/*
* Copyright (c) 2000, 2005, 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
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*/
package sun.jvm.hotspot.code;
import sun.jvm.hotspot.debugger.*;
/** NOTE that this class takes the address of a buffer. This means
that it can read previously-generated debug information directly
from the target VM. However, it also means that you can't create a
"wrapper" object for a CompressedStream down in the VM. It looks
like these are only kept persistently in OopMaps, and the code has
been special-cased in OopMap.java to handle this. */
public class CompressedStream {
protected Address buffer;
protected int position;
/** Equivalent to CompressedStream(buffer, 0) */
public CompressedStream(Address buffer) {
this(buffer, 0);
}
public CompressedStream(Address buffer, int position) {
this.buffer = buffer;
this.position = position;
}
public Address getBuffer() {
return buffer;
}
public static final int LogBitsPerByte = 3;
public static final int BitsPerByte = 1 << 3;
// Constants for UNSIGNED5 coding of Pack200
public static final int lg_H = 6;
public static final int H = 1<<lg_H; // number of high codes (64)
public static final int L = (1<<BitsPerByte) - H; // number of low codes (192)
public static final int MAX_i = 4; // bytes are numbered in (0..4)
// Positioning
public int getPosition() {
return position;
}
public void setPosition(int position) {
this.position = position;
}
// 32-bit one-to-one sign encoding taken from Pack200
// converts leading sign bits into leading zeros with trailing sign bit
public int encodeSign(int value) {
return (value << 1) ^ (value >> 31);
}
public int decodeSign(int value) {
return (value >>> 1) ^ -(value & 1);
}
// 32-bit self-inverse encoding of float bits
// converts trailing zeros (common in floats) to leading zeros
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