NetNews Usenet Archive 1993 #3/NN_1993_3.iso/spool/comp/sys/mac/programm/22000

Internet Message Format | 1993-01-23 | 1.7 KB

Path: sparky!uunet!zaphod.mps.ohio-state.edu!magnus.acs.ohio-state.edu!usenet.ins.cwru.edu!agate!darkstar.UCSC.EDU!cats.ucsc.edu!speth
From: [e-mail] (James Gustave)
Newsgroups: comp.sys.mac.programmer
Subject: Recommended way to deal with large memory buffers?
Date: 23 Jan 1993 03:35:43 GMT
Organization: University of California; Santa Cruz
Lines: 24
Message-ID: <[e-mail]>
References: <[e-mail]>
NNTP-Posting-Host: am.ucsc.edu


  I'm working on an encryption application, and I need to go through a file,
encrypt it, and write it to a new file.  The encryption routine takes a Ptr
to a buffer, and a count of the number of bytes to process.  For small files,
it makes sense to read the whole file into the buffer and do the encryption.
However, this means that the maximum size of the file to be encrypted is
determined by the amount of memory the program can allocate.  On the other
hand, if I did the encryption incrementally, writing the parts to a temp file,
then there might be a lot of unnecessary disk access which would slow down
the process.

  What is the recommended way of working with large files?  Should I read it
all in, or use temp files?  Or should I read as much in as possible and only
create temp files when necessary (maybe I just answered my own question :)

  Another question, sometimes I need to add a prefix packet to the beginning
of the buffer.  Is there an easy way to prepend stuff to a buffer, without
allocating a new buffer, writing the info, then doing a block move?

Thanks.

--
________________________________________________________________________________
james speth           email for pgp 2.0 public-key           [e-mail]