2018-03-05 14:49:51 -05:00
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subroutine extractmessage174(decoded,msgreceived,ncrcflag)
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2018-02-08 21:28:33 -05:00
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use iso_c_binding, only: c_loc,c_size_t
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use crc
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use packjt
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2018-08-05 17:40:19 -04:00
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character*68 alphabet
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2018-02-08 21:28:33 -05:00
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character*22 msgreceived
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character*87 cbits
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integer*1 decoded(87)
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integer*1, target:: i1Dec8BitBytes(11)
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integer*4 i4Dec6BitWords(12)
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2018-08-06 10:18:11 -04:00
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alphabet='0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz-+/?.'
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2018-08-05 17:40:19 -04:00
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2018-02-08 21:28:33 -05:00
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! Write decoded bits into cbits: 75-bit message plus 12-bit CRC
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write(cbits,1000) decoded
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1000 format(87i1)
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read(cbits,1001) i1Dec8BitBytes
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1001 format(11b8)
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read(cbits,1002) ncrc12 !Received CRC12
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1002 format(75x,b12)
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i1Dec8BitBytes(10)=iand(i1Dec8BitBytes(10),128+64+32)
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i1Dec8BitBytes(11)=0
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icrc12=crc12(c_loc(i1Dec8BitBytes),11) !CRC12 computed from 75 msg bits
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2018-10-03 18:25:55 -04:00
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! icrc12=xor(icrc12, 41) ! TODO: jsherer - could change the crc here
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2018-02-08 21:28:33 -05:00
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2018-03-05 14:49:51 -05:00
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if(ncrc12.eq.icrc12 .or. sum(decoded(57:87)).eq.0) then !### Kludge ###
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2018-02-08 21:28:33 -05:00
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! CRC12 checks out --- unpack 72-bit message
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do ibyte=1,12
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itmp=0
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do ibit=1,6
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itmp=ishft(itmp,1)+iand(1,decoded((ibyte-1)*6+ibit))
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enddo
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i4Dec6BitWords(ibyte)=itmp
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enddo
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2018-08-05 17:40:19 -04:00
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!call unpackmsg(i4Dec6BitWords,msgreceived,.false.,' ')
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msgreceived=' '
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do ibyte=1,12
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itmp=i4Dec6BitWords(ibyte)
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msgreceived(ibyte:ibyte) = alphabet(itmp+1:itmp+1)
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enddo
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2018-02-08 21:28:33 -05:00
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ncrcflag=1
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else
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msgreceived=' '
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ncrcflag=-1
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endif
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return
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end subroutine extractmessage174
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