[fpc-pascal] old school crc32

[Mark Morgan Lloyd]

wkitty42 at windstream.net wrote:
> this is driving me battier than i already am :(
> 
> i have a binary file that contains a record of data... the first field 
> of the data is a crc32 value of a string of characters... the string of 
> characters is lower cased before being fed to the crc32 function... i 
> need to calculate the same crc32 value as what is stored in the file...
> 
> i've already checked the polynomial ($edb88320) is the same in both, the 
> original implementation (converted to TP4 in 1988) and this 
> implementation...
> 
> the original routine uses longint and speaks of initializing the 
> variable to $ffffffff before feeding it to the crc32 routine... the 
> existing routine in FPC says "Pre- and post-conditioning (one's 
> complement) is performed within this function so it shouldn't be done by 
> the application." but that doesn't give me the proper answer in this 
> case... i've tried using cardinal types and longint types to no avail...

Have you tried running your test case through a different 
implementation? I use http://www.wolfgang-ehrhardt.de/crchash_en.html

-- 
Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk

[Opinions above are the author's, not those of his employers or colleagues]