Fix osGetTime(), this time for real (also: race condition fix by mtheall)

diff --git a/libctru/source/os.c b/libctru/source/os.c
index f622105d934d235493de794c8b837f092c1a2169..d0287ad1d7cd74e04aca610f3fae11de71b57294 100644 (file)
--- a/libctru/source/os.c
+++ b/libctru/source/os.c
@@ -13,9 +13,9 @@ typedef struct {
 
 static volatile u32* __datetime_selector =
        (u32*) 0x1FF81000;
-static volatile datetime_t* __datetime1 =
+static volatile datetime_t* __datetime0 =
        (datetime_t*) 0x1FF81020;
-static volatile datetime_t* __datetime2 =
+static volatile datetime_t* __datetime1 =
        (datetime_t*) 0x1FF81040;
 
 
@@ -41,19 +41,27 @@ u32 osConvertOldLINEARMemToNew(u32 vaddr)
 
 // Returns number of milliseconds since 1st Jan 1900 00:00.
 u64 osGetTime() {
-       volatile datetime_t* dt;
+       u32 s1, s2 = *__datetime_selector & 1;
+       datetime_t dt;
 
-       switch(*__datetime_selector & 1) {
-       case 0:
-               dt = __datetime1;
-               break;
-       case 1:
-               dt = __datetime2;
-               break;
-       }
+       do {
+               s1 = s2;
+               if(!s1)
+                       dt = *__datetime0;
+               else
+                       dt = *__datetime1;
+               s2 = *__datetime_selector & 1;
+       } while(s2 != s1);
+
+       u64 delta = svcGetSystemTick() - dt.update_tick;
+
+       // Work around the VFP not supporting 64-bit integer <--> floating point conversion
+       double temp = (u32)(delta >> 32);
+       temp *= 0x100000000ULL;
+       temp += (u32)delta;
 
-       u64 offset = (u32)((u32)(svcGetSystemTick() - dt->update_tick) / TICKS_PER_MSEC);
-       return dt->date_time + offset;
+       u32 offset = temp / TICKS_PER_MSEC;
+       return dt.date_time + offset;
 }
 
 u32 osGetFirmVersion() {