How to manage memory alignments and generic pointer arithmetics in a portable way in C?

Question

I have to implement an optimized version of malloc/realloc/free (tailored for my particular application). At the moment the code runs on a particular platform, but I would l

Answer 1

C says malloc returns a pointer to memory aligned for any purpose. There is no portable way in C to achieve that with C features. This has the consequence that malloc is a function that if written in C cannot be written in a portable way.

(C99, 7.20.3p1) "The pointer returned if the allocation succeeds is suitably aligned so that it may be assigned to a pointer to any type of object and then used to access such an object or an array of such objects in the space allocated (until the space is explicitly deallocated)."