WSJT-X/lib/genmsk144.f90
Bill Somerville dd1362b69a Rationalize NA contest mode
Generic message packing and unpacking routines now understand antipode
grid contest messages.  These messages  are now recognized as standard
messages in  message response processing and  dealt with appropriately
when contest mode is selected and applicable (currently FT8 and MSK144
only).

git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@8062 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
2017-09-01 20:10:35 +00:00

148 lines
4.2 KiB
Fortran

subroutine genmsk144(msg0,mygrid,ichk,bcontest,msgsent,i4tone,itype)
! s8 + 48bits + s8 + 80 bits = 144 bits (72ms message duration)
!
! Encode an MSK144 message
! Input:
! - msg0 requested message to be transmitted
! - ichk if ichk=1, return only msgsent
! if ichk.ge.10000, set imsg=ichk-10000 for short msg
! - msgsent message as it will be decoded
! - i4tone array of audio tone values, 0 or 1
! - itype message type
! 1 = standard message "Call_1 Call_2 Grid/Rpt"
! 2 = type 1 prefix
! 3 = type 1 suffix
! 4 = type 2 prefix
! 5 = type 2 suffix
! 6 = free text (up to 13 characters)
! 7 = short message "<Call_1 Call2> Rpt"
use iso_c_binding, only: c_loc,c_size_t
use packjt
use hashing
character*22 msg0
character*22 message !Message to be generated
character*22 msgsent !Message as it will be received
character*6 mygrid
integer*4 i4Msg6BitWords(13) !72-bit message as 6-bit words
integer*4 i4tone(144) !
integer*1, target:: i1Msg8BitBytes(10) !80 bits represented in 10 bytes
integer*1 codeword(128) !Encoded bits before re-ordering
integer*1 msgbits(80) !72-bit message + 8-bit hash
integer*1 bitseq(144) !Tone #s, data and sync (values 0-1)
integer*1 i1hash(4)
integer*1 s8(8)
logical bcontest
real*8 pp(12)
real*8 xi(864),xq(864),pi,twopi
data s8/0,1,1,1,0,0,1,0/
equivalence (ihash,i1hash)
logical first
data first/.true./
save
if(first) then
first=.false.
nsym=128
pi=4.0*atan(1.0)
twopi=8.*atan(1.0)
do i=1,12
pp(i)=sin((i-1)*pi/12)
enddo
endif
if(msg0(1:1).eq.'@') then !Generate a fixed tone
read(msg0(2:5),*,end=1,err=1) nfreq !at specified frequency
go to 2
1 nfreq=1000
2 i4tone(1)=nfreq
else
message=msg0
do i=1,22
if(ichar(message(i:i)).eq.0) then
message(i:)=' '
exit
endif
enddo
do i=1,22 !Strip leading blanks
if(message(1:1).ne.' ') exit
message=message(i+1:)
enddo
if(message(1:1).eq.'<') then
call genmsk40(message,msgsent,ichk,i4tone,itype)
if(itype.lt.0) go to 999
i4tone(41)=-40
go to 999
endif
call packmsg(message,i4Msg6BitWords,itype,bcontest) !Pack into 12 6-bit bytes
call unpackmsg(i4Msg6BitWords,msgsent,bcontest,mygrid) !Unpack to get msgsent
if(ichk.eq.1) go to 999
i4=0
ik=0
im=0
do i=1,12
nn=i4Msg6BitWords(i)
do j=1, 6
ik=ik+1
i4=i4+i4+iand(1,ishft(nn,j-6))
i4=iand(i4,255)
if(ik.eq.8) then
im=im+1
i1Msg8BitBytes(im)=i4
ik=0
endif
enddo
enddo
ihash=nhash(c_loc(i1Msg8BitBytes),int(9,c_size_t),146)
ihash=2*iand(ihash,32767) !Generate the 8-bit hash
i1Msg8BitBytes(10)=i1hash(1) !CRC to byte 10
mbit=0
do i=1, 10
i1=i1Msg8BitBytes(i)
do ibit=1,8
mbit=mbit+1
msgbits(mbit)=iand(1,ishft(i1,ibit-8))
enddo
enddo
call encode_msk144(msgbits,codeword)
!Create 144-bit channel vector:
!8-bit sync word + 48 bits + 8-bit sync word + 80 bits
bitseq=0
bitseq(1:8)=s8
bitseq(9:56)=codeword(1:48)
bitseq(57:64)=s8
bitseq(65:144)=codeword(49:128)
bitseq=2*bitseq-1
xq(1:6)=bitseq(1)*pp(7:12) !first bit is mapped to 1st half-symbol on q
do i=1,71
is=(i-1)*12+7
xq(is:is+11)=bitseq(2*i+1)*pp
enddo
xq(864-5:864)=bitseq(1)*pp(1:6) !last half symbol
do i=1,72
is=(i-1)*12+1
xi(is:is+11)=bitseq(2*i)*pp
enddo
! Map I and Q to tones.
i4tone=0
do i=1,72
i4tone(2*i-1)=(bitseq(2*i)*bitseq(2*i-1)+1)/2;
i4tone(2*i)=-(bitseq(2*i)*bitseq(mod(2*i,144)+1)-1)/2;
enddo
endif
! Flip polarity
i4tone=-i4tone+1
999 return
end subroutine genmsk144