93 lines
4.0 KiB
Fortran
93 lines
4.0 KiB
Fortran
subroutine jt9fano(i1SoftSymbols,limit,nlim,msg)
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! Decoder for JT9
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! Input: i1SoftSymbols(207) - Single-bit soft symbols
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! Output: msg - decoded message (blank if erasure)
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use packjt
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character*22 msg
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integer*4 i4DecodedBytes(9)
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integer*4 i4Decoded6BitWords(12)
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integer*1 i1DecodedBytes(13) !72 bits and zero tail as 8-bit bytes
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integer*1 i1SoftSymbols(207)
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integer*1 i1DecodedBits(72)
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real*4 xx0(0:262)
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logical first
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integer*4 mettab(-128:127,0:1)
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data first/.true./
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data xx0/ & !Metric table
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1.000, 1.000, 1.000, 1.000, 1.000, 1.000, 1.000, 1.000, &
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1.000, 1.000, 1.000, 1.000, 1.000, 1.000, 1.000, 1.000, &
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1.000, 1.000, 1.000, 1.000, 1.000, 1.000, 1.000, 1.000, &
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1.000, 1.000, 1.000, 1.000, 1.000, 1.000, 1.000, 1.000, &
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1.000, 1.000, 1.000, 1.000, 1.000, 1.000, 1.000, 1.000, &
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1.000, 1.000, 1.000, 1.000, 1.000, 1.000, 1.000, 1.000, &
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0.988, 1.000, 0.991, 0.993, 1.000, 0.995, 1.000, 0.991, &
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1.000, 0.991, 0.992, 0.991, 0.990, 0.990, 0.992, 0.996, &
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0.990, 0.994, 0.993, 0.991, 0.992, 0.989, 0.991, 0.987, &
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0.985, 0.989, 0.984, 0.983, 0.979, 0.977, 0.971, 0.975, &
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0.974, 0.970, 0.970, 0.970, 0.967, 0.962, 0.960, 0.957, &
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0.956, 0.953, 0.942, 0.946, 0.937, 0.933, 0.929, 0.920, &
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0.917, 0.911, 0.903, 0.895, 0.884, 0.877, 0.869, 0.858, &
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0.846, 0.834, 0.821, 0.806, 0.790, 0.775, 0.755, 0.737, &
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0.713, 0.691, 0.667, 0.640, 0.612, 0.581, 0.548, 0.510, &
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0.472, 0.425, 0.378, 0.328, 0.274, 0.212, 0.146, 0.075, &
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0.000,-0.079,-0.163,-0.249,-0.338,-0.425,-0.514,-0.606, &
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-0.706,-0.796,-0.895,-0.987,-1.084,-1.181,-1.280,-1.376, &
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-1.473,-1.587,-1.678,-1.790,-1.882,-1.992,-2.096,-2.201, &
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-2.301,-2.411,-2.531,-2.608,-2.690,-2.829,-2.939,-3.058, &
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-3.164,-3.212,-3.377,-3.463,-3.550,-3.768,-3.677,-3.975, &
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-4.062,-4.098,-4.186,-4.261,-4.472,-4.621,-4.623,-4.608, &
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-4.822,-4.870,-4.652,-4.954,-5.108,-5.377,-5.544,-5.995, &
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-5.632,-5.826,-6.304,-6.002,-6.559,-6.369,-6.658,-7.016, &
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-6.184,-7.332,-6.534,-6.152,-6.113,-6.288,-6.426,-6.313, &
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-9.966,-6.371,-9.966,-7.055,-9.966,-6.629,-6.313,-9.966, &
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-5.858,-9.966,-9.966,-9.966,-9.966,-9.966,-9.966,-9.966, &
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-9.966,-9.966,-9.966,-9.966,-9.966,-9.966,-9.966,-9.966, &
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-9.966,-9.966,-9.966,-9.966,-9.966,-9.966,-9.966,-9.966, &
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-9.966,-9.966,-9.966,-9.966,-9.966,-9.966,-9.966,-9.966, &
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-9.966,-9.966,-9.966,-9.966,-9.966,-9.966,-9.966,-9.966, &
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-9.966,-9.966,-9.966,-9.966,-9.966,-9.966,-9.966,-9.966, &
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1.43370769e-019,2.64031087e-006,6.25548654e+028, &
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2.44565251e+020,4.74227538e+030,10497312.,7.74079654e-039/
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save
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if(first) then
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! Get the metric table
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bias=0.5
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scale=50
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ndelta=nint(3.4*scale)
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ib=160 !Break point
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slope=2 !Slope beyond break
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do i=0,255
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mettab(i-128,0)=nint(scale*(xx0(i)-bias))
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if(i.gt.ib) mettab(i-128,0)=mettab(ib-128,0) - slope*(i-ib)
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if(i.ge.1) mettab(128-i,1)=mettab(i-128,0)
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enddo
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mettab(-128,1)=mettab(-127,1)
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first=.false.
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endif
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msg=' '
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nbits=72
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call fano232(i1SoftSymbols,nbits+31,mettab,ndelta,limit,i1DecodedBytes, &
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ncycles,metric,ierr)
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nlim=ncycles/(nbits+31)
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if(ncycles.lt.((nbits+31)*limit)) then
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nbytes=(nbits+7)/8
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do i=1,nbytes
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n=i1DecodedBytes(i)
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i4DecodedBytes(i)=iand(n,255)
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enddo
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call unpackbits(i4DecodedBytes,nbytes,8,i1DecodedBits)
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call packbits(i1DecodedBits,12,6,i4Decoded6BitWords)
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call unpackmsg(i4Decoded6BitWords,msg,.false.,' ') !Unpack decoded msg
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if(index(msg,'000AAA ').gt.0) msg=' '
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endif
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return
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end subroutine jt9fano
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