Comments on: asc-gzip/.xfd compression

By: Neil

Neil — Wed, 16 Feb 2011 21:42:13 +0000

Thanks, Steven.
I linked to you as well: http://stackoverflow.com/questions/6811/how-can-i-encode-xml-files-to-xfdl-base64-gzip/5021875#5021875

By: Steven

Steven — Mon, 07 Feb 2011 17:45:39 +0000

Sorry, no, I haven’t done anything more with these file. The particular chunk of code I wrote was replaced by a completely different system and I haven’t been involved.

(You’re aware of http://wxpython.org/ , right? Just want to make sure you aren’t punishing yourself with C unnecessarily .

By: Zachary D. Skelton

Zachary D. Skelton — Mon, 07 Feb 2011 17:38:48 +0000

Last year, I led a group of open source devs in creating an online utility to create XFDL files in mass based on a database. In all the google searching, we never came by this post and what a shame, as our page was run by python! Currently, I’m working to create a Linux based XFDL/XFD file viewer and am wondering if you’ve dealt with these files in C? It is far easier in Python but I’m going with C right now to utilize wx and create an app that can be compiled on Windows, Mac, and Linux with only minor changes. I plan to reference this post in my blog but thanks for your research!!

By: Steven’s weblog » asc-gzip/.xfd decompression

Steven’s weblog » asc-gzip/.xfd decompression — Thu, 10 Dec 2009 17:30:14 +0000

[...] to post code for asc-gzip/.xfd decompression to go with my asc-gzip/.xfd compression code. See this comment. I’m also reposting it here because the comment formatting is a little more bad than the [...]

By: Scott Stafford

Scott Stafford — Thu, 10 Dec 2009 17:08:03 +0000

Thanks for your post. Of course, I needed the opposite, I had one I needed to decompress. So I backwarded your algorithm and here is the result:

def decompress(fc):
    fc2 = fc.splitlines(True)
    fc3 = "".join(fc2[1:]) # could verify that it's asc-gzip here if we wanted to...
    unb64 = base64.standard_b64decode(fc3)
    
    ctr = 0
    ret = []
    while 1:
        if ctr == len(unb64): break
        
        ccltop = ord(unb64[ctr])
        ctr += 1
        cclbottom = ord(unb64[ctr])
        ctr += 1
        compressedchunklen = ccltop * 256 + cclbottom
        
        cltop = ord(unb64[ctr])
        ctr += 1
        clbottom = ord(unb64[ctr])
        ctr += 1
        chunklen = cltop * 256 + clbottom
        #~ print compressedchunklen, chunklen
        
        compressedchunk = unb64[ctr:ctr+compressedchunklen]
        ctr += compressedchunklen
        
        chunk = zlib.decompress(compressedchunk)
        assert(len(chunk) ==  chunklen)
        ret.append(chunk)
    
    return "".join(ret)

By: anna

anna — Wed, 21 Oct 2009 18:11:20 +0000

ahhh, code beautiful code! Remember the night I “watched you write code”? OO