Mercurial > hg > truffle
view agent/src/share/classes/sun/jvm/hotspot/code/CompressedStream.java @ 12704:0e998f0daddf
Code cache: make sure we collect statistics even if the compiler is not recognized
author | Gilles Duboscq <duboscq@ssw.jku.at> |
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date | Thu, 07 Nov 2013 11:17:23 +0100 |
parents | c18cbe5936b8 |
children |
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/* * 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 * or visit www.oracle.com if you need additional information or have any * questions. * */ 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 public int reverseInt(int i) { // Hacker's Delight, Figure 7-1 i = (i & 0x55555555) << 1 | (i >>> 1) & 0x55555555; i = (i & 0x33333333) << 3 | (i >>> 2) & 0x33333333; i = (i & 0x0f0f0f0f) << 4 | (i >>> 4) & 0x0f0f0f0f; i = (i << 24) | ((i & 0xff00) << 8) | ((i >>> 8) & 0xff00) | (i >>> 24); return i; } }