From 5a0a582193490961ce43500a89735cfef8670500 Mon Sep 17 00:00:00 2001
From: Steven Franke <s.j.franke@icloud.com>
Date: Fri, 29 Jul 2016 19:04:42 +0000
Subject: [PATCH] genmsk40: (32,16) code with 8-bit sync word.

git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@6965 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
---
 lib/genmsk40.f90 | 80 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 80 insertions(+)
 create mode 100644 lib/genmsk40.f90

diff --git a/lib/genmsk40.f90 b/lib/genmsk40.f90
new file mode 100644
index 000000000..89bb4e240
--- /dev/null
+++ b/lib/genmsk40.f90
@@ -0,0 +1,80 @@
+subroutine genmsk32(msg,msgsent,ichk,itone,itype)
+
+  use hashing
+  character*22 msg,msgsent,hashmsg
+  character*4 crpt,rpt(0:63)
+  logical first
+  integer itone(144)
+  integer ig32(0:65536-1)  !Codewords for LDPC (32,16) code (PEG generated, regular, col wt 3) 
+  integer*1 codeword(32),bitseq(40)
+  integer*1 s8r(8)
+  data s8r/1,0,1,1,0,0,0,1/
+  data first/.true./
+  save first,rpt,ig32
+
+  if(first) then
+     call ldpc32_table(ig32)             !Define the Golay(24,12) codewords
+     do i=0,30
+       if( i.lt.5 ) then
+         write(rpt(i),'(a1,i2.2,a1)') '-',abs(i-5)
+         write(rpt(i+31),'(a2,i2.2,a1)') 'R-',abs(i-5)
+       else
+         write(rpt(i),'(a1,i2.2,a1)') '+',i-5
+         write(rpt(i+31),'(a2,i2.2,a1)') 'R+',i-5
+       endif
+     enddo
+     rpt(62)='RRR '
+     rpt(63)='73  '
+     first=.false.
+  endif
+
+  itype=-1
+  msgsent='*** bad message ***'
+  itone=0
+  i1=index(msg,'>')
+  if(i1.lt.9) go to 900
+  call fmtmsg(msg,iz)
+  crpt=msg(i1+2:i1+5)
+  do i=0,63
+     if(crpt.eq.rpt(i)) go to 10
+  enddo
+  go to 900
+
+10 irpt=i                               !Report index, 0-31
+  if(ichk.lt.10000) then
+     hashmsg=msg(2:i1-1)//' '//crpt
+     call hash(hashmsg,22,ihash)          
+     ihash=iand(ihash,1023)                 !10-bit hash 
+     ig=64*ihash + irpt                     !6-bit report 
+  else
+     ig=ichk-10000
+  endif
+
+  ncodeword=ig32(ig)
+
+!  write(*,*) 'codeword is: ',ncodeword,'message is: ',ig,'report index: ',irpt,'hash: ',ihash
+
+  do i=1,32
+    codeword(i)=iand(1,ishft(ncodeword,1-i))
+  enddo
+
+  bitseq(1:8)=s8r
+  bitseq(9:40)=codeword
+  bitseq=2*bitseq-1
+
+! Map I and Q  to tones.
+  itone=0
+  do i=1, 20
+    itone(2*i-1)=(bitseq(2*i)*bitseq(2*i-1)+1)/2;
+    itone(2*i)=-(bitseq(2*i)*bitseq(mod(2*i,32)+1)-1)/2;
+  enddo
+
+! Flip polarity
+  itone=-itone+1 
+
+  msgsent=msg
+  itype=7
+
+900 return
+end subroutine genmsk32
+