Subversion Repositories mkgmap

/*
 * Copyright (C) 2006 Steve Ratcliffe
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 as
 *  published by the Free Software Foundation.
 *
 *  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 General Public License for more details.
 *
 *
 * Author: Steve Ratcliffe
 * Create date: 07-Dec-2006
 */
package uk.me.parabola.imgfmt.app;

import java.io.Closeable;
import java.util.concurrent.atomic.AtomicInteger;

import uk.me.parabola.imgfmt.ReadFailedException;

/**
 * For reading subfiles from the img.  The focus of mkgmap is on writing,
 * but some limited reading is needed for several operations.
 *
 * @author Steve Ratcliffe
 */
public interface ImgFileReader extends Closeable {

        /**
         * Get the position.  Needed because may not be reflected in the underlying
         * file if being buffered.
         *
         * @return The logical position within the file.
         */
        public long position();

        /**
         * Set the position of the file.
         * @param pos The new position in the file.
         */
        public void position(long pos);

        /**
         * Read in a single byte.
         * Should not be used for reading numbers, use get1s/u instead.
         * @return The byte that was read.
         */
        public byte get() throws ReadFailedException;

        /**
         * Read in a single byte.
         * @return int sign-extended value that was read.
         */
        public int get1s() throws ReadFailedException;

        /**
         * Read in two bytes in little endian byte order.
         * @return int sign-extended value that was read.
         */
        public int get2s() throws ReadFailedException;

        /**
         * Read in three bytes in little endian byte order.
         * @return int sign-extended value that was read.
         */
        public int get3s() throws ReadFailedException;

        public int get1u() throws ReadFailedException;

        public int get2u() throws ReadFailedException;

        public int get3u() throws ReadFailedException;

        /**
         * Read a variable sized integer.  The size is given.
         * @param nBytes The size of the integer to read. Must be 1 to 4.
         * @return The integer which will not be sign extended.
         */
        public int getNu(int nBytes) throws ReadFailedException;

        /**
         * Read in a 4 byte signed value.
         * @return A 4 byte integer.
         */
        public int get4() throws ReadFailedException;

        /**
         * Read in an arbitrary length sequence of bytes.
         *
         * @param len The number of bytes to read.
         */
        public byte[] get(int len) throws ReadFailedException;

        /**
         * Read a zero terminated string from the file.
         * @return A string
         * @throws ReadFailedException For failures.
         */
        public byte[] getZString() throws ReadFailedException;

        /**
         * Read in a string of digits in the compressed base 11 format that is used
         * for phone numbers in the POI section.
         * @param delimiter This will replace all digit 11 characters.  Usually a
         * '-' to separate numbers in a telephone.  No doubt there is a different
         * standard in each country.
         * @return A phone number possibly containing the delimiter character.
         */
        public String getBase11str(byte firstChar, char delimiter);

        /**
         * Get the offset in the GMP file.
         * @return the offset, 0 if not a GMP file  
         */
        default int getGMPOffset() {
                return 0;
        }

        /**
         * Read varying length integer where first byte also gives number of following bytes.
         * See also imgfmt/app/mdr/MdrUtils.writeVarLength() and ./MdrDisplay.printSect17()
         *
         * @return the length
         */
        default int readVarLength(AtomicInteger varLength) {
                int peek = get1u();
                if ((peek & 0x1) == 0x1) {
                        varLength.set(1);
                        return peek >> 1;
                } else if ((peek & 0x3) == 0x2) {
                        varLength.set(2);
                        return peek >> 2 | get1u() << 6;
                } else if ((peek & 0x7) == 0x4) {
                        varLength.set(3);
                        return peek >> 3 | get2u() << 5;
                }  else { // bottom 3 bits clear so assume:
                        varLength.set(4);
                        return peek >> 4 | get3u() << 4; // mkgmap writeVarLength does this
                }
        }
}