// A version of function heapStatistics that performs some
// checks of the heap's structure; helps debugging a garbage 
// collector.  sestoft@itu.dk 2009-11-11

// Delete the old heapStatistics from listmachine.c and insert 
// this one instead.  

void heapStatistics() {
  int blocks = 0, free = 0, orphans = 0, 
    blocksSize = 0, freeSize = 0, largestFree = 0;
  word* heapPtr = heap;
  while (heapPtr < afterHeap) {
    if (Length(heapPtr[0]) > 0) {
      blocks++;
      blocksSize += Length(heapPtr[0]);
    } else 
      orphans++;
    word* nextBlock = heapPtr + Length(heapPtr[0]) + 1;
    if (nextBlock > afterHeap) {
      printf("HEAP ERROR: block at heap[%d] extends beyond heap\n", 
	     heapPtr-heap);
      exit(-1);
    }
    heapPtr = nextBlock;
  }
  word* freePtr = freelist;
  while (freePtr != 0) {
    free++; 
    int length = Length(freePtr[0]);
    if (freePtr < heap || afterHeap < freePtr+length+1) {
      printf("HEAP ERROR: freelist item %d (at heap[%d], length %d)  is outside heap\n", 
	     free, freePtr-heap, length);
      exit(-1);
    }
    freeSize += length;
    largestFree = length > largestFree ? length : largestFree;
    if (Color(freePtr[0])!=Blue)
      printf("Non-blue block at heap[%d] on freelist\n", (int)freePtr);
    freePtr = (word*)freePtr[1];
  }
  printf("Heap: %d blocks (%d words); of which %d free (%d words, largest %d words); %d orphans\n", 
	 blocks, blocksSize, free, freeSize, largestFree, orphans);
}