Merge pull request #11236 from hugueskamba/hk-iotcore-1315-remove-floating-point-ticker

Force inline Timer::attach() to get rid of floating-point instructions

Author: 0xc0170

TESTS/mbed_hal/rtc/main.cpp

@@ -42,7 +42,7 @@ static const uint32_t TOLERANCE_ACCURACY_US = (DELAY_10S *US_PER_SEC / ACCURACY_
 #if DEVICE_LPTICKER
 volatile bool expired;
 
-void callback(void)
+void set_flag_true(void)
 {
     expired = true;
 }
@@ -72,7 +72,7 @@ void rtc_sleep_test_support(bool deepsleep_mode)
 
     rtc_write(start);
 
-    timeout.attach(callback, DELAY_4S);
+    timeout.attach(set_flag_true, DELAY_4S);
 
     TEST_ASSERT(sleep_manager_can_deep_sleep_test_check() == deepsleep_mode);
 

drivers/Ticker.h

@@ -17,6 +17,7 @@
 #ifndef MBED_TICKER_H
 #define MBED_TICKER_H
 
+#include <mstd_utility>
 #include "drivers/TimerEvent.h"
 #include "platform/Callback.h"
 #include "platform/mbed_toolchain.h"
@@ -75,12 +76,17 @@ class Ticker : public TimerEvent, private NonCopyable<Ticker> {
 
     /** Attach a function to be called by the Ticker, specifying the interval in seconds
      *
+     *  The method forwards its arguments to attach_us() rather than copying them which
+     *  may not be trivial depending on the callback copied.
+     *  The function is forcibly inlined to not use floating-point operations. This is
+     *  possible given attach_us() expects an integer value for the callback interval.
      *  @param func pointer to the function to be called
      *  @param t the time between calls in seconds
      */
-    void attach(Callback<void()> func, float t)
+    template <typename F>
+    MBED_FORCEINLINE void attach(F &&func, float t)
     {
-        attach_us(func, t * 1000000.0f);
+        attach_us(std::forward<F>(func), t * 1000000.0f);
     }
 
     /** Attach a member function to be called by the Ticker, specifying the interval in seconds