src/java.base/share/classes/jdk/internal/util/DecimalDigits.java - master - githubmirror/jdk22

src/java.base/share/classes/jdk/internal/util/DecimalDigits.java
162 строки5 KB
Claes Redestad
8316582: Minor startup regression in 22-b15 due JDK-8310929
21 сен 2023, 12:36
21 сен 2023, 12:36913e43f
/*
 * Copyright (c) 2023, 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * 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 jdk.internal.util;

import java.lang.invoke.MethodHandle;

import jdk.internal.vm.annotation.Stable;

/**
 * Digits class for decimal digits.
 *
 * @since 21
 */
public final class DecimalDigits implements Digits {

    /**
     * Each element of the array represents the packaging of two ascii characters based on little endian:<p>
     * <pre>
     *      00 -> '0' | ('0' << 8) -> 0x3030
     *      01 -> '1' | ('0' << 8) -> 0x3130
     *      02 -> '2' | ('0' << 8) -> 0x3230
     *
     *     ...
     *
     *      10 -> '0' | ('1' << 8) -> 0x3031
     *      11 -> '1' | ('1' << 8) -> 0x3131
     *      12 -> '2' | ('1' << 8) -> 0x3231
     *
     *     ...
     *
     *      97 -> '7' | ('9' << 8) -> 0x3739
     *      98 -> '8' | ('9' << 8) -> 0x3839
     *      99 -> '9' | ('9' << 8) -> 0x3939
     * </pre>
     */
    @Stable
    private static final short[] DIGITS;

    static {
        short[] digits = new short[10 * 10];

        for (int i = 0; i < 10; i++) {
            short hi = (short) (i + '0');
            for (int j = 0; j < 10; j++) {
                short lo = (short) ((j + '0') << 8);
                digits[i * 10 + j] = (short) (hi | lo);
            }
        }
        DIGITS = digits;
    }

    /**
     * Singleton instance of DecimalDigits.
     */
    public static final Digits INSTANCE = new DecimalDigits();

    /**
     * Constructor.
     */
    private DecimalDigits() {
    }

    @Override
    public int digits(long value, byte[] buffer, int index,
                      MethodHandle putCharMH) throws Throwable {
        boolean negative = value < 0;
        if (!negative) {
            value = -value;
        }

        long q;
        int r;
        while (value <= Integer.MIN_VALUE) {
            q = value / 100;
            r = (int)((q * 100) - value);
            value = q;
            int digits = DIGITS[r];

            putCharMH.invokeExact(buffer, --index, digits >> 8);
            putCharMH.invokeExact(buffer, --index, digits & 0xFF);
        }

        int iq, ivalue = (int)value;
        while (ivalue <= -100) {
            iq = ivalue / 100;
            r = (iq * 100) - ivalue;
            ivalue = iq;
            int digits = DIGITS[r];
            putCharMH.invokeExact(buffer, --index, digits >> 8);
            putCharMH.invokeExact(buffer, --index, digits & 0xFF);
        }

        if (ivalue < 0) {
            ivalue = -ivalue;
        }

        int digits = DIGITS[ivalue];
        putCharMH.invokeExact(buffer, --index, digits >> 8);

        if (9 < ivalue) {
            putCharMH.invokeExact(buffer, --index, digits & 0xFF);
        }

        if (negative) {
            putCharMH.invokeExact(buffer, --index, (int)'-');
        }

        return index;
    }

    @Override
    public int size(long value) {
        boolean negative = value < 0;
        int sign = negative ? 1 : 0;

        if (!negative) {
            value = -value;
        }

        long precision = -10;
        for (int i = 1; i < 19; i++) {
            if (value > precision)
                return i + sign;

            precision = 10 * precision;
        }

        return 19 + sign;
    }

    /**
     * For values from 0 to 99 return a short encoding a pair of ASCII-encoded digit characters in little-endian
     * @param i value to convert
     * @return a short encoding a pair of ASCII-encoded digit characters
     */
    public static short digitPair(int i) {
        return DIGITS[i];
    }
}