On Thu, Jul 16, 2020 at 9:25 AM 孙世龙 sunshilong wrote:
>
> >The 'A' is the constraint EAX:RDX register pair.
> >Also see https://gcc.gnu.org/onlinedocs/gcc/Machine-Constraints.html
> >and https://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html.
> Thanks to your attached document, I find a lot of
Hi, Jeff
Thank you for taking the time to respond to my question.
Thanks to your help, I have a deeper understanding of this matter.
>Also read the note in the Machine Constraints for:
> unsigned long long rdtsc (void)
>{
> unsigned long long tick;
> __asm__
On Thu, Jul 16, 2020 at 8:22 AM 孙世龙 sunshilong wrote:
>
> Here is the code snippet:
> #define ipipe_read_tsc(t) \
> __asm__ __volatile__("rdtsc" : "=A"(t))
I hope that is i386 only, and not x86_64.
> I found that the rdtsc (Read Time-Stamp Counter) instruction is used
> to
Hi, list
Here is the code snippet:
#define ipipe_read_tsc(t) \
__asm__ __volatile__("rdtsc" : "=A"(t))
I found that the rdtsc (Read Time-Stamp Counter) instruction is used
to determine how many CPU ticks took place since the processor was
reset.
But what does
"=A"(t)
mean?
Thank
