I see... and thank you for the knowledge. Just to clarify, I am using the full gzip format when file compression takes place (when compression level > 0). When the data is not compressed I do not include the header or trailing data.
Are saying that even if the data is not compressed, I still need to include the header and trailing data if I am going to pass the data to the deflate function? Are you also saying that if I do not want the extra bytes of info added to the file if it is not being compressed, I could alter the deflate function so when a compression method other than 8 is specified, no compression will take place and no extra data will be added? > But you > could cheat a little and > define your own compression method code to indicate > raw bytes. Cheers, Joe --- Scott Johnson <[EMAIL PROTECTED]> wrote: > From: joe bloggs [mailto:[EMAIL PROTECTED] > > If they decide not to compress the files, the app > sets > > the deflate compression level to 0 (indicating > that no > > compression is to take place). This works as > expected > > except that the deflate function seems to add a > few bytes [...] > > Does anyone know why this extra data is added to > every > > chunk passed to the deflate function? > > That's just how the deflate format works, as defined > in RFC 1951. > > Do your (optionally) compressed files consist only > of the raw zlib > stream? If so, and if you want the option to store > a raw uncompressed > byte stream as well (to avoid this inflation issue) > then you'll need at > least a small header on the front to indicate which > format it is. If > so, then consider using the full gzip format (RFC > 1952). The gzip > header has fields for the original file name and > timestamp and whatnot, > which may be useful as you are compressing files. > It also has a field > ("CM") to specify compression method. Oddly the RFC > defines only one > allowable compression method (deflate = 8) and > doesn't define one for > the "identity algorithm" of raw bytes. But you > could cheat a little and > define your own compression method code to indicate > raw bytes. > > -slj- > > > -- > For information on using the Palm Developer Forums, > or to unsubscribe, please see http://www.palmos.com/dev/support/forums/ __________________________________ Do you Yahoo!? Yahoo! Finance Tax Center - File online. File on time. http://taxes.yahoo.com/filing.html -- For information on using the Palm Developer Forums, or to unsubscribe, please see http://www.palmos.com/dev/support/forums/
