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      1 package org.bouncycastle.crypto.util;
      2 
      3 public abstract class Pack
      4 {
      5     public static int bigEndianToInt(byte[] bs, int off)
      6     {
      7         int n = bs[  off] << 24;
      8         n |= (bs[++off] & 0xff) << 16;
      9         n |= (bs[++off] & 0xff) << 8;
     10         n |= (bs[++off] & 0xff);
     11         return n;
     12     }
     13 
     14     public static void intToBigEndian(int n, byte[] bs, int off)
     15     {
     16         bs[  off] = (byte)(n >>> 24);
     17         bs[++off] = (byte)(n >>> 16);
     18         bs[++off] = (byte)(n >>>  8);
     19         bs[++off] = (byte)(n       );
     20     }
     21 
     22     public static long bigEndianToLong(byte[] bs, int off)
     23     {
     24         int hi = bigEndianToInt(bs, off);
     25         int lo = bigEndianToInt(bs, off + 4);
     26         return ((long)(hi & 0xffffffffL) << 32) | (long)(lo & 0xffffffffL);
     27     }
     28 
     29     public static void longToBigEndian(long n, byte[] bs, int off)
     30     {
     31         intToBigEndian((int)(n >>> 32), bs, off);
     32         intToBigEndian((int)(n & 0xffffffffL), bs, off + 4);
     33     }
     34 
     35     public static int littleEndianToInt(byte[] bs, int off)
     36     {
     37         int n = bs[  off];
     38         n |= (bs[++off] & 0xff) << 8;
     39         n |= (bs[++off] & 0xff) << 16;
     40         n |= (bs[++off] & 0xff) << 24;
     41         return n;
     42     }
     43 
     44     public static void intToLittleEndian(int n, byte[] bs, int off)
     45     {
     46         bs[  off] = (byte)(n       );
     47         bs[++off] = (byte)(n >>>  8);
     48         bs[++off] = (byte)(n >>> 16);
     49         bs[++off] = (byte)(n >>> 24);
     50     }
     51 
     52     public static long littleEndianToLong(byte[] bs, int off)
     53     {
     54         int lo = littleEndianToInt(bs, off);
     55         int hi = littleEndianToInt(bs, off + 4);
     56         return ((long)(hi & 0xffffffffL) << 32) | (long)(lo & 0xffffffffL);
     57     }
     58 
     59     public static void longToLittleEndian(long n, byte[] bs, int off)
     60     {
     61         intToLittleEndian((int)(n & 0xffffffffL), bs, off);
     62         intToLittleEndian((int)(n >>> 32), bs, off + 4);
     63     }
     64 }
     65