Microlib slow division causes HAL_GetTick API performance issue, so optimized HAL_GetTick API to improve performance.

Author: rajkan01

TESTS/mbed_hal/common_tickers/main.cpp

@@ -476,7 +476,7 @@ void ticker_speed_test(void)
         intf->clear_interrupt();
     }
     stop = us_ticker_read();
-
+        
     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. ---- */

targets/TARGET_STM/hal_tick_overrides.c

@@ -27,11 +27,10 @@ extern int mbed_sdk_inited;
 void init_16bit_timer(void);
 void init_32bit_timer(void);
 
-#if TIM_MST_BIT_WIDTH == 16
 // Variables also reset in us_ticker_init()
+uint32_t total_ticks = 0;
 uint32_t prev_time = 0;
-uint32_t elapsed_time = 0;
-#endif
+uint16_t prev_tick_remainder = 0;
 
 // Overwrite default HAL functions defined as "weak"
 
@@ -47,26 +46,28 @@ HAL_StatusTypeDef HAL_InitTick(uint32_t TickPriority)
 
 uint32_t HAL_GetTick()
 {
-#if TIM_MST_BIT_WIDTH == 16
-    uint32_t new_time;
-    if (mbed_sdk_inited) {
-        // Apply the latest time recorded just before the sdk is inited
-        new_time = ticker_read_us(get_us_ticker_data()) + prev_time;
-        prev_time = 0; // Use this time only once
-        return (new_time / 1000);
+    uint32_t new_time = us_ticker_read();
+    uint32_t elapsed_ticks = 0;
+    uint32_t elapsed_time = (((new_time - prev_time) & US_TICKER_MASK) + prev_tick_remainder);
+    prev_time = new_time;
+    if (elapsed_time < 1000) { // elapsed time less than 1ms
+        elapsed_ticks = 0;
+        prev_tick_remainder = elapsed_time;
+    } else if (elapsed_time < 2000) { // elapsed time less than 2ms
+        elapsed_ticks = 1;
+        prev_tick_remainder = elapsed_time - 1000;
+    } else if (elapsed_time < 65536) { // For 16-bit ticker max value of 2^16 = 65536
+        while (elapsed_time >= 1000) {
+            elapsed_ticks++;
+            elapsed_time -= 1000;
+        }
+        prev_tick_remainder = elapsed_time;
     } else {
-        new_time = us_ticker_read();
-        elapsed_time += (new_time - prev_time) & 0xFFFF; // Only use the lower 16 bits
-        prev_time = new_time;
-        return (elapsed_time / 1000);
+        elapsed_ticks = elapsed_ticks / 1000;
+        prev_tick_remainder = elapsed_time % 1000;
     }
-#else // 32-bit timer
-    if (mbed_sdk_inited) {
-        return (ticker_read_us(get_us_ticker_data()) / 1000);
-    } else {
-        return (us_ticker_read() / 1000);
-    }
-#endif
+    total_ticks += elapsed_ticks;
+    return total_ticks;
 }
 
 void HAL_SuspendTick(void)

targets/TARGET_STM/us_ticker.c

@@ -39,12 +39,13 @@ const ticker_info_t *us_ticker_get_info()
 
 void us_ticker_irq_handler(void);
 
+extern uint32_t total_ticks;
+extern uint32_t prev_time;
+extern uint16_t prev_tick_remainder;
+
 // ************************************ 16-bit timer ************************************
 #if TIM_MST_BIT_WIDTH == 16
 
-extern uint32_t prev_time;
-extern uint32_t elapsed_time;
-
 #if defined(TARGET_STM32F0)
 void timer_update_irq_handler(void)
 {
@@ -130,8 +131,9 @@ void init_16bit_timer(void)
     __HAL_TIM_DISABLE_IT(&TimMasterHandle, TIM_IT_CC1);
 
     // Used by HAL_GetTick()
+    total_ticks = 0;
     prev_time = 0;
-    elapsed_time = 0;
+    prev_tick_remainder = 0;
 }
 
 // ************************************ 32-bit timer ************************************
@@ -216,6 +218,11 @@ void init_32bit_timer(void)
 #endif
 
     __HAL_TIM_DISABLE_IT(&TimMasterHandle, TIM_IT_CC1);
+
+    // Used by HAL_GetTick()
+    total_ticks = 0;
+    prev_time = 0;
+    prev_tick_remainder = 0;
 }
 
 #endif // 16-bit/32-bit timer