From fdc0ce7623b8456c96147abd8980888ef4e89be8 Mon Sep 17 00:00:00 2001
From: hyung-hwan <hyunghwan.chung@gmail.com>
Date: Fri, 1 Aug 2014 17:17:00 +0000
Subject: [PATCH] added some time calc functions

---
 qse/include/qse/cmn/time.h | 29 ++++++++++++++++++++++++++---
 qse/lib/cmn/time.c         | 30 ++++++++++++++++++++++++++++++
 2 files changed, 56 insertions(+), 3 deletions(-)

diff --git a/qse/include/qse/cmn/time.h b/qse/include/qse/cmn/time.h
index e9e428b7..64174fd4 100644
--- a/qse/include/qse/cmn/time.h
+++ b/qse/include/qse/cmn/time.h
@@ -110,6 +110,11 @@ struct qse_btime_t
 	/*int offset;*/
 };
 
+#define qse_cleartime(x) ((x)->tv = (x)->nsec = 0);
+#define qse_cmptime(x,y) \
+	(((x)->sec == (y)->sec)? ((x)->nsec - (y)->nsec): \
+	                         ((x)->sec -  (y)->sec))
+
 #ifdef __cplusplus
 extern "C" {
 #endif
@@ -138,7 +143,7 @@ QSE_EXPORT int qse_gmtime (
 );
 
 /**
- * The qse_localtime() converts numeric time to broken-down time 
+ * The qse_localtime() function converts numeric time to broken-down time 
  */
 QSE_EXPORT int qse_localtime (
 	const qse_ntime_t*  nt, 
@@ -146,8 +151,8 @@ QSE_EXPORT int qse_localtime (
 ); 
 
 /**
- * The qse_timegm() converts broken-down time to numeric time. It is the 
- * inverse of qse_gmtime(). It is useful if the broken-down time is in UTC
+ * The qse_timegm() function converts broken-down time to numeric time. It is 
+ * the inverse of qse_gmtime(). It is useful if the broken-down time is in UTC
  * and the local environment is not.
  */
 QSE_EXPORT int qse_timegm (
@@ -164,6 +169,24 @@ QSE_EXPORT int qse_timelocal (
 	qse_ntime_t*       nt
 );
 
+/**
+ * The qse_addtime() function adds x and y and stores the result in z 
+ */
+QSE_EXPORT void qse_addtime (
+	const qse_ntime_t* x,
+	const qse_ntime_t* y,
+	qse_ntime_t*       z
+);
+
+/**
+ * The qse_subtime()  function subtract y from x and stores the result in z.
+ */
+QSE_EXPORT void qse_subtime (
+	const qse_ntime_t* x,
+	const qse_ntime_t* y,
+	qse_ntime_t*       z
+);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/qse/lib/cmn/time.c b/qse/lib/cmn/time.c
index a7c27876..a26ece5e 100644
--- a/qse/lib/cmn/time.c
+++ b/qse/lib/cmn/time.c
@@ -501,3 +501,33 @@ int qse_timelocal (const qse_btime_t* bt, qse_ntime_t* nt)
 	nt->nsec = 0;
 	return 0;
 }
+
+void qse_addtime (const qse_ntime_t* x, const qse_ntime_t* y, qse_ntime_t* z)
+{
+	QSE_ASSERT (x->nsec < QSE_NSECS_PER_SEC);
+	QSE_ASSERT (y->nsec < QSE_NSECS_PER_SEC);
+
+	z->sec = x->sec + y->sec;
+	z->nsec = x->nsec + y->nsec;
+
+	if (z->nsec >= QSE_NSECS_PER_SEC)
+	{
+		z->sec = z->sec + 1;
+		z->nsec = z->nsec - QSE_NSECS_PER_SEC;
+	}
+}
+
+void qse_subtime (const qse_ntime_t* x, const qse_ntime_t* y, qse_ntime_t* z)
+{
+	QSE_ASSERT (x->nsec < QSE_NSECS_PER_SEC);
+	QSE_ASSERT (y->nsec < QSE_NSECS_PER_SEC);
+
+	z->sec = x->sec - y->sec;
+	z->nsec = x->nsec - y->nsec;
+
+	if (z->nsec < 0)
+	{
+		z->sec = z->sec - 1;
+		z->nsec = z->nsec + QSE_NSECS_PER_SEC;
+	}
+}