/*
 * CKIPCT.REXX
 *
 * This program is a de-boo'er for the Amiga, written in Amiga REXX.  It is
 * intended for use as a decoder for a BOO file of Amiga Kermit.
 *
 * Written by Stephen Walton, 20 October 1990.  Based on MSBPCT.C
 *
 */

parse arg InName
if InName = '' then do
  say 'usage: rx ckipct boo-file'
  exit 10
end

if ~open(InFile,InName,'Read') then do
  say 'Can''t open file' InName
  exit 10
end

OutName = readln(InFile)
if Outname = '' then do
   say 'Illegal BOO file'
   exit
end

call open OutFile, OutName,'Write'

say 'Creating file' OutName 'from input BOO file' InName

NULLCHAR = fixchar('~')
line = readln(InFile)

do while ~eof(InFile)
   do while length(line) >= 2
      if fixchar(left(line,1)) = NULLCHAR then do /* Handle null compress */
         line = substr(line,2)
         do fixchar(left(line,1))		/* For repeat count... */
            call writech(OutFile,d2c(0))	/* ...output nulls */
         end
         line = substr(line,2)			/* Trim off output count */
      end
      else do					/* Decode a quad */
         a = fixchar(left(line,1))
         b = fixchar(substr(line,2,1))
         c = fixchar(substr(line,3,1))
         d = fixchar(substr(line,4,1))
         call writech(OutFile,d2c(((a*4) + (b%16))//256))
         call writech(OutFile,d2c(((b*16) + int(c/4))//256))
         call writech(OutFile,d2c((c*64 + d)//256))
         line = substr(line,5)			/* Trim off the quad */
      end
   end
   line = readln(InFile)
end

call close(InFile)
call close(OutFile)
exit

fixchar: procedure
   parse arg c

   return c2d(c) - c2d('0')