1/*
2 * Copyright (c) 1997, 2010, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25#ifndef SHARE_VM_CODE_COMPRESSEDSTREAM_HPP
26#define SHARE_VM_CODE_COMPRESSEDSTREAM_HPP
27
28#include "memory/allocation.hpp"
29
30// Simple interface for filing out and filing in basic types
31// Used for writing out and reading in debugging information.
32
33class CompressedStream : public ResourceObj {
34  friend class VMStructs;
35 protected:
36  u_char* _buffer;
37  int     _position;
38
39  enum {
40    // Constants for UNSIGNED5 coding of Pack200
41    lg_H = 6, H = 1<<lg_H,    // number of high codes (64)
42    L = (1<<BitsPerByte)-H,   // number of low codes (192)
43    MAX_i = 4                 // bytes are numbered in (0..4), max 5 bytes
44  };
45
46  // these inlines are defined only in compressedStream.cpp
47  static inline juint encode_sign(jint  value);  // for Pack200 SIGNED5
48  static inline jint  decode_sign(juint value);  // for Pack200 SIGNED5
49  static inline juint reverse_int(juint bits);   // to trim trailing float 0's
50
51 public:
52  CompressedStream(u_char* buffer, int position = 0) {
53    _buffer   = buffer;
54    _position = position;
55  }
56
57  u_char* buffer() const               { return _buffer; }
58
59  // Positioning
60  int position() const                 { return _position; }
61  void set_position(int position)      { _position = position; }
62};
63
64
65class CompressedReadStream : public CompressedStream {
66 private:
67  inline u_char read()                 { return _buffer[_position++]; }
68
69  jint     read_int_mb(jint b0);  // UNSIGNED5 coding, 2-5 byte cases
70
71 public:
72  CompressedReadStream(u_char* buffer, int position = 0)
73  : CompressedStream(buffer, position) {}
74
75  jboolean read_bool()                 { return (jboolean) read();      }
76  jbyte    read_byte()                 { return (jbyte   ) read();      }
77  jchar    read_char()                 { return (jchar   ) read_int();  }
78  jshort   read_short()                { return (jshort  ) read_signed_int(); }
79  jint     read_int()                  { jint   b0 = read();
80                                         if (b0 < L)  return b0;
81                                         else         return read_int_mb(b0);
82                                       }
83  jint     read_signed_int();
84  jfloat   read_float();               // jfloat_cast(reverse_int(read_int()))
85  jdouble  read_double();              // jdouble_cast(2*reverse_int(read_int))
86  jlong    read_long();                // jlong_from(2*read_signed_int())
87};
88
89
90class CompressedWriteStream : public CompressedStream {
91 private:
92  bool full() {
93    return _position >= _size;
94  }
95  void store(u_char b) {
96    _buffer[_position++] = b;
97  }
98  void write(u_char b) {
99    if (full()) grow();
100    store(b);
101  }
102  void grow();
103
104  void write_int_mb(jint value);  // UNSIGNED5 coding, 1-5 byte cases
105
106 protected:
107  int _size;
108
109 public:
110  CompressedWriteStream(int initial_size);
111  CompressedWriteStream(u_char* buffer, int initial_size, int position = 0)
112  : CompressedStream(buffer, position) { _size = initial_size; }
113
114  void write_bool(jboolean value)      { write(value);      }
115  void write_byte(jbyte value)         { write(value);      }
116  void write_char(jchar value)         { write_int(value); }
117  void write_short(jshort value)       { write_signed_int(value);  }
118  void write_int(jint value)           { if ((juint)value < L && !full())
119                                               store((u_char)value);
120                                         else  write_int_mb(value);  }
121  void write_signed_int(jint value);   // write_int(encode_sign(value))
122  void write_float(jfloat value);      // write_int(reverse_int(jint_cast(v)))
123  void write_double(jdouble value);    // write_int(reverse_int(<low,high>))
124  void write_long(jlong value);        // write_signed_int(<low,high>)
125};
126
127#endif // SHARE_VM_CODE_COMPRESSEDSTREAM_HPP
128