Bytes KB MB TB PB..

(1<<n) != (1L<<n)

1KB = 1024 Bytes = 2^10 Bytes = (1L << 10) Bytes

1Page = 4KB = 4096 Bytes = 4 * 1024 Bytes = 2^2 * 2^10 Bytes = 2^12 Bytes = (1L << 12) Bytes

1Block = 1M = 1024 * 1KB = 1048576 Bytes = (1L << 20) Bytes

so

1MB = (1L << 20) Bytes

128MB = (128L << 20) Bytes

1GB=(1024 * 1MB) = (1L < 30)Bytes