Adler32 Checksum

Submitted by Sergey on January 1, 2008 - 19:52 UTC
topic: 
code
vfp
checksum
foxpro
dll
crc

Adler32 is different from CRC32. It's much faster but a little bit less reliable.
The free ZLIB.DLL from http://www.zlib.net/ has a function to calculate Adler32.


$SAMPLECODE$





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DECLARE Long adler32 IN Zlib Long Adler32, String Buffer, Long BuffLen

* Initialize Adler32 and calculate 1st checksum
lnAdler32 = adler32(0, Null, 0)
lcText = "Adler32 checksum"
lnAdler32 = adler32(lnAdler32, lcText, LEN(lcText))
? TRANSFORM(lnAdler32, "@0")

* Initialize Adler32 again and calculate 2nd checksum
lnAdler32 = adler32(0, Null, 0)
lcText = "DECLARE Long adler32 IN Zlib Long Adler32, String Buffer, Long BuffLen"
lnAdler32 = adler32(lnAdler32, lcText, LEN(lcText))
? TRANSFORM(lnAdler32, "@0")

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