tests-mbed_hal-common_tickers: use low level ticker API for time measuring.

In `ticker speed` test case execution time of ticker API functions is measured using Timer object. Test replaces original ticker handler for testing purposes, so test should not relay on higher level ticker based features(like Timer).
Use low level ticker API for time measuring.

Author: mprse

TESTS/mbed_hal/common_tickers/main.cpp

@@ -33,6 +33,8 @@ extern "C" {
 #error [NOT_SUPPORTED] test not supported
 #endif
 
+#define US_PER_S 1000000
+
 #define FORCE_OVERFLOW_TEST (false)
 #define TICKER_INT_VAL 500
 #define TICKER_DELTA 10
@@ -47,7 +49,7 @@ extern "C" {
 
 #define MAX_FUNC_EXEC_TIME_US 20
 #define DELTA_FUNC_EXEC_TIME_US 5
-#define NUM_OF_CALLS 1000
+#define NUM_OF_CALLS 100
 
 #define NUM_OF_CYCLES 100000
 
@@ -150,6 +152,19 @@ void wait_cycles(volatile unsigned int cycles)
     while (cycles--);
 }
 
+/* Auxiliary function to determine how long ticker function are executed.
+ * This function returns number of us between <start_ticks> and <stop_ticks>
+ * taking into account counter roll-over, counter size and frequency.
+ */
+uint32_t diff_us(uint32_t start_ticks, uint32_t stop_ticks, const ticker_info_t * info)
+{
+    uint32_t counter_mask = ((1 << info->bits) - 1);
+
+    uint32_t diff_ticks = ((stop_ticks - start_ticks) & counter_mask);
+
+    return (uint32_t) ((uint64_t) diff_ticks * US_PER_S / info->frequency);
+}
+
 /* Test that ticker_init can be called multiple times and
  * ticker_init allows the ticker to keep counting and disables the ticker interrupt.
  */
@@ -420,85 +435,82 @@ void ticker_increment_test(void)
 /* Test that common ticker functions complete with the required amount of time. */
 void ticker_speed_test(void)
 {
-    Timer timer;
-#if DEVICE_LPTICKER
-    LowPowerTimer lptimer;
-#endif
     int counter = NUM_OF_CALLS;
+    uint32_t start;
+    uint32_t stop;
+
+    const ticker_info_t * us_ticker_info = get_us_ticker_data()->interface->get_info();
 
     /* Free function will disable the ticker. For time measurement
-     * we need to use other one.
+     * we need to use other one if available.
      */
 #if DEVICE_LPTICKER
+    const ticker_info_t * lp_ticker_info = get_lp_ticker_data()->interface->get_info();
     bool us_ticker_test = (intf == get_us_ticker_data()->interface);
-    Timer * free_timer = us_ticker_test ? &lptimer : &timer;
 #endif
 
     /* ---- Test ticker_read function. ---- */
-    timer.reset();
-    timer.start();
+    start = us_ticker_read();
     while (counter--) {
         intf->read();
     }
-    timer.stop();
+    stop = us_ticker_read();
 
-    TEST_ASSERT(timer.read_us() < (NUM_OF_CALLS * (MAX_FUNC_EXEC_TIME_US + DELTA_FUNC_EXEC_TIME_US)));
+    TEST_ASSERT(diff_us(start, stop, us_ticker_info) < (NUM_OF_CALLS * (MAX_FUNC_EXEC_TIME_US + DELTA_FUNC_EXEC_TIME_US)));
 
     /* ---- Test ticker_clear_interrupt function. ---- */
     counter = NUM_OF_CALLS;
-    timer.reset();
-    timer.start();
+    start = us_ticker_read();
     while (counter--) {
         intf->clear_interrupt();
     }
-    timer.stop();
+    stop = us_ticker_read();
 
-    TEST_ASSERT(timer.read_us() < (NUM_OF_CALLS * (MAX_FUNC_EXEC_TIME_US + DELTA_FUNC_EXEC_TIME_US)));
+    TEST_ASSERT(diff_us(start, stop, us_ticker_info) < (NUM_OF_CALLS * (MAX_FUNC_EXEC_TIME_US + DELTA_FUNC_EXEC_TIME_US)));
 
     /* ---- Test ticker_set_interrupt function. ---- */
     counter = NUM_OF_CALLS;
-    timer.reset();
-    timer.start();
+    start = us_ticker_read();
     while (counter--) {
         intf->set_interrupt(0);
     }
-    timer.stop();
+    stop = us_ticker_read();
 
-    TEST_ASSERT(timer.read_us() < (NUM_OF_CALLS * (MAX_FUNC_EXEC_TIME_US + DELTA_FUNC_EXEC_TIME_US)));
+    TEST_ASSERT(diff_us(start, stop, us_ticker_info) < (NUM_OF_CALLS * (MAX_FUNC_EXEC_TIME_US + DELTA_FUNC_EXEC_TIME_US)));
 
     /* ---- Test fire_interrupt function. ---- */
     counter = NUM_OF_CALLS;
-    timer.reset();
-    timer.start();
+    start = us_ticker_read();
     while (counter--) {
         intf->fire_interrupt();
     }
-    timer.stop();
+    stop = us_ticker_read();
 
-    TEST_ASSERT(timer.read_us() < (NUM_OF_CALLS * (MAX_FUNC_EXEC_TIME_US + DELTA_FUNC_EXEC_TIME_US)));
+    TEST_ASSERT(diff_us(start, stop, us_ticker_info) < (NUM_OF_CALLS * (MAX_FUNC_EXEC_TIME_US + DELTA_FUNC_EXEC_TIME_US)));
 
     /* ---- Test disable_interrupt function. ---- */
     counter = NUM_OF_CALLS;
-    timer.reset();
-    timer.start();
+    start = us_ticker_read();
     while (counter--) {
         intf->disable_interrupt();
     }
-    timer.stop();
+    stop = us_ticker_read();
 
-    TEST_ASSERT(timer.read_us() < (NUM_OF_CALLS * (MAX_FUNC_EXEC_TIME_US + DELTA_FUNC_EXEC_TIME_US)));
+    TEST_ASSERT(diff_us(start, stop, us_ticker_info) < (NUM_OF_CALLS * (MAX_FUNC_EXEC_TIME_US + DELTA_FUNC_EXEC_TIME_US)));
 
     /* ---- Test free function. ---- */
 #if DEVICE_LPTICKER
     counter = NUM_OF_CALLS;
-    free_timer->reset();
-    free_timer->start();
+    if (us_ticker_test) {
+        lp_ticker_init();
+    }
+    start = us_ticker_test ? lp_ticker_read() : us_ticker_read();
     while (counter--) {
         intf->free();
     }
-    free_timer->stop();
+    stop = us_ticker_test ? lp_ticker_read() : us_ticker_read();
 
-    TEST_ASSERT(free_timer->read_us() < (NUM_OF_CALLS * (MAX_FUNC_EXEC_TIME_US + DELTA_FUNC_EXEC_TIME_US)));
+    TEST_ASSERT(diff_us(start, stop, us_ticker_info) < (NUM_OF_CALLS * (MAX_FUNC_EXEC_TIME_US + DELTA_FUNC_EXEC_TIME_US)));
 #endif
 }