/*

 * Copyright (c) 1997, 2013, 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_CLASSFILE_CLASSFILESTREAM_HPP

#define SHARE_VM_CLASSFILE_CLASSFILESTREAM_HPP

#include "utilities/top.hpp"

// Input stream for reading .class file

//

// The entire input stream is present in a buffer allocated by the caller.

// The caller is responsible for deallocating the buffer and for using

// ResourceMarks appropriately when constructing streams.

class ClassFileStream: public ResourceObj {

 private:

  u1*   _buffer_start; // Buffer bottom

  u1*   _buffer_end;   // Buffer top (one past last element)

  u1*   _current;      // Current buffer position

  char* _source;       // Source of stream (directory name, ZIP/JAR archive name)

  bool  _need_verify;  // True if verification is on for the class file

  void truncated_file_error(TRAPS);

 public:

  // Constructor

  ClassFileStream(u1* buffer, int length, char* source);

  // Buffer access

  u1* buffer() const           { return _buffer_start; }

  int length() const           { return _buffer_end - _buffer_start; }

  u1* current() const          { return _current; }

  void set_current(u1* pos)    { _current = pos; }

  char* source() const         { return _source; }

  void set_verify(bool flag)   { _need_verify = flag; }

  void check_truncated_file(bool b, TRAPS) {

    if (b) {

      truncated_file_error(THREAD);

    }

  }

  void guarantee_more(int size, TRAPS) {

    size_t remaining = (size_t)(_buffer_end - _current);

    unsigned int usize = (unsigned int)size;

    check_truncated_file(usize > remaining, CHECK);

  }

  // Read u1 from stream

  u1 get_u1(TRAPS);

  u1 get_u1_fast() {

    return *_current++;

  }

  // Read u2 from stream

  u2 get_u2(TRAPS);

  u2 get_u2_fast() {

    u2 res = Bytes::get_Java_u2(_current);

    _current += 2;

    return res;

  }

  // Read u4 from stream

  u4 get_u4(TRAPS);

  u4 get_u4_fast() {

    u4 res = Bytes::get_Java_u4(_current);

    _current += 4;

    return res;

  }

  // Read u8 from stream

  u8 get_u8(TRAPS);

  u8 get_u8_fast() {

    u8 res = Bytes::get_Java_u8(_current);

    _current += 8;

    return res;

  }

  // Get direct pointer into stream at current position.

  // Returns NULL if length elements are not remaining. The caller is

  // responsible for calling skip below if buffer contents is used.

  u1* get_u1_buffer() {

    return _current;

  }

  u2* get_u2_buffer() {

    return (u2*) _current;

  }

  // Skip length u1 or u2 elements from stream

  void skip_u1(int length, TRAPS);

  void skip_u1_fast(int length) {

    _current += length;

  }

  void skip_u2(int length, TRAPS);

  void skip_u2_fast(int length) {

    _current += 2 * length;

  }

  void skip_u4(int length, TRAPS);

  void skip_u4_fast(int length) {

    _current += 4 * length;

  }

  // Tells whether eos is reached

  bool at_eos() const          { return _current == _buffer_end; }

};

#endif // SHARE_VM_CLASSFILE_CLASSFILESTREAM_HPP