ql02raw.f

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c  This program reads a 22180-byte SeaWiFS formatted record and compresses
c  the S/C ID, time tag, instrument telemetry and scan line data from 2-byte
c  words to 10 bits.  The data are written in 13860-byte records formatted
c  as SeaWiFS minor frames.  The leading and trailing frame synch words are
c  filled with zeros.  
 
        integer*2 ints(4),isync
        integer*4 irec
        byte inbuf(512),inrec(22180),outrec(13860),b10(5),bint(8)
        byte frsync(7),ausync(125)
        character*50 l0file
        character*50 outfile
        data outrec/13860*0/,ints/4*0/
        data isync/5/
        data frsync/x'a1',x'16',x'fd',x'71',x'9d',x'83',x'c9'/
        data ausync/
     *   x'f8',x'bf',x'36',x'd6',x'bd',x'a1',x'11',x'57',x'11',x'd3',
     *   x'd0',x'4e',x'0a',x'db',x'de',x'37',x'19',x'9f',
     *   x'c9',x'93',x'a3',x'86',x'90',x'fb',x'63',
     *   x'12',x'c9',x'55',x'02',x'd5',x'a7',x'24',x'5d',
     *   x'88',x'6d',x'29',x'ba',x'df',x'f8',x'3b',
     *   x'f7',x'4b',x'67',x'34',x'c5',x'bb',x'd6',x'7b',
     *   x'00',x'42',x'60',x'ce',x'ed',x'4a',x'ea',
     *   x'76',x'63',x'd4',x'68',x'06',x'35',x'0a',x'99',
     *   x'be',x'f9',x'f4',x'd5',x'23',x'e5',x'c0',
     *   x'52',x'f8',x'fd',x'56',x'18',x'50',x'eb',x'fb',
     *   x'21',x'72',x'07',x'b8',x'48',x'3f',x'd1',
     *   x'47',x'89',x'e0',x'6b',x'1c',x'b0',x'46',x'46',
     *   x'c2',x'03',x'9e',x'44',x'd1',x'05',x'e9',
     *   x'2e',x'86',x'56',x'5a',x'30',x'25',x'16',x'6b',
     *   x'98',x'71',x'db',x'9c',x'57',x'd7',x'72',
     *   x'83',x'79',x'd5',x'e5',x'44',x'93',x'65',x'27',x'c3',x'cc'/
 
        equivalence(ints,bint)
 
        write(*,*) 'Enter Level 0 file name'
        read (5,'(a50)') l0file
        write(*,*) 'Enter Output file name'
        read (5,'(a50)') outfile
 
        open(unit=11,file=l0file,access='direct',recl=22180,
     *    status='old',action='READ')
        open(unit=12,file=outfile,access='direct',recl=13860)
 
c  Initialize output record with frame and auxillary synchs 
        do i=1,7
          outrec(i) = frsync(i)
        end do
        do i=1,125
          outrec(i+13735) = ausync(i)
        end do
 
c  Skip header records
        nrec = 0
        irec = 2
 
c  Now loop through input records
      dowhile(.true.)
 
c  Read a complete L0 record
        read (11,err=999,rec=irec) inrec
        irec = irec + 1
        nrec = nrec + 1
 
c  Reverse bytes (not needed for linux)
c        do i=1,22180,2
c            bval       = inrec(i)
c            inrec(i)   = inrec(i+1)
c            inrec(i+1) = bval
c        enddo
        
c  Remaining 10-bit data (instrument telemetry and scan line) 
        do l=1,2772
          do i=1,8
            bint(i) = inrec(i+(l-1)*8)
          end do
          call i2to10bit(ints,b10)
          do i=1,5
            outrec(i+(l-1)*5) = b10(i)
          end do
        end do
 
        write (12,rec=nrec) outrec
 
        if (mod(nrec,100) .eq. 0) then
            write(*,*) 'Writing record ',nrec
c            goto 999
        endif
 
      end do
 
  999 continue
 
      stop
      end
 
        subroutine i2to10bit(ints,bit10)
 
c  This subroutine compresses a 4-element I*2 array into a 5-element byte 
c  array, taking the 10 least significant bits of each integer.  
 
        integer*2 ints(4)
        byte bit10(5)
        integer*2 m3fc,m003,m3f0,m3c0,m300,m00f,m03f,m0ff
        data m3fc/1020/,m003/3/,m3f0/1008/,m00f/15/
        data m3c0/960/,m03f/63/,m300/768/,m0ff/255/
        bit10(1) = iand(ints(1),m3fc)/4
        bit10(2) = iand(ints(1),m003)*64 + iand(ints(2),m3f0)/16
        bit10(3) = iand(ints(2),m00f)*16 + iand(ints(3),m3c0)/64
        bit10(4) = iand(ints(3),m03f)*4  + iand(ints(4),m300)/256
        bit10(5) = iand(ints(4),m0ff)
        return
        end