[PATCH v3 1/4] perf util: Add parse_nsec_time() function

[Namhyung Kim <namhyung@kernel.org>]

From: Namhyung Kim <namhyung.kim@lge.com>

The parse_nsec_time() function is for parsing a string of time into
64-bit nsec value.  It's a preparation of time filtering in some of
perf commands.

Cc: David Ahern <dsahern@gmail.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/util/util.c | 33 +++++++++++++++++++++++++++++++++
 tools/perf/util/util.h |  2 ++
 2 files changed, 35 insertions(+)

diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
index 59d868add275..205972f6addb 100644
--- a/tools/perf/util/util.c
+++ b/tools/perf/util/util.c
@@ -269,3 +269,36 @@ void perf_debugfs_set_path(const char *mntpt)
 	snprintf(debugfs_mountpoint, strlen(debugfs_mountpoint), "%s", mntpt);
 	set_tracing_events_path(mntpt);
 }
+
+int parse_nsec_time(const char *str, u64 *ptime)
+{
+	u64 time_sec, time_nsec;
+	char *end;
+
+	time_sec = strtoul(str, &end, 10);
+	if (*end != '.' && *end != '\0')
+		return -1;
+
+	if (*end == '.') {
+		int i;
+		char nsec_buf[10];
+
+		if (strlen(++end) > 9)
+			return -1;
+
+		strncpy(nsec_buf, end, 9);
+		nsec_buf[9] = '\0';
+
+		/* make it nsec precision */
+		for (i = strlen(nsec_buf); i < 9; i++)
+			nsec_buf[i] = '0';
+
+		time_nsec = strtoul(nsec_buf, &end, 10);
+		if (*end != '\0')
+			return -1;
+	} else
+		time_nsec = 0;
+
+	*ptime = time_sec * NSEC_PER_SEC + time_nsec;
+	return 0;
+}
diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h
index 7a484c97e500..6c8baf312c8a 100644
--- a/tools/perf/util/util.h
+++ b/tools/perf/util/util.h
@@ -204,6 +204,8 @@ static inline int has_extension(const char *filename, const char *ext)
 #define NSEC_PER_MSEC	1000000L
 #endif
 
+int parse_nsec_time(const char *str, u64 *ptime);
+
 extern unsigned char sane_ctype[256];
 #define GIT_SPACE		0x01
 #define GIT_DIGIT		0x02
-- 
1.7.11.7