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hotspot/src/share/vm/code/compressedStream.hpp

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+/*
+ * Copyright 1997-2005 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+// 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>)
+};