minor update

perf_counter.c

@@ -127,6 +127,11 @@ void perfc_port_insert_to_system_timer_insert_ovf_handler(void)
 
 }
 
+uint32_t perfc_get_systimer_frequency(void)
+{
+    return perfc_port_get_system_timer_freq();
+}
+
 __WEAK
 void __perf_os_patch_init(void)
 {
@@ -157,7 +162,8 @@ bool init_cycle_counter(bool bIsSysTickOccupied)
     s_lSystemClockCounts = 0;                       // reset system cycle counter
     s_lSystemMS = 0;                                // reset system millisecond counter
     s_lSystemUS = 0;                                // reset system microsecond counter
-
+    s_lOldTimestamp = 0;
+
     __perf_os_patch_init();
 
     return bResult;

perf_counter.h

@@ -669,6 +669,12 @@ int64_t stop_cycle_counter(void)
  * @{
  */
 
+/*!
+ * \brief get the system timer frequency
+ * \return uint32_t the system timer frequency in Hz
+ */
+extern uint32_t perfc_get_systimer_frequency(void);
+
 /*!
  * \brief get the elapsed milliseconds since perf_counter is initialised
  * \return int64_t the elapsed milliseconds