PWM_RESOLUTION hardening

Following Arduino API, analogWriteResolution range is:  0 < x <= 32

Signed-off-by: Frederic Pillon <frederic.pillon@st.com>

Author: fpistm

cores/arduino/pins_arduino.h

@@ -315,6 +315,10 @@ PinName analogInputToPinName(uint32_t pin);
 #ifndef PWM_RESOLUTION
 #define PWM_RESOLUTION              8
 #endif
+
+_Static_assert((PWM_RESOLUTION > 0) &&(PWM_RESOLUTION <= 32),
+               "PWM_RESOLUTION must be 0 < x <= 32!");
+
 #ifndef PWM_FREQUENCY
 #define PWM_FREQUENCY               1000
 #endif

cores/arduino/wiring_analog.c

@@ -29,6 +29,8 @@ extern "C" {
 uint32_t g_anOutputPinConfigured[MAX_NB_PORT] = {0};
 #endif
 
+#define MAX_PWM_RESOLUTION 16
+
 static int _readResolution = 10;
 int _writeResolution = PWM_RESOLUTION;
 static uint32_t _writeFreq = PWM_FREQUENCY;
@@ -40,7 +42,11 @@ void analogReadResolution(int res)
 
 void analogWriteResolution(int res)
 {
-  _writeResolution = res;
+  if ((res > 0) && (res <= 32)) {
+    _writeResolution = res;
+  } else {
+    Error_Handler();
+  }
 }
 
 void analogWriteFrequency(uint32_t freq)
@@ -112,10 +118,15 @@ void analogWrite(uint32_t ulPin, uint32_t ulValue)
 #endif //HAL_DAC_MODULE_ENABLED && !HAL_DAC_MODULE_ONLY
 #if defined(HAL_TIM_MODULE_ENABLED) && !defined(HAL_TIM_MODULE_ONLY)
       if (pin_in_pinmap(p, PinMap_PWM)) {
+        int internalResolution = _writeResolution;
         if (is_pin_configured(p, g_anOutputPinConfigured) == false) {
           set_pin_configured(p, g_anOutputPinConfigured);
         }
-        pwm_start(p, _writeFreq, ulValue, _writeResolution);
+        if (_writeResolution > MAX_PWM_RESOLUTION) {
+          internalResolution = MAX_PWM_RESOLUTION;
+          ulValue = mapResolution(ulValue, _writeResolution, internalResolution);
+        }
+        pwm_start(p, _writeFreq, ulValue, internalResolution);
       } else
 #endif /* HAL_TIM_MODULE_ENABLED && !HAL_TIM_MODULE_ONLY */
       {