mirror of
https://github.com/saitohirga/WSJT-X.git
synced 2024-11-22 12:23:37 -05:00
26 lines
626 B
Fortran
26 lines
626 B
Fortran
subroutine get_crc14(mc,len,ncrc)
|
|
!
|
|
! 1. To calculate 14-bit CRC, mc(1:len-14) is the message and mc(len-13:len) are zero.
|
|
! 2. To check a received CRC, mc(1:len is the received message plus CRC.
|
|
! ncrc will be zero if the received message/CRC are consistent
|
|
!
|
|
character c14*14
|
|
integer*1 mc(len)
|
|
integer*1 r(15),p(15)
|
|
integer ncrc
|
|
! polynomial for 14-bit CRC 0x6757
|
|
data p/1,1,0,0,1,1,1,0,1,0,1,0,1,1,1/
|
|
|
|
! divide by polynomial
|
|
r=mc(1:15)
|
|
do i=0,len-15
|
|
r(15)=mc(i+15)
|
|
r=mod(r+r(1)*p,2)
|
|
r=cshift(r,1)
|
|
enddo
|
|
|
|
write(c14,'(14b1)') r(1:14)
|
|
read(c14,'(b14.14)') ncrc
|
|
|
|
end subroutine get_crc14
|