NumberFormat.java

/**
 * Copyright 2016 Yahoo Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.yahoo.pulsar.utils;

import io.netty.buffer.ByteBuf;

public class NumberFormat {

    static void format(ByteBuf out, long num) {
        if (num == 0) {
            out.writeByte('0');
            return;
        }

        // Long.MIN_VALUE needs special handling since abs(Long.MIN_VALUE) = abs(Long.MAX_VALUE) + 1
        boolean encounteredMinValue = (num == Long.MIN_VALUE);
        if (num < 0) {
            out.writeByte('-');
            num += encounteredMinValue ? 1 : 0;
            num *= -1;
        }

        // Putting the number in bytebuf in reverse order
        int start = out.writerIndex();
        formatHelper(out, num);
        int end = out.writerIndex();

        if (encounteredMinValue) {
            out.setByte(start, out.getByte(start) + 1);
        }

        // Reversing the digits
        end--;
        for (int i = 0; i <= (end - start) / 2; i++) {
            byte tmp = out.getByte(end - i);
            out.setByte(end - i, out.getByte(start + i));
            out.setByte(start + i, tmp);
        }
    }

    static void formatHelper(ByteBuf out, long num) {
        while (num != 0) {
            out.writeByte((int) ('0' + num % 10));
            num /= 10;
        }
    }
}