Add a high resolution timer module

The new timer module provides an cross-platform interface for a high
resolution monotonic clock. The timestamps are always relative to the
creation of the timer and their unit is one microseconds.

The timers can be used for logging, measuring elapsed time and
implementing timeouts.

configure.ac

@@ -157,6 +157,7 @@ AC_CHECK_HEADERS([IOKit/serial/ioss.h])
 AC_CHECK_HEADERS([getopt.h])
 AC_CHECK_HEADERS([sys/param.h])
 AC_CHECK_HEADERS([pthread.h])
+AC_CHECK_HEADERS([mach/mach_time.h])
 
 # Checks for global variable declarations.
 AC_CHECK_DECLS([optreset])
@@ -169,6 +170,7 @@ AC_CHECK_MEMBERS([struct tm.tm_gmtoff],,,[
 # Checks for library functions.
 AC_FUNC_STRERROR_R
 AC_CHECK_FUNCS([localtime_r gmtime_r timegm _mkgmtime])
+AC_CHECK_FUNCS([clock_gettime mach_absolute_time])
 AC_CHECK_FUNCS([getopt_long])
 
 # Checks for supported compiler options.

msvc/libdivecomputer.vcproj

@@ -482,6 +482,10 @@
 				RelativePath="..\src\suunto_vyper_parser.c"
 				>
 			</File>
+			<File
+				RelativePath="..\src\timer.c"
+				>
+			</File>
 			<File
 				RelativePath="..\src\usbhid.c"
 				>
@@ -820,6 +824,10 @@
 				RelativePath="..\src\suunto_vyper2.h"
 				>
 			</File>
+			<File
+				RelativePath="..\src\timer.h"
+				>
+			</File>
 			<File
 				RelativePath="..\include\libdivecomputer\units.h"
 				>

src/Makefile.am

@@ -24,6 +24,7 @@ libdivecomputer_la_SOURCES = \
 	device-private.h device.c \
 	parser-private.h parser.c \
 	datetime.c \
+	timer.h timer.c \
 	suunto_common.h suunto_common.c \
 	suunto_common2.h suunto_common2.c \
 	suunto_solution.h suunto_solution.c suunto_solution_parser.c \

src/timer.c

@@ -0,0 +1,161 @@
+/*
+ * libdivecomputer
+ *
+ * Copyright (C) 2018 Jef Driesen
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA 02110-1301 USA
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <stdlib.h>
+
+#ifdef _WIN32
+#define NOGDI
+#include <windows.h>
+#else
+#include <time.h>
+#include <sys/time.h>
+#ifdef HAVE_MACH_MACH_TIME_H
+#include <mach/mach_time.h>
+#endif
+#endif
+
+#include "timer.h"
+
+struct dc_timer_t {
+#if defined (_WIN32)
+	LARGE_INTEGER timestamp;
+	LARGE_INTEGER frequency;
+#elif defined (HAVE_CLOCK_GETTIME)
+	struct timespec timestamp;
+#elif defined (HAVE_MACH_ABSOLUTE_TIME)
+	uint64_t timestamp;
+	mach_timebase_info_data_t info;
+#else
+	struct timeval timestamp;
+#endif
+};
+
+dc_status_t
+dc_timer_new (dc_timer_t **out)
+{
+	dc_timer_t *timer = NULL;
+
+	if (out == NULL)
+		return DC_STATUS_INVALIDARGS;
+
+	timer = (dc_timer_t *) malloc (sizeof (dc_timer_t));
+	if (timer == NULL) {
+		return DC_STATUS_NOMEMORY;
+	}
+
+#if defined (_WIN32)
+	if (!QueryPerformanceFrequency(&timer->frequency) ||
+		!QueryPerformanceCounter(&timer->timestamp)) {
+		free(timer);
+		return DC_STATUS_IO;
+	}
+#elif defined (HAVE_CLOCK_GETTIME)
+	if (clock_gettime(CLOCK_MONOTONIC, &timer->timestamp) != 0) {
+		free(timer);
+		return DC_STATUS_IO;
+	}
+#elif defined (HAVE_MACH_ABSOLUTE_TIME)
+	if (mach_timebase_info(&timer->info) != KERN_SUCCESS) {
+		free(timer);
+		return DC_STATUS_IO;
+	}
+
+	timer->timestamp = mach_absolute_time();
+#else
+	if (gettimeofday (&timer->timestamp, NULL) != 0) {
+		free(timer);
+		return DC_STATUS_IO;
+	}
+#endif
+
+	*out = timer;
+
+	return DC_STATUS_SUCCESS;
+}
+
+dc_status_t
+dc_timer_now (dc_timer_t *timer, dc_usecs_t *usecs)
+{
+	dc_status_t status = DC_STATUS_SUCCESS;
+	dc_usecs_t value = 0;
+
+	if (timer == NULL) {
+		status = DC_STATUS_INVALIDARGS;
+		goto out;
+	}
+
+#if defined (_WIN32)
+	LARGE_INTEGER now;
+	if (!QueryPerformanceCounter(&now)) {
+		status = DC_STATUS_IO;
+		goto out;
+	}
+
+	value = (now.QuadPart - timer->timestamp.QuadPart) * 1000000 / timer->frequency.QuadPart;
+#elif defined (HAVE_CLOCK_GETTIME)
+	struct timespec now, delta;
+	if (clock_gettime(CLOCK_MONOTONIC, &now) != 0) {
+		status = DC_STATUS_IO;
+		goto out;
+	}
+
+	if (now.tv_nsec < timer->timestamp.tv_nsec) {
+		delta.tv_nsec = 1000000000 + now.tv_nsec - timer->timestamp.tv_nsec;
+		delta.tv_sec = now.tv_sec - timer->timestamp.tv_sec - 1;
+	} else {
+		delta.tv_nsec = now.tv_nsec - timer->timestamp.tv_nsec;
+		delta.tv_sec = now.tv_sec - timer->timestamp.tv_sec;
+	}
+
+	value = (dc_usecs_t) delta.tv_sec * 1000000 + delta.tv_nsec / 1000;
+#elif defined (HAVE_MACH_ABSOLUTE_TIME)
+	uint64_t now = mach_absolute_time();
+	value = (now - timer->timestamp) * timer->info.numer / timer->info.denom;
+#else
+	struct timeval now, delta;
+	if (gettimeofday (&now, NULL) != 0) {
+		status = DC_STATUS_IO;
+		goto out;
+	}
+
+	timersub (&now, &timer->timestamp, &delta);
+
+	value = (dc_usecs_t) delta.tv_sec * 1000000 + delta.tv_usec;
+#endif
+
+out:
+	if (usecs)
+		*usecs = value;
+
+	return status;
+}
+
+dc_status_t
+dc_timer_free (dc_timer_t *timer)
+{
+	free (timer);
+
+	return DC_STATUS_SUCCESS;
+}

src/timer.h

@@ -0,0 +1,51 @@
+/*
+ * libdivecomputer
+ *
+ * Copyright (C) 2018 Jef Driesen
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA 02110-1301 USA
+ */
+
+#ifndef DC_TIMER_H
+#define DC_TIMER_H
+
+#include <libdivecomputer/common.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
+#if defined (_WIN32) && !defined (__GNUC__)
+typedef unsigned __int64 dc_usecs_t;
+#else
+typedef unsigned long long dc_usecs_t;
+#endif
+
+typedef struct dc_timer_t dc_timer_t;
+
+dc_status_t
+dc_timer_new (dc_timer_t **timer);
+
+dc_status_t
+dc_timer_now (dc_timer_t *timer, dc_usecs_t *usecs);
+
+dc_status_t
+dc_timer_free (dc_timer_t *timer);
+
+#ifdef __cplusplus
+}
+#endif /* __cplusplus */
+#endif /* DC_TIMER_H */