CODEWITHSUNDEEP
c++memorymemory-managementarduino
WildBill
WildBill

Reputation: 9291

Why is free() not freeing up RAM on my Arduino Uno

I'm trying to free up RAM by removing a variable after it is used with the free() function, yet my RAM is not cleaning up. I suppose there is no garbage cleanup taking place? The space cleans up after I exit the section of code (scoped if-statement, while-loop or function), but not the free() statement itself.

I'm doing the following to check the RAM:

int freeRam () {
  extern int __heap_start, *__brkval; 
  int v; 
  return (int) &v - (__brkval == 0 ? (int) &__heap_start : (int) __brkval); 
}

Additionally, how would one 'free' up such memory?

Upvotes: 4

Views: 2728

Answers (1)

Greg Hewgill
Greg Hewgill

Reputation: 993095

You can't expect the __brkval to decrease just because you called free() on a single memory block. The memory block will be marked as free and available for reuse, but in general the __brkval will only move in one direction according to the maximum amount of memory that your program uses at any one time.

Upvotes: 7

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