Mercurial > hg > truffle
diff agent/src/share/classes/sun/jvm/hotspot/code/CompressedStream.java @ 0:a61af66fc99e jdk7-b24
Initial load
author | duke |
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date | Sat, 01 Dec 2007 00:00:00 +0000 |
parents | |
children | c18cbe5936b8 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/agent/src/share/classes/sun/jvm/hotspot/code/CompressedStream.java Sat Dec 01 00:00:00 2007 +0000 @@ -0,0 +1,91 @@ +/* + * Copyright 2000-2005 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. + * + */ + +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; + } +}