port: use gettimeofday() as timing source; use smaller tick multiplier to avoid overflows

port/include/system.h

@@ -3,8 +3,8 @@
 
 #include <PR/ultratypes.h>
 
-u64 sysGetTicks(void);
-u64 sysGetTicksPerSecond(void);
+void sysInitTicks(void);
+u64 sysGetMicroseconds(void);
 
 void sysFatalError(const char *fmt, ...) __attribute__((noreturn));
 

port/src/libultra.c

@@ -15,6 +15,9 @@
 #define EEPROM_FNAME "./eeprom.bin"
 #define OS_COUNTER_RATE 46875000ULL
 
+#define OS_COUNTER_NUM (OS_COUNTER_RATE / 1000ULL)
+#define OS_COUNTER_DEN (1000000ULL / 1000ULL)
+
 u64 osClockRate = OS_CLOCK_RATE;
 u32 osMemSize = 16 * 1024 * 1024; /* expansion pak installed plus some extra */
 s32 osTvType = OS_TV_NTSC;        /* 0 = PAL, 1 = NTSC, 2 = MPAL */
@@ -26,7 +29,7 @@ s32 osViClock = VI_NTSC_CLOCK;
 OSTime osGetTime(void)
 {
 	// u64 should be enough to last a while
-	return (sysGetTicks() * OS_COUNTER_RATE) / sysGetTicksPerSecond();
+	return (sysGetMicroseconds() * OS_COUNTER_NUM) / OS_COUNTER_DEN;
 }
 
 u32 osGetCount(void)

port/src/main.c

@@ -60,6 +60,7 @@ static void cleanup(void)
 
 int main(int argc, const char **argv)
 {
+	sysInitTicks();
 	fsInit();
 	configInit();
 	videoInit();

port/src/system.c

@@ -2,33 +2,25 @@
 #include <stdarg.h>
 #include <stdio.h>
 #include <string.h>
+#include <sys/time.h>
 #include <SDL.h>
 #include <PR/ultratypes.h>
 #include "system.h"
 
+#define USEC_IN_SEC 1000000ULL
+
 static u64 startTick = 0;
-static u64 tickFreq = 0;
 
-static void sysInitTicks(void)
+void sysInitTicks(void)
 {
-	tickFreq = SDL_GetPerformanceFrequency();
-	startTick = SDL_GetPerformanceCounter();
+	startTick = sysGetMicroseconds();
 }
 
-u64 sysGetTicks(void)
+u64 sysGetMicroseconds(void)
 {
-	if (tickFreq == 0) {
-		sysInitTicks();
-	}
-	return (SDL_GetPerformanceCounter() - startTick);
-}
-
-u64 sysGetTicksPerSecond(void)
-{
-	if (tickFreq == 0) {
-		sysInitTicks();
-	}
-	return tickFreq;
+	struct timeval tv;
+	gettimeofday(&tv, NULL);
+	return ((u64)tv.tv_sec * USEC_IN_SEC + (u64)tv.tv_usec) - startTick;
 }
 
 void sysFatalError(const char *fmt, ...)