WSJT-X/lib/77bit/t1.f90
2018-06-21 10:51:19 -04:00

55 lines
1.2 KiB
Fortran

program t1
real x(13)
real(KIND=16) :: dlong,dlong0
character wd*13,w*13,error*5
character c*44 !NB: 44^13 = 2^(70.973)
data c/' 0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ+-./?@$'/
nargs=iargc()
if(nargs.ne.1) then
print*,'Usage: t1 "FreeText13"'
print*,' t1 <iters>'
go to 999
endif
call getarg(1,w)
iters=1
read(w,*,err=10) iters
10 continue
do iter=1,iters
if(iters.gt.1) then
! Create a random free-text word
call random_number(x)
do i=1,13
j=44*x(i) + 1
w(i:i)=c(j:j)
enddo
endif
! Encode a 13-character free-text message into a 71-bit integer.
dlong=0.d0
do i=1,13
n=index(c,w(i:i))-1
dlong=44.d0*dlong + n
enddo
dlong0=dlong
! Decode a a 71-bit integer into a 13-character free-text message.
do i=13,1,-1
j=mod(dlong,44.d0)+1.d0
wd(i:i)=c(j:j)
dlong=dlong/44.d0
enddo
error=' '
if(wd.ne.w) then
error='ERROR'
write(*,1010) w,dlong0,wd,error
1010 format('"',a13,'"',f25.1,2x,'"',a13'"',2x,a5)
endif
if(mod(iter,1000).eq.0) print*,iter
enddo
999 end program t1