code: private final int getNumPages(long numBytes) {
  		if (numBytes < 0) {
  			throw new IllegalArgumentException("The number of bytes to allocate must not be negative.");
  		}
  		
  		final long numPages = numBytes >>> this.pageSizeBits;
  		if (numPages <= Integer.MAX_VALUE) {
  			return (int) numPages;
  		} else {
  			throw new IllegalArgumentException("The given number of bytes correstponds to more than MAX_INT pages.");
  		}
  	}
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