/*
* Copyright 2010, 2011, 2012 mapsforge.org
*
* This file is part of the OpenScienceMap project (http://www.opensciencemap.org).
*
* 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, or (at your option) any later version.
*
* 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 <http://www.gnu.org/licenses/>.
*/
package org.oscim.tiling.source.mapfile;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.io.UnsupportedEncodingException;
import java.util.logging.Logger;
import org.oscim.core.Tag;
import org.oscim.core.TagSet;
/**
* Reads from a {@link RandomAccessFile} into a buffer and decodes the data.
*/
public class ReadBuffer {
private static final String CHARSET_UTF8 = "UTF-8";
private static final Logger LOG = Logger.getLogger(ReadBuffer.class.getName());
/**
* Maximum buffer size which is supported by this implementation.
*/
static final int MAXIMUM_BUFFER_SIZE = 8000000;
private byte[] mBufferData;
private int mBufferPosition;
private final RandomAccessFile mInputFile;
ReadBuffer(RandomAccessFile inputFile) {
mInputFile = inputFile;
}
/**
* Returns one signed byte from the read buffer.
*
* @return the byte value.
*/
public byte readByte() {
return mBufferData[mBufferPosition++];
}
/**
* Reads the given amount of bytes from the file into the read buffer and
* resets the internal buffer position. If
* the capacity of the read buffer is too small, a larger one is created
* automatically.
*
* @param length
* the amount of bytes to read from the file.
* @return true if the whole data was read successfully, false otherwise.
* @throws IOException
* if an error occurs while reading the file.
*/
public boolean readFromFile(int length) throws IOException {
// ensure that the read buffer is large enough
if (mBufferData == null || mBufferData.length < length) {
// ensure that the read buffer is not too large
if (length > MAXIMUM_BUFFER_SIZE) {
LOG.warning("invalid read length: " + length);
return false;
}
mBufferData = new byte[length];
}
mBufferPosition = 0;
// reset the buffer position and read the data into the buffer
// bufferPosition = 0;
return mInputFile.read(mBufferData, 0, length) == length;
}
/**
* Converts four bytes from the read buffer to a signed int.
* <p>
* The byte order is big-endian.
*
* @return the int value.
*/
public int readInt() {
int pos = mBufferPosition;
byte[] data = mBufferData;
mBufferPosition += 4;
return data[pos] << 24
| (data[pos + 1] & 0xff) << 16
| (data[pos + 2] & 0xff) << 8
| (data[pos + 3] & 0xff);
}
/**
* Converts eight bytes from the read buffer to a signed long.
* <p>
* The byte order is big-endian.
*
* @return the long value.
*/
public long readLong() {
int pos = mBufferPosition;
byte[] data = mBufferData;
mBufferPosition += 8;
return (data[pos] & 0xffL) << 56
| (data[pos + 1] & 0xffL) << 48
| (data[pos + 2] & 0xffL) << 40
| (data[pos + 3] & 0xffL) << 32
| (data[pos + 4] & 0xffL) << 24
| (data[pos + 5] & 0xffL) << 16
| (data[pos + 6] & 0xffL) << 8
| (data[pos + 7] & 0xffL);
}
/**
* Converts two bytes from the read buffer to a signed int.
* <p>
* The byte order is big-endian.
*
* @return the int value.
*/
public int readShort() {
mBufferPosition += 2;
return mBufferData[mBufferPosition - 2] << 8 | (mBufferData[mBufferPosition - 1] & 0xff);
}
/**
* Converts a variable amount of bytes from the read buffer to a signed int.
* <p>
* The first bit is for continuation info, the other six (last byte) or
* seven (all other bytes) bits are for data. The second bit in the last
* byte indicates the sign of the number.
*
* @return the value.
*/
public int readSignedInt() {
int pos = mBufferPosition;
byte[] data = mBufferData;
int flag;
if ((data[pos] & 0x80) == 0) {
mBufferPosition += 1;
flag = ((data[pos] & 0x40) >> 6);
return ((data[pos] & 0x3f) ^ -flag) + flag;
}
if ((data[pos + 1] & 0x80) == 0) {
mBufferPosition += 2;
flag = ((data[pos + 1] & 0x40) >> 6);
return (((data[pos] & 0x7f)
| (data[pos + 1] & 0x3f) << 7) ^ -flag) + flag;
}
if ((data[pos + 2] & 0x80) == 0) {
mBufferPosition += 3;
flag = ((data[pos + 2] & 0x40) >> 6);
return (((data[pos] & 0x7f)
| (data[pos + 1] & 0x7f) << 7
| (data[pos + 2] & 0x3f) << 14) ^ -flag) + flag;
}
if ((data[pos + 3] & 0x80) == 0) {
mBufferPosition += 4;
flag = ((data[pos + 3] & 0x40) >> 6);
return (((data[pos] & 0x7f)
| ((data[pos + 1] & 0x7f) << 7)
| ((data[pos + 2] & 0x7f) << 14)
| ((data[pos + 3] & 0x3f) << 21)) ^ -flag) + flag;
}
mBufferPosition += 5;
flag = ((data[pos + 4] & 0x40) >> 6);
return ((((data[pos] & 0x7f)
| (data[pos + 1] & 0x7f) << 7
| (data[pos + 2] & 0x7f) << 14
| (data[pos + 3] & 0x7f) << 21
| (data[pos + 4] & 0x3f) << 28)) ^ -flag) + flag;
}
/**
* Converts a variable amount of bytes from the read buffer to a signed int
* array.
* <p>
* The first bit is for continuation info, the other six (last byte) or
* seven (all other bytes) bits are for data. The second bit in the last
* byte indicates the sign of the number.
*
* @param values
* result values
* @param length
* number of values to read
*/
public void readSignedInt(int[] values, int length) {
int pos = mBufferPosition;
byte[] data = mBufferData;
int flag;
for (int i = 0; i < length; i++) {
if ((data[pos] & 0x80) == 0) {
flag = ((data[pos] & 0x40) >> 6);
values[i] = ((data[pos] & 0x3f) ^ -flag) + flag;
pos += 1;
} else if ((data[pos + 1] & 0x80) == 0) {
flag = ((data[pos + 1] & 0x40) >> 6);
values[i] = (((data[pos] & 0x7f)
| ((data[pos + 1] & 0x3f) << 7)) ^ -flag) + flag;
pos += 2;
} else if ((data[pos + 2] & 0x80) == 0) {
flag = ((data[pos + 2] & 0x40) >> 6);
values[i] = (((data[pos] & 0x7f)
| ((data[pos + 1] & 0x7f) << 7)
| ((data[pos + 2] & 0x3f) << 14)) ^ -flag) + flag;
pos += 3;
} else if ((data[pos + 3] & 0x80) == 0) {
flag = ((data[pos + 3] & 0x40) >> 6);
values[i] = (((data[pos] & 0x7f)
| ((data[pos + 1] & 0x7f) << 7)
| ((data[pos + 2] & 0x7f) << 14)
| ((data[pos + 3] & 0x3f) << 21)) ^ -flag) + flag;
pos += 4;
} else {
flag = ((data[pos + 4] & 0x40) >> 6);
values[i] = ((((data[pos] & 0x7f)
| ((data[pos + 1] & 0x7f) << 7)
| ((data[pos + 2] & 0x7f) << 14)
| ((data[pos + 3] & 0x7f) << 21)
| ((data[pos + 4] & 0x3f) << 28))) ^ -flag) + flag;
pos += 5;
}
}
mBufferPosition = pos;
}
/**
* Converts a variable amount of bytes from the read buffer to an unsigned
* int.
* <p>
* The first bit is for continuation info, the other seven bits are for
* data.
*
* @return the int value.
*/
public int readUnsignedInt() {
int pos = mBufferPosition;
byte[] data = mBufferData;
if ((data[pos] & 0x80) == 0) {
mBufferPosition += 1;
return (data[pos] & 0x7f);
}
if ((data[pos + 1] & 0x80) == 0) {
mBufferPosition += 2;
return (data[pos] & 0x7f)
| (data[pos + 1] & 0x7f) << 7;
}
if ((data[pos + 2] & 0x80) == 0) {
mBufferPosition += 3;
return (data[pos] & 0x7f)
| ((data[pos + 1] & 0x7f) << 7)
| ((data[pos + 2] & 0x7f) << 14);
}
if ((data[pos + 3] & 0x80) == 0) {
mBufferPosition += 4;
return (data[pos] & 0x7f)
| ((data[pos + 1] & 0x7f) << 7)
| ((data[pos + 2] & 0x7f) << 14)
| ((data[pos + 3] & 0x7f) << 21);
}
mBufferPosition += 5;
return (data[pos] & 0x7f)
| ((data[pos + 1] & 0x7f) << 7)
| ((data[pos + 2] & 0x7f) << 14)
| ((data[pos + 3] & 0x7f) << 21)
| ((data[pos + 4] & 0x7f) << 28);
}
/**
* Decodes a variable amount of bytes from the read buffer to a string.
*
* @return the UTF-8 decoded string (may be null).
*/
public String readUTF8EncodedString() {
return readUTF8EncodedString(readUnsignedInt());
}
/**
* @return ...
*/
public int getPositionAndSkip() {
int pos = mBufferPosition;
int length = readUnsignedInt();
skipBytes(length);
return pos;
}
/**
* Decodes the given amount of bytes from the read buffer to a string.
*
* @param stringLength
* the length of the string in bytes.
* @return the UTF-8 decoded string (may be null).
*/
public String readUTF8EncodedString(int stringLength) {
if (stringLength > 0 && mBufferPosition + stringLength <= mBufferData.length) {
mBufferPosition += stringLength;
try {
return new String(mBufferData, mBufferPosition - stringLength, stringLength,
CHARSET_UTF8);
} catch (UnsupportedEncodingException e) {
throw new IllegalStateException(e);
}
}
LOG.warning("invalid string length: " + stringLength);
return null;
}
/**
* Decodes a variable amount of bytes from the read buffer to a string.
*
* @param position
* buffer offset position of string
* @return the UTF-8 decoded string (may be null).
*/
public String readUTF8EncodedStringAt(int position) {
int curPosition = mBufferPosition;
mBufferPosition = position;
String result = readUTF8EncodedString(readUnsignedInt());
mBufferPosition = curPosition;
return result;
}
/**
* @return the current buffer position.
*/
int getBufferPosition() {
return mBufferPosition;
}
/**
* @return the current size of the read buffer.
*/
int getBufferSize() {
return mBufferData.length;
}
/**
* Sets the buffer position to the given offset.
*
* @param bufferPosition
* the buffer position.
*/
void setBufferPosition(int bufferPosition) {
mBufferPosition = bufferPosition;
}
/**
* Skips the given number of bytes in the read buffer.
*
* @param bytes
* the number of bytes to skip.
*/
void skipBytes(int bytes) {
mBufferPosition += bytes;
}
boolean readTags(TagSet tags, Tag[] wayTags, byte numberOfTags) {
tags.clear();
int maxTag = wayTags.length;
for (byte i = 0; i < numberOfTags; i++) {
int tagId = readUnsignedInt();
if (tagId < 0 || tagId >= maxTag) {
LOG.warning("invalid tag ID: " + tagId);
return true;
}
tags.add(wayTags[tagId]);
}
return true;
}
private static final int WAY_NUMBER_OF_TAGS_BITMASK = 0x0f;
int lastTagPosition;
int skipWays(int queryTileBitmask, int elements) {
int pos = mBufferPosition;
byte[] data = mBufferData;
int cnt = elements;
int skip;
lastTagPosition = -1;
while (cnt > 0) {
// read way size (unsigned int)
if ((data[pos] & 0x80) == 0) {
skip = (data[pos] & 0x7f);
pos += 1;
} else if ((data[pos + 1] & 0x80) == 0) {
skip = (data[pos] & 0x7f)
| (data[pos + 1] & 0x7f) << 7;
pos += 2;
} else if ((data[pos + 2] & 0x80) == 0) {
skip = (data[pos] & 0x7f)
| ((data[pos + 1] & 0x7f) << 7)
| ((data[pos + 2] & 0x7f) << 14);
pos += 3;
} else if ((data[pos + 3] & 0x80) == 0) {
skip = (data[pos] & 0x7f)
| ((data[pos + 1] & 0x7f) << 7)
| ((data[pos + 2] & 0x7f) << 14)
| ((data[pos + 3] & 0x7f) << 21);
pos += 4;
} else {
skip = (data[pos] & 0x7f)
| ((data[pos + 1] & 0x7f) << 7)
| ((data[pos + 2] & 0x7f) << 14)
| ((data[pos + 3] & 0x7f) << 21)
| ((data[pos + 4] & 0x7f) << 28);
pos += 5;
}
// invalid way size
if (skip < 0) {
mBufferPosition = pos;
return -1;
}
// check if way matches queryTileBitmask
if ((((data[pos] << 8) | (data[pos + 1] & 0xff)) & queryTileBitmask) == 0) {
// remember last tags position
if ((data[pos + 2] & WAY_NUMBER_OF_TAGS_BITMASK) != 0)
lastTagPosition = pos + 2;
pos += skip;
cnt--;
} else {
pos += 2;
break;
}
}
mBufferPosition = pos;
return cnt;
}
}