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Groups > comp.lang.c++ > #91218
| From | Bonita Montero <Bonita.Montero@gmail.com> |
|---|---|
| Newsgroups | comp.lang.c++ |
| Subject | Unbelievable |
| Date | 2023-08-09 08:01 +0200 |
| Organization | A noiseless patient Spider |
| Message-ID | <uava4i$3ps0s$1@dont-email.me> (permalink) |
| References | <uattpk$3g31h$1@dont-email.me> |
I disassembled GetSystemTimeAsFileTime() some years ago and it used
x86's RDTSC internally. But now it switched to a memory-mapped hard-
ware register with about millisecond resolution. Before it had 100ns
-resolution.
#include <Windows.h>
#include <iostream>
#include <chrono>
using namespace std;
using namespace chrono;
int main()
{
constexpr int64_t ROUNDS = 100'000'000;
auto tGet = []()
{
int64_t t;
GetSystemTimeAsFileTime( &(FILETIME &)t );
return t;
};
int64_t tSum = 0, n = 0, tBefore = tGet();
for( int64_t r = ROUNDS, t, tDiff; r--; )
t = tGet(),
tDiff = t - tBefore,
tSum += tDiff,
n += (bool)tDiff,
tBefore = t;
cout << (double)tSum / n << endl;
}
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Cool ! Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-08 19:25 +0200
Unbelievable Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-09 08:01 +0200
Re: Unbelievable Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-09 08:17 +0200
Re: Unbelievable scott@slp53.sl.home (Scott Lurndal) - 2023-08-09 13:57 +0000
Re: Unbelievable Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-09 16:18 +0200
Re: Unbelievable scott@slp53.sl.home (Scott Lurndal) - 2023-08-09 16:01 +0000
Re: Unbelievable Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-10 12:11 +0200
Re: Unbelievable scott@slp53.sl.home (Scott Lurndal) - 2023-08-10 14:44 +0000
Re: Unbelievable Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-10 17:40 +0200
Re: Unbelievable scott@slp53.sl.home (Scott Lurndal) - 2023-08-10 15:49 +0000
Re: Unbelievable Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-10 19:03 +0200
Re: Unbelievable David Brown <david.brown@hesbynett.no> - 2023-08-11 08:28 +0200
Re: Unbelievable Bonita Montero <Bonita.Montero@gmail.com> - 2023-08-11 09:17 +0200
Re: Unbelievable Ben Bacarisse <ben.usenet@bsb.me.uk> - 2023-08-11 12:02 +0100
Re: Unbelievable Paavo Helde <eesnimi@osa.pri.ee> - 2023-08-11 15:31 +0300
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