mirror of
https://github.com/saitohirga/WSJT-X.git
synced 2024-11-25 13:48:42 -05:00
2786c20ba2
git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@8585 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
483 lines
12 KiB
Fortran
483 lines
12 KiB
Fortran
subroutine bpdecode204(llr,apmask,maxiterations,decoded,cw,nharderror,iter)
|
|
!
|
|
! A log-domain belief propagation decoder for the (204,68) code.
|
|
!
|
|
integer, parameter:: N=204, K=68, M=N-K
|
|
integer*1 codeword(N),cw(N),apmask(N)
|
|
integer colorder(N)
|
|
integer*1 decoded(K)
|
|
integer Nm(6,M) ! 4, 5, or 6 bits per check
|
|
integer Mn(3,N) ! 3 checks per bit
|
|
integer synd(M)
|
|
real tov(3,N)
|
|
real toc(6,M)
|
|
real tanhtoc(6,M)
|
|
real zn(N)
|
|
real llr(N)
|
|
real Tmn
|
|
integer nrw(M)
|
|
|
|
data colorder/ &
|
|
0, 1, 2, 3, 4, 5, 47, 6, 7, 8, 9, 10, 11, 12, 58, 55, 13, &
|
|
14, 15, 46, 17, 18, 60, 19, 20, 21, 22, 23, 24, 25, 57, 26, 27, 49, &
|
|
28, 52, 65, 16, 50, 73, 59, 68, 63, 29, 30, 31, 32, 51, 62, 56, 66, &
|
|
45, 33, 34, 53, 67, 35, 36, 37, 61, 69, 54, 38, 71, 82, 39, 77, 80, &
|
|
83, 78, 84, 48, 41, 85, 40, 64, 75, 96, 74, 72, 76, 86, 87, 89, 90, &
|
|
79, 70, 92, 99, 93,101, 95,100, 97, 94, 42, 98,103,105,102, 43,104, &
|
|
88, 44,106, 81,107,110,108,111,112,109,113,114,117,118,116,121,115, &
|
|
119,122,120,125,129,124,127,126,128, 91,123,133,131,130,134,135,137, &
|
|
136,132,138,139,140,141,142,143,144,145,146,147,148,149,150,151,152, &
|
|
153,154,155,156,157,158,159,160,161,162,163,164,165,166,167,168,169, &
|
|
170,171,172,173,174,175,176,177,178,179,180,181,182,183,184,185,186, &
|
|
187,188,189,190,191,192,193,194,195,196,197,198,199,200,201,202,203/
|
|
|
|
data Mn/ &
|
|
1, 38, 107, &
|
|
2, 7, 114, &
|
|
3, 48, 106, &
|
|
4, 79, 94, &
|
|
5, 97, 108, &
|
|
6, 50, 122, &
|
|
8, 78, 134, &
|
|
9, 55, 65, &
|
|
10, 62, 100, &
|
|
11, 16, 99, &
|
|
12, 113, 119, &
|
|
13, 31, 125, &
|
|
14, 15, 127, &
|
|
17, 87, 103, &
|
|
18, 81, 98, &
|
|
19, 43, 77, &
|
|
20, 102, 130, &
|
|
21, 36, 111, &
|
|
22, 23, 60, &
|
|
24, 39, 112, &
|
|
25, 37, 42, &
|
|
26, 41, 51, &
|
|
27, 67, 70, &
|
|
28, 64, 136, &
|
|
29, 61, 68, &
|
|
30, 91, 124, &
|
|
32, 80, 121, &
|
|
33, 40, 117, &
|
|
34, 35, 90, &
|
|
44, 88, 93, &
|
|
45, 128, 133, &
|
|
46, 56, 69, &
|
|
47, 49, 52, &
|
|
53, 76, 131, &
|
|
54, 104, 116, &
|
|
57, 84, 86, &
|
|
58, 120, 135, &
|
|
59, 75, 92, &
|
|
63, 71, 109, &
|
|
66, 74, 126, &
|
|
72, 85, 105, &
|
|
73, 82, 95, &
|
|
83, 89, 123, &
|
|
96, 115, 118, &
|
|
101, 110, 129, &
|
|
52, 99, 132, &
|
|
1, 3, 20, &
|
|
2, 77, 89, &
|
|
4, 72, 75, &
|
|
5, 34, 79, &
|
|
6, 24, 130, &
|
|
7, 48, 88, &
|
|
8, 36, 116, &
|
|
9, 71, 114, &
|
|
10, 87, 101, &
|
|
11, 22, 121, &
|
|
12, 50, 64, &
|
|
13, 39, 53, &
|
|
14, 41, 78, &
|
|
15, 68, 96, &
|
|
16, 83, 90, &
|
|
17, 23, 45, &
|
|
18, 47, 126, &
|
|
19, 70, 91, &
|
|
21, 57, 76, &
|
|
25, 110, 117, &
|
|
26, 82, 135, &
|
|
27, 46, 58, &
|
|
28, 37, 56, &
|
|
29, 66, 102, &
|
|
30, 62, 125, &
|
|
31, 85, 93, &
|
|
32, 104, 113, &
|
|
33, 81, 92, &
|
|
35, 100, 118, &
|
|
38, 95, 133, &
|
|
40, 86, 109, &
|
|
42, 61, 124, &
|
|
43, 59, 119, &
|
|
44, 49, 134, &
|
|
51, 97, 122, &
|
|
54, 105, 107, &
|
|
55, 128, 136, &
|
|
60, 67, 84, &
|
|
63, 112, 115, &
|
|
65, 74, 131, &
|
|
69, 80, 94, &
|
|
73, 98, 123, &
|
|
103, 130, 134, &
|
|
46, 106, 111, &
|
|
1, 84, 108, &
|
|
120, 129, 132, &
|
|
65, 75, 127, &
|
|
2, 80, 101, &
|
|
3, 118, 119, &
|
|
4, 52, 124, &
|
|
5, 13, 68, &
|
|
6, 27, 81, &
|
|
7, 51, 76, &
|
|
8, 77, 108, &
|
|
9, 31, 58, &
|
|
10, 18, 57, &
|
|
11, 63, 105, &
|
|
12, 14, 132, &
|
|
15, 56, 123, &
|
|
16, 21, 128, &
|
|
17, 37, 59, &
|
|
19, 85, 126, &
|
|
20, 71, 91, &
|
|
22, 26, 117, &
|
|
23, 79, 98, &
|
|
24, 32, 95, &
|
|
25, 90, 93, &
|
|
28, 49, 109, &
|
|
29, 116, 120, &
|
|
30, 54, 136, &
|
|
33, 53, 107, &
|
|
34, 64, 103, &
|
|
35, 39, 67, &
|
|
36, 71, 73, &
|
|
38, 47, 125, &
|
|
40, 66, 94, &
|
|
41, 70, 104, &
|
|
42, 55, 112, &
|
|
43, 44, 82, &
|
|
29, 45, 88, &
|
|
48, 86, 127, &
|
|
50, 72, 135, &
|
|
60, 74, 96, &
|
|
61, 121, 131, &
|
|
62, 78, 92, &
|
|
69, 100, 133, &
|
|
83, 122, 129, &
|
|
87, 97, 106, &
|
|
89, 102, 113, &
|
|
24, 99, 108, &
|
|
20, 72, 110, &
|
|
111, 115, 117, &
|
|
35, 52, 114, &
|
|
1, 44, 94, &
|
|
2, 23, 107, &
|
|
3, 81, 136, &
|
|
4, 8, 96, &
|
|
5, 37, 70, &
|
|
6, 43, 131, &
|
|
7, 103, 115, &
|
|
9, 94, 122, &
|
|
10, 68, 82, &
|
|
11, 56, 88, &
|
|
12, 46, 126, &
|
|
13, 16, 75, &
|
|
14, 79, 112, &
|
|
15, 47, 110, &
|
|
17, 36, 39, &
|
|
18, 63, 120, &
|
|
19, 22, 55, &
|
|
21, 49, 113, &
|
|
25, 54, 57, &
|
|
26, 89, 125, &
|
|
27, 101, 109, &
|
|
28, 31, 60, &
|
|
30, 74, 97, &
|
|
32, 92, 93, &
|
|
33, 83, 91, &
|
|
34, 58, 121, &
|
|
38, 65, 111, &
|
|
40, 99, 118, &
|
|
3, 41, 61, &
|
|
42, 50, 100, &
|
|
45, 78, 106, &
|
|
48, 95, 129, &
|
|
51, 85, 133, &
|
|
53, 59, 69, &
|
|
11, 62, 66, &
|
|
64, 73, 124, &
|
|
67, 123, 134, &
|
|
76, 104, 132, &
|
|
77, 100, 127, &
|
|
36, 80, 119, &
|
|
84, 102, 135, &
|
|
86, 105, 124, &
|
|
4, 87, 128, &
|
|
90, 106, 116, &
|
|
65, 98, 130, &
|
|
92, 108, 114, &
|
|
1, 52, 121, &
|
|
2, 84, 117, &
|
|
5, 83, 105, &
|
|
6, 15, 63, &
|
|
7, 28, 82, &
|
|
8, 32, 135, &
|
|
9, 104, 134, &
|
|
9, 10, 89, &
|
|
12, 62, 107, &
|
|
13, 40, 103, &
|
|
14, 31, 95, &
|
|
16, 27, 74, &
|
|
17, 90, 132, &
|
|
18, 34, 69, &
|
|
19, 103, 129, &
|
|
20, 76, 87, &
|
|
21, 22, 130, &
|
|
23, 25, 99, &
|
|
24, 101, 126/
|
|
|
|
data Nm/ &
|
|
1, 47, 91, 140, 186, 0, &
|
|
2, 48, 94, 141, 187, 0, &
|
|
3, 47, 95, 142, 168, 0, &
|
|
4, 49, 96, 143, 182, 0, &
|
|
5, 50, 97, 144, 188, 0, &
|
|
6, 51, 98, 145, 189, 0, &
|
|
2, 52, 99, 146, 190, 0, &
|
|
7, 53, 100, 143, 191, 0, &
|
|
8, 54, 101, 147, 192, 193, &
|
|
9, 55, 102, 148, 193, 0, &
|
|
10, 56, 103, 149, 174, 0, &
|
|
11, 57, 104, 150, 194, 0, &
|
|
12, 58, 97, 151, 195, 0, &
|
|
13, 59, 104, 152, 196, 0, &
|
|
13, 60, 105, 153, 189, 0, &
|
|
10, 61, 106, 151, 197, 0, &
|
|
14, 62, 107, 154, 198, 0, &
|
|
15, 63, 102, 155, 199, 0, &
|
|
16, 64, 108, 156, 200, 0, &
|
|
17, 47, 109, 137, 201, 0, &
|
|
18, 65, 106, 157, 202, 0, &
|
|
19, 56, 110, 156, 202, 0, &
|
|
19, 62, 111, 141, 203, 0, &
|
|
20, 51, 112, 136, 204, 0, &
|
|
21, 66, 113, 158, 203, 0, &
|
|
22, 67, 110, 159, 0, 0, &
|
|
23, 68, 98, 160, 197, 0, &
|
|
24, 69, 114, 161, 190, 0, &
|
|
25, 70, 115, 126, 0, 0, &
|
|
26, 71, 116, 162, 0, 0, &
|
|
12, 72, 101, 161, 196, 0, &
|
|
27, 73, 112, 163, 191, 0, &
|
|
28, 74, 117, 164, 0, 0, &
|
|
29, 50, 118, 165, 199, 0, &
|
|
29, 75, 119, 139, 0, 0, &
|
|
18, 53, 120, 154, 179, 0, &
|
|
21, 69, 107, 144, 0, 0, &
|
|
1, 76, 121, 166, 0, 0, &
|
|
20, 58, 119, 154, 0, 0, &
|
|
28, 77, 122, 167, 195, 0, &
|
|
22, 59, 123, 168, 0, 0, &
|
|
21, 78, 124, 169, 0, 0, &
|
|
16, 79, 125, 145, 0, 0, &
|
|
30, 80, 125, 140, 0, 0, &
|
|
31, 62, 126, 170, 0, 0, &
|
|
32, 68, 90, 150, 0, 0, &
|
|
33, 63, 121, 153, 0, 0, &
|
|
3, 52, 127, 171, 0, 0, &
|
|
33, 80, 114, 157, 0, 0, &
|
|
6, 57, 128, 169, 0, 0, &
|
|
22, 81, 99, 172, 0, 0, &
|
|
33, 46, 96, 139, 186, 0, &
|
|
34, 58, 117, 173, 0, 0, &
|
|
35, 82, 116, 158, 0, 0, &
|
|
8, 83, 124, 156, 0, 0, &
|
|
32, 69, 105, 149, 0, 0, &
|
|
36, 65, 102, 158, 0, 0, &
|
|
37, 68, 101, 165, 0, 0, &
|
|
38, 79, 107, 173, 0, 0, &
|
|
19, 84, 129, 161, 0, 0, &
|
|
25, 78, 130, 168, 0, 0, &
|
|
9, 71, 131, 174, 194, 0, &
|
|
39, 85, 103, 155, 189, 0, &
|
|
24, 57, 118, 175, 0, 0, &
|
|
8, 86, 93, 166, 184, 0, &
|
|
40, 70, 122, 174, 0, 0, &
|
|
23, 84, 119, 176, 0, 0, &
|
|
25, 60, 97, 148, 0, 0, &
|
|
32, 87, 132, 173, 199, 0, &
|
|
23, 64, 123, 144, 0, 0, &
|
|
39, 54, 109, 120, 0, 0, &
|
|
41, 49, 128, 137, 0, 0, &
|
|
42, 88, 120, 175, 0, 0, &
|
|
40, 86, 129, 162, 197, 0, &
|
|
38, 49, 93, 151, 0, 0, &
|
|
34, 65, 99, 177, 201, 0, &
|
|
16, 48, 100, 178, 0, 0, &
|
|
7, 59, 131, 170, 0, 0, &
|
|
4, 50, 111, 152, 0, 0, &
|
|
27, 87, 94, 179, 0, 0, &
|
|
15, 74, 98, 142, 0, 0, &
|
|
42, 67, 125, 148, 190, 0, &
|
|
43, 61, 133, 164, 188, 0, &
|
|
36, 84, 91, 180, 187, 0, &
|
|
41, 72, 108, 172, 0, 0, &
|
|
36, 77, 127, 181, 0, 0, &
|
|
14, 55, 134, 182, 201, 0, &
|
|
30, 52, 126, 149, 0, 0, &
|
|
43, 48, 135, 159, 193, 0, &
|
|
29, 61, 113, 183, 198, 0, &
|
|
26, 64, 109, 164, 0, 0, &
|
|
38, 74, 131, 163, 185, 0, &
|
|
30, 72, 113, 163, 0, 0, &
|
|
4, 87, 122, 140, 147, 0, &
|
|
42, 76, 112, 171, 196, 0, &
|
|
44, 60, 129, 143, 0, 0, &
|
|
5, 81, 134, 162, 0, 0, &
|
|
15, 88, 111, 184, 0, 0, &
|
|
10, 46, 136, 167, 203, 0, &
|
|
9, 75, 132, 169, 178, 0, &
|
|
45, 55, 94, 160, 204, 0, &
|
|
17, 70, 135, 180, 0, 0, &
|
|
14, 89, 118, 146, 195, 200, &
|
|
35, 73, 123, 177, 192, 0, &
|
|
41, 82, 103, 181, 188, 0, &
|
|
3, 90, 134, 170, 183, 0, &
|
|
1, 82, 117, 141, 194, 0, &
|
|
5, 91, 100, 136, 185, 0, &
|
|
39, 77, 114, 160, 0, 0, &
|
|
45, 66, 137, 153, 0, 0, &
|
|
18, 90, 138, 166, 0, 0, &
|
|
20, 85, 124, 152, 0, 0, &
|
|
11, 73, 135, 157, 0, 0, &
|
|
2, 54, 139, 185, 0, 0, &
|
|
44, 85, 138, 146, 0, 0, &
|
|
35, 53, 115, 183, 0, 0, &
|
|
28, 66, 110, 138, 187, 0, &
|
|
44, 75, 95, 167, 0, 0, &
|
|
11, 79, 95, 179, 0, 0, &
|
|
37, 92, 115, 155, 0, 0, &
|
|
27, 56, 130, 165, 186, 0, &
|
|
6, 81, 133, 147, 0, 0, &
|
|
43, 88, 105, 176, 0, 0, &
|
|
26, 78, 96, 175, 181, 0, &
|
|
12, 71, 121, 159, 0, 0, &
|
|
40, 63, 108, 150, 204, 0, &
|
|
13, 93, 127, 178, 0, 0, &
|
|
31, 83, 106, 182, 0, 0, &
|
|
45, 92, 133, 171, 200, 0, &
|
|
17, 51, 89, 184, 202, 0, &
|
|
34, 86, 130, 145, 0, 0, &
|
|
46, 92, 104, 177, 198, 0, &
|
|
31, 76, 132, 172, 0, 0, &
|
|
7, 80, 89, 176, 192, 0, &
|
|
37, 67, 128, 180, 191, 0, &
|
|
24, 83, 116, 142, 0, 0/
|
|
|
|
data nrw/ &
|
|
5,5,5,5,5,5,5,5,6,5,5,5,5,5,5,5,5, &
|
|
5,5,5,5,5,5,5,5,4,5,5,4,4,5,5,4,5, &
|
|
4,5,4,4,4,5,4,4,4,4,4,4,4,4,4,4,4, &
|
|
5,4,4,4,4,4,4,4,4,4,5,5,4,5,4,4,4, &
|
|
5,4,4,4,4,5,4,5,4,4,4,4,4,5,5,5,4, &
|
|
4,5,4,5,5,4,5,4,5,5,4,4,4,5,5,5,4, &
|
|
6,5,5,5,5,5,4,4,4,4,4,4,4,4,5,4,4, &
|
|
4,5,4,4,5,4,5,4,4,5,5,4,5,4,5,5,4/
|
|
|
|
ncw=3
|
|
|
|
decoded=0
|
|
toc=0
|
|
tov=0
|
|
tanhtoc=0
|
|
! initialize messages to checks
|
|
do j=1,M
|
|
do i=1,nrw(j)
|
|
toc(i,j)=llr((Nm(i,j)))
|
|
enddo
|
|
enddo
|
|
|
|
ncnt=0
|
|
|
|
do iter=0,maxiterations
|
|
|
|
! Update bit log likelihood ratios (tov=0 in iteration 0).
|
|
do i=1,N
|
|
if( apmask(i) .ne. 1 ) then
|
|
zn(i)=llr(i)+sum(tov(1:ncw,i))
|
|
else
|
|
zn(i)=llr(i)
|
|
endif
|
|
enddo
|
|
|
|
! Check to see if we have a codeword (check before we do any iteration).
|
|
cw=0
|
|
where( zn .gt. 0. ) cw=1
|
|
ncheck=0
|
|
do i=1,M
|
|
synd(i)=sum(cw(Nm(1:nrw(i),i)))
|
|
if( mod(synd(i),2) .ne. 0 ) ncheck=ncheck+1
|
|
! if( mod(synd(i),2) .ne. 0 ) write(*,*) 'check ',i,' unsatisfied'
|
|
enddo
|
|
! write(*,*) 'number of unsatisfied parity checks ',ncheck
|
|
if( ncheck .eq. 0 ) then ! we have a codeword - reorder the columns and return it
|
|
codeword=cw(colorder+1)
|
|
decoded=codeword(M+1:N)
|
|
nerr=0
|
|
do i=1,N
|
|
if( (2*cw(i)-1)*llr(i) .lt. 0.0 ) nerr=nerr+1
|
|
enddo
|
|
nharderror=nerr
|
|
return
|
|
endif
|
|
|
|
if( iter.gt.0 ) then ! this code block implements an early stopping criterion
|
|
! if( iter.gt.10000 ) then ! this code block implements an early stopping criterion
|
|
nd=ncheck-nclast
|
|
if( nd .lt. 0 ) then ! # of unsatisfied parity checks decreased
|
|
ncnt=0 ! reset counter
|
|
else
|
|
ncnt=ncnt+1
|
|
endif
|
|
! write(*,*) iter,ncheck,nd,ncnt
|
|
if( ncnt .ge. 5 .and. iter .ge. 10 .and. ncheck .gt. 15) then
|
|
nharderror=-1
|
|
return
|
|
endif
|
|
endif
|
|
nclast=ncheck
|
|
|
|
! Send messages from bits to check nodes
|
|
do j=1,M
|
|
do i=1,nrw(j)
|
|
ibj=Nm(i,j)
|
|
toc(i,j)=zn(ibj)
|
|
do kk=1,ncw ! subtract off what the bit had received from the check
|
|
if( Mn(kk,ibj) .eq. j ) then
|
|
toc(i,j)=toc(i,j)-tov(kk,ibj)
|
|
endif
|
|
enddo
|
|
enddo
|
|
enddo
|
|
|
|
! send messages from check nodes to variable nodes
|
|
do i=1,M
|
|
tanhtoc(1:6,i)=tanh(-toc(1:6,i)/2)
|
|
enddo
|
|
|
|
do j=1,N
|
|
do i=1,ncw
|
|
ichk=Mn(i,j) ! Mn(:,j) are the checks that include bit j
|
|
Tmn=product(tanhtoc(1:nrw(ichk),ichk),mask=Nm(1:nrw(ichk),ichk).ne.j)
|
|
call platanh(-Tmn,y)
|
|
! y=atanh(-Tmn)
|
|
tov(i,j)=2*y
|
|
enddo
|
|
enddo
|
|
|
|
enddo
|
|
nharderror=-1
|
|
return
|
|
end subroutine bpdecode204
|