[PATCH weston 2/7] timespec: Add timespec_add_msec helper

[Daniel Stone]

Add a (timespec) = (timespec) + (msec) helper, to save intermediate
conversions in its users.

Signed-off-by: Daniel Stone <daniels at collabora.com>
---
 shared/timespec-util.h | 21 +++++++++++++++++++++
 tests/timespec-test.c  | 11 +++++++++++
 2 files changed, 32 insertions(+)

diff --git a/shared/timespec-util.h b/shared/timespec-util.h
index 80b557859..c2bc8635c 100644
--- a/shared/timespec-util.h
+++ b/shared/timespec-util.h
@@ -70,6 +70,27 @@ timespec_add_nsec(struct timespec *r, const struct timespec *a, int64_t b)
 	}
 }
 
+/* Add a millisecond value to a timespec
+ *
+ * \param r[out] result: a + b
+ * \param a[in] base operand as timespec
+ * \param b[in] operand in milliseconds
+ */
+static inline void
+timespec_add_msec(struct timespec *r, const struct timespec *a, int64_t b)
+{
+	r->tv_sec = a->tv_sec + (b / 1000);
+	r->tv_nsec = a->tv_nsec + ((b % 1000) * 1000000);
+
+	if (r->tv_nsec >= NSEC_PER_SEC) {
+		r->tv_sec++;
+		r->tv_nsec -= NSEC_PER_SEC;
+	} else if (r->tv_nsec <= -NSEC_PER_SEC) {
+		r->tv_sec--;
+		r->tv_nsec += NSEC_PER_SEC;
+	}
+}
+
 /* Convert timespec to nanoseconds
  *
  * \param a timespec
diff --git a/tests/timespec-test.c b/tests/timespec-test.c
index f1193507a..bfb9e0362 100644
--- a/tests/timespec-test.c
+++ b/tests/timespec-test.c
@@ -124,3 +124,14 @@ ZUC_TEST(timespec_test, timespec_add_nsec)
 	ZUC_ASSERT_EQ(16, r.tv_sec);
 	ZUC_ASSERT_EQ(0, r.tv_nsec);
 }
+
+ZUC_TEST(timespec_test, timespec_add_msec)
+{
+	struct timespec a, r;
+
+	a.tv_sec = 1000;
+	a.tv_nsec = 1;
+	timespec_add_msec(&r, &a, 2002);
+	ZUC_ASSERT_EQ(1002, r.tv_sec);
+	ZUC_ASSERT_EQ(2000001, r.tv_nsec);
+}
-- 
2.11.0