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view graal/com.oracle.max.base/src/com/sun/max/lang/WordWidth.java @ 4231:d713eaf4d288
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author | Christian Wimmer <Christian.Wimmer@Oracle.com> |
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date | Thu, 05 Jan 2012 16:09:47 -0800 |
parents | e233f5660da4 |
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/* * Copyright (c) 2007, 2011, 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 com.sun.max.lang; import java.util.*; /** * A word width value describes how many bits there are in a machine word. */ public enum WordWidth { BITS_8(8, byte.class, Byte.MIN_VALUE, Byte.MAX_VALUE, 3), BITS_16(16, short.class, Short.MIN_VALUE, Short.MAX_VALUE, 4), BITS_32(32, int.class, Integer.MIN_VALUE, Integer.MAX_VALUE, 5), BITS_64(64, long.class, Long.MIN_VALUE, Long.MAX_VALUE, 6); public static final List<WordWidth> VALUES = java.util.Arrays.asList(values()); /** * Number of bits in a Word. * This must be a positive power of two. */ public final int numberOfBits; /** * Log2 of the number of bits. */ public final int log2numberOfBits; /** * Log2 of the number of bytes. */ public final int log2numberOfBytes; /** * Number of bytes in a Word. * This must be a positive power of two. */ public final int numberOfBytes; public final Class canonicalPrimitiveType; public final long min; public final long max; private WordWidth(int numberOfBits, Class canonicalPrimitiveType, long min, long max, int log2numberOfBits) { this.numberOfBits = numberOfBits; this.numberOfBytes = numberOfBits / 8; this.canonicalPrimitiveType = canonicalPrimitiveType; this.min = min; this.max = max; this.log2numberOfBits = log2numberOfBits; this.log2numberOfBytes = log2numberOfBits - 3; } public boolean lessThan(WordWidth other) { return numberOfBits < other.numberOfBits; } public boolean lessEqual(WordWidth other) { return numberOfBits <= other.numberOfBits; } public boolean greaterThan(WordWidth other) { return numberOfBits > other.numberOfBits; } public boolean greaterEqual(WordWidth other) { return numberOfBits >= other.numberOfBits; } @Override public String toString() { return Integer.toString(numberOfBits); } public static WordWidth fromInt(int wordWidth) { if (wordWidth <= 8) { return WordWidth.BITS_8; } if (wordWidth <= 16) { return WordWidth.BITS_16; } if (wordWidth <= 32) { return WordWidth.BITS_32; } return WordWidth.BITS_64; } /** * @return which word width is minimally required to represent all the non-one bits in the signed argument, and a sign bit */ public static WordWidth signedEffective(int signed) { return fromInt(Ints.numberOfEffectiveSignedBits(signed)); } /** * @return which word width is minimally required to represent all the non-zero bits in the unsigned argument */ public static WordWidth unsignedEffective(int unsigned) { return fromInt(Ints.numberOfEffectiveUnsignedBits(unsigned)); } /** * @return which word width is minimally required to represent all the non-one bits in the signed argument, and a sign bit */ public static WordWidth signedEffective(long signed) { return fromInt(Longs.numberOfEffectiveSignedBits(signed)); } /** * @return which word width is minimally required to represent all the non-zero bits in the unsigned argument */ public static WordWidth unsignedEffective(long unsigned) { return fromInt(Longs.numberOfEffectiveUnsignedBits(unsigned)); } }