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enum { BLOCK_HEADER_SIZE = 16 };

void *AllocateBlock(size_t length) {
  struct memBlock *mBlock;

  if ((unsigned long long)length + BLOCK_HEADER_SIZE > SIZE_MAX) {
    return NULL;
  }
  mBlock = (struct memBlock *)malloc(
    length + BLOCK_HEADER_SIZE
  );
  if (!mBlock) return NULL;

  /* fill in block header and return data portion */

  return mBlock;
}

void *AllocBlocks(size_t cBlocks) {
  if (cBlocks == 0) return NULL;
  unsigned long long alloc = cBlocks * 16;
  return (alloc < UINT_MAX) ? malloc(cBlocks * 16) : NULL;
}

static_assert(
  CHAR_BIT * sizeof(unsigned long long) >= 
  CHAR_BIT * sizeof(size_t) + 4, 
  "Unable to detect wrapping after multiplication"
);

void *AllocBlocks(size_t cBlocks) {
  if (cBlocks == 0) return NULL;
  unsigned long long alloc = (unsigned long long)cBlocks * 16;
  return (alloc < UINT_MAX) ? malloc(cBlocks * 16) : NULL;
}