[PD] Fwd: Variable number of objects?

Mathieu Bouchard matju at artengine.ca
Fri Sep 30 18:10:41 CEST 2011

Le 2011-09-30 à 12:01:00, Mathieu Bouchard a écrit :

> size_t real_size (size_t n) {return 1<<highest_bit(n+sizeof(void *));}

erratum :

size_t real_size (size_t n) {return 2<<highest_bit(n+sizeof(void *)-1);}

because the first version I wrote gets the PREVIOUS-or-equal power, which 
is nonsense. Doubling that gives the NEXT power, but not next-or-equal, so 
I subtract 1 to compensate for that.

BTW, I haven't looked at modern glibc mallocs. I suspect it might do 
things similar to the Perl Allocator nowadays, though I have not checked, 
and it's probably not documented (?). Chances are that it's a different 
formula, anyway.

| Mathieu BOUCHARD ----- téléphone : +1.514.383.3801 ----- Montréal, QC

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