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Merge branch 'mach_monotonic_time_use_timebase_struct' into 'master'

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gmain: fix fetching timebase on non-Intel Darwin

Closes #858

See merge request GNOME/glib!1566
This commit is contained in:
Philip Withnall 2020-07-26 13:22:48 +00:00
commit c60d6599c9
2 changed files with 40 additions and 36 deletions
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65
glib/gmain.c
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@ -2906,47 +2906,40 @@ g_get_monotonic_time (void)
gint64
g_get_monotonic_time (void)
{
static mach_timebase_info_data_t timebase_info;
mach_timebase_info_data_t timebase_info;
guint64 val;
if (timebase_info.denom == 0)
/* we get nanoseconds from mach_absolute_time() using timebase_info */
mach_timebase_info (&timebase_info);
val = mach_absolute_time ();
if (timebase_info.numer != timebase_info.denom)
{
/* This is a fraction that we must use to scale
* mach_absolute_time() by in order to reach nanoseconds.
*
* We've only ever observed this to be 1/1, but maybe it could be
* 1000/1 if mach time is microseconds already, or 1/1000 if
* picoseconds. Try to deal nicely with that.
*/
mach_timebase_info (&timebase_info);
#ifdef HAVE_UINT128_T
val = ((__uint128_t) val * (__uint128_t) timebase_info.numer) / timebase_info.denom / 1000;
#else
guint64 t_high, t_low;
guint64 result_high, result_low;
/* We actually want microseconds... */
if (timebase_info.numer % 1000 == 0)
timebase_info.numer /= 1000;
else
timebase_info.denom *= 1000;
/* We want to make the numer 1 to avoid having to multiply... */
if (timebase_info.denom % timebase_info.numer == 0)
{
timebase_info.denom /= timebase_info.numer;
timebase_info.numer = 1;
}
else
{
/* We could just multiply by timebase_info.numer below, but why
* bother for a case that may never actually exist...
*
* Plus -- performing the multiplication would risk integer
* overflow. If we ever actually end up in this situation, we
* should more carefully evaluate the correct course of action.
*/
mach_timebase_info (&timebase_info); /* Get a fresh copy for a better message */
g_error ("Got weird mach timebase info of %d/%d. Please file a bug against GLib.",
timebase_info.numer, timebase_info.denom);
}
/* 64 bit x 32 bit / 32 bit with 96-bit intermediate
* algorithm lifted from qemu */
t_low = (val & 0xffffffffLL) * (guint64) timebase_info.numer;
t_high = (val >> 32) * (guint64) timebase_info.numer;
t_high += (t_low >> 32);
result_high = t_high / (guint64) timebase_info.denom;
result_low = (((t_high % (guint64) timebase_info.denom) << 32) +
(t_low & 0xffffffff)) /
(guint64) timebase_info.denom;
val = ((result_high << 32) | result_low) / 1000;
#endif
}
else
{
/* nanoseconds to microseconds */
val = val / 1000;
}
return mach_absolute_time () / timebase_info.denom;
return val;
}
#else
gint64

11
meson.build
View File

@ -772,6 +772,17 @@ if cc.links('''#include <sys/eventfd.h>
glib_conf.set('HAVE_EVENTFD', 1)
endif
# Check for __uint128_t (gcc) by checking for 128-bit division
uint128_t_src = '''int main() {
static __uint128_t v1 = 100;
static __uint128_t v2 = 10;
static __uint128_t u;
u = v1 / v2;
}'''
if cc.compiles(uint128_t_src, name : '__uint128_t available')
glib_conf.set('HAVE_UINT128_T', 1)
endif
clock_gettime_test_code = '''
#include <time.h>
struct timespec t;