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Implement clock_gettime syscall

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This implements the syscalls for `clock_gettime` and `clock_getres`. We
support two clocks: CLOCK_REALTIME and CLOCK_MONOTONIC. I've opted to
use the existing `osGetTime()` code for the realtime clock, because it's
known to work.

For CLOCK_MONOTONIC I've used `svcGetSystemTick()` directly, as it has a
higher resolution. We can ignore the drift and so on, because it's
supposed to be just the number of ticks since last boot.
This commit is contained in:
Teodor Spæren 2022-05-28 09:52:49 +02:00 committed by fincs
parent 82f821156a
commit 813d28ddc4
1 changed files with 62 additions and 1 deletions
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63
libctru/source/system/syscalls.c
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@ -3,12 +3,15 @@
#include <sys/lock.h>
#include <sys/reent.h>
#include <string.h>
#include <time.h>
#include <errno.h>
#include <3ds/types.h>
#include <3ds/svc.h>
#include <3ds/env.h>
#include <3ds/os.h>
#include <3ds/synchronization.h>
#include "../internal.h"
void __ctru_exit(int rc);
@ -28,6 +31,64 @@ struct _reent* __SYSCALL(getreent)()
return tv->reent;
}
int __SYSCALL(clock_gettime)(clockid_t clock_id, struct timespec *tp) {
if (clock_id == CLOCK_REALTIME)
{
if (tp != NULL)
{
// Retrieve current time, adjusting epoch from 1900 to 1970
s64 ms_since_epoch = osGetTime() - 2208988800000ULL;
tp->tv_sec = ms_since_epoch / 1000;
tp->tv_nsec = (ms_since_epoch % 1000) * 1000000;
}
}
else if (clock_id == CLOCK_MONOTONIC)
{
if (tp != NULL)
{
// Use the ticks directly, as it offer the highest precision
u64 ticks_since_boot = svcGetSystemTick();
tp->tv_sec = ticks_since_boot / SYSCLOCK_ARM11;
tp->tv_nsec = ((ticks_since_boot % SYSCLOCK_ARM11) * 1000000000ULL) / SYSCLOCK_ARM11;
}
}
else
{
errno = EINVAL;
return -1;
}
return 0;
}
int __SYSCALL(clock_getres)(clockid_t clock_id, struct timespec *res) {
if (clock_id == CLOCK_REALTIME)
{
if (res != NULL)
{
res->tv_sec = 0;
res->tv_nsec = 1000000;
}
}
else if (clock_id == CLOCK_MONOTONIC)
{
if (res != NULL)
{
res->tv_sec = 0;
res->tv_nsec = 1;
}
}
else
{
errno = EINVAL;
return -1;
}
return 0;
}
//---------------------------------------------------------------------------------
int __SYSCALL(gettod_r)(struct _reent *ptr, struct timeval *tp, struct timezone *tz) {
//---------------------------------------------------------------------------------
@ -37,7 +98,7 @@ int __SYSCALL(gettod_r)(struct _reent *ptr, struct timeval *tp, struct timezone
// Convert to struct timeval
tp->tv_sec = now / 1000;
tp->tv_usec = (now - 1000*tp->tv_sec) * 1000;
tp->tv_usec = (now % 1000) * 1000;
}
if (tz != NULL) {