Make timing virtual; sync with real time each video frame

7 files changed, 83 insertions, 133 deletions

diff --git a/emu.c b/emu.c
index 5b24524..a9170a1 100644
--- a/emu.c
+++ b/emu.c
@@ -20,13 +20,11 @@
 
 
 #define FREQ 50
-#define PERIOD (500000/FREQ)
+#define PERIOD (1000000/FREQ)
 
 
 u16 mem[N_MEM];
 
-static u32 timer_handled;
-
 static int trace = 0;
 static int trace_new = 0;
 static int store_trace = 0;
@@ -48,7 +46,10 @@ static u8 irq_active, fiq_active;
 static u8 irq_enabled, fiq_enabled;
 
 static u64 insn_count;
-static u32 cycle_count;  // 1728 cycles/line for PAL, 1716 for NTSC
+static u32 cycle_count;
+static u32 line_count;
+static const u32 cycles_per_line = 1728;  // 1728 for PAL, 1716 for NTSC
+static const u32 lines_per_field = 312;   // 312 for PAL, 262 for NTSC
 
 
 u32 get_ds(void)
@@ -762,11 +763,11 @@ bad:
 	fatal("! UNIMPLEMENTED\n");
 }
 
-static u32 last_retrace_time = 0;
-
 static void do_idle(void)
 {
-	u32 now = timer_now();
+	static u32 last_retrace_time = 0;
+
+	u32 now = get_realtime();
 	if (now < last_retrace_time + PERIOD) {
 //		printf("  sleeping %dus\n", last_retrace_time + PERIOD - now);
 		usleep(last_retrace_time + PERIOD - now);
@@ -775,17 +776,16 @@ static void do_idle(void)
 
 u16 get_video_line(void)
 {
-	u32 now = timer_now();
-	return (now - last_retrace_time) * 625 * FREQ / 2 / 1000000;	// 525 for NTSC
+	return line_count;
 }
 
-static void run_main(void)
+static void run_line(void)
 {
 	int idle = 0;
 
 	for (;;) {
-		if (timer_triggered != timer_handled)
-			break;
+//		if (timer_triggered != timer_handled)
+//			break;
 
 		if (trace)
 			print_state();
@@ -797,20 +797,20 @@ static void run_main(void)
 
 		if (cs_pc() == board->idle_pc) {
 			idle++;
-			if (idle == 2)
+			if (idle == 2) {
+				cycle_count = 0;
 				break;
+			}
 		}
 
 		step();
 		insn_count++;
+		if (cycle_count >= cycles_per_line) {
+//			printf("PING!\n");
+			cycle_count -= cycles_per_line;
+			break;
+		}
 	}
-
-	if (timer_triggered != timer_handled) {
-		timer_run();
-		timer_handled++;
-		timer_set(1000000/250);
-	} else
-		do_idle();
 }
 
 static void do_controller(void)
@@ -888,66 +888,64 @@ static void do_controller(void)
 
 struct timer timer_controller = {
 	.name = "controller",
-	.time = 20000,
+	.time = 0,
 	.interval = 20000,
 	.run = do_controller
 };
 
 static void run(void)
 {
-	run_main();
+	for (line_count = 0; line_count < lines_per_field; line_count++) {
+		run_line();
 
-	u32 now = timer_now();
+		timer_run(cycles_per_line);
 
-	if (now - last_retrace_time >= PERIOD) {
-		static int count = 0;
-		count++;
-		if (count == 5) {
-			screen_needs_update = 1;
-			count = 0;
-		}
+		if (line_count == 240)
+			mem[0x2863] |= 1;	// trigger vblank IRQ
+		if (line_count == mem[0x2836])
+			mem[0x2863] |= 2;	// trigger vpos IRQ
 
-		// video
-		// FIXME: make this better
-		static u32 which = 1;
+		maybe_enter_irq();
+	}
 
-		mem[0x2863] |= which;
-		which ^= 3;
+//	static u32 last;
+//	u32 now = get_realtime();
+//	printf("-> %uus for this field (cpu)\n", now - last);
+//	last = now;
 
-		last_retrace_time = now;
+	update_screen();
 
-		if (do_extint1) {
-			mem[0x3d22] |= 0x0200;
-			do_extint1 = 0;
-		}
-		if (do_extint2) {
-			mem[0x3d22] |= 0x1000;
-			do_extint2 = 0;
-		}
+//	now = get_realtime();
+//	printf("-> %uus for this field (gfx)\n", now - last);
+//	last = now;
 
-		// UART		FIXME
-mem[0x3d22] |= 0x0100;
-	}
+	do_controller();
 
-	maybe_enter_irq();
+	mem[0x3d22] |= 0x0100; // UART  FIXME
 
+	if (do_extint1) {
+		mem[0x3d22] |= 0x0200;
+		do_extint1 = 0;
+	}
+	if (do_extint2) {
+		mem[0x3d22] |= 0x1000;
+		do_extint2 = 0;
+	}
 
-#if 0
-// XXX: move this elsewhere
 	if (pause_after_every_frame) {
 		printf("*** paused, press a key to continue\n");
 
 		while (update_controller() == 0)
 			;
 	}
-#endif
+
+	do_idle();
 }
 
 void emu(void)
 {
 	platform_init();
 	read_rom(0);
-	timer_init();
 	board_init();
 	io_init();
 	audio_init();
diff --git a/io.c b/io.c
index ddde04a..bc54089 100644
--- a/io.c
+++ b/io.c
@@ -132,13 +132,13 @@ static void do_tmb2(void)
 
 static struct timer timer_tmb1 = {
 	.name = "TMB1",
-	.interval = 1000000/8,
+	.interval = 27000000/8,
 	.run = do_tmb1
 };
 
 static struct timer timer_tmb2 = {
 	.name = "TMB2",
-	.interval = 1000000/128,
+	.interval = 27000000/128,
 	.run = do_tmb2
 };
 
@@ -190,12 +190,12 @@ void io_store(u16 val, u32 addr)
 		if ((mem[addr] & 0x0003) != (val & 0x0003)) {
 			u16 hz = 8 << (val & 0x0003);
 			printf("*** TMB1 FREQ set to %dHz\n", hz);
-			timer_tmb1.interval = 1000000 / hz;
+			timer_tmb1.interval = 27000000 / hz;
 		}
 		if ((mem[addr] & 0x000c) != (val & 0x000c)) {
 			u16 hz = 128 << ((val & 0x000c) >> 2);
 			printf("*** TMB2 FREQ set to %dHz\n", hz);
-			timer_tmb2.interval = 1000000 / hz;
+			timer_tmb2.interval = 27000000 / hz;
 		}
 		break;
 
@@ -225,7 +225,6 @@ void io_store(u16 val, u32 addr)
 		break;
 
 	case 0x3d22:		// IRQ ack
-//printf("######## ACK %04x\n", val);
 		mem[addr] &= ~val;
 		return;
 
diff --git a/platform-sdl.c b/platform-sdl.c
index 2199f1a..8e3e140 100644
--- a/platform-sdl.c
+++ b/platform-sdl.c
@@ -5,6 +5,7 @@
 #include <stdio.h>
 #include <stdarg.h>
 #include <sys/stat.h>
+#include <sys/time.h>
 #include <SDL.h>
 
 #include "types.h"
@@ -260,6 +261,16 @@ char update_controller(void)
 	return 0;
 }
 
+
+u32 get_realtime(void)
+{
+	struct timeval tv;
+
+	gettimeofday(&tv, 0);
+	return 1000000*tv.tv_sec + tv.tv_usec;
+}
+
+
 void warn(const char *format, ...)
 {
 	va_list ap;
@@ -275,6 +286,7 @@ void fatal(const char *format, ...)
 	exit(1);
 }
 
+
 static void mix(void *cookie, u8 *data, int n)
 {
 	if (mute_audio) {
@@ -285,6 +297,7 @@ static void mix(void *cookie, u8 *data, int n)
 	audio_render((s16 *)data, n/2);
 }
 
+
 void platform_init(void)
 {
 	if (SDL_Init(SDL_INIT_AUDIO|SDL_INIT_VIDEO) < 0)
diff --git a/platform.h b/platform.h
index a9ce58f..57398f2 100644
--- a/platform.h
+++ b/platform.h
@@ -28,6 +28,8 @@ void save_eeprom(void *cookie, u8 *data, u32 len);
 void update_screen(void);
 char update_controller(void);
 
+u32 get_realtime(void);
+
 void fatal(const char *format, ...);
 void warn(const char *format, ...);
 
diff --git a/timer.c b/timer.c
index ed9988a..aa3b898 100644
--- a/timer.c
+++ b/timer.c
@@ -2,52 +2,22 @@
 // Licensed under the terms of the GNU GPL, version 2
 // http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt
 
-#include <sys/time.h>
-#include <signal.h>
-#include <unistd.h>
 #include <stdio.h>
 
 #include "types.h"
-#include "platform.h"
 
 #include "timer.h"
 
 
-static int trace_timer = 1;
-
-volatile u32 timer_triggered;
+static int trace_timer = 0;
 
 static struct timer *timers;
-static u32 timer_time;
-
-u32 timer_now(void)
-{
-	struct timeval tv;
-
-	gettimeofday(&tv, 0);
-	return 1000000*tv.tv_sec + tv.tv_usec;
-}
-
-void timer_set(u32 usecs)
-{
-	struct itimerval it;
-
-	it.it_value.tv_sec = usecs / 1000000;
-	it.it_value.tv_usec = usecs % 1000000;
-	it.it_interval.tv_sec = 0;
-	it.it_interval.tv_usec = 0;
-
-	int err = setitimer(ITIMER_REAL, &it, 0);
-	if (err)
-		fatal("setitimer failed");
-}
 
 void timer_debug(void)
 {
-	printf("timer head = %u, now = %u\n", timer_time, timer_now());
 	struct timer *timer;
 	for (timer = timers; timer; timer = timer->next)
-		printf("timer \"%s\" %dus\n", timer->name, timer->time);
+		printf("timer \"%s\" %u ticks\n", timer->name, timer->time);
 }
 
 void timer_add(struct timer *timer)
@@ -55,7 +25,7 @@ void timer_add(struct timer *timer)
 	if (timer->time == 0)
 		timer->time = timer->interval;
 
-	u32 time = timer_now() - timer_time + timer->time;
+	u32 time = timer->time;
 	struct timer **p = &timers;
 
 	while (*p && (*p)->time <= time) {
@@ -70,19 +40,18 @@ void timer_add(struct timer *timer)
 		timer->next->time -= time;
 }
 
-void timer_run(void)
+void timer_run(u32 ticks)
 {
-	u32 now = timer_now();
-	u32 elapsed = now - timer_time;
+//printf("going to run for %u ticks...\n", ticks);
+//timer_debug();
 
 	struct timer *timer;
-	while ((timer = timers) && timer->time <= elapsed) {
+	while ((timer = timers) && timer->time <= ticks) {
 		timers = timer->next;
-		timer_time += timer->time;
-		elapsed -= timer->time;
+		ticks -= timer->time;
 
 		if (trace_timer)
-			printf("running timer \"%s\" (%u)\n", timer->name, now);
+			printf("running timer \"%s\"\n", timer->name);
 
 		if (timer->run)
 			timer->run();
@@ -94,25 +63,8 @@ void timer_run(void)
 	}
 
 	if (timer)
-		timer->time -= elapsed;
-	timer_time = now;
-}
-
-static void alarm_handler(int signo, siginfo_t *si, void *uc)
-{
-	timer_triggered++;
-}
-
-void timer_init(void)
-{
-	struct sigaction sa;
-
-	sa.sa_sigaction = alarm_handler;
-	sigemptyset(&sa.sa_mask);
-	sa.sa_flags = SA_SIGINFO;
-	sigaction(SIGALRM, &sa, 0);
-
-	timer_time = timer_now();
+		timer->time -= ticks;
 
-	timer_set(1);
+//printf("timers done:\n");
+//timer_debug();
 }
diff --git a/timer.h b/timer.h
index 2f0fb25..3bc2f86 100644
--- a/timer.h
+++ b/timer.h
@@ -7,8 +7,6 @@
 
 #include "types.h"
 
-extern volatile u32 timer_triggered;
-
 struct timer {
 	const char *name;
 	u32 time;
@@ -19,13 +17,7 @@ struct timer {
 
 void timer_debug(void);
 
-u32 timer_now(void);
 void timer_add(struct timer *timer);
-void timer_run(void);
-
-// XXX: temp
-void timer_set(u32 usecs);
-
-void timer_init(void);
+void timer_run(u32 ticks);
 
 #endif
diff --git a/video.c b/video.c
index d98e6f0..a3e0e0f 100644
--- a/video.c
+++ b/video.c
@@ -23,8 +23,6 @@ int hide_page_2;
 int hide_sprites;
 int trace_unknown_video = 1;
 
-int screen_needs_update;
-
 
 static const u8 sizes[] = { 8, 16, 32, 64 };
 static const u8 colour_sizes[] = { 2, 4, 6, 8 };
@@ -100,7 +98,7 @@ static void do_dma(u32 len)
 		mem[dst+j] = mem[src+j];
 
 	mem[0x2872] = 0;
-	mem[0x2863] |= 0x0004;
+	mem[0x2863] |= 4;	// trigger video DMA IRQ
 }
 
 void video_store(u16 val, u32 addr)
@@ -176,10 +174,6 @@ void video_store(u16 val, u32 addr)
 
 		case 0x2863:		// video IRQ status
 			mem[addr] &= ~val;
-			if (val & 1 && screen_needs_update) {
-				update_screen();
-				screen_needs_update = 0;
-			}
 			return;
 
 		case 0x2870:		// video DMA src