_iterations," navg= ",navg," s= ",s
|
||||
|
||||
allocate ( codeword(N), decoded(K), message(K) )
|
||||
allocate ( lratio(N), rxdata(N), rxavgd(N), yy(N), llr(N) )
|
||||
|
||||
msg="K9AN K1JT EN50"
|
||||
call packmsg(msg,i4Msg6BitWords,itype,.false.) !Pack into 12 6-bit bytes
|
||||
call unpackmsg(i4Msg6BitWords,msgsent,.false.,' ') !Unpack to get msgsent
|
||||
write(*,*) "message sent ",msgsent
|
||||
|
||||
tmpchar=' '
|
||||
write(tmpchar,'(12b6.6)') i4Msg6BitWords
|
||||
tmpchar(73:77)="00000" !i5bit
|
||||
write(*,*) tmpchar
|
||||
|
||||
read(tmpchar,'(10b8)') i1Msg8BitBytes(1:10)
|
||||
write(*,*) i1Msg8BitBytes
|
||||
|
||||
i1Msg8BitBytes(10:12)=0
|
||||
checksum = crc13 (c_loc (i1Msg8ZBitZBytes), 12)
|
||||
i1Msg8BitBytes(11)=checksum/256
|
||||
i1Msg8BitBytes(12)=iand (checksum,255)
|
||||
checksumok = crc13_check(c_loc (i1Msg8ZBitBytes), 12)
|
||||
if( checksumok ) write(*,*) 'Good checksum'
|
||||
|
||||
write(tmpchar,'(12b8.8)') i1Msg8BitBytes(1:9)
|
||||
read(tmpchar,'(77b)') msgbits(1:77)
|
||||
read(tmpchar(84:96),'(6b)') msgbits(78:90)
|
||||
call encode_128_90(msgbits,codeword)
|
||||
|
||||
call init_random_seed()
|
||||
|
||||
write(*,*) "Eb/N0 SNR2500 ngood nundetected nbadhash sigma"
|
||||
do idb = -6, 14
|
||||
db=idb/2.0-1.0
|
||||
sigma=1/sqrt( 2*rate*(10**(db/10.0)) )
|
||||
ngood=0
|
||||
nue=0
|
||||
nbadhash=0
|
||||
|
||||
do itrial=1, ntrials
|
||||
rxavgd=0d0
|
||||
do iav=1,navg
|
||||
call sgran()
|
||||
! Create a realization of a noisy received word
|
||||
do i=1,N
|
||||
rxdata(i) = 2.0*codeword(i)-1.0 + sigma*gran()
|
||||
enddo
|
||||
rxavgd=rxavgd+rxdata
|
||||
enddo
|
||||
rxdata=rxavgd
|
||||
nerr=0
|
||||
do i=1,N
|
||||
if( rxdata(i)*(2*codeword(i)-1.0) .lt. 0 ) nerr=nerr+1
|
||||
enddo
|
||||
nerrtot(nerr)=nerrtot(nerr)+1
|
||||
|
||||
! Correct signal normalization is important for this decoder.
|
||||
rxav=sum(rxdata)/N
|
||||
rx2av=sum(rxdata*rxdata)/N
|
||||
rxsig=sqrt(rx2av-rxav*rxav)
|
||||
rxdata=rxdata/rxsig
|
||||
! To match the metric to the channel, s should be set to the noise standard deviation.
|
||||
! For now, set s to the value that optimizes decode probability near threshold.
|
||||
! The s parameter can be tuned to trade a few tenth's dB of threshold for an order of
|
||||
! magnitude in UER
|
||||
if( s .lt. 0 ) then
|
||||
ss=sigma
|
||||
else
|
||||
ss=s
|
||||
endif
|
||||
|
||||
llr=2.0*rxdata/(ss*ss)
|
||||
lratio=exp(llr)
|
||||
yy=rxdata
|
||||
|
||||
! max_iterations is max number of belief propagation iterations
|
||||
call bpdecode128_90(llr, apmask, max_iterations, decoded, cw, nharderrors, niterations)
|
||||
|
||||
! If the decoder finds a valid codeword, nharderrors will be .ge. 0.
|
||||
if( nharderrors .ge. 0 ) then
|
||||
call extractmessage1128_90(decoded,msgreceived,ncrcflag)
|
||||
if( nncrcflag .ne. 1 ) then
|
||||
nbadcrc=nbadcrc+1
|
||||
endif
|
||||
|
||||
nueflag=0
|
||||
nerrmpc=0
|
||||
do i=1,K
|
||||
if( msgbits(i) .ne. decoded(i) ) then
|
||||
nueflag=1
|
||||
nerrmpc=nerrmpc+1
|
||||
endif
|
||||
enddo
|
||||
if(nerrmpc.ge.1) nmpcbad(nerrmpc)=nmpcbad(nerrmpc)+1
|
||||
if( ncrcflag .eq. 1) then
|
||||
ngood=ngood+1
|
||||
if(nerr.ge.1) nerrdec(nerr)=nerrdec(nerr)+1
|
||||
else if(nueflag .eq. 1 ) then
|
||||
nue=nue+1;
|
||||
endif
|
||||
endif
|
||||
enddo
|
||||
snr2500=db-3.5
|
||||
pberr=real(nberr)/real(ntrials*N)
|
||||
write(*,"(f4.1,4x,f5.1,1x,i8,1x,i8,1x,i8,8x,f5.2,8x,e10.3)") db,snr2500,ngood,nue,nbadcrc,ss,pberr
|
||||
|
||||
enddo
|
||||
|
||||
open(unit=23,file='nerrhisto.dat',status='unknown')
|
||||
do i=1,N
|
||||
write(23,'(i4,2x,i10,i10,f10.2)') i,nerrdec(i),nerrtot(i),real(nerrdec(i))/real(nerrtot(i)+1e-10)
|
||||
enddo
|
||||
close(23)
|
||||
open(unit=25,file='nmpcbad.dat',status='unknown')
|
||||
do i=1,K
|
||||
write(25,'(i4,2x,i10)') i,nmpcbad(i)
|
||||
enddo
|
||||
close(25)
|
||||
|
||||
end program ldpcsim
|
||||
Loading…
x
Reference in New Issue
Block a user