Re: cross-platform compress & decompress

[Wouter]

On 02 Dec 2003, at 03:38, [EMAIL PROTECTED] wrote:

Message: 4
Date: Mon, 1 Dec 2003 16:36:59 -0800
From: Mark Brownell <[EMAIL PROTECTED]>
Subject: Re: cross-platform compress & decompress
To: How to use Revolution <[EMAIL PROTECTED]>
Message-ID: <[EMAIL PROTECTED]>
Content-Type: text/plain; charset=US-ASCII; format=flowed


snip


I have tried compressing and decompressing the whole file as the first
test. I tried compressing the data from a variable as a second test.
I've looked at the same data in a text editor on both platforms and I
did a comparison of charToNum() of the compressed data on both
platforms. This was the exact same problem I had with blowfish I think.
I solved it by constricting cross-platform data transfers to less than
ascii 127; even though the data can represent up to ascii 255. My
blowfish algorithm does it all as numerical values until the final
rendering. I had to drop binaryEncode() & binaryDecode() in order to
get numerical only results within the process. That's why I think it's
something like upper ascii character values across platforms.
The < put binaryDecode("N",str,halfBlock) into numConverted >
in your blowfish handler can produce an unsigned integer on
the Windows platform where as on the Mac a signed integer is
 produced. This is probably an engine related problem.
To test this try the following on both platforms and compare:
on mouseUp
  put num2char("169,170,171,172") into x
  ## N - decode signed four-byte integers in network order
  put binaryDecode("N",x,halfBlock1) into numConverted
  ## I - decode unsigned four-byte integers in host order
  put binaryDecode("I",x,halfBlock2) into numConverted
  put halfblock1 && halfblock2
end mouseUp
function num2char sx
  repeat for each item i in sx
    put numtochar(i)  after z
  end repeat
  return z
end num2char
Greetings,
WA
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