gcc inline assembler - filling a structure

Vincent De Groote list.encelade@gmail.com
Thu Apr 2 16:23:00 GMT 2009


Hello,

I would like to execute the cpuid instruction on a x86

So I declared

typedef unsigned long int register_t;

struct response_t {
  register_t eax;
  register_t ebx;
   register_t ecx;
   register_t edx;
};

void cpuid ( register_t command, struct response_t * response )  {

...

}

How can I, in assembler, assign the value of a register (for example
ebx) to the response->ebx field ?

I also would like to wrap such function under a preprocessor #ifdef
directive, to check the target machine.
Is there a preprocessor definition I can use for this (a target like
x86) ?  I cannot find the list of all preprocessor definitions defined
by gcc.


Thanks for your replies and your time

Vincent De Groote



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