BlockInput (STIL)

java.lang.Object
- uk.ac.starlink.fits.BlockInput

All Implemented Interfaces:

BasicInput

Direct Known Subclasses:

BlockMappedInput, MultiByteBufferInput
```
public abstract class BlockInput
extends java.lang.Object
implements BasicInput
```
Partial random-access BasicInput implementation based on a set of ByteBuffers. These may be obtained eagerly or lazily, as defined by the implementation.

Since:

18 Mar 2021

Constructor Summary

Constructors
Modifier Constructor and Description

protected BlockInput(int nblock)
Constructor.

Constructors
Modifier	Constructor and Description
`protected`	`BlockInput(int nblock)` Constructor.

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`protected abstract java.nio.ByteBuffer`	`acquireBlock(int iblock)` Obtains a buffer corresponding to a named block of the stream.
`void`	`close()` Releases resources belonging to this object.
`int`	`getBlockCount()` Returns the number of mapped blocks used.
`abstract long`	`getBlockOffset(int iblock, int offsetInBlock)` Returns the offset into this stream corresponding to a given block index and offset into that block.
`abstract int[]`	`getBlockPos(long offset)` Returns the block location of a given byte offset.
`long`	`getOffset()` Returns the curent position in this stream (optional operation).
`boolean`	`isRandom()` Indicates whether this object supports random access.
`byte`	`readByte()` Reads a byte from the stream.
`void`	`readBytes(byte[] bbuf)` Reads bytes into an array from the stream.
`double`	`readDouble()` Reads an 8-byte floating point value from the stream.
`float`	`readFloat()` Reads a 4-byte floating point value from the stream.
`int`	`readInt()` Reads a 4-byte integer from the stream.
`long`	`readLong()` Reads an 8-byte integer from the stream.
`short`	`readShort()` Reads a 2-byte integer from the stream.
`void`	`seek(long offset)` Moves the current position of this stream to a given byte offset (optional operation).
`void`	`skip(long nbyte)` Skips a given number of bytes forwards through the stream.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - BlockInput
```
protected BlockInput(int nblock)
```
    Constructor.
    
    Parameters:
    
    nblock - number of buffers
- Method Detail
  - readByte
```
public byte readByte()
              throws java.io.IOException
```
    Description copied from interface: BasicInput
    
    Reads a byte from the stream. The current position is advanced.
    
    Specified by:
    
    readByte in interface BasicInput
    
    Returns:
    
    byte value
    
    Throws:
    
    java.io.IOException
  - readShort
```
public short readShort()
                throws java.io.IOException
```
    Description copied from interface: BasicInput
    
    Reads a 2-byte integer from the stream. The current position is advanced.
    
    Specified by:
    
    readShort in interface BasicInput
    
    Returns:
    
    short value
    
    Throws:
    
    java.io.IOException
  - readInt
```
public int readInt()
            throws java.io.IOException
```
    Description copied from interface: BasicInput
    
    Reads a 4-byte integer from the stream. The current position is advanced.
    
    Specified by:
    
    readInt in interface BasicInput
    
    Returns:
    
    int value
    
    Throws:
    
    java.io.IOException
  - readLong
```
public long readLong()
              throws java.io.IOException
```
    Description copied from interface: BasicInput
    
    Reads an 8-byte integer from the stream. The current position is advanced.
    
    Specified by:
    
    readLong in interface BasicInput
    
    Returns:
    
    long value
    
    Throws:
    
    java.io.IOException
  - readFloat
```
public float readFloat()
                throws java.io.IOException
```
    Description copied from interface: BasicInput
    
    Reads a 4-byte floating point value from the stream. The current position is advanced.
    
    Specified by:
    
    readFloat in interface BasicInput
    
    Returns:
    
    float value
    
    Throws:
    
    java.io.IOException
  - readDouble
```
public double readDouble()
                  throws java.io.IOException
```
    Description copied from interface: BasicInput
    
    Reads an 8-byte floating point value from the stream. The current position is advanced.
    
    Specified by:
    
    readDouble in interface BasicInput
    
    Returns:
    
    double value
    
    Throws:
    
    java.io.IOException
  - readBytes
```
public void readBytes(byte[] bbuf)
               throws java.io.IOException
```
    Description copied from interface: BasicInput
    
    Reads bytes into an array from the stream. The current position is advanced.
    
    Specified by:
    
    readBytes in interface BasicInput
    
    Parameters:
    
    bbuf - array into which the bytes are read; the number of bytes read is the length of the array
    
    Throws:
    
    java.io.IOException
  - close
```
public void close()
```
    Description copied from interface: BasicInput
    
    Releases resources belonging to this object. Attempts to use it after a call to this method result in undefined behaviour.
    
    Specified by:
    
    close in interface BasicInput
  - isRandom
```
public boolean isRandom()
```
    Description copied from interface: BasicInput
    
    Indicates whether this object supports random access. The seek and getOffset methods may only be called if this method returns true.
    
    Specified by:
    
    isRandom in interface BasicInput
    
    Returns:
    
    true iff random access is supported
  - getBlockPos
```
public abstract int[] getBlockPos(long offset)
```
    Returns the block location of a given byte offset.
    This does the opposite of getBlockOffset.
    
    Parameters:
    
    offset - offset into this input stream
    
    Returns:
    
    2-element array giving [blockIndex, offsetInBlock]
  - getBlockOffset
```
public abstract long getBlockOffset(int iblock,
                                    int offsetInBlock)
```
    Returns the offset into this stream corresponding to a given block index and offset into that block.
    This does the opposite of getBlockPos.
    
    Parameters:
    
    iblock - block index
    
    offsetInBlock - offset into that block
    
    Returns:
    
    offset into stream
  - acquireBlock
```
protected abstract java.nio.ByteBuffer acquireBlock(int iblock)
                                             throws java.io.IOException
```
    Obtains a buffer corresponding to a named block of the stream. The buffer's position must be zero. This method is called whenever a buffer is required which is not the same as the most recently used one.
    
    Parameters:
    
    iblock - block index
    
    Returns:
    
    byte buffer for given block, positioned at start
    
    Throws:
    
    java.io.IOException
  - seek
```
public void seek(long offset)
          throws java.io.IOException
```
    Description copied from interface: BasicInput
    
    Moves the current position of this stream to a given byte offset (optional operation).
    
    Specified by:
    
    seek in interface BasicInput
    
    Throws:
    
    java.io.IOException
  - getOffset
```
public long getOffset()
```
    Description copied from interface: BasicInput
    
    Returns the curent position in this stream (optional operation).
    
    Specified by:
    
    getOffset in interface BasicInput
  - skip
```
public void skip(long nbyte)
          throws java.io.IOException
```
    Description copied from interface: BasicInput
    
    Skips a given number of bytes forwards through the stream. An exception is thrown if there are not enough bytes left.
    
    Specified by:
    
    skip in interface BasicInput
    
    Parameters:
    
    nbyte - number of bytes to skip
    
    Throws:
    
    java.io.IOException
  - getBlockCount
```
public int getBlockCount()
```
    Returns the number of mapped blocks used.
    
    Returns:
    
    block count

Class BlockInput

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

BlockInput

Method Detail

readByte

readShort

readInt

readLong

readFloat

readDouble

readBytes

close

isRandom

getBlockPos

getBlockOffset

acquireBlock

seek

getOffset

skip

getBlockCount