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From: ittium <ittium@gmail.com>
Newsgroups: comp.programming.threads
Subject: Re: Threads and statically allocated buffer
Date: Sun, 25 Sep 2011 11:45:44 +0530
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On 25-09-2011 AM 01:12, David Schwartz wrote:
> On Sep 23, 9:38 pm, ittium<itt...@gmail.com>  wrote:
>
>> Is there any operation that is guaranteed to be atomic ?
>
> Your platform might have some.
>
>>  From your
>> reasoning it seems operations like ++a or a=b are also not atomic.
>
> Exactly. Some CPUs don't even have atomic increment operations. And
> even if the CPU does, the compiler might see that it needs the value
> later and prefer to have it in a register, so it might not use an
> atomic in-memory increment even if it has one.

You are saying even if there is some atomic operation available for some 
compiler+OS+CPU, this is not guaranteed to be portable, In other words, 
there is no portable atomic operation.