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Date:      Thu, 18 Aug 2005 12:08:50 +0400
From:      Sergey Matveychuk <sem@FreeBSD.org>
To:        Chuck Swiger <cswiger@mac.com>
Cc:        questions@FreeBSD.org
Subject:   Re: man malloc
Message-ID:  <43044212.20909@FreeBSD.org>
In-Reply-To: <4303B016.3030201@mac.com>
References:  <4303A632.1000809@FreeBSD.org> <4303B016.3030201@mac.com>

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Chuck Swiger wrote:

>> What does "suitable aligned for storage of *any* type of object" means?
> 
> 
> On some platforms, it is either desirable or required that, say, a 
> 8-byte double is stored at a memory location which is is also aligned to 
> 8-bytes:

Oh, it was told for different architectures. It's quite clear for me now.

> 
>> What is pointer coercion? I have no pointer before malloc() returns.
> 
> 
> Right.  Well, malloc returns a (void *), but most people want to use the 
> memory malloc returns to hold their own arrays, structs, whatever, which 
> means that you need to be able to coerce the (void *) malloc gave you 
> into whatever pointer type you want to actually use.
> 
> So the memory malloc gives you needs to be aligned so that it's OK to be 
> used for even the most restrictive datatype known to the system, 
> commonly 8, 16, or 32 bytes.
> 

Pointer coercion means a type cast? I see now.
I read it as 'force change of pointer value' before.

Thanks, guys!
--
Sem.



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