WSJT-X/lib/fst4/genfst4.f90
2020-07-23 19:13:05 +01:00

112 lines
2.8 KiB
Fortran

subroutine genfst4(msg0,ichk,msgsent,msgbits,i4tone,iwspr)
! Input:
! - msg0 requested message to be transmitted
! - ichk if ichk=1, return only msgsent
! - msgsent message as it will be decoded
! - i4tone array of audio tone values, {0,1,2,3}
! - iwspr in: 0: FST4 1: FST4W
! out 0: (240,101)/crc24, 1: (240,74)/crc24
!
! Frame structure:
! s8 d30 s8 d30 s8 d30 s8 d30 s8
use packjt77
include 'fst4_params.f90'
character*37 msg0
character*37 message !Message to be generated
character*37 msgsent !Message as it will be received
character*77 c77
character*24 c24
integer*4 i4tone(NN),itmp(ND)
integer*1 codeword(2*ND)
integer*1 msgbits(101),rvec(77)
integer isyncword1(8),isyncword2(8)
integer ncrc24
logical unpk77_success
data isyncword1/0,1,3,2,1,0,2,3/
data isyncword2/2,3,1,0,3,2,0,1/
data rvec/0,1,0,0,1,0,1,0,0,1,0,1,1,1,1,0,1,0,0,0,1,0,0,1,1,0,1,1,0, &
1,0,0,1,0,1,1,0,0,0,0,1,0,0,0,1,0,1,0,0,1,1,1,1,0,0,1,0,1, &
0,1,0,1,0,1,1,0,1,1,1,1,1,0,0,0,1,0,1/
message=msg0
do i=1, 37
if(ichar(message(i:i)).eq.0) then
message(i:37)=' '
exit
endif
enddo
do i=1,37 !Strip leading blanks
if(message(1:1).ne.' ') exit
message=message(i+1:)
enddo
i3=-1
n3=-1
if(iwspr.eq.1) then
i3=0
n3=6
endif
call pack77(message,i3,n3,c77)
call unpack77(c77,0,msgsent,unpk77_success) !Unpack to get msgsent
msgbits=0
iwspr=0
if(i3.eq.0.and.n3.eq.6) then
iwspr=1
read(c77,'(50i1)') msgbits(1:50)
call get_crc24(msgbits,74,ncrc24)
write(c24,'(b24.24)') ncrc24
read(c24,'(24i1)') msgbits(51:74)
else
read(c77,'(77i1)') msgbits(1:77)
msgbits(1:77)=mod(msgbits(1:77)+rvec,2)
call get_crc24(msgbits,101,ncrc24)
write(c24,'(b24.24)') ncrc24
read(c24,'(24i1)') msgbits(78:101)
endif
if(ichk.eq.1) go to 999
if(unpk77_success) go to 2
1 msgbits=0
itone=0
msgsent='*** bad message *** '
go to 999
entry get_fst4_tones_from_bits(msgbits,i4tone,iwspr)
2 continue
if(iwspr.eq.0) then
call encode240_101(msgbits,codeword)
else
call encode240_74(msgbits(1:74),codeword)
endif
! Grayscale mapping:
! bits tone
! 00 0
! 01 1
! 11 2
! 10 3
do i=1,ND
is=codeword(2*i)+2*codeword(2*i-1)
if(is.le.1) itmp(i)=is
if(is.eq.2) itmp(i)=3
if(is.eq.3) itmp(i)=2
enddo
i4tone( 1: 8)=isyncword1
i4tone( 9: 38)=itmp( 1: 30)
i4tone( 39: 46)=isyncword2
i4tone( 47: 76)=itmp( 31: 60)
i4tone( 77: 84)=isyncword1
i4tone( 85:114)=itmp( 61: 90)
i4tone(115:122)=isyncword2
i4tone(123:152)=itmp( 91:120)
i4tone(153:160)=isyncword1
999 return
end subroutine genfst4