atari: Do not use system interrupt for handling timer. Do it from use…

…rspace, like RISCOS backend.

configure.in

@@ -2865,7 +2865,6 @@ case "$host" in
             else
                 AC_DEFINE(SDL_TIMER_MINT)
                 SOURCES="$SOURCES $srcdir/src/timer/mint/*.c"
-                SOURCES="$SOURCES $srcdir/src/timer/mint/*.S"
             fi
             have_timers=yes
         fi

src/timer/mint/SDL_systimer.c

@@ -25,7 +25,7 @@
 
 /*
  *	TOS/MiNT timer driver
- *	based on vbl vector
+ *	based on RISCOS backend
  *
  *	Patrice Mandin
  */
@@ -44,106 +44,119 @@
 
 #include "SDL_timer.h"
 #include "../SDL_timer_c.h"
-#include "SDL_thread.h"
 
 #include "../../video/ataricommon/SDL_atarisuper.h"
 
-#include "SDL_vbltimer_s.h"
+/* from src/video/ataricommon/SDL_atarievents.c */
+void SDL_AtariMint_BackgroundTasks(void);
 
-/* from audio/mint */
-void SDL_MintAudio_CheckFpu(void);
+static Uint32 readHz200Timer(void);
 
 /* The first ticks value of the application */
 static Uint32 start;
-static SDL_bool read_hz200_from_vbl = SDL_FALSE;
+
 static int mint_present; /* can we use Syield() ? */
 
+/* Timer  SDL_arraysize(Timer ),start/reset time */
+static Uint32 timerStart;
+
 void SDL_StartTicks(void)
 {
-	void *old_stack;
 	long dummy;
 
-	/* Set first ticks value */
-	old_stack = (void *)Super(0);
-	start = *((volatile long *)_hz_200);
-	SuperToUser(old_stack);
-
-	start *= 5;	/* One _hz_200 tic is 5ms */
+	/* Set first ticks value, one _hz_200 tic is 5ms */
+	start = readHz200Timer() * 5;
 
 	mint_present = (Getcookie(C_MiNT, &dummy) == C_FOUND);
 }
 
 Uint32 SDL_GetTicks (void)
 {
-	Uint32 now = start;
-
-	if (read_hz200_from_vbl) {
-		now = SDL_Atari_hz200;
-	} else {
-		void *old_stack = (void *)Super(0);
-		now = *((volatile long *)_hz_200);
-		SuperToUser(old_stack);
-	}
+	Uint32 now = readHz200Timer() * 5;
 
-	return((now*5)-start);
+	return(now-start);
 }
 
 void SDL_Delay (Uint32 ms)
 {
 	Uint32 now;
 
+	/* No need to loop for delay below resolution */
+	if (ms<5) {
+		SDL_AtariMint_BackgroundTasks();
+		if (mint_present) {
+			Syield();
+		}
+		return;
+	}
+
 	now = SDL_GetTicks();
 	while ((SDL_GetTicks()-now)<ms){
+		SDL_AtariMint_BackgroundTasks();
 		if (mint_present) {
 			Syield();
 		}
 	}
 }
 
-/* Data to handle a single periodic alarm */
-static SDL_bool timer_installed=SDL_FALSE;
-
-/* This is only called if the event thread is not running */
-int SDL_SYS_TimerInit(void)
+static Uint32 readHz200Timer(void)
 {
 	void *old_stack;
+	Uint32 now;
 
-	SDL_MintAudio_CheckFpu();
-
-	/* Install RunTimer in vbl vector */
 	old_stack = (void *)Super(0);
-	timer_installed = !SDL_AtariVblInstall(SDL_ThreadedTimerCheck);
+	now = *((volatile long *)_hz_200);
 	SuperToUser(old_stack);
 
-	if (!timer_installed) {
-		return(-1);
-	}
+	return now;
+}
+
+/* Non-threaded version of timer */
 
-	read_hz200_from_vbl = SDL_TRUE;
-	return(SDL_SetTimerThreaded(0));
+int SDL_SYS_TimerInit(void)
+{
+	return(0);
 }
 
 void SDL_SYS_TimerQuit(void)
 {
-	/* Uninstall RunTimer vbl vector */
-	if (timer_installed) {
-		void *old_stack = (void *)Super(0);
-		SDL_AtariVblUninstall(SDL_ThreadedTimerCheck);
-		SuperToUser(old_stack);
-		timer_installed = SDL_FALSE;
-	}
-	read_hz200_from_vbl = SDL_FALSE;
+	SDL_SetTimer(0, NULL);
 }
 
 int SDL_SYS_StartTimer(void)
 {
-	SDL_SetError("Internal logic error: MiNT uses vbl timer");
-	return(-1);
+	timerStart = SDL_GetTicks();
+
+	return(0);
 }
 
 void SDL_SYS_StopTimer(void)
 {
-	return;
+	/* Don't need to do anything as we use SDL_timer_running
+	   to detect if we need to check the timer */
+}
+
+
+void SDL_AtariMint_CheckTimer(void)
+{
+	if (SDL_timer_running && SDL_GetTicks() - timerStart >= SDL_alarm_interval)
+	{
+		Uint32 ms;
+
+		ms = SDL_alarm_callback(SDL_alarm_interval);
+		if ( ms != SDL_alarm_interval )
+		{
+			if ( ms )
+			{
+				SDL_alarm_interval = ROUND_RESOLUTION(ms);
+			} else
+			{
+				SDL_alarm_interval = 0;
+				SDL_timer_running = 0;
+			}
+		}
+		if (SDL_alarm_interval) timerStart = SDL_GetTicks();
+	}
 }
 
 #endif /* SDL_TIMER_MINT */