compressedStream.hpp revision 0:a61af66fc99e 
1/*
2 * Copyright 1997-2005 Sun Microsystems, Inc.  All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25// Simple interface for filing out and filing in basic types
26// Used for writing out and reading in debugging information.
27
28class CompressedStream : public ResourceObj {
29  friend class VMStructs;
30 protected:
31  u_char* _buffer;
32  int     _position;
33
34  enum {
35    // Constants for UNSIGNED5 coding of Pack200
36    lg_H = 6, H = 1<<lg_H,    // number of high codes (64)
37    L = (1<<BitsPerByte)-H,   // number of low codes (192)
38    MAX_i = 4                 // bytes are numbered in (0..4), max 5 bytes
39  };
40
41  // these inlines are defined only in compressedStream.cpp
42  static inline juint encode_sign(jint  value);  // for Pack200 SIGNED5
43  static inline jint  decode_sign(juint value);  // for Pack200 SIGNED5
44  static inline juint reverse_int(juint bits);   // to trim trailing float 0's
45
46 public:
47  CompressedStream(u_char* buffer, int position = 0) {
48    _buffer   = buffer;
49    _position = position;
50  }
51
52  u_char* buffer() const               { return _buffer; }
53
54  // Positioning
55  int position() const                 { return _position; }
56  void set_position(int position)      { _position = position; }
57};
58
59
60class CompressedReadStream : public CompressedStream {
61 private:
62  inline u_char read()                 { return _buffer[_position++]; }
63
64  jint     read_int_mb(jint b0);  // UNSIGNED5 coding, 2-5 byte cases
65
66 public:
67  CompressedReadStream(u_char* buffer, int position = 0)
68  : CompressedStream(buffer, position) {}
69
70  jboolean read_bool()                 { return (jboolean) read();      }
71  jbyte    read_byte()                 { return (jbyte   ) read();      }
72  jchar    read_char()                 { return (jchar   ) read_int();  }
73  jshort   read_short()                { return (jshort  ) read_signed_int(); }
74  jint     read_int()                  { jint   b0 = read();
75                                         if (b0 < L)  return b0;
76                                         else         return read_int_mb(b0);
77                                       }
78  jint     read_signed_int();
79  jfloat   read_float();               // jfloat_cast(reverse_int(read_int()))
80  jdouble  read_double();              // jdouble_cast(2*reverse_int(read_int))
81  jlong    read_long();                // jlong_from(2*read_signed_int())
82};
83
84
85class CompressedWriteStream : public CompressedStream {
86 private:
87  bool full() {
88    return _position >= _size;
89  }
90  void store(u_char b) {
91    _buffer[_position++] = b;
92  }
93  void write(u_char b) {
94    if (full()) grow();
95    store(b);
96  }
97  void grow();
98
99  void write_int_mb(jint value);  // UNSIGNED5 coding, 1-5 byte cases
100
101 protected:
102  int _size;
103
104 public:
105  CompressedWriteStream(int initial_size);
106  CompressedWriteStream(u_char* buffer, int initial_size, int position = 0)
107  : CompressedStream(buffer, position) { _size = initial_size; }
108
109  void write_bool(jboolean value)      { write(value);      }
110  void write_byte(jbyte value)         { write(value);      }
111  void write_char(jchar value)         { write_int(value); }
112  void write_short(jshort value)       { write_signed_int(value);  }
113  void write_int(jint value)           { if ((juint)value < L && !full())
114                                               store((u_char)value);
115                                         else  write_int_mb(value);  }
116  void write_signed_int(jint value);   // write_int(encode_sign(value))
117  void write_float(jfloat value);      // write_int(reverse_int(jint_cast(v)))
118  void write_double(jdouble value);    // write_int(reverse_int(<low,high>))
119  void write_long(jlong value);        // write_signed_int(<low,high>)
120};
121