t_block         *checkMergeTop(t_block *currentBlock)
{
  t_block       *previousBlock;
  int           previousBlockSize;

  if ((void *)currentBlock > firstAddress + sizeof(t_block))
    {
      previousBlockSize = *(int *)((void *)(currentBlock) - (int)sizeof(int));
      if (previousBlockSize <= 0)
           return (NULL);
      previousBlock = (void *)(currentBlock) - previousBlockSize;
      previousBlock->size += currentBlock->size;
      previousBlock->footerSize = (void *)(previousBlock) + previousBlock->size - (int)sizeof(int);
      *previousBlock->footerSize = previousBlock->size;
      currentBlock->magicNumber = 0;
      return (previousBlock);
    }
  return (NULL);
}

int         checkMergeBot(t_block *currentBlock)
{
  t_block       *nextBlock;

  if ((void *)currentBlock  + currentBlock->size + sizeof(t_block) < sbrk(0))
    {
      printf("currentBlock %pnsize %dn", (void *)currentBlock, currentBlock->size);
      nextBlock = (void *)currentBlock + currentBlock->size;
     printf("nextblock %p nextblocksize%dn", nextBlock->back, currentBlock->size);
      if ((nextBlock->magicNumber == ALLOCATED_MAGIC_NUMBER || nextBlock->magicNumber == FREE_MAGIC_NUMBER)
        && (*nextBlock->footerSize <= 0))
          return (0);
//      printf("header : %d footer : %dn", nextBlock->size, *nextBlock->footerSize);
      currentBlock->size += nextBlock->size;
      printf("mergeTop %dn", currentBlock->size);
      nextBlock->magicNumber = 0;
      nextBlock->back->next = nextBlock->next;
      printf("sbrk 0 %p nextblock %pn", sbrk(0), nextBlock->next);
      nextBlock->next->back = nextBlock->back;
      printf("endn");
      return (1);
    }
  return (0);
}

currentBlock 0x5568618517a8
size 136
nextblock 0x7fe05cd9af48 nextblocksize136
mergeTop 136
sbrk 0 0x55686188d090 nextblock 0x3c1
Segmentation fault (core dumped)

previousBlock = checkMergeTop(freeBlock);
  if (previousBlock != NULL)
    {
      // checkMergeBot(previousBlock);
      // previousBlock->footerSize = (void *)(previousBlock) + previousBlock->size - (int)sizeof(int);
      // *previousBlock->footerSize = previousBlock->size;
//       if (previousBlock->size > getpagesize() && (void *)previousBlock + previousBlock->size == sbrk(0))
//         {
// //          printf("decrease sizen");
//           sbrk((int)previousBlock->size * -1);
//         }
    }
    else
    {
      checkMergeBot(freeBlock);
    //  printf("add to free list %dn", freeBlock->size);
      hashedSize = hashSize(freeBlock->size) - 1;
      if (hashedSize < 0)
        hashedSize = 0;
      addToFreeList(freeBlock, hashedSize);
    }