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Re: How is the APFS block checksum calculated?
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Re: How is the APFS block checksum calculated?


  • Subject: Re: How is the APFS block checksum calculated?
  • From: Toby Thain <email@hidden>
  • Date: Sat, 29 Apr 2017 19:47:22 -0400

On 2017-04-29 7:42 PM, Thomas Tempelmann wrote:
On Sun, Apr 30, 2017 at 1:37 AM, Toby Thain <email@hidden
<mailto:email@hidden>> wrote:

    Seems you have % instead of & ? And watch out for sign extension on
    those literal 0xFFFFFFFF's. You probably want an unsigned and long
    long suffix on them.


Nope, both are correct, at least for standard fletcher algorithm. It's
always modulo (%) MAXINT-1.

Ah, OK. Thanks for clarifying!

> And 0xFFFFFFFF's gets properly expanded to
unsigned 64 bit, as it should. I double checked using uint64_t variable
all the way, and it didn't change the outcome.

--
Thomas Tempelmann, http://www.tempel.org/
Follow me on Twitter: https://twitter.com/tempelorg
Read my programming blog: http://blog.tempel.org/

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References: 
 >How is the APFS block checksum calculated? (From: Thomas Tempelmann <email@hidden>)
 >Re: How is the APFS block checksum calculated? (From: Toby Thain <email@hidden>)
 >Re: How is the APFS block checksum calculated? (From: Thomas Tempelmann <email@hidden>)

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