Mercurial > hg > truffle
view agent/src/share/classes/sun/jvm/hotspot/code/CompressedReadStream.java @ 7353:b5280041f59e
Experiment with soft alignment for branch targets.
author | Thomas Wuerthinger <thomas.wuerthinger@oracle.com> |
---|---|
date | Sun, 13 Jan 2013 19:32:16 +0100 |
parents | c18cbe5936b8 |
children |
line wrap: on
line source
/* * 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.*; public class CompressedReadStream extends CompressedStream { /** Equivalent to CompressedReadStream(buffer, 0) */ public CompressedReadStream(Address buffer) { this(buffer, 0); } public CompressedReadStream(Address buffer, int position) { super(buffer, position); } public boolean readBoolean() { return (read() != 0); } public byte readByte() { return (byte) read(); } public char readChar() { return (char) readInt(); } public short readShort() { return (short) readSignedInt(); } public int readSignedInt() { return decodeSign(readInt()); } public int readInt() { int b0 = read(); if (b0 < L) { return b0; } else { return readIntMb(b0); } } public float readFloat() { return Float.intBitsToFloat(reverseInt(readInt())); } public double readDouble() { int rh = readInt(); int rl = readInt(); int h = reverseInt(rh); int l = reverseInt(rl); return Double.longBitsToDouble((h << 32) | ((long)l & 0x00000000FFFFFFFFL)); } public long readLong() { long low = readSignedInt() & 0x00000000FFFFFFFFL; long high = readSignedInt(); return (high << 32) | low; } //-------------------------------------------------------------------------------- // Internals only below this point // // This encoding, called UNSIGNED5, is taken from J2SE Pack200. // It assumes that most values have lots of leading zeroes. // Very small values, in the range [0..191], code in one byte. // Any 32-bit value (including negatives) can be coded, in // up to five bytes. The grammar is: // low_byte = [0..191] // high_byte = [192..255] // any_byte = low_byte | high_byte // coding = low_byte // | high_byte low_byte // | high_byte high_byte low_byte // | high_byte high_byte high_byte low_byte // | high_byte high_byte high_byte high_byte any_byte // Each high_byte contributes six bits of payload. // The encoding is one-to-one (except for integer overflow) // and easy to parse and unparse. private int readIntMb(int b0) { int pos = position - 1; int sum = b0; // must collect more bytes: b[1]...b[4] int lg_H_i = lg_H; for (int i = 0; ;) { int b_i = read(pos + (++i)); sum += b_i << lg_H_i; // sum += b[i]*(64**i) if (b_i < L || i == MAX_i) { setPosition(pos+i+1); return sum; } lg_H_i += lg_H; } } private short read(int index) { return (short) buffer.getCIntegerAt(index, 1, true); } /** Reads an unsigned byte, but returns it as a short */ private short read() { short retval = (short) buffer.getCIntegerAt(position, 1, true); ++position; return retval; } }