mirror of
https://github.com/saitohirga/WSJT-X.git
synced 2025-10-31 04:50:34 -04:00
59 lines
1.4 KiB
Fortran
59 lines
1.4 KiB
Fortran
subroutine encode174_91(message77,codeword)
|
|
!
|
|
! Add a 14-bit CRC to a 77-bit message and return a 174-bit codeword
|
|
!
|
|
use, intrinsic :: iso_c_binding
|
|
use iso_c_binding, only: c_loc,c_size_t
|
|
use crc
|
|
|
|
integer, parameter:: N=174, K=91, M=N-K
|
|
character*91 tmpchar
|
|
integer*1 codeword(N)
|
|
integer*1 gen(M,K)
|
|
integer*1 message77(77),message(K)
|
|
integer*1 pchecks(M)
|
|
integer*1, target :: i1MsgBytes(12)
|
|
include "ldpc_174_91_c_generator.f90"
|
|
logical first
|
|
data first/.true./
|
|
save first,gen
|
|
|
|
if( first ) then ! fill the generator matrix
|
|
gen=0
|
|
do i=1,M
|
|
do j=1,23
|
|
read(g(i)(j:j),"(Z1)") istr
|
|
ibmax=4
|
|
if(j.eq.23) ibmax=3
|
|
do jj=1, ibmax
|
|
icol=(j-1)*4+jj
|
|
if( btest(istr,4-jj) ) gen(i,icol)=1
|
|
enddo
|
|
enddo
|
|
enddo
|
|
first=.false.
|
|
endif
|
|
|
|
! Add 14-bit CRC to form 91-bit message+CRC14
|
|
write(tmpchar,'(77i1)') message77
|
|
tmpchar(78:80)='000'
|
|
i1MsgBytes=0
|
|
read(tmpchar,'(10b8)') i1MsgBytes(1:10)
|
|
ncrc14 = crc14 (c_loc (i1MsgBytes), 12)
|
|
write(tmpchar(78:91),'(b14)') ncrc14
|
|
read(tmpchar,'(91i1)') message
|
|
|
|
do i=1,M
|
|
nsum=0
|
|
do j=1,K
|
|
nsum=nsum+message(j)*gen(i,j)
|
|
enddo
|
|
pchecks(i)=mod(nsum,2)
|
|
enddo
|
|
|
|
codeword(1:K)=message
|
|
codeword(K+1:N)=pchecks
|
|
|
|
return
|
|
end subroutine encode174_91
|