mirror of
https://github.com/saitohirga/WSJT-X.git
synced 2024-11-04 08:21:17 -05:00
For (174,91) code, move CRC generation and testing into encode and decode routines. Make ldpcsim174_91.f90 work with the new encode/decode routines.
This commit is contained in:
Steve Franke
parent
2cdb164446
commit
1a31e5b2d6
@ -1,7 +1,6 @@
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subroutine encode128_90(message77,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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! Add a 13-bit CRC to a 77-bit message and return a 128-bit codeword
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!
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use, intrinsic :: iso_c_binding
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use iso_c_binding, only: c_loc,c_size_t
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@ -1,10 +1,14 @@
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subroutine bpdecode174_91(llr,apmask,maxiterations,decoded,cw,nharderror,iter)
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subroutine bpdecode174_91(llr,apmask,maxiterations,message77,cw,nharderror,iter)
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!
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! A log-domain belief propagation decoder for the (174,91) code.
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!
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use iso_c_binding, only: c_loc,c_size_t
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use crc
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integer, parameter:: N=174, K=91, M=N-K
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integer*1 codeword(N),cw(N),apmask(N)
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integer*1 cw(N),apmask(N)
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integer*1 decoded(K)
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integer*1 message77(77)
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integer nrw(M),ncw
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integer Nm(7,M)
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integer Mn(3,N) ! 3 checks per bit
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integer synd(M)
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@ -14,7 +18,6 @@ real tanhtoc(7,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_174_91_c_reordered_parity.f90"
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@ -52,15 +55,14 @@ do iter=0,maxiterations
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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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if( ncheck .eq. 0 ) then ! we have a codeword - if crc is good, return it
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decoded=cw(1:K)
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call chkcrc14a(decoded,nbadcrc)
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nharderror=count( (2*cw-1)*llr .lt. 0.0 )
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if(nbadcrc.eq.0) then
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message77=decoded(1:77)
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return
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endif
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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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@ -1,15 +1,18 @@
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subroutine encode174_91(message,codeword)
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! Encode an 91-bit message and return a 174-bit codeword.
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! The generator matrix has dimensions (83,91).
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! The code is a (174,91) regular ldpc code with column weight 3.
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subroutine encode174_91(message77,codeword)
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!
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! Add a 14-bit CRC to a 77-bit message and return a 174-bit codeword
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!
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use, intrinsic :: iso_c_binding
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use iso_c_binding, only: c_loc,c_size_t
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use crc
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integer, parameter:: N=174, K=91, M=N-K
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character*91 tmpchar
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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 message77(77),message(K)
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integer*1 pchecks(M)
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integer*1, target :: i1MsgBytes(12)
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include "ldpc_174_91_c_generator.f90"
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logical first
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data first/.true./
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@ -31,6 +34,15 @@ if( first ) then ! fill the generator matrix
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first=.false.
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endif
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! Add 14-bit CRC to form 91-bit message+CRC14
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write(tmpchar,'(77i1)') message77
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tmpchar(78:80)='000'
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i1MsgBytes=0
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read(tmpchar,'(10b8)') i1MsgBytes(1:10)
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ncrc14 = crc14 (c_loc (i1MsgBytes), 12)
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write(tmpchar(78:91),'(b14)') ncrc14
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read(tmpchar,'(91i1)') message
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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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@ -7,20 +7,18 @@ integer, parameter:: N=174, K=91, M=N-K
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character*22 msg,msgsent,msgreceived
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character*8 arg
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character*6 grid
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character*96 tmpchar
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integer*1, allocatable :: codeword(:), decoded(:), message(:)
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integer*1, target:: i1Msg8BitBytes(12)
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integer*1 msgbits(K)
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integer*1 msgbits(77)
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integer*1 message77(77)
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integer*1 apmask(N), cw(N)
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integer*2 checksum
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integer*4 i4Msg6BitWords(13)
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integer nerrtot(N),nerrdec(N),nmpcbad(K)
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logical checksumok
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integer nerrtot(0:N),nerrdec(0:N)
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real*8, allocatable :: rxdata(:)
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real, allocatable :: llr(:)
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nerrtot=0
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nerrdec=0
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nmpcbad=0 ! Used to collect the number of errors in the message+crc part of the codeword
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nargs=iargc()
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if(nargs.ne.4) then
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@ -54,73 +52,31 @@ allocate ( rxdata(N), llr(N) )
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call unpackmsg(i4Msg6BitWords,msgsent,.false.,grid) !Unpack to get msgsent
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write(*,*) "message sent ",msgsent
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i4=0
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ik=0
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im=0
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do i=1,12
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nn=i4Msg6BitWords(i)
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do j=1, 6
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ik=ik+1
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i4=i4+i4+iand(1,ishft(nn,j-6))
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i4=iand(i4,255)
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if(ik.eq.8) then
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im=im+1
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! if(i4.gt.127) i4=i4-256
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i1Msg8BitBytes(im)=i4
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ik=0
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endif
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enddo
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enddo
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i1Msg8BitBytes(10:12)=0
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checksum = crc14 (c_loc (i1Msg8BitBytes), 12)
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! For reference, the next 3 lines show how to check the CRC
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i1Msg8BitBytes(11)=checksum/256
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i1Msg8BitBytes(12)=iand (checksum,255)
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checksumok = crc14_check(c_loc (i1Msg8BitBytes), 12)
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if( checksumok ) write(*,*) 'Good checksum'
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! K=91, For now:
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! msgbits(1:72) JT message bits
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! msgbits(73:77) 5 free message bits (set to 0)
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! msgbits(78:91) CRC14
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mbit=0
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do i=1, 9
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i1=i1Msg8BitBytes(i)
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do ibit=1,8
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mbit=mbit+1
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msgbits(mbit)=iand(1,ishft(i1,ibit-8))
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enddo
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enddo
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msgbits(73:77)=0 ! the five extra message bits go here
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i1=i1Msg8BitBytes(11) ! First 6 bits of crc12 are LSB of this byte
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do ibit=1,6
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msgbits(77+ibit)=iand(1,ishft(i1,ibit-6))
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enddo
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i1=i1Msg8BitBytes(12) ! Now shift in last 8 bits of the CRC
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do ibit=1,8
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msgbits(83+ibit)=iand(1,ishft(i1,ibit-8))
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enddo
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tmpchar=' '
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write(tmpchar,'(12b6.6)') i4Msg6BitWords(1:12)
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tmpchar(73:77)='00000' !i5bit
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read(tmpchar,'(77i1)') msgbits(1:77)
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write(*,*) 'message'
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write(*,'(12(8i1,1x))') msgbits
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write(*,'(28i1,1x,28i1,1x,16i1,1x,5i1)') msgbits
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! msgbits is the 77-bit message, codeword is 174 bits
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call encode174_91(msgbits,codeword)
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call init_random_seed()
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! call sgran()
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write(*,*) 'codeword'
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write(*,'(22(8i1,1x))') codeword
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write(*,*) "Eb/N0 SNR2500 ngood nundetected nbadcrc sigma"
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write(*,*) "Eb/N0 SNR2500 ngood nundetected sigma psymerr"
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do idb = 20,-10,-1
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!do idb = 0,0,-1
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db=idb/2.0-1.0
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sigma=1/sqrt( 2*rate*(10**(db/10.0)) )
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ngood=0
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nue=0
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nbadcrc=0
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nberr=0
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nsumerr=0
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do itrial=1, ntrials
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! Create a realization of a noisy received word
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do i=1,N
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@ -131,7 +87,6 @@ do idb = 20,-10,-1
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if( rxdata(i)*(2*codeword(i)-1.0) .lt. 0 ) nerr=nerr+1
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enddo
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if(nerr.ge.1) nerrtot(nerr)=nerrtot(nerr)+1
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nberr=nberr+nerr
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rxav=sum(rxdata)/N
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rx2av=sum(rxdata*rxdata)/N
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@ -150,38 +105,26 @@ do idb = 20,-10,-1
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apmask(1:nap)=1
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! max_iterations is max number of belief propagation iterations
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call bpdecode174_91(llr, apmask, max_iterations, decoded, cw, nharderrors,niterations)
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if( ndepth .ge. 0 .and. nharderrors .lt. 0 ) call osd174_91(llr, apmask, ndepth, decoded, cw, nharderrors, dmin)
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call bpdecode174_91(llr, apmask, max_iterations, message77, cw, nharderrors,niterations)
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if( ndepth .ge. 0 .and. nharderrors .lt. 0 ) call osd174_91(llr, apmask, ndepth, message77, cw, nharderrors, dmin)
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! If the decoder finds a valid codeword, nharderrors will be .ge. 0.
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if( nharderrors .ge. 0 ) then
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call extractmessage174_91(decoded,msgreceived,ncrcflag)
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if( ncrcflag .ne. 1 ) then
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nbadcrc=nbadcrc+1
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endif
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nueflag=0
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nerrmpc=0
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do i=1,K ! find number of errors in message+crc part of codeword
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if( msgbits(i) .ne. decoded(i) ) then
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nueflag=1
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nerrmpc=nerrmpc+1
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endif
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enddo
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if(nerrmpc.ge.1) nmpcbad(nerrmpc)=nmpcbad(nerrmpc)+1
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if( ncrcflag .eq. 1 ) then
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if( nueflag .eq. 0 ) then
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ngood=ngood+1
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if(nerr.ge.1) nerrdec(nerr)=nerrdec(nerr)+1
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else if( nueflag .eq. 1 ) then
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nue=nue+1;
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endif
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call extractmessage77(message77,msgreceived)
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nhw=count(cw.ne.codeword)
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if(nhw.eq.0) then ! this is a good decode
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ngood=ngood+1
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nerrdec(nerr)=nerrdec(nerr)+1
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else
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nue=nue+1
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endif
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endif
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nsumerr=nsumerr+nerr
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enddo
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baud=12000/1920
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snr2500=db+10.0*log10((baud/2500.0))
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pberr=real(nberr)/(real(ntrials*N))
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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
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pberr=real(nsumerr)/(real(ntrials*N))
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write(*,"(f4.1,4x,f5.1,1x,i8,1x,i8,8x,f5.2,8x,e10.3)") db,SNR2500,ngood,nue,ss,pberr
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enddo
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@ -190,10 +133,5 @@ do i=1,174
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write(23,'(i4,2x,i10,i10,f10.2)') i,nerrdec(i),nerrtot(i),real(nerrdec(i))/real(nerrtot(i)+1e-10)
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enddo
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close(23)
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open(unit=25,file='nmpcbad.dat',status='unknown')
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do i=1,87
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write(25,'(i4,2x,i10)') i,nmpcbad(i)
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enddo
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close(25)
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end program ldpcsim174_91
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@ -1,4 +1,4 @@
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subroutine osd174_91(llr,apmask,ndeep,decoded,cw,nhardmin,dmin)
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subroutine osd174_91(llr,apmask,ndeep,message77,cw,nhardmin,dmin)
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!
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! An ordered-statistics decoder for the (174,91) code.
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!
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@ -11,6 +11,7 @@ integer*1 r2pat(N-K)
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integer indices(N),nxor(N)
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integer*1 cw(N),ce(N),c0(N),hdec(N)
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integer*1 decoded(K)
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integer*1 message77(77)
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integer indx(N)
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real llr(N),rx(N),absrx(N)
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@ -247,6 +248,10 @@ endif
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cw(indices)=cw
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hdec(indices)=hdec
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decoded=cw(1:K)
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call chkcrc14a(decoded,nbadcrc)
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message77=decoded(1:77)
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if(nbadcrc.eq.1) nhardmin=-nhardmin
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return
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end subroutine osd174_91
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@ -9,9 +9,8 @@ character*8 arg
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integer*1 codeword(N), message77(77)
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integer*1 apmask(N),cw(N)
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integer*1 msgbits(77)
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integer*2 ncrc13
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integer*4 i4Msg6BitWords(13)
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integer nerrtot(0:N),nerrdec(0:N),nmpcbad(0:K),nbadwt(0:N)
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integer nerrtot(0:N),nerrdec(0:N)
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real*8 rxdata(N), rxavgd(N)
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real llr(N)
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@ -20,8 +19,6 @@ do i=1,NRECENT
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enddo
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nerrtot=0
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nerrdec=0
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nmpcbad=0
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nbadwt=0
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nargs=iargc()
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if(nargs.ne.4) then
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@ -55,7 +52,7 @@ msg="G4WJS K1JT FN20"
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read(tmpchar,'(77i1)') msgbits(1:77)
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write(*,*) 'msgbits'
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write(*,'(28i1,1x,28i1,1x,16i1,1x,5i1,1x,13i1)') msgbits
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write(*,'(28i1,1x,28i1,1x,16i1,1x,5i1)') msgbits
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! msgbits is the 77-bit message, codeword is 128 bits
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call encode128_90(msgbits,codeword)
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@ -109,7 +106,7 @@ do idb = 14,-6,-1
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! If the decoder finds a valid codeword, nharderrors will be .ge. 0.
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if( nharderrors .ge. 0 ) then
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call extractmessage77(message77,msgreceived)
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nhw=count(message77.ne.codeword(1:77))
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nhw=count(cw.ne.codeword)
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if(nhw.eq.0) then ! this is a good decode
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ngood=ngood+1
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nerrdec(nerr)=nerrdec(nerr)+1
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@ -132,10 +129,4 @@ do i=0,N
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enddo
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close(23)
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open(unit=25,file='badcrc_hamming_weight.dat',status='unknown')
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do i=0,N
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write(25,'(i4,2x,i10)') i,nbadwt(i)
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enddo
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close(25)
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end program ldpcsim
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