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      1 package org.bouncycastle.asn1;
      2 
      3 import java.io.FilterOutputStream;
      4 import java.io.IOException;
      5 import java.io.OutputStream;
      6 
      7 public class DEROutputStream
      8     extends FilterOutputStream implements DERTags
      9 {
     10     public DEROutputStream(
     11         OutputStream    os)
     12     {
     13         super(os);
     14     }
     15 
     16     private void writeLength(
     17         int length)
     18         throws IOException
     19     {
     20         if (length > 127)
     21         {
     22             int size = 1;
     23             int val = length;
     24 
     25             while ((val >>>= 8) != 0)
     26             {
     27                 size++;
     28             }
     29 
     30             write((byte)(size | 0x80));
     31 
     32             for (int i = (size - 1) * 8; i >= 0; i -= 8)
     33             {
     34                 write((byte)(length >> i));
     35             }
     36         }
     37         else
     38         {
     39             write((byte)length);
     40         }
     41     }
     42 
     43     void writeEncoded(
     44         int     tag,
     45         byte[]  bytes)
     46         throws IOException
     47     {
     48         write(tag);
     49         writeLength(bytes.length);
     50         write(bytes);
     51     }
     52 
     53     void writeTag(int flags, int tagNo)
     54         throws IOException
     55     {
     56         if (tagNo < 31)
     57         {
     58             write(flags | tagNo);
     59         }
     60         else
     61         {
     62             write(flags | 0x1f);
     63             if (tagNo < 128)
     64             {
     65                 write(tagNo);
     66             }
     67             else
     68             {
     69                 byte[] stack = new byte[5];
     70                 int pos = stack.length;
     71 
     72                 stack[--pos] = (byte)(tagNo & 0x7F);
     73 
     74                 do
     75                 {
     76                     tagNo >>= 7;
     77                     stack[--pos] = (byte)(tagNo & 0x7F | 0x80);
     78                 }
     79                 while (tagNo > 127);
     80 
     81                 write(stack, pos, stack.length - pos);
     82             }
     83         }
     84     }
     85 
     86     void writeEncoded(int flags, int tagNo, byte[] bytes)
     87         throws IOException
     88     {
     89         writeTag(flags, tagNo);
     90         writeLength(bytes.length);
     91         write(bytes);
     92     }
     93 
     94     protected void writeNull()
     95         throws IOException
     96     {
     97         write(NULL);
     98         write(0x00);
     99     }
    100 
    101     public void write(byte[] buf)
    102         throws IOException
    103     {
    104         out.write(buf, 0, buf.length);
    105     }
    106 
    107     public void write(byte[] buf, int offSet, int len)
    108         throws IOException
    109     {
    110         out.write(buf, offSet, len);
    111     }
    112 
    113     public void writeObject(
    114         Object    obj)
    115         throws IOException
    116     {
    117         if (obj == null)
    118         {
    119             writeNull();
    120         }
    121         else if (obj instanceof DERObject)
    122         {
    123             ((DERObject)obj).encode(this);
    124         }
    125         else if (obj instanceof DEREncodable)
    126         {
    127             ((DEREncodable)obj).getDERObject().encode(this);
    128         }
    129         else
    130         {
    131             throw new IOException("object not DEREncodable");
    132         }
    133     }
    134 }
    135