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package ij.io;
import ij.IJ;
import java.io.*;
import java.util.Vector;
/** This is a class that uses a memory cache to allow seeking within
an InputStream. Based on the JAI MemoryCacheSeekableStream class.
Can also be constructed from a RandomAccessFile, which uses less
memory since the memory cache is not required.
*/
public final class RandomAccessStream extends InputStream {
private static final int BLOCK_SIZE = 512;
private static final int BLOCK_MASK = 511;
private static final int BLOCK_SHIFT = 9;
private InputStream src;
private RandomAccessFile ras;
private long pointer;
private Vector data;
private int length;
private boolean foundEOS;
/** Constructs a RandomAccessStream from an InputStream. Seeking
backwards is supported using a memory cache. */
public RandomAccessStream(InputStream inputstream) {
pointer = 0L;
data = new Vector();
length = 0;
foundEOS = false;
src = inputstream;
}
/** Constructs a RandomAccessStream from an RandomAccessFile. */
public RandomAccessStream(RandomAccessFile ras) {
this.ras = ras;
}
public int getFilePointer() throws IOException {
if (ras!=null)
return (int)ras.getFilePointer();
else
return (int)pointer;
}
public long getLongFilePointer() throws IOException {
if (ras!=null)
return ras.getFilePointer();
else
return pointer;
}
public int read() throws IOException {
if (ras!=null)
return ras.read();
long l = pointer + 1L;
long l1 = readUntil(l);
if(l1 >= l) {
byte abyte0[] = (byte[])data.elementAt((int)(pointer>>BLOCK_SHIFT));
return abyte0[(int)(pointer++ & BLOCK_MASK)] & 0xff;
} else
return -1;
}
public int read(byte[] bytes, int off, int len) throws IOException {
if(bytes == null)
throw new NullPointerException();
if (ras!=null)
return ras.read(bytes, off, len);
if(off<0 || len<0 || off+len>bytes.length)
throw new IndexOutOfBoundsException();
if(len == 0)
return 0;
long l = readUntil(pointer+len);
if (l<=pointer)
return -1;
else {
byte abyte1[] = (byte[])data.elementAt((int)(pointer >> BLOCK_SHIFT));
int k = Math.min(len, BLOCK_SIZE - (int)(pointer & BLOCK_MASK));
System.arraycopy(abyte1, (int)(pointer & BLOCK_MASK), bytes, off, k);
pointer += k;
return k;
}
}
public final void readFully(byte[] bytes) throws IOException {
readFully(bytes, bytes.length);
}
public final void readFully(byte[] bytes, int len) throws IOException {
int read = 0;
do {
int l = read(bytes, read, len - read);
if(l < 0) break;
read += l;
} while (read<len);
}
private long readUntil(long l) throws IOException {
if(l<length)
return l;
if(foundEOS)
return length;
int i = (int)(l >> BLOCK_SHIFT);
int j = length >> BLOCK_SHIFT;
for(int k = j; k <= i; k++) {
byte abyte0[] = new byte[BLOCK_SIZE];
data.addElement(abyte0);
int i1 = BLOCK_SIZE;
int j1 = 0;
while(i1 > 0) {
int k1 = src.read(abyte0, j1, i1);
if(k1 == -1) {
foundEOS = true;
return length;
}
j1 += k1;
i1 -= k1;
length += k1;
}
}
return length;
}
public void seek(long loc) throws IOException {
//IJ.log("seek (long): "+loc+" "+(ras!=null));
if (ras!=null)
{ras.seek(loc); return;}
if (loc<0L)
pointer = 0L;
else
pointer = loc;
}
public void seek(int loc) throws IOException {
long lloc = ((long)loc)&0xffffffffL;
//IJ.log("seek (int): "+lloc+" "+(ras!=null));
if (ras!=null) {
ras.seek(lloc);
return;
}
if (lloc<0L)
pointer = 0L;
else
pointer = lloc;
}
public final int readInt() throws IOException {
int i = read();
int j = read();
int k = read();
int l = read();
if((i | j | k | l) < 0)
throw new EOFException();
else
return (i << 24) + (j << 16) + (k << 8) + l;
}
public final long readLong() throws IOException {
return ((long)readInt() << 32) + ((long)readInt() & 0xffffffffL);
}
public final double readDouble() throws IOException {
return Double.longBitsToDouble(readLong());
}
public final short readShort() throws IOException {
int i = read();
int j = read();
if((i | j) < 0)
throw new EOFException();
else
return (short)((i << 8) + j);
}
public final float readFloat() throws IOException {
return Float.intBitsToFloat(readInt());
}
public void close() throws IOException {
//ij.IJ.log("close: "+(data!=null?""+data.size():""));
if (ras!=null)
ras.close();
else {
data.removeAllElements();
src.close();
}
}
}
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