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Question on volatile functions and GCC


Hi All,

I was looking at some slides on OpenSSL and secure memory wiping using
volatile (Slide 36 at
http://www.slideshare.net/guanzhi/crypto-with-openssl).

I believe GCC's interpretation of the use for 'volatile' is memory
mapped hardware. I think Ian stated it for me some time ago when I was
trying to understand different interpretations among compilers. If
volatile is for memory mapped hardware, why does GCC compile the
following:

volatile void clean_memory(volatile void* dest, size_t len)
{
  volatile unsigned char* p;
  for(p = (volatile unsigned char*)dest; len; dest[--len] = 0)
    ;;
}

How does a function become a 'volatile' memory mapped object related
to hardware?

Jeff


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