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Atomic operations in assembly

Hi,
I want to write atomic operations (incr, dec, xchg, mod) which should support on almost all architectures.
Can anyone point me to resource available on thsi on net or in EE?

Someone explain what each following line is doing?

int32 func()
{
int32 val = -1;

asm volatile ("lock; xaddl %0,%1"
: "=r" (val), "=m" (*mem)
: "0" (val), "m" (*mem)
: "memory", "cc");
return val;
}

=r
=m
"0"
"m"
"memory"

What all these above do? Can someone explains all these? I am looking for resource/tutorial to understand these.

Thanks,
Ram

SOLUTION

ravenpl

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ASKER CERTIFIED SOLUTION

NovaDenizen

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shiningram

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Ravenpl you gave a great start and NovaDenizen you are awesome. You will be rewarded points when i close the question.
Can some one help writting increment and decrement atomic operations for linux and windos for 32 and 64 architecture.
Thanks,
Ram

SOLUTION

ravenpl

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shiningram

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Another question added to get clear suggestion from experts