Switch to using PresentHEADmaster

This measures the delta from when present reports the frame as being
shown to when the device detects the change in color.

Signed-off-by: Keith Packard <keithp@keithp.com>

2 files changed, 84 insertions, 21 deletions

diff --git a/Makefile b/Makefile
index 65acc36..d29660e 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,10 @@
 SRCS=vidtime.c
 OBJS=$(SRCS:.c=.o)
-LIBS=-lX11 -lpthread
-CFLAGS=-O0 -g
+LIBS=$(shell pkg-config x11 xpresent --libs) -lpthread
+CFLAGS=-O0 -g $(shell pkg-config x11 xpresent --cflags)
 
 vidtime: $(OBJS)
 	$(CC) $(CFLAGS) -o $@ $(OBJS) $(LIBS)
+
+clean:
+	rm -f $(OBJS) vidtime
diff --git a/vidtime.c b/vidtime.c
index 59cabf7..41a9f25 100644
--- a/vidtime.c
+++ b/vidtime.c
@@ -13,6 +13,7 @@
  */
 
 #include <X11/Xlib.h>
+#include <X11/extensions/Xpresent.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <stdint.h>
@@ -31,11 +32,14 @@ struct monitor {
 	int	fd;
 };
 
+#define BILLION 1000000000ULL
+#define MILLION 1000000ULL
+
 static uint64_t vid_clock(void)
 {
 	struct timespec	ts;
-	clock_gettime(CLOCK_REALTIME, &ts);
-	return ((uint64_t) ts.tv_sec * 1000000000ULL + (uint64_t) ts.tv_nsec);
+	clock_gettime(CLOCK_MONOTONIC, &ts);
+	return ((uint64_t) ts.tv_sec * BILLION + (uint64_t) ts.tv_nsec);
 }
 
 static void flush(int fd)
@@ -52,6 +56,7 @@ static void flush(int fd)
 }
 
 static uint64_t		vid_time[2];
+static int		vid_value;
 
 static pthread_mutex_t	time_mutex = PTHREAD_MUTEX_INITIALIZER;
 static pthread_cond_t	time_cond = PTHREAD_COND_INITIALIZER;
@@ -65,6 +70,7 @@ static void *monitor_device(void *arg)
 	int	n;
 	struct termios	termios;
 	uint64_t	t;
+	int	v;
 
 	tcgetattr(fd, &termios);
 	cfmakeraw(&termios);
@@ -86,10 +92,12 @@ static void *monitor_device(void *arg)
 		switch(buf[0]) {
 		case '1':
 		case '0':
+			v = buf[0] - '0';
 			pthread_mutex_lock(&time_mutex);
-			vid_time[buf[0] - '0'] = t;
-			pthread_cond_signal(&time_cond);
+			vid_value = v;
+			vid_time[v] = t;
 			pthread_mutex_unlock(&time_mutex);
+			pthread_cond_signal(&time_cond);
 			break;
 		}
 	}
@@ -104,14 +112,22 @@ int main(int argc, char **argv)
 	Display	*dpy;
 	int	scr;
 	Window	root;
-	Window	w;
+	Window	win;
 	GC	gc;
 	Pixmap	pix;
 	int	v = 0;
-	struct timespec	ts = { .tv_sec = 1, .tv_nsec = 0 };
+	struct timespec	ts = { .tv_sec = 0, .tv_nsec = 100 * MILLION };
 	pthread_t	monitor_thread;
 	struct monitor	monitor;
-	uint64_t	put, got;
+	uint64_t	put, show, got;
+	uint32_t	serial = 0;
+	XEvent		ev;
+	int		ge_event_base, ge_error_base;
+	int		present_opcode, present_event_base, present_error_base;
+	bool		got_event, exposed;
+	XSetWindowAttributes	swa = {
+		.event_mask = ExposureMask
+	};
 
 	monitor.fd = open(DEV, O_RDWR);
 	if (monitor.fd < 0) {
@@ -123,24 +139,68 @@ int main(int argc, char **argv)
 	dpy = XOpenDisplay(NULL);
 	scr = DefaultScreen(dpy);
 	root = RootWindow(dpy, scr);
-	w = XCreateSimpleWindow(dpy, root, 0, 0, W, H, 0, 0, 0);
-	gc = XCreateGC(dpy, w, 0, NULL);
-	XMapWindow(dpy, w);
+	win = XCreateWindow(dpy, root,
+			    0, 0, W, H, 0, DefaultDepth(dpy, scr),
+			    InputOutput, CopyFromParent,
+			    CWEventMask, &swa);
+	pix = XCreatePixmap(dpy, win, W, H, DefaultDepth(dpy, scr));
+	gc = XCreateGC(dpy, win, 0, NULL);
+	XMapWindow(dpy, win);
+	XPresentQueryExtension(dpy, &present_opcode, &present_event_base, &present_error_base);
+	XPresentSelectInput(dpy, win, PresentCompleteNotifyMask);
 	for (;;) {
 		XSetForeground(dpy, gc, v ? WhitePixel(dpy, scr) : BlackPixel(dpy, scr));
-		XFillRectangle(dpy, w, gc, 0, 0, W, H);
+		XFillRectangle(dpy, pix, gc, 0, 0, W, H);
+		XPresentPixmap(dpy, win, pix, ++serial,
+			       None, None, 0, 0, None, None, None,
+			       PresentOptionNone,
+			       0,
+			       0, 0, NULL, 0);
 		put = vid_clock();
 		XFlush(dpy);
-		pthread_mutex_lock(&time_mutex);
-		for (;;) {
-			if (vid_time[v] > put) {
-				got = vid_time[v];
-				break;
+		got_event = false;
+		exposed = false;
+		while (!got_event) {
+			XGenericEventCookie *cookie = (void *) &ev;
+			XNextEvent(dpy, &ev);
+			if (XGetEventData(dpy, cookie)) {
+				if (cookie->extension == present_opcode &&
+				    cookie->evtype == PresentCompleteNotify) {
+					XPresentCompleteNotifyEvent	*ce = cookie->data;
+					if (ce->serial_number == serial) {
+						show = ce->ust * 1000;
+						got_event = true;
+					}
+				}
+				XFreeEventData(dpy, cookie);
+			} else {
+				switch (ev.type) {
+				case Expose:
+					if (ev.xexpose.count == 0)
+						exposed = true;
+					break;
+				}
+			}
+		}
+		if (!exposed) {
+			pthread_mutex_lock(&time_mutex);
+			for (;;) {
+				if (vid_value == v) {
+					got = vid_time[v];
+					break;
+				}
+				pthread_cond_wait (&time_cond, &time_mutex);
+			}
+			pthread_mutex_unlock(&time_mutex);
+			if (show >= put && got >= show) {
+				printf("%d delay put->show %f show->got %f\n", v,
+				       (show - put) / 1e9,
+				       (got - show) / 1e9);
+			} else {
+				printf("%d invalid\n", v);
 			}
-			pthread_cond_wait (&time_cond, &time_mutex);
 		}
-		pthread_mutex_unlock(&time_mutex);
-		printf("delay %f\n", (got - put) / 1e9);
 		v = 1-v;
+		nanosleep(&ts, NULL);
 	}
 }