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util/clock.c: Fix clock skew mod

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Local time needs to be JST or some games (at least ID Zero) will
malfunction.
This commit is contained in:
Tau 2019-05-04 16:51:00 -04:00
parent c19d140589
commit 036730840d
1 changed files with 35 additions and 15 deletions
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50
util/clock.c
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@ -72,9 +72,11 @@ static void WINAPI my_GetSystemTimeAsFileTime(FILETIME *out)
next_GetSystemTimeAsFileTime(&in);
real_jiffies = (((int64_t) in.dwHighDateTime) << 32) | in.dwLowDateTime;
/* Apply bias: shift [02:00, 07:00) to [19:00, 24:00) */
/* Keepout period is JST [02:00, 07:00), which is equivalent to
UTC [17:00, 22:00). Bias UTC forward by 2 hours, changing this interval
to [19:00, 00:00) to make the math easier. We revert this bias later. */
real_jiffies_biased = real_jiffies + 17LL * jiffies_per_hour;
real_jiffies_biased = real_jiffies + 2LL * jiffies_per_hour;
/* Split date and time */
@ -89,7 +91,8 @@ static void WINAPI my_GetSystemTimeAsFileTime(FILETIME *out)
clock_current_day = day;
/* We want to skip the final five hours, so scale time-of-day by 19/24. */
/* We want to skip the final five hours of our UTC+2 biased reference frame,
so scale time-of-day by 19/24. */
fake_time = (real_time * 19LL) / 24LL;
@ -97,9 +100,9 @@ static void WINAPI my_GetSystemTimeAsFileTime(FILETIME *out)
fake_jiffies_biased = day * jiffies_per_day + fake_time;
/* Remove bias */
/* Revert bias */
fake_jiffies = fake_jiffies_biased - 17LL * jiffies_per_hour;
fake_jiffies = fake_jiffies_biased - 2LL * jiffies_per_hour;
/* Return result */
@ -109,8 +112,20 @@ static void WINAPI my_GetSystemTimeAsFileTime(FILETIME *out)
static BOOL WINAPI my_GetLocalTime(SYSTEMTIME *out)
{
/* Use UTC to simplify things */
return my_GetSystemTime(out);
ULARGE_INTEGER arith;
FILETIME linear;
/* Force JST */
my_GetSystemTimeAsFileTime(&linear);
arith.LowPart = linear.dwLowDateTime;
arith.HighPart = linear.dwHighDateTime;
arith.QuadPart += 9ULL * jiffies_per_hour;
linear.dwLowDateTime = arith.LowPart;
linear.dwHighDateTime = arith.HighPart;
return FileTimeToSystemTime(&linear, out);
}
static BOOL WINAPI my_GetSystemTime(SYSTEMTIME *out)
@ -146,20 +161,25 @@ static BOOL WINAPI my_GetSystemTime(SYSTEMTIME *out)
static DWORD WINAPI my_GetTimeZoneInformation(TIME_ZONE_INFORMATION *tzinfo)
{
/* Use UTC to simplify things */
dprintf("%s\n", __func__);
if (tzinfo != NULL) {
memset(tzinfo, 0, sizeof(*tzinfo));
SetLastError(ERROR_SUCCESS);
return TIME_ZONE_ID_UNKNOWN;
} else {
if (tzinfo == NULL) {
SetLastError(ERROR_INVALID_PARAMETER);
return TIME_ZONE_ID_INVALID;
}
/* Force JST (UTC+9), SEGA games malfunction in any other time zone.
Strings and boundary times don't matter, we only set the offset. */
memset(tzinfo, 0, sizeof(*tzinfo));
tzinfo->Bias = -9 * 60;
SetLastError(ERROR_SUCCESS);
/* "Unknown" here means that this region does not observe DST */
return TIME_ZONE_ID_UNKNOWN;
}
static BOOL WINAPI my_SetLocalTime(SYSTEMTIME *in)