net.openhft.chronicle.algo.bytes.CharSequenceAccess Maven / Gradle / Ivy

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Chronicle-Algorithms
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/*
 *     Copyright (C) 2015  higherfrequencytrading.com
 *
 *     This program is free software: you can redistribute it and/or modify
 *     it under the terms of the GNU Lesser General Public License as published by
 *     the Free Software Foundation, either version 3 of the License.
 *
 *     This program 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 Lesser General Public License for more details.
 *
 *     You should have received a copy of the GNU Lesser General Public License
 *     along with this program.  If not, see .
 */

package net.openhft.chronicle.algo.bytes;

import java.nio.ByteOrder;

import static java.nio.ByteOrder.BIG_ENDIAN;
import static java.nio.ByteOrder.LITTLE_ENDIAN;

abstract class CharSequenceAccess implements ReadAccess {

    private CharSequenceAccess() {
    }

    private static CharSequenceAccess charSequenceAccess(ByteOrder order) {
        return order == LITTLE_ENDIAN ?
                LittleEndianCharSequenceAccess.INSTANCE :
                BigEndianCharSequenceAccess.INSTANCE;
    }

    private static int ix(long offset) {
        return (int) (offset >> 1);
    }

    private static long getLong(CharSequence input, long offset,
                                int char0Off, int char1Off, int char2Off, int char3Off) {
        int base = ix(offset);
        long char0 = input.charAt(base + char0Off);
        long char1 = input.charAt(base + char1Off);
        long char2 = input.charAt(base + char2Off);
        long char3 = input.charAt(base + char3Off);
        return char0 | (char1 << 16) | (char2 << 32) | (char3 << 48);
    }

    private static long getUnsignedInt(CharSequence input, long offset,
                                       int char0Off, int char1Off) {
        int base = ix(offset);
        long char0 = input.charAt(base + char0Off);
        long char1 = input.charAt(base + char1Off);
        return char0 | (char1 << 16);
    }

    private static int getUnsignedByte(CharSequence input, long offset, int shift) {
        return (input.charAt(ix(offset)) >> shift) & 0xFF;
    }

    @Override
    public int readInt(CharSequence input, long offset) {
        return (int) readUnsignedInt(input, offset);
    }

    @Override
    public int readUnsignedShort(CharSequence input, long offset) {
        return input.charAt(ix(offset));
    }

    @Override
    public short readShort(CharSequence input, long offset) {
        return (short) input.charAt(ix(offset));
    }

    @Override
    public byte readByte(CharSequence input, long offset) {
        return (byte) readUnsignedByte(input, offset);
    }

    static class LittleEndianCharSequenceAccess extends CharSequenceAccess {
        static final CharSequenceAccess INSTANCE = new LittleEndianCharSequenceAccess();

        private LittleEndianCharSequenceAccess() {
        }

        @Override
        public long readLong(CharSequence input, long offset) {
            return getLong(input, offset, 0, 1, 2, 3);
        }

        @Override
        public long readUnsignedInt(CharSequence input, long offset) {
            return getUnsignedInt(input, offset, 0, 1);
        }

        @Override
        public int readUnsignedByte(CharSequence input, long offset) {
            return getUnsignedByte(input, offset, ((int) offset & 1) << 3);
        }

        @Override
        public ByteOrder byteOrder(CharSequence input) {
            return LITTLE_ENDIAN;
        }
    }

    static class BigEndianCharSequenceAccess extends CharSequenceAccess {
        static final CharSequenceAccess INSTANCE = new BigEndianCharSequenceAccess();

        private BigEndianCharSequenceAccess() {
        }

        @Override
        public long readLong(CharSequence input, long offset) {
            return getLong(input, offset, 3, 2, 1, 0);
        }

        @Override
        public long readUnsignedInt(CharSequence input, long offset) {
            return getUnsignedInt(input, offset, 1, 0);
        }

        @Override
        public int readUnsignedByte(CharSequence input, long offset) {
            return getUnsignedByte(input, offset, (((int) offset & 1) ^ 1) << 3);
        }

        @Override
        public ByteOrder byteOrder(CharSequence input) {
            return BIG_ENDIAN;
        }
    }
}