#!/usr/local/bin/perl
#open input file for reading
#open(FIZZLE,"unzip -p /data/popdata/usa/census/1970/st23a4cp.zip |")
#open(FIZZLE,"unzip -p /work/econ/nbrooks/outmove1.1.zip |")
open(FIZZLE,"ST35B4CP")  || die "Can't do it\n";
$debug=1;
open(OUTPUT,"1970-4B-WI") || die "Can't open output file";
print "\n\n";
$foffset=0;
$nblocks=0;
$nrecs=0;

while( ! eof(FIZZLE)  ) {

     read(FIZZLE,$blklen,4);           #grab the block size
     $blklen=unpack("S",$blklen);

     $blokread=4;
     while($blokread < $blklen){
         $cumlen=0;
         read(FIZZLE,$reclen,6);
         ($reclen,$junk,$st_codes)=unpack("S3",$reclen);

         $a1=read(FIZZLE,$inbuf,$st_codes);
         $a2=read(FIZZLE,$bytepairs,($reclen-(6+$st_codes)));
         @byteary=unpack("C*",$bytepairs);
         $i=0;
         while( $i < $#byteary){
             $nfill=$byteary[$i];
             $rbyte=$byteary[$i+1];
             $zerofill=$rbyte%2;
             $dbytes = $rbyte >> 1;
             ($data,$inbuf)=unpack("a$dbytes a*", $inbuf);
             if ($zerofill eq 1) {
                 $fill= "\xf0" x $nfill ;
                 }
             else { $fill = "\x40" x $nfill ; }
             $out=$data.$fill;
             $len=length($out);
             $cumlen=$len+$cumlen;
             print OUTPUT $data.$fill;
             $i=$i+2;
             }
         if ($cumlen lt 2040) {
             $cumlen=$cumlen+length($inbuf);
             print OUTPUT $inbuf;
             }
         if ($debug ==1) {
           print "blklen=".$blklen." ,reclen=".$reclen."\n";
            }
         $blokread=$blokread+$reclen;
         ++$nrecs;
        }
     ++$nblocks;
     print "Read ".$nblocks." blocks and processed ".$nrecs." Records\n";
     }