subroutine decode1(iarg)

! Get data and parameters from gcom, then call the decoders when needed.
! This routine runs in a background thread and will never return.

#ifdef CVF
  use dflib
#endif

  character sending0*28,mode0*6,cshort*11
  integer sendingsh0

  include 'datcom.f90'
  include 'gcom1.f90'
  include 'gcom2.f90'
  include 'gcom3.f90'
  include 'gcom4.f90'
  data kbuf0/0/,ns00/-999/
  data sending0/'                      '/
  save

  kkdone=-99
  ns0=999999
  newdat2=0
  kbuf=1

10 continue
  if(newdat2.gt.0) then
     call getfile2(fname80,nlen)
     newdat2=0
     kbuf=1
     kk=NSMAX
     kkdone=0
     newdat=1
  endif

  if(kbuf.ne.kbuf0) kkdone=0
  kbuf0=kbuf
  kkk=kk
  if(kbuf.eq.2) kkk=kk-5760000
  n=Tsec

  if((ndiskdat.eq.1 .or. ndecoding.eq.0) .and. ((kkk-kkdone).gt.32768)) then
     call symspec(id,kbuf,kk,kkdone,nutc,newdat)
     call sleep_msec(10)
  endif

  if(ndecoding.gt.0 .and. mode(1:4).eq.'JT65') then
     ndecdone=0
     call map65a(newdat)
     if(mousebutton.eq.0) ndecoding0=ndecoding
     ndecoding=0
  endif

  if(ns0.lt.0) then
     rewind 21
     ns0=999999
  endif
  if(n.lt.ns0 .and. utcdate(1:1).eq.'2') then
     call cs_lock('decode1a')
     write(21,1001) utcdate(:11)
1001 format(/'UTC Date: ',a11/'---------------------')
     ns0=n
     call cs_unlock
  endif

  if(transmitting.eq.1 .and. (sending.ne.sending0 .or.       &
       sendingsh.ne.sendingsh0 .or. mode.ne.mode0)) then
     ih=n/3600
     im=mod(n/60,60)
     is=mod(n,60)
     cshort='           '
     if(sendingsh.eq.1) cshort='(Shorthand)'
     call cs_lock('decode1b')
     write(21,1010) ih,im,is,mode,sending,cshort
1010 format(3i2.2,'  Transmitting: ',a6,2x,a28,2x,a11)
     call flushqqq(21)
     call cs_unlock
     sending0=sending
     sendingsh0=sendingsh
     mode0=mode
  endif

  call sleep_msec(100)                  !### was 100
  go to 10

end subroutine decode1