/*

 * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#ifndef SHARE_VM_CODE_COMPRESSEDSTREAM_HPP

#define SHARE_VM_CODE_COMPRESSEDSTREAM_HPP

#include "memory/allocation.hpp"

// Simple interface for filing out and filing in basic types

// Used for writing out and reading in debugging information.

class CompressedStream : public ResourceObj {

  friend class VMStructs;

 protected:

  u_char* _buffer;

  int     _position;

  enum {

    // Constants for UNSIGNED5 coding of Pack200

    lg_H = 6, H = 1<<lg_H,    // number of high codes (64)

    L = (1<<BitsPerByte)-H,   // number of low codes (192)

    MAX_i = 4                 // bytes are numbered in (0..4), max 5 bytes

  };

  // these inlines are defined only in compressedStream.cpp

  static inline juint encode_sign(jint  value);  // for Pack200 SIGNED5

  static inline jint  decode_sign(juint value);  // for Pack200 SIGNED5

  static inline juint reverse_int(juint bits);   // to trim trailing float 0's

 public:

  CompressedStream(u_char* buffer, int position = 0) {

    _buffer   = buffer;

    _position = position;

  }

  u_char* buffer() const               { return _buffer; }

  // Positioning

  int position() const                 { return _position; }

  void set_position(int position)      { _position = position; }

};

class CompressedReadStream : public CompressedStream {

 private:

  inline u_char read()                 { return _buffer[_position++]; }

  jint     read_int_mb(jint b0);  // UNSIGNED5 coding, 2-5 byte cases

 public:

  CompressedReadStream(u_char* buffer, int position = 0)

  : CompressedStream(buffer, position) {}

  jboolean read_bool()                 { return (jboolean) read();      }

  jbyte    read_byte()                 { return (jbyte   ) read();      }

  jchar    read_char()                 { return (jchar   ) read_int();  }

  jshort   read_short()                { return (jshort  ) read_signed_int(); }

  jint     read_int()                  { jint   b0 = read();

                                         if (b0 < L)  return b0;

                                         else         return read_int_mb(b0);

                                       }

  jint     read_signed_int();

  jfloat   read_float();               // jfloat_cast(reverse_int(read_int()))

  jdouble  read_double();              // jdouble_cast(2*reverse_int(read_int))

  jlong    read_long();                // jlong_from(2*read_signed_int())

};

class CompressedWriteStream : public CompressedStream {

 private:

  bool full() {

    return _position >= _size;

  }

  void store(u_char b) {

    _buffer[_position++] = b;

  }

  void write(u_char b) {

    if (full()) grow();

    store(b);

  }

  void grow();

  void write_int_mb(jint value);  // UNSIGNED5 coding, 1-5 byte cases

 protected:

  int _size;

 public:

  CompressedWriteStream(int initial_size);

  CompressedWriteStream(u_char* buffer, int initial_size, int position = 0)

  : CompressedStream(buffer, position) { _size = initial_size; }

  void write_bool(jboolean value)      { write(value);      }

  void write_byte(jbyte value)         { write(value);      }

  void write_char(jchar value)         { write_int(value); }

  void write_short(jshort value)       { write_signed_int(value);  }

  void write_int(jint value)           { if ((juint)value < L && !full())

                                               store((u_char)value);

                                         else  write_int_mb(value);  }

  void write_signed_int(jint value);   // write_int(encode_sign(value))

  void write_float(jfloat value);      // write_int(reverse_int(jint_cast(v)))

  void write_double(jdouble value);    // write_int(reverse_int(<low,high>))

  void write_long(jlong value);        // write_signed_int(<low,high>)

};

#endif // SHARE_VM_CODE_COMPRESSEDSTREAM_HPP