[Solved] Given the following code using heap_2: void *ptr1 = pvPortMalloc(100); void *ptr2 = pvPortMalloc(200); pvPortFree(ptr1);... What is the expected behavior of ptr3 allocation? | FreeRTOS

FreeRTOS - Memory Management

Given the following code using heap_2:

void *ptr1 = pvPortMalloc(100);
void *ptr2 = pvPortMalloc(200);
pvPortFree(ptr1);
void *ptr3 = pvPortMalloc(50);

What is the expected behavior of ptr3 allocation?

Aptr3 will point to the same address as ptr2

Bptr3 will reuse the freed 100-byte block from ptr1

Cptr3 allocation will fail due to fragmentation

Dptr3 will allocate a new block without reusing freed memory

Step-by-Step Solution

Solution:

Step 1: Understand heap_2 behavior
heap_2 supports freeing memory and reuses freed blocks, but does not coalesce adjacent free blocks.
Step 2: Analyze allocation of ptr3
ptr1's 100-byte block is freed and added to the free list. ptr3 (50 bytes) fits in it, so ptr3 reuses the freed block from ptr1.
Final Answer:
ptr3 will reuse the freed 100-byte block from ptr1 -> Option B
Quick Check:
heap_2 reuses freed blocks [OK]

Quick Trick: heap_2 reuses freed blocks but does not coalesce [OK]

Common Mistakes:

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