libutil: Introduce util_time

Introduce util_time as a place for time related macros, definitions,
and functions that are commonly used. Add NSEC_PER_USEC, NSEC_PER_MSEC,
USEC_PER_SEC and NSEC_PER_SEC definitions that are used for time
conversion calculations as a start. Add time conversion helper functions.

Reviewed-by: Jan Höppner <hoeppner@linux.ibm.com>
Signed-off-by: Mete Durlu <meted@linux.ibm.com>
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>

include/lib/util_time.h

@@ -0,0 +1,202 @@
+/*
+ * util_time - Time related helper functions and definitions
+ *
+ * Copyright IBM Corp. 2025
+ *
+ * s390-tools is free software; you can redistribute it and/or modify
+ * it under the terms of the MIT license. See LICENSE for details.
+ */
+
+#ifndef LIB_UTIL_TIME_H
+#define LIB_UTIL_TIME_H
+
+#define NSEC_PER_USEC	1000L
+#define NSEC_PER_MSEC	1000000L
+#define NSEC_PER_SEC	1000000000L
+
+#define USEC_PER_MSEC	1000L
+#define USEC_PER_SEC	1000000L
+
+#define MSEC_PER_SEC	1000L
+
+/**
+ * Convert nanoseconds to microseconds
+ *
+ * Convert value from nanoseconds to microseconds by dividing the
+ * value to NSEC_PER_USEC constant.
+ *
+ * @param[in] val Time value in nanoseconds
+ *
+ * @returns Time value in microseconds
+ */
+static inline double util_nsecs_to_usecs(double val)
+{
+	return val / NSEC_PER_USEC;
+}
+
+/**
+ * Convert nanoseconds to milliseconds
+ *
+ * Convert value from nanoseconds to milliseconds by dividing the
+ * value to NSEC_PER_MSEC constant.
+ *
+ * @param[in] val Time value in nanoseconds
+ *
+ * @returns Time value in milliseconds
+ */
+static inline double util_nsecs_to_msecs(double val)
+{
+	return val / NSEC_PER_MSEC;
+}
+
+/**
+ * Convert nanoseconds to seconds
+ *
+ * Convert value from nanoseconds to seconds by dividing the
+ * value to NSEC_PER_SEC constant.
+ *
+ * @param[in] val Time value in nanoseconds
+ *
+ * @returns Time value in seconds
+ */
+static inline double util_nsecs_to_secs(double val)
+{
+	return val / NSEC_PER_SEC;
+}
+
+/**
+ * Convert microseconds to nanoseconds
+ *
+ * Convert value from microseconds to nanoseconds by multiplying the
+ * value with NSEC_PER_USEC constant.
+ *
+ * @param[in] val Time value in microseconds
+ *
+ * @returns Time value in nanoseconds
+ */
+static inline double util_usecs_to_nsecs(double val)
+{
+	return val * NSEC_PER_USEC;
+}
+
+/**
+ * Convert microseconds to milliseconds
+ *
+ * Convert value from microseconds to milliseconds by dividing the
+ * value to USEC_PER_MSEC constant.
+ *
+ * @param[in] val Time value in microseconds
+ *
+ * @returns Time value in milliseconds
+ */
+static inline double util_usecs_to_msecs(double val)
+{
+	return val / USEC_PER_MSEC;
+}
+
+/**
+ * Convert microseconds to seconds
+ *
+ * Convert value from microseconds to seconds by dividing the
+ * value to USEC_PER_SEC constant.
+ *
+ * @param[in] val Time value in nanoseconds
+ *
+ * @returns Time value in seconds
+ */
+static inline double util_usecs_to_secs(double val)
+{
+	return val / USEC_PER_SEC;
+}
+
+/**
+ * Convert milliseconds to nanoseconds
+ *
+ * Convert value from milliseconds to nanoseconds by multiplying the
+ * value with NSEC_PER_MSEC constant.
+ *
+ * @param[in] val Time value in milliseconds
+ *
+ * @returns Time value in nanoseconds
+ */
+static inline double util_msecs_to_nsecs(double val)
+{
+	return val * NSEC_PER_MSEC;
+}
+
+/**
+ * Convert milliseconds to microseconds
+ *
+ * Convert value from milliseconds to microseconds by multiplying the
+ * value with USEC_PER_MSEC constant.
+ *
+ * @param[in] val Time value in milliseconds
+ *
+ * @returns Time value in microseconds
+ */
+static inline double util_msecs_to_usecs(double val)
+{
+	return val * USEC_PER_MSEC;
+}
+
+/**
+ * Convert milliseconds to seconds
+ *
+ * Convert value from milliseconds to seconds by dividing the
+ * value to MSEC_PER_SEC constant.
+ *
+ * @param[in] val Time value in milliseconds
+ *
+ * @returns Time value in seconds
+ */
+static inline double util_msecs_to_secs(double val)
+{
+	return val / MSEC_PER_SEC;
+}
+
+/**
+ * Convert seconds to nanoseconds
+ *
+ * Convert value from seconds to nanoseconds by multiplying the
+ * value with NSEC_PER_SEC constant.
+ *
+ * @param[in] val Time value in seconds
+ *
+ * @returns Time value in nanoseconds
+ */
+static inline double util_secs_to_nsecs(double val)
+{
+	return val * NSEC_PER_SEC;
+}
+
+/**
+ * Convert seconds to microseconds
+ *
+ * Convert value from seconds to microseconds by multiplying the
+ * value with USEC_PER_SEC constant.
+ *
+ * @param[in] val Time value in seconds
+ *
+ * @returns Time value in microseconds
+ */
+static inline double util_secs_to_usecs(double val)
+{
+	return val * USEC_PER_SEC;
+}
+
+/**
+ * Convert seconds to milliseconds
+ *
+ * Convert value from seconds to milliseconds by multiplying the
+ * value with MSEC_PER_SEC constant.
+ *
+ * @param[in] val Time value in seconds
+ *
+ * @returns Time value in milliseconds
+ */
+static inline double util_secs_to_msecs(double val)
+{
+	return val * MSEC_PER_SEC;
+}
+
+#endif /* LIB_UTIL_TIME_H */