From 20ff822c86fea9641def4305b49b171d4fe2dd0b Mon Sep 17 00:00:00 2001
From: Ian Kelling <ianowl@gmail.com>
Date: Mon, 19 Aug 2013 21:50:26 -0700
Subject: [PATCH] Create evhz.c

---
 evhz.c | 112 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 112 insertions(+)
 create mode 100644 evhz.c

diff --git a/evhz.c b/evhz.c
new file mode 100644
index 0000000..a7a42be
--- /dev/null
+++ b/evhz.c
@@ -0,0 +1,112 @@
+#include <stdio.h>
+#include <linux/input.h>
+#include <fcntl.h>
+#include <signal.h>
+
+#define EVENTS 10
+#define HZ_LIST 64
+
+typedef struct event_s {
+	int fd;
+	int hz[HZ_LIST];
+	int count;
+	double prvtime;
+} event_t;
+
+int quit = 0;
+
+void sigint() {
+	signal(SIGINT, sigint);
+	quit = 1;
+}
+
+int main(int argc, char **argv) {
+	int i;
+	event_t events[EVENTS];
+
+	signal(SIGINT, sigint);
+
+	printf("Press CTRL-C to exit.\n\n");
+
+	memset(events, 0, sizeof(events));
+
+	for(i = 0; i < EVENTS; i++) {
+		char device[18];
+
+		sprintf(device, "/dev/input/event%i", i);
+		events[i].fd = open(device, O_RDONLY);
+		
+		if(events[i].fd != -1) {
+			char name[128];
+			ioctl(events[i].fd, EVIOCGNAME(sizeof(name)), name);
+			printf("event%i: %s\n", i, name);
+		}
+	}
+
+	while(!quit) {
+		fd_set set;
+
+		FD_ZERO(&set);
+
+		for(i = 0; i < EVENTS; i++) {
+			if(events[i].fd != -1) {
+				FD_SET(events[i].fd, &set);
+			}
+		}
+
+		if(select(FD_SETSIZE, &set, NULL, NULL, NULL) > 0) {
+			int bytes;
+			struct input_event event;
+
+			for(i = 0; i < EVENTS; i++) {
+				if(events[i].fd == -1) {
+					continue;
+				}
+
+				if(!FD_ISSET(events[i].fd, &set)) {
+					continue;
+				}
+
+				bytes = read(events[i].fd, &event, sizeof(event));
+
+				if(bytes != sizeof(event)) {
+					continue;
+				}
+
+				if(event.type == EV_REL) {
+					double time;
+					int hz;
+
+					time = event.time.tv_sec * 1000 + event.time.tv_usec / 1000;
+					hz = 1000 / (time - events[i].prvtime);
+
+					if(hz > 0) {
+						int avghz;
+						int j;
+
+						events[i].count++;
+						events[i].hz[events[i].count & (HZ_LIST - 1)] = hz;
+
+						avghz = 0;
+
+						for(j = 0; j < HZ_LIST; j++) {
+							avghz += events[i].hz[j];
+						}
+
+						avghz /= (events[i].count > HZ_LIST) ? HZ_LIST : events[i].count;
+
+						printf("event%i: latest hz = %i (average hz = %i)\n", i, hz, avghz);
+					}
+
+					events[i].prvtime = time;
+				}
+			}
+		}
+	}
+
+	for(i = 0; i < EVENTS; i++) {
+		if(events[i].fd != -1) {
+			close(events[i].fd);
+		}
+	}
+}
-- 
2.30.2