Create Thread Local Storage for micros()

micros() is using thread specific cycle counts. So, when micros() or delayMicroseconds() are called from different tasks, false rollover events are detected.  The cycle count is task specific, and micros() was using `if(currentCycleCount < lastCycleCount) processRollover()`.

The lastCycleCount variable was updated each time micros() exited with the current Tasks cycle count. So, if the next micros() or delayMicroseconds() was not called from the same Task lastCycleCount had no relation.

Author: stickbreaker

cores/esp32/esp32-hal-misc.c

@@ -38,20 +38,42 @@ void yield()
 }
 
 portMUX_TYPE microsMux = portMUX_INITIALIZER_UNLOCKED;
+static pthread_key_t microsStore=NULL; // Thread Local Storage Handle
 
-unsigned long IRAM_ATTR micros()
-{
-    static unsigned long lccount = 0;
-    static unsigned long overflow = 0;
-    unsigned long ccount;
-    portENTER_CRITICAL_ISR(&microsMux);
-    __asm__ __volatile__ ( "rsr     %0, ccount" : "=a" (ccount) );
-    if(ccount < lccount){
-        overflow += UINT32_MAX / CONFIG_ESP32_DEFAULT_CPU_FREQ_MHZ;
-    }
-    lccount = ccount;
-    portEXIT_CRITICAL_ISR(&microsMux);
-    return overflow + (ccount / CONFIG_ESP32_DEFAULT_CPU_FREQ_MHZ);
+void* microsStoreDelete(void * storage){ // release thread local data when task is delete.
+if(storage) free(storage);
+}
+
+unsigned long IRAM_ATTR micros(){
+
+if (!microsStore){ // first Time Ever thread local not init'd
+  portENTER_CRITICAL_ISR(&microsMux);
+  pthread_key_create(&microsStore,microsStoreDelete); // create initial holder
+  portEXIT_CRITICAL_ISR(&microsMux);
+  }
+  
+uint32_t *ptr;// [0] is lastCount, [1] is overFlow
+
+ptr = pthread_getspecific(microsStore); // get address of storage
+ 
+if(ptr == NULL){ // first time in this thread, allocate mem, init it.  
+  portENTER_CRITICAL_ISR(&microsMux);
+  ptr = (uint32_t*)malloc(sizeof(uint32_t)*2);
+  pthread_setspecific(microsStore,ptr); // store the pointer to this thread's values
+  ptr[0] = 0; // lastCount value
+  ptr[1] = 0; // overFlow
+  portEXIT_CRITICAL_ISR(&microsMux);
+  }  
+
+unsigned long ccount;
+portENTER_CRITICAL_ISR(&microsMux);
+__asm__ __volatile__ ( "rsr     %0, ccount" : "=a" (ccount) );
+if(ccount < ptr[0]){
+  ptr[1] += UINT32_MAX / CONFIG_ESP32_DEFAULT_CPU_FREQ_MHZ;
+  }
+ptr[0] = ccount;
+portEXIT_CRITICAL_ISR(&microsMux);
+return ptr[1] + (ccount / CONFIG_ESP32_DEFAULT_CPU_FREQ_MHZ);
 }
 
 unsigned long IRAM_ATTR millis()