Re: gzip/deflate compression/encoding

Charles Lindsey wrote:
 
> Are the usual audio, image, etc. formats truly 8bit clean
> (i.e. are they guaranteed not to contain NUL or naked CR or
> LF)?

Of course not, this thread is about introducing yenc as CTE,
in pseudo-REXX (untested, ignoring trailing SP or HT issues):

   CRLF = x2c( 0D0A )
   BAD  = CRLF || x2c( 0 ) || '='
   OUT  = ''
   LIM  = 500 /* REXX idiosyncrasy on my side ;-) */
   
   do while INPUT \== '' /* strict comparison */
      parse var INPUT TOP 2 INPUT
      TOP = d2c( c2d( TOP ) + 64 ) // 256 )
      
      if sign( pos( TOP, BAD )) then OUT = OUT || '='
      OUT = OUT || TOP
       
      if LIM <= length( OUT ) then do
         call charout /* stdout */, OUT || CRLF
         OUT = ''
      end
   end  

> If not, then you are back to the 37+% expansion of base64.

The worst case is slightly more than 50% if the entire input
is d2c(192), d2c(202), d2c(205), or d2c(253).  And for runs
of d2c(201) or d2c(224) for the trailing SP / HT issue.

Ignoring the latter using Bruce's formula; 260/256 * 502/500
or less than 102%.  Sometimes it's 503/501, but we don't need
it more precisely while ignoring the trailing HT / SP stuff.

                        Bye, Frank