* GNAT.CRC32.Get_Value
@ 2017-07-15 19:56 Aurele
2017-07-15 20:06 ` GNAT.CRC32.Get_Value Simon Wright
0 siblings, 1 reply; 4+ messages in thread
From: Aurele @ 2017-07-15 19:56 UTC (permalink / raw)
Hi all, can someone explain the use of the GNAT.CRC32.Get_Value function as it would apply in a typical CRC32 or Checksum application. The function returns CRC32 XOR 16FFFF_FFFF# without changing the CRC32 value. Hence, I'm not grasping its full meaning/purpose. Thanks in advance o7
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* Re: GNAT.CRC32.Get_Value
2017-07-15 19:56 GNAT.CRC32.Get_Value Aurele
@ 2017-07-15 20:06 ` Simon Wright
2017-07-15 22:32 ` GNAT.CRC32.Get_Value Aurele
0 siblings, 1 reply; 4+ messages in thread
From: Simon Wright @ 2017-07-15 20:06 UTC (permalink / raw)
Aurele <aurele.vitali@gmail.com> writes:
> Hi all, can someone explain the use of the GNAT.CRC32.Get_Value
> function as it would apply in a typical CRC32 or Checksum
> application. The function returns CRC32 XOR 16FFFF_FFFF# without
> changing the CRC32 value. Hence, I'm not grasping its full
> meaning/purpose. Thanks in advance o7
Probably related to this:
https://en.wikipedia.org/wiki/Computation_of_cyclic_redundancy_checks#CRC_variants
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: GNAT.CRC32.Get_Value
2017-07-15 20:06 ` GNAT.CRC32.Get_Value Simon Wright
@ 2017-07-15 22:32 ` Aurele
2017-07-16 13:30 ` GNAT.CRC32.Get_Value gautier_niouzes
0 siblings, 1 reply; 4+ messages in thread
From: Aurele @ 2017-07-15 22:32 UTC (permalink / raw)
There is very little documentation on it but I think its typically used as value for a computed Checksum, or as a starting point for a reverse CRC32. I'm not sure.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: GNAT.CRC32.Get_Value
2017-07-15 22:32 ` GNAT.CRC32.Get_Value Aurele
@ 2017-07-16 13:30 ` gautier_niouzes
0 siblings, 0 replies; 4+ messages in thread
From: gautier_niouzes @ 2017-07-16 13:30 UTC (permalink / raw)
> There is very little documentation on it but I think its typically used as value for a computed Checksum, or as a starting point for a reverse CRC32. I'm not sure.
Are you asking about Get_Value or CRC32 in general?
Get_Value finalizes the computation of CRC32 (GNAT's System.CRC32 spec (s-crc32.ads) is pretty clear about the initialization and update parts).
HTH
Gautier
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