asum - Very fast MD5 checksum tool.

This tool can be used both to generate a list of MD5 checksums and verify
such list. The format of the generated list is compatible with many other
similar tools.

The main idea with this tool is to offer as quick MD5 checksum calculations
as possible, in a simple way, without extra options required.

It uses highly optimized 68k MD5 code and reasonably optimized PPC MD5 code.
The latter is utilized automatically if WarpOS is available, or if the
MorphOS or AmigaOS4 versions are used. This is coupled with asynchronous
reads, to allow the CPU to calculate the checksums, while the files are
being read in the background, which makes it very efficient with DMA
controllers.


Thanks:

* K-P Koljonen for his tireless and inspiring efforts optimizing the
  HippoPlayer MD5 code this tool is based on.
* Crab at #amihelp for all the meticulous testing and feedback.


Usage:
> asum ? 
FILES/M,ALL/S,TO/K,CHECK/K: 

FILES: Files to checksum. If directories or volumes are supplied, the
       contained files will be checksummed. AmigaDOS patterns can be used.
ALL:   Traverse directories and volumes found in FILES recursively.
TO:    Output the generated list of checksums to this file, instead of the
       standard output.
CHECK: Validate this previously generated list of checksums. Resultcode 10
       for checksum mismatch and 5 for missing file.


Examples:

A couple of files:
> C:
C> asum Dir List Version
c896a610895a36be0dea489cd6dd83ee  Dir
f300978a06ba9e5e7258ad43241126eb  List
d5c482ac3cc004d57465db051db1365c  Version

Using AmigaDOS patterns:
> asum S:#?-Startup 
c23e2afc5cea3b09bc2dcb890b441a3a  S:Network-Startup
17ab20b698004d01f1197c4e9f27ec51  S:User-Startup
e979a38b5f13a3fb8a8e67d0d3873547  S:Shell-startup
14fa4c0562f540a9d250365eb5d65818  S:Network-User-Startup
d5cae30fc54900a314dd2c6cf2175825  S:WHDLoad-Startup

Generate a list of an entire partition and then verify it:
> asum Work: ALL TO=RAM:Work.md5sums
> asum CHECK=RAM:Work.md5sums
> echo $RC
0

Generate a list, change a file and then verify it catches the change:
> asum S: TO=RAM:checkfile.md5sums
> echo "" >>S:User-Startup
> asum CHECK=RAM:checkfile.md5sums
S:User-Startup: MD5 mismatch!
> echo $RC
10

Generate a list, remove a file and then verify it catches the missing file:
> copy S:User-Startup S:User-Startup.backup
> asum S: TO=RAM:checkfile.md5sums
> delete S:User-Startup.backup
S:User-Startup.backup  Deleted
> asum CHECK=RAM:checkfile.md5sums
S:User-Startup.backup: object not found
> echo $RC
5