perf util: Add parse_nsec_time() function

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.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: David Ahern <dsahern@gmail.com>
Acked-by: David Ahern <dsahern@gmail.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1370310629-9642-1-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

2 files changed, 35 insertions, 0 deletions

diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
index 9a0658405760..6d17b18e915d 100644
--- a/tools/perf/util/util.c
+++ b/tools/perf/util/util.c
@@ -328,3 +328,36 @@ void put_tracing_file(char *file)
 {
         free(file);
 }
+
+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 cc1574edcd9a..a53535949043 100644
--- a/tools/perf/util/util.h
+++ b/tools/perf/util/util.h
@@ -208,6 +208,8 @@ 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